Cristal Structure Dimer Rh Cl COD

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  • 8/12/2019 Cristal Structure Dimer Rh Cl COD

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    Acta Cryst . (1962) . 15, 923r y s ta l S t r u c t u r e o f t h e D i m e r o f R h o d i u m h l o r i d e 1 5-cyclooctadien e

    BY JA MES A. IBER S AND I~OBERT G. SNYD ERS h e l l D e v e lo p m e n t C o m p a n y , E m e r y v il le , C a l i fo r n i a , U . S . A .

    Received 11 December 1961)R h o d i u m ( I ) c h l o r i d e 1,5-cyclooctadiene, R hC l ( C sH 12) , c r ys t a l l i ze s i n t he space g r oup C~h-P21/n,w i t h f o u r d i m e r i c m o l e c u l e s in t h e u n i t c e l l o f d i m e n s i o n s

    a = 9 . 0 5 , b=25.4 , c = 7 . 2 8 / ~ ; f l = 9 1 . 7 .T h e c r y s t a l s t r u c t u re h a s b e e n d e t e r m i n e d f r o m t h r e e - d im e n s i o n a l P a t t e r s o n a n d d i ff e r en c e F o u r i e rf u n c t io n s a n d h a s b e e n r e f in e d b y l e a s t- s q u a re s t e c h n i q u e s . T h e c o n f o r m a t i o n o f t h e d i m e r i cm o l e c u le s su g g e s te d b y C h a r t & V e n a n z i is c o n fi r m e d . E a c h r h o d i u m a t o m i s b o n d e d t o t h e d o u b l e -b o n d c e n t e r s o f a cyclooctadiene r i n g ( b o a t c o n f i g u r a t io n ) a n d t o t w o c h l o r i n e a t o m s i n s u c h a w a ya s to g i v e i t a s q u a r e - p l a n a r c o n f i g u r a t i o n . T h e b o n d i n g i n th i s c o m p o u n d i s t h u s v e r y d i f f e r e n tf r o m t h a t i n ( R hC I( CO )2 ) 2, i n w h i c h t h e r h o d i u m a t o m s a r e d e s c r i b e d b y D a h l , M a r t e l l & W a m p l e ra s o c t a h e d r a l l y c o o r d i n a t e d . T h e g e o m e t r y o f t h e cyclooctadiene r i n g s i s n o t t o o w e l l d e f i n e d i n t h ep r e s e n t s t u d y . N e v e r t h e l e s s t h e l e n g t h e n i n g o f t h e d o u b l e b o n d s f r o m a ' n o r m a l ' v a l u e o f 1 .3 4 At o 1 . 4 4 _ 0 . 07 / ~ i s s i g n i f i c a n t , a n d i s c o n s i s t e n t w i t h e v i d e n c e b a s e d o n t h e i n f r a r e d s p e c t r a o f t h ec o m p o u n d a n d o f 1,5-cyclooctadiene.

    I n t r o d u c t i o nT h e p r e s e n t d e t a i l e d i n v e s t i g a t i o n o f t h e m o l e c u l a ra n d c r y s t a l s t r u c t u r e o f r h o d i u m ( I ) c h l o r i d e 1 ,5 -cyc looc tad iene w a s u n d e r t a k e n f o r t w o m a i n r e a so n s .F i r s t , D a h l , M a r t e l l & W a m p l e r ( 19 61 ) r e p o r t e d a nu n e x p e c t e d s t r u c t u r e f o r ( R hC I (C O )2 )~ , i n w h i c h e a c hr h o d i u m i s d e s c r i b e d a s o c t a h e d r a l l y c o o r d i n a t e d .T h e c lo s e p a r a l l e l is m b e t w e e n t h e p h y s i c a l p r o p e r t ie so f o l ef i n c o m p l e x e s a n d c a r b o n y l h a l i d e s o f t r a n s i t i o nm e t a l s h a s f r e q u e n t l y b e e n n o t e d , a n d , i n f a c t, C h a t t& V e n a n z i ( 19 5 7) r e m a r k o n t h i s p a r a l l e l i s m i n t h ec a s e o f ( R h C l ( C O ) 2 ) e a n d r h o d i u m c h l o r i d e 1,5-cyclo.o c t a d ie n e . W e t h u s t h o u g h t i t o f i n t e r e s t to i n v e s t i g a t et h e s t r u c t u r e o f r h o d i u m c h l o ri d e 1,5-cyclooctadiene,e s p e c i a l l y s i n c e w e w e r e u n a b l e t o v i s u a l i z e a s t r u c t u r ei n w h i c h t h e r h o d i u m a t o m s w e r e o c t a h e d r a l l y c o -o r d i n a t e d . A s e c o n d r e a s o n f o r t h e p r e s e n t i n v e s t i g a -t i o n w a s to a t t e m p t t o a n s w e r t h e q u e s t i o n : H o ww e l l c a n c a r b o n r i n g g e o m e t r y b e d e f i n e d i n th ep r e s e n c e o f s e co n d - r ow t r a n s i t i o n m e t a l s , i f i n t e n s i t yd a t a c o l le c t ed a t ro o m t e m p e r a t u r e a n d e s t i m a t e dv i s u a l l y a r e u s e d ? P r e v i o u s s t u d i e s ( e. g. , B a e n z i g e r ,D o y l e , R i c h a r d s & C a r p e n t e r , 1 96 1) h a v e r e v e a l e dt h a t u n d e r t h e s e c o n d i t io n s t h e r i n g g e o m e t r ie s a r ed i f f i c u l t t o d e f i n e a c c u r a t e l y , b u t s i n c e s u c h s t u d i e si n g e n e r a l d i d n o t t a k e a c c o u n t o f a n i s o t r o p y i n t h et h e r m a l v i b r a t i o n s o f t h e h e a v y a t o m s i t w a s n o t c l ea rt o u s w h e t h e r s u c h p o o r d e f i n i t i o n r e s u lt s f r o mi n a d e q u a c i e s i n t h e d a t a o r in t h e t h e o r e t i c a l m o d e l .I n a p r e l i m i n a r y c o m m u n i c a t i o n ( I b e r s & S n y d e r ,1 96 2) w e i n d i c a t e d t h a t t h e c o n f o r m a t i o n o f t h e

    Presen t address : De par tme nt o f Chemist ry, BrookhavenNat ional Laboratory , Upton , L .I . , New York .

    r h o d i u m c h l o r i d e 1 , 5 -c y c l o o c ta d i e n e d i m e r i c m o l e c u ls u g g e s t e d b y C h a t t & V e n a n z i ( 19 5 7) is c o r r e c t : e a c hr h o d i u m a t o m i s i n a s q u a r e - p l a n a r c o n f i g u r a t i o nI n t h e p r e s e n t p a p e r w e p r e s e n t t h e d e t a i l s o f o u rs t u d y , d e f i n e m o r e t h o r o u g h l y t h e s tr u c t u r e , a n di n d i c a t e t h a t t h e r i n g g e o m e t r y i s d i f f ic u l t t o d e f i n ee v e n w h e n a n i s o t r o p i c t h e r m a l m o t i o n s o f t h e h e a v ya t o m s a r e i n c o r p o r a t e d i n t o t h e t h e o r e t i c a l m o d e l .

    U n i t c e l l a n d p r o b a b l e s p a c e g r o u pT h e c r y s t a l s of r h o d i u m c h J o r id e 1,5-cyclooctadieneu s e d i n t h e p r e s e n t s t u d y w e r e k i n d l y p r e p a r e d b yD . W . B a r n u m o f th e s e l a b o r a t o r ie s b y t h e r e a c t i o no f r h o d i u m c h l o ri d e t r i h y d r a t e w i t h t h e d i e ne , a sd e s c r i b e d b y C h a r t & V e n a n z i ( 19 5 7) . T h e d e e py e l l o w c ry s t a l s e x h i b i t a t a b u l a r h a b i t . O n t h e b a s i so f c a li b r a t e d p r ec e s s io n p h o t o g r a p h s t a k e n w i t h M o K ar a d i a t i o n R h C I ( C s H l e ) c r y s t a l l iz e s i n a m o n o c l i n i c c e lo f d i m e n s i o n s

    a = 9 -0 5 _ + 0 0 5 , b = 2 5 . 4 _ 0 . 1 , c = 7 . 28 + _ 0 . 0 5 A ;fl = 91 .7 +__0.2 .

    T h e o n l y s y s t e m a t i c a b s e n c e s o b s e r v e d o n o v e r -e x p o s e d p r e c e s s io n p h o t o g r a p h s o f t h e hkO a n d hOz o n e s a n d o n W e i s s e n b e r g p h o t o g r a p h s o f t h e h k lt h r o u g h h k 6 z o n e s w e r e : 0 k 0 , k o d d ; h O 1, h + l o d d .T h u s t h e s p a c e g r o u p i s p r o b a b l y C~I~-P21/n, a n d ar e a s o n a b l e s t r u c t u r e h a s b e e n f o u n d o n t h i s a s s u m p -t i o n .A d e n s i t y o f 1 . 9 3 _ + 0 .0 2 g . c m . - 3 w a s m e a s u r e dp y c n o m e t r i c a l l y . W a t e r , w i t h a s m a l l a m o u n t o fA e r o s o l O T 7 5 % w e t t i n g a g e n t a d d e d , w a s u s e d a s

    A C 15-- 60

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    924 S T R U C T U I ~ E O F T H E D I M E R O F R H O D I U M C H L O I ~ I D E 1 5 - CY CL O O CT AD I ENEt h e p y c n o m e t r i c f lu i d . T h e c a l c u l a t e d d e n s i t y f o r e ig h tm o n o m e r m o l e c u le s o f m o l e c u l a r w e i g h t 2 4 7 i n t h eu n i t c e l l i s 1 . 9 5 g . c m . - ~ .H e n c e t h e s o l u t i o n o f t h e s t r u c t u r e i n v o l v e s t h el o c a t io n o f t w o r h o d i u m , t w o c h l o ri n e , a n d s i x t e e nc a r b o n a t o m s ( a n d , o f c o u r se , i d e a l l y t h e t w e n t y - f o u rh y d r o g e n a t o m s ) .

    o l l e c t io n a n d r e d u c t i o n o f i n t e n s i t y d a t aA c r y s t a l o f a p p r o x i m a t e d i m e n s i o n s 0 -0 6 0. 0 2 0 .0 0 3c m . w a s c h o s e n f o r t h e i n t e n s i t y w o r k . T h e u s e o f ac r y s t a l o f t h i s s i ze i s a r e a s o n a b l e c o m p r o m i s e b e t w e e np o s s ib l e a b s o r p t i o n e r r or s a n d c o n v e n i e n t e x p o s u r et i m e s ( M o K c~ r a d i a t i o n ) . W i t h a p r i s m a t i c c r y s t a lt h e p o s s i b i l i ty e x is t s t h a t t h e a b s o r p t i o n c o r re c t io n st o p a r t i c u l a r i n t e n s i t i e s m a y b e l ar g e , e v e n t h o u g ht h e a v e r a g e v a l u e o f /~ R i s s m a l l ( a b o u t 0 .3 h e r e )a n d t h e a n g u l a r r a n g e o f t h e d a t a l i m i t e d ( 0 _< 2 3 h e re ) . T h e r e a s o n a b l e n e s s o f t h e a n i s o t r o p i c t h e r m a lp a r a m e t e r s o f t h e h e a v y a t o m s ( se e be lo w ) is ta k e na s a n i n d i c a t i o n t h a t a b s o r p t i o n e r r o r s w e re n o ts e r i o u s .S i n c e l ~ h C l( C s H 1 2) i s s t a b l e , t h e s e l e c t e d c r y s t a l w a ss i m p l y a t t a c h e d t o a q u a r t z r o d w i t h s i l ic o n e g r e as ea n d m o u n t e d i n a ir . D a t a f o r t h e hkO t h r o u g h hk6z o n es w e re c o l l e ct e d a t ro o m t e m p e r a t u r e b y t h ee q u i - i n c l i n a t io n W e i s s e n b e r g te c h n i q u e w i t h t h e u s eo f M o K a r a d i a t i o n f i l t e r e d t h r o u g h Z r f o il . E x -p o s u r e s o f t h e o r d e r o f 10 0 0 m A - h r , w e r e t a k e n .F o r e a c h e x p o s u r e t h e c a m e r a w a s l o a d e d w i t h t h r e es h e e t s of I lf o r d G I n d u s t r i a l X - r a y f i lm i n t e r l e a v e dw i t h c o p p e r s h e e ts . T h e d a t a w e r e a r b i t r a r i l y l i m i t e dt o t h e r e f l e c t i n g s p h e r e 2 - 1 s i n 0 _< 0 . 5 5 A - 1. T h er a t io o f t e m p e r a t u r e - m o d i f i e d a t o m i c s c a t t e r i n g f a c-t o r s o f R h : C 1 : C i s a b o u t 3 0 : 6 : 1 o n t h i s s p h e r e ;w e f e lt t h a t d a t a b e y o n d t h i s p o i n t w o u l d c o n t r i b u t eo n l y t o t h e b e t t e r r e s o l u t i o n o f t h e h e a v y a t o m s ,p o s s i b l y a t t h e e x p e n s e o f t h e r e s o l u t i o n o f t h e l i g h ta t o m s .T h e i n t e n s i t i e s w er e e s t i m a t e d v i s u a l l y b y c o m p a r -i s o n w i t h a n i n t e n s i t y s t r ip . T h i s s t r i p , w h i c h c o n s i s t e do f t i m e d e x p o s u r e s o f t h e ( 27 0 ) r e f l e c ti o n , h a d a s c a lef r o m 1 t o 8 0 , w i t h 1 b a r e l y v i s i b l e . I n i t i a l l y t h ei n t e n s i t i e s o f o n l y t h o s e r e f l e c t i o n s w i t h i n t h e s p h e r e2 -1 s i n 0

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    J A M E S A . ] [ B E R S A N D ~ O B E I ~ T G . S N Y D E ~ 9 2t u r e i s t h a t p r o p o s e d b y C h a r t & V e n a n z i ( 1 9 57 ),a n d d e s c r i b e d b e l o w ( F i g . 1 ) .

    e f i n e m e n t o f t h e s t r u c t u r eR e f i n e m e n t o f t h e s t r u c t u r e w a s c a rr i e d o u t a l m o s te n t i r e l y b y l e a s t - s q u a r e s t e c h n i q u e s . S i n c e n o r e fl e c-t i o n s w e r e o b s e r v e d i n d e p e n d e n t l y m o r e t h a n o n c et h e w e i g h t i n g s c h e m e s u g g e s t e d p r e v i o u s l y ( I be r s,1 9 5 6) c o u l d n o t b e e m p l o y e d ; r a t h e r , a s c h e m ed e s i g n e d to b e a s m o o t h e d a p p r o x i m a t i o n t o w e i g h t ( F )i n v e r s e ly p r o p o r t i o n a l t o t h e v a r i a n c e ( F ) w a s a d o p t e d .T h e s c h e m e a l l o t t e d c o n s t a n t w e i g h t f o r F _ 3 5 Fm l n,a n d w e i g h t p r o p o r t i o n a l t o F - 2 f o r F > 3 5 F m in . T h i si s e s s e n t i a l l y t h e s c h e m e d e v i s e d b y H u g h e s ( 19 4 1 ).A l t h o u g h d i f fe r e n t, ' r e as o n a b l e ' w e i g h t i n g s c h e m e sm a y r e s u l t i n d i f f e r e n t b o n d d i s t a n c e s , s u c h d i f f e r e n c e sw i l l p r o b a b l y n o t b e s i g n i f i c a n t ( c f. e. g. I b e r s &C r o m e r , 1 9 5 8 ; B a e n z i g e r , D o y l e , R i c h a r d s & C a r p e n -t e r , 1 9 6 1 ). R e f i n e m e n t s w e r e b a s e d o n F , n o t F 2 a n do n o b s e r v e d r e f le c t i o n s o n l y . T h e B u s i n g - L e v y ( 1 95 9 a )l e a s t- s q u a r e s p r o g r a m f o r t h e I B M 7 0 4, w i t h s p e c i a lp a t c h e s a s n e c e s s ar y , w a s u s e d w i t h t h e ' C o m p a t i b i l i t yP a c k a g e ' o n t h e I B M 7 0 90 . I n th i s w a y a b o u t at h r e e f o l d a d v a n t a g e i n s p e e d is r e a l i z e d o v e r c a l c u l a -t i o n s o n t h e 7 0 4 . I n t h e p r e s e n t c a s e o n e c y c l e o ff u l l - m a t r i x l e a s t - s q u a r e s ( 8 0 0 d a t a , 8 7 p a r a m e t e r s ,i s o t r o p i c t h e r m a l p a r a m e t e r s ) r e q u i r e s a b o u t 8 r a in .o f m a c h i n e t i m e .

    F o r t h e c a l c u l a t i o n o f s t r u c t u r e f a c t o r s t h e a t o m i cs c a t t e r i n g f a c t o r s f o r R h , C 1, a n d C of T h o m a s &U m e d ~ ( 19 5 7 ), D a w s o n ( 19 6 0 ), a n d H o e r n i & I b e r s( 1 95 4 ) w e r e u se d . A c o r r e c t i o n f o r a n o m a l o u s d i s p e rs i on w a s a p p l ie d t o t h e r h o d i u m a t o m s c a t t e r i n g f a c to( T e m p l e t o n , 1 9 6 2 ) .

    T h e i n i t i a l r e f i n e m e n t w a s b a s e d o n a l l o f t h eo b s e r v e d r e f le c t i o n s , o n s e p a r a t e s c a le f a c to r s f o r t hi n d i v i d u a l z o n e s, a n d o n i n d i v i d u a l i s o tr o p i c t h e r m ap a r a m e t e r s f o r a l l a t o m s . T h u s t h e r e w e r e 8 7 p a r a m -e t e r s to b e d e t e r m i n e d f r o m t h e 7 7 9 n o n - z e r o r e fl e ct i o n s . ( T h e p r es e n c e o f h y d r o g e n a t o m s i n t h e s t r u c t u r ew a s i g n o r e d i n t h i s a n d i n s u b s e q u e n t r e f i n e m e n t s .T h i s r e f i n e m e n t c o n v e r g e d a f t e r s e v e r a l c y c l es t o s t r u c t u r e i n w h i c h t h e C - C s i n g le b o n d s r a n g e d f r o m1 .2 t o 1 . 8 J~ i n l e n g t h . A d i f f e r e n c e F o u r i e r , i n w h i c ht h e F c o f t h e h e a v y a t o m s w e r e s u b t r a c t e d f r o m F ow a s t h e n c a l c u l a te d . T h e c a r b o n a t o m p o s i t io n s ot h i s d i f fe r e n c e F o u r i e r w e r e fa r b e t t e r r e s o l v e d t h a nt h e y w e r e o n t h e i n i t i a l d i f f e re n c e F o u r i e r . T h e g e n e r aa g r e e m e n t b e t w e e n t h e s e p o s i t i o n s a n d t h o s e o f t hl e a s t - s q u a r e s w a s n o t t o o g o o d ; s o m e p o s i t i o n s d ev i a t e d b y a s m u c h a s 0 3 ~ f r o m t h e l e a s t - s q u a r ep o s i t io n s . * C o n t r a r y t o t h e e x p e r i e n c e o f o t h e r

    * T h e p e a k c e n t e r s w e r e c a l c u l a t e d w i t h t h e u s e o f aI B M 7 0 9 0 p r o g r a m b a s e d o n t h e 27 p o i n t l e a s t - s q u a r e s m e t h oo f S h o e m a k e r et al ( 1 95 0 ). S i n c e t h e g r i d s p a c i n g w a s a b o u0 2 /it a n d s i n c e t h e p e a k s o v e r l a p s l i g h t l y , t h e u n c e r t a i n t y it h e p o s i t i o n s o f t h e p e a k c e n t e r s is p r o b a b l y a b o u t 0 . 1 A

    T a b l e 1 . A t o m i c p a r a m e t e r s f o r ( R h C I ( C s H l e ) ) 2 *A t o m x a x ) y a y ) z a z ) B a B )

    R h 0.3894 0.0004 0.3248 0.0002 0.4347 0.0005 2.21 0.10R h ' 0.6419 0.0004 0.4137 0.0001 0.6342 0.0005 2-39 0.10C1 0.4242 0-0015 0.3677 0.0006 0.7225 0.0018 3-71 0.30CI ' 0.6241 0.0014 0.3605 0.0006 0.3645 0.0020 3.81 0.301 0.394 0-006 0.265 0.002 0.236 0-008 4.8 1.42 0.318 0.004 0.314 0.002 0.164 0.006 2-0 0.93 0.154 0.008 0.327 0.003 0-119 0.010 7.3 1.84 0.080 0.007 0.317 0.003 0-286 0-010 6-5 1.75 0.155 0.006 0-317 0-002 0-487 0.008 4.4 1.26 0.238 0.005 0.272 0.002 0.544 0.007 3-1 1.07 0.236 0-005 0.215 0.002 0.440 0-007 3.4 1.18 0.299 0.005 0.219 0.002 0.270 0.007 3.3 1.11' 0.870 0.005 0.431 0.002 0.597 0.008 3-6 1.22' 0.787 0.006 0.468 0.002 0.510 0.009 4.7 1.33 0.773 0.007 0.526 0.002 0.600 0.009 5.5 1.54' 0.649 0.010 0.529 0.004 0.753 0.015 10.8 2.85' 0.595 0.005 0.474 0-002 0.831 0.007 2.8 1-06' 0.695 0-005 0.436 0.002 0.912 0.007 3.4 1.27' 0.858 0.006 0.439 0.002 0.954 0-009 4.9 1.48 0.925 0.006 0.438 0.002 0.790 0.009 5.2 1-5

    A t o m #11 U( #ll ) #22 (7( #2 2) #33 (~( #3 3) #12 (Y(#12) #13 (Y(#13) #23 (Y(~23R h 0 0 0 5 6 0 0 0 0 4 0 0 0 1 0 0 0 0 0 1 0 0 1 0 5 0 0 0 0 8 - - 0 0 0 0 1 0 0 0 0 2 - - 0 0 0 0 3 0 - 0 0 0 5 - - 0 . 0 0 0 1 0 0 0 0 2l~h ' 0.0077 0.0005 0.0009 0-000 t 0-0113 0.0009 --0.00 04 0.0002 --0.00 03 0.0005 -- 0.0001 0.0002CI 0.0146 0.0021 0.0016 0.0003 0.0121 0.0032 --0.0 024 0.0006 0-0018 0.0019 --0.00 12 0-0007CI ' 0.0124 0.0020 0.0014 0 0003 0.0201 0 003 8 -- 0.0010 0.0006 0.0031 0.0020 -- 0.0010 0.0008

    * T he po s i t i ona l pa r a m e t e r s o f aU t he a t om s a nd t h e a n i s o t r op i c t he r m a l pa r a m e t e r s o f the he a vy a t om s a r e ba s e d on t ha n i s o t r op i c r e f i ne m e n t i n w h i c h t he i s o tr op i c t he r m a l pa r a m e t e r s o f t he c a r bon a t om s g i ve n he r e w e re he l d c ons t a n t . T he i s o t ropt he r m a l pa r a m e t e r s o f t he he a vy a t om s g i ve n he r e a r e t hos e de r i ve d f r om t he i s o t r op i c r e f i ne m e n t .

  • 8/12/2019 Cristal Structure Dimer Rh Cl COD

    4/8

    9 2 6 S T R U C T U R E O F T H E D I M E R O F R H O D I U M C H L O R I D E 1 5 - C YC L O O C T A D I E N Ee.g. l~ossmann e t a l . , 1959) the thermal parametersof the misplaced carbon atoms were not significantlylarger than the average. A final refinement withisotropie thermal parameters and the carbon atomsrelocated in accordance with the positions of thedifference Fourier converged rapidly to a structurewith more reasonable bond distances. The value ofthe R factor, ~ l F o - f F o [ J / ~ F o ) , was 0-101 for the

    779 non-zero reflections; the error of fit functionX W F o - - J F c J )~ / m - n ) ) had the value 7.15.The difference Fourier provided evidence that theheavy atoms, particularly the chlorine atoms, werevibrating anisotropically. On the assumption that

    proper account of such motion would lead to impr ovedpositions for the carbon atoms, a refinement based onanisotropic thermal parameters of the heavy atomswas attempted. The first attempt, in which thepositional parameters of all the atoms, the six in-dependent thermal parameters of each of the heavyatoms, and the scale ~aetors were varied, was un-successful: physica lly unreasonable shifts in the scalefactors were obtained. We had failed to realize thatsince the scale ~actors and the ~s of the heavy atomsdepend only upon l, and since the heavy atoms arethe principal contributors to the structure amplitudes,the least squares matrix of normal equations is nearly

    Table 2. Obs e r ve d a nd c a l c u l a t e d s t r uc t u r e f ac t o r sK o 5 5 C At . I ~ X 0 8 S C ~ t . ~ < 0 8 S C At . ~ K O ~ S C ~ t . ~ ~ 0 8 S C a ' , ~ ~ O ~ S C ~ " 0 ~ C ' t .

    e e e e e l - l O e l e e e e O o I I L I e l I I e l ~ o l 0 5 1 o a .~ 0 0 6 1 0 1 0 8 0 6 1 0 0 5 9 - 0 6 2 5 2 1 0 6 0 ~ 0 7 5 1 1 0 1 1 2 - 1 1 00 o o A 8 T I , 2 I O 0 B - O , Z O l O S l 0 6 , 1 0 6 0 , , 0 . 1 6 I 1 1 2 , 0 2 3 1 I 2 2 0 5 6 - 0 5 , ~ z n 0 6 8 0 6 542 . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . 2 . . . . . . . . ~ ....... . 2 . . . . . . . . . . . . . . . . . .o o 2 9 9 - 2 9 9 o o 0 , 8 - 0 , 7 5 0 l 0 , 8 0 2 9 . 1 0 6 0 ~ .5 0 , ~ 1 1 1 5 0 - 1 5 1 . 2 k 0 5 9 0 5 1 I 1 1 0 8 0 - 0 8 98 o o 1 0 , 0 9 , 7 o o 1 0 3 0 9 8 6 0 l 0 5 1 . - 0 , 8 q 0 6 1 5 8 - 1 3 3 7 1 1 0 6 6 - 0 7 1 ~ . I I O z . ( , 0 ~ * .1

    Ol 100 -116 01 B 073 80l OT, 077 07 ~4~ 188 ~ 12 05~ -058 I O0LR 3 08 12 05, 0,6

    o 6 : i : i i . . . . . . . .o 1 0 6 2 7 6 0 l 0 ~ 5 0 5 5 o ~ o 6 5 - 0 ? 20 2 - 0 5 6 0 0 2 - 0 7 0 0 3 1 6 " 1 6 3 6 0 7 0 6 2 - 0 8 6 0 9 5 - 1 0 8 O 1 1 0 8 1 0 2 0 7 9 0 8 1O Z 0 5 9 - 0 4 7 0 2 8 - 0 7 1 6 o i 0 5 ~ 0 5 9 0 7 0 6 7 - 0 5 7 1 0 Z - 1 0 ~ * . 1 0 1 0 4 6 0 " 8 5 0 6 1 - 0 6 32 0 2 0 2 6 - 0 1 6 0 2 0 7 6 0 7 6 7 0 1 0 , 9 0 5 8 9 0 7 0 3 9 0 2 5 ~ 1 5 0 7 2 0 7 2 z ,. 0 1 0 6 8 0 8 1 6 ~ . , 0 5 3 - 0 5 31 0 2 o , 1 0 5 6 5 0 Z 0 5 6 0 6 7 I 0 z ~ 0 7 - 0 8 0 O 0 8 1 2 6 - 1 1 6 1 6 0 5 5 - 0 ~ ' 6 0 1 O S T - 0 6 7 2 5 0 6 9 0 6 90 2 0 , 9 0 5 2 0 2 0 = 7 0 - 0 5 6 1 , 6 1 2 , 08 i ~ I i i , 1 8 0 6 0 0 5 ~ 1 0 . 1 0 7 7 ~ 1 6 0 4 9 - 0 * 57 0 2 0 ' 5 - 0 4 5 0 0 1 - 1 7 7 Z . 0 ( , 1 8 ~ - 1 7 2 3 0 8 0 7 9 - 0 8 6 4 1 9 0 7 6 0 7 9 0 3 1 0 5 - 1 0 ( , 3 1 7 1 0 8 - 1 1 1

    . . . . ~ . . . . ~ 03 98 . . . . . 00~ . . . . . . z . . . . . . . . . 23 . . . . . . . . . . . . . . . . . . . 0 . . . . . . . .I o ~ - 1 7 6 o .1 o . 1 - o m s 6 IO O .116 5 0 8 0 8 0 - 0 8 2 2 0 0 5 2 0 6 0 5 0 ~ 0 7 8 - O B ? 1 8 0 ( , 8 - 0 4 905 088 08.1 k 03 102 12~ 1 5 030 -025 0 09 133 120 21 079 076 151 -178 1 20 061 -06,. . . . . . . . . ~ . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . o ~ . . . . . . ~ . . . . . . . .

    6 ~ 0 3 1 0 7 1 1 6 o , 0 6 5 - o 5 9 " * o 5 o 6 9 0 7 0 o 9 1 1 , - 1 0 3 8 o 8 8 0 5 9 2 1 o 6 8 - o 5 ( ,o , 0 7 9 0 0 ~ 0 0 4 1 9 , - 2 5 5 6 0 5 0 4 5 - 0 4 5 5 0 9 0 7 7 0 7 1 ~ e e e e L l S e e e e 1 0 5 1 3 2 1 1 1 2 1 0 6 4 - 0 6 69 o, o 6 6 - o 5 9 z o, 1 6 , . - 1 , 5 T os o 9 2 o e ~ , , 0 9 1 2 5 - 1 ~ o ~ o o e - 2 o 9 . 1 o~ o 5 , - o 7 60 o , 8 - 1 , 7 o , 1 9 5 - 1 6 9 1 0 7 0 " *1 0 , 9 5 0 9 0 7 9 0 7 5 o o 0 2 0 6 1 , o s 0 6 2 - 0 7 0 * * * * * c . - - ~ * * * *00: 98 . . . . . . . . . . . . . . . . . . . . . 6 . . . . . . . . o o l B . . . . . . . . . . . . . . . . . . . . . . .0 o - 0 7 0 " ' 1 0 3 1 1 6 3 0 7 2 5 8 2 0 3 1 0 0 5 9 - 0 6 1 O l 1 8 2 I 0 6 0 9 9 0 8 9 z . O 0 1 , 5 1 5 ~ .5 0 ~ . . . . . . . . . . . . . . . . . . . . . . . . 32 . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . 6 . . . . . . . . . 1 5 2 1 5 1 1 5 0 3 6 - o , o 1 o 8 2 5 2 - 1 9 5 1 o 1 1 8 - 1 2 3 O l 0 ( , 6 o , ~ . o 7 o ~ 6 - 0 5 0 o o 1 1 2 - 0 9 2 '

    o ~ 0 6 ~ 0 6 7 5 0 5 0 5 8 0 6 2 t 0 8 0 7 1 - 0 6 2 1 0 0 9 3 0 8 5 9 O 1 0 7 5 0 6 8 5 0 9 8 0 9 1 2 0 1 0 6 ~ 0 6 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . ~ o ? o ~ . . . . . . . . . . . . . . . . . .0 5 0 7 9 - 0 7 7 & 0 5 0 6 6 0 5 3 5 0 8 0 9 6 0 9 8 1 1 0 , 6 - 0 5 1 * I 0 2 - 0 5 1 0 8 O & 3 - 0 , 6 ~ * O 1 0 7 1 0 7 .1. .. . . .. . 10 . .. . . .. . 16 . . . . . .. . . 36 . . . .. . . . . ~ . . . . . . . . . . . . . . . . . . . .. . . .. . . .0 5 0 * 6 - 0 , 7 0 6 1 0 3 1 0 1 0 9 0 ' 0 - 0 1 9 1 1 0 5 1 0 3 8 0 2 0 8 2 0 7 9 " * o e 0 9 2 1 1 2 2 0 2 0 5 6 - 0 6 1o 0 7 2 ~ . . . . . . . . ; . . . . . . . .

    OO6 O57 O6 125 -12~. ~ 09 O69 O68 12 O37 O35 O2 I 8 -12 9 08 O5O 0 ~, O3 0~2 -O570 6 0 3 6 0 3 .1 6 0 6 0 4 5 - 0 4 3 ~ * 0 9 0 5 6 0 ~ 9 2 1 2 1 6 6 - 1 ~ 5 0 3 0 3 0 7 0 8 0 7 5 0 6 ~ * 2 0 . 1 1 ' 1 1 5 02 0 6 0 8 0 6 1 9 0 6 1 0 9 0 9 2 6 0 9 0 ~ . 8 0 " T 3 1 2 0 8 ~ * 0 8 " * 32 0 3 1 6 0 1 37 8 0 8 0 8 2 - 0 7 8 , o : 1 , 2 - 1 2 . 13 0 6 0 , 1 0 2 9 I 0 7 2 2 0 1 9 6 1 1 0 0 8 2 0 7 8 , 1 2 0 , 5 - 0 , 2 0 .1 0 7 5 0 8 1 . I 0 9 1 . 1 1 - 1 1 6 6 0(,5 - 0 6 1, 06 0,, -022 2 07 1,I 11, 2 11 169 165 6 12 051 0 5 9 " * 02 O,T 05.1 6 09 057 -060 70 ~ 068 0695 06 05" - 0 5 8 .1 07 055 0 6 2 ' I I 156 -123 42 I~ 153 126 5 0 0~ 0 6 9 - 0 7 6 0 9 0 6 0 0~5 I 0* 128 1 2 81 3 0 ' 6 0 ~ 5 6 O ' 9 - 0 5 . 1 2 1 0 0 5 9 - 0 6 e 2 0 ~ 0 8 0 - 0 6 5o ? 0 6 6 0 5 1 0 7 0 8 7 - 0 6 9 I ~ 1 8 8 1 9 6 1 .1 0 9 0 6 a 0 - 1 9 7 l o 0 6 .9 0 4 8 6 ~ * 0 9 0 - 0 ? 70 7 2 0 2 1 7 , 0 0 8 1 8 6 1 6 5 2 1 2 0 5 0 5 ~ 1 3 0 7 Z . - 0 8 4 1 1 I 1 3 5 1 1 1 3 8 1 , ' * ' ' l z . 3 - 1 2 20 7 0 0 9 - 0 " 1 0 0 0 6 2 0 7 , t . 1 0 , 8 0 2 8 ' 0 ( , ~ 0 ' 2 ~ * 1 1 6 1 0 9 6 l l 1 , 7 - 1 2 , 1 5 l l . 1 0 9 8

    06 . . . . . . . . . 3 . . . . . . . . . 143 . . . . . . . ' . . . . . . . . i O0 . . . . . . . . . . . . . . . . . . . . . . . . .o e 1 9 0 - 1 7 , 0 8 0 0 8 - 0 9 S Z O 7 O - O 6 7 4 1 , O 6 7 O 7 O 2 1 8 8 1 7 2 . 1 1 2 1 2 1 l O S ~ . 0 5 0 8 .1 - 0 ~ 71 0 8 196 1 6 0 5 0 8 0 , 4 0 3 8 1 , 0 5 1 - 0 5 1 0 1 5 1 0 ' - l O ~ * 0 5 1 6 8 - 1 3 9 5 1 2 O 9 2 - 0 8 0 5 0 5 O 5 7 - 0 5 73 O 8 O 9 4 O 8 6 8 O 8 O 5 5 O ~ * S ~ 1 5 0 ~ . 1 - 0 , 1 . 1 1 5 O S 6 O 6 2 23 O 5 O 3 2 - 0 , 1 7 1 2 o 8 9 - o 7 9 6 o 5 o ~ .5 - o z . ,, * 0 8 1 2 9 1 0 9 l O O 9 0 5 2 - 0 7 3 1 5 O 6 7 - O T , , l S O 5 9 O 7 , O5 O 5 6 0 ~ 1 Z 1 . 1 0 ' . 0 O 3 6 I O 6 O 6 O -0 5 ~, 08 090 -086 09 038 00 3 15 172 -1,8 I 16 063 -098 z. 05 139 -13,. I/* 079 -089 2 O6 I16 111. . . . . . . . . . . . . . . . . . . 76 . .. .. .. . . .. .. .. .. 85 . .. .. .. . ~ ~ . .. .. . ~ . .. .. .. .z . 0 9 0 , 9 - 0 8 8 , 0 9 0 7 0 0 7 5 1 5 0 6 9 0 7 1 0 1 8 0 5 8 0 5 6 0 5 0 6 9 0 7 6 0 6 ~ 0 5 7 0 " 7 0 6 9 - 0 6 6O 9 o ~ . . . . . . . . . . . . ~ . . . . . . . . . ~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I 0 0 1 5 I I 0 0 , 8 - 0 5 7 1 6 o 9 3 - 1 0 5 l e 0 6 8 - 0 6 7 . 1 0 6 1 . 1 9 - 1 2 ~ 2 i s o 5 6 - o s ? 6 o 7 0 5 6 o 6 0

    1 0 0 4 8 0 5 7 1 0 0 6 0 - 0 6 0 6 1 6 0 6 6 0 7 0 1 9 0 , 9 0 5 2 0 6 o 7 5 o 9 2 1 5 o 6 8 0 7 1 . o 8 0 " * l - 0 ' *1 1 1 0 8 1 0 7 9 4 l O 0 6 6 - 0 6 7 2 1 8 0 5 1 o 8 o 2 2 1 0 5 2 - 0 5 0 0 0 7 0 ~ 5 0 3 2 ~ , 1 6 1 0 6 - 0 9 5 5 0 8 0 9 1 0 8 63 1 1 1 1 7 - 1 2 1 ~ 1 0 0 5 5 O aO 3 19 0 9 3 093 2 2 2 0 6 6 - 0 5 7 ~ O 7 0 8 2 0 7 3 1 1 9 O 7 2 - 0 7 1 2 0 9 0 . 1. 1 - O 3 8z . 1 1 0 , 9 - 0 1 . 4 6 1 0 0 9 1 . 0 8 8 ~ * 1 9 O 6 5 0 7 , ~ 2 . 1 0 7 0 - O 6 " 0 7 O 6 O - 0 5 9 ~ 1 9 O 5 2 - 0 , ~ i 1 1 o 6 8 o 7 o5 1 1 0 2 .2 - 0 2 . 2 8 l O 0 6 9 0 7 3 ~ 2 0 0 7 8 - 0 7 8 2 7 0 7 ~ * - 0 8 1 " * 7 0 7 8 - 0 9 0 1 9 0 8 2 0 7 8 7 l l 0 6 5 - 0 6 91 1 0 6 0 o 6 2 0 l l 1 , 6 1 , 5 2 0 O , 9 0 5 6 5 0 7 0 ~ 6 - 0 6 2 . 1 2 2 0 2 7 0 7 I I 1 2 0 . 18 - O ' 212 1 5 6 1 ' 5 3 2 1 1 l Z * . 1 - I k 7 ~ 20 0 6 7 0 6 9 e * * * e L e - 2 * e * e 0 0 8 1 , 5 1 5 8 2 2~ 0 9 1 0 8 5 2 1 2 0 3 8 O z . '12 0 9 8 0 8 6 11 0 5 8 - 0 2 6 2 2 0 6 3 0 7 8 2 O 0 B 0 8 0 I 0 8 0 5 6 0 6 . 1 ~ * 12 0 5 4 0 6 73 12 O39 051 , Ii 120 -112 8 22 071 -072 a oo 05, -0,6 ~ 08 050 -0~ 8 e**etL-+~*eeee l ~ 05, -0634 1 2 1 5 7 - 1 4 5 ~ I I 0 5 9 0 6 0 2 .1 0 9 1 - 0 9 1 ~ O 0 1 1 0 - I 1 5 0 8 0 7 2 0 5 9 : 0 O 0 B - 0 9 1 ~ 0 5 0 - 0 6 .18 1 2 0 6 6 O 6 5 1 2 0 , 8 0 5 5 1 2 ~ 0 5 5 0 5 6 O 0 O 6 6 0 6 7 ~ . O 8 0 " *3 -O 6 5 2 O 0 O 6 8 -0 7 . 1 1 5 0 8 0 O 8 8. . . . . . . . . . . . . . . . . . . 3~ ol 86 0 5 6 0 . . . . . . . . . . . . . ~ . . . . . . . . . . . . ., 1 5 0 , 8 - O 5 , 1 2 O S " O , 6 * * * * * L = + 2 * * * ~ - 0 1 0 6 O 6 5 O 9 0 6 8 - 0 6 ~ 0 0 Z 1 1 8 6 1 5 O 5 , - 0 5 60 ~ 4 . . . . 7 6 . . . . . . . . . 26 oo 9~ . . . . " ... .... . 23 . . . . . . . . . . . B . . . . . . . . . . . . .0 6 - 0 , 8 1 2 0 7 6 O 7 O O 0 0 7 O 9 2 5 0 1 0 7 0 - O 9 O O 9 o e e - 0 6 9 2 0 1 0 z . 0 9 1 ~ 1 6 O 8 O - 0 8 0. . . . . . . . . . . . . . . . . . o o l ~ o i . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 5 0 . 1 9 - O , 2 2 1 5 O , 9 - O , 7 O l - I 0~ , , O 3 i ' 0 - I ' 0 ~ O 9 O 5 7 O 6 3 ' * 0 1 I 0 2 - 0 8 8 ~ 1 8 0 ' , 5 - 0 5 1

    . . . . . . . . . o . . . . . . . . . i o . . . . .8 1 ~ O 6 9 O 6 6 1 o c - 0 1 6 O 2 1 9 0 * ' * ' * L ' . 5 * * ' *. . . . . . : . . . . . . . . 6 0 1 l~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 8 0 9 8 0 9 7 5 a 0 6 2 O 6 5 0 2 - 0 , ~ 3 0 ' * 2 0 5 - 1 5 8 2 1 0 1 0 8 - 0 9 9 ( , 0 2 0 . 15 0 4 1 ~ oo 0 3 1 0 2 8

    o o . o . o o I . . . . . . . . . . . . . . .1 6 I 0 -1 , ~ . 1 0 1 8 0 9 2 -0 T 6 O 2 0 5 0 ST 7 0 0 ~, 0 5 1 -0 S '~ 1 1 0 5 g -0 6 t 0 6 -0 ~ *S 0 1 B 0 6 81 6 0 4 1 O ' 5 1 5 1 ' 7 - 1 ' 1 " 0 2 0 5 2 0 7 O " * 0 9 .1 1 0 9 1 1 i I I - 0 9 6 0 7 8 O 1 0 , 8 - 0 5 ~1 6 1 0 6 - 1 0 1 2 1 5 1 1 3 1 0 9 5 0 2 O 7 2 - 0 B 8 2 O 5 0 2 8 - 0 3 0 5 1 1 0 ~ 7 O ' 2 2 0 ~ 11 4 1 0 ~ . 5 0 l O 5 2 - O 5 7~ 1 6 O 8 9 O 8 7 3 1 5 O 4 - 0 3 8 7 O 2 O 8 O - O 7 , & 0 5 1 1 - 1 2 2 6 1 1 0 5 2 O S 6 3 0 1 0 ~ 5 O 6 O 0 O 2 0 O T 8; ~ o o:73 1 7 0 5 , 0 ~ 0 0 1 5 0 9 3 0 9 6 0 2 0 8 5 8 0 6 0 0 6 0 5 2 - 0 ~ . 8 1 ~ 0 8 8 - 0 9 0 " 3 0 5 7 0 5 8 3 0 2 0 6 .1 0 5 117 08 - O , 9 16 O 9 5 -O 9 0 0 0 . 1 -li t .1 O 6 0 4 9 O 5 2 5 1 2 O 5 0 0 5 9 6 0 " * 0 , 8 - 0 3 ~ * " * O 2 O 7 8 - 0 6 60 . . . . .. . . . ~ . . . . .. . . . ~ . . . . . . . 21 . . . . .. . . . 0 . . . . .. . . . 0 0 5 c . . . . ~ . . . . .. . . .1 8 o 8 6 0 8 7 1 6 0 , 8 o , 6 0 3 0 2 8 0 2 1 o 7 o 9 o 0 8 ~. 1 .1 0 5 7 o 6 0 o 5 1 2 - 1 1 7 o ~ R O 6 53 1 8 0 5 5 0 6 2 6 1 6 0 7 7 0 7 9 . 1 0 3 1 5 6 12 1 3 0 7 0 9 , - 1 0 3 1 .1 0 8 2 0 7 6 7 0 5 0 8 7 08 . 1 O ~ 0 5 8 06 ~ .I 19 O 9 0 - 0 8 9 1 17 0 , 5 - 0 , 7 4 0 3 0 5 Z 0 5 S , 0 7 1 6 16/* ' 11 O 5 O - 0 6 8 0 0 6 0 7. 1 6 ~ O 5 9 - O S ?

    19 0 5 8 0 5 8 1 8 O , B 0 6 5 0 1 0 ~ ,6 - 0 ' 2 ? 0 6 7 - 0 9 5 3 0 8 0 0 7 , 0 6 0 , 4 - 0 , . 1 5 1 2 1 - 1 1 71 9 0 6 2 0 6 1 1 8 0 5 " - 0 / * 9 7 0 , 0 6 2 - 0 5 , 0 8 1 , 2 - 1 ~ 0 1 8 0 , 6 o ~ * o 0 6 6 O 5 O 8 5 0 9 0. . . . . . . . . . . . . . . . . . . 0043 . . . . . . . . . . . . . . . . o . . . . . . . . ~ . . . . . . . . . . . . . . . . .o 2 0 1 3 8 - 1 1 8 0 1 19 1"3 1 3 2 ~ 1 9 7 - 2 1 . 1 , 0 8 2 0 6 1 6 6 1 6 0 6 5 -071 0 7 " 0 7 7 . 1 0 6 0 8 2 - 0 7 3, 2 0 0 7 1 0 6 7 2 ~ 0 8 5 0 9 1 O z . 0 ~ 6 0 5 8 , 0 8 0 / * 9 0 ' 2 1 6 0 5 9 - 0 6 ( , 2 O 7 0 6 8 - 0 6 9 , 0 6 0 8 5 0 8 7

    o 22 129 If 5 O" 156 12~. 06 io i 1o9 17 O~T -0" , 07 0~9 -O,5 07 051 05.1a 2 2 0 6 2 - 0 7 5 * * * * * L = - I * * * * 6 O , 0 ~ 6 - 0 , , 7 O 8 1 0 "* - 1 0 6 4 1 7 0 8 5 - 0 9 4 0 0 8 O 4 8 O , 6 I O 8 O 7 O 5 61 2 8 O 8 6 O89 1 o o 0 , 0 7 0 0 5 1 2 1 - 1 1 6 1 o 9 1 0 5 - 1 0 2 0 1 8 o 6 2 0 6 1 0 8 0 . 18 - 0 , 8 1 o 9 0 . 8 , - 0 9 12 3 0 5 4 - O 6 , O 0 1 8 1 - 2 " 2 O 5 0 ~ .6 - 0 5 ~ ~ O 9 0 ~ .2 O ' 5 1 0 O 6 3 - 0 6 ~ * O 9 O 7 2 - O 6 3 ~ ) 9 O 8 O 0 7 7

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    o ol a o56o l 0 6 8 - 0 7 7' . 0 1 0 7 4 - o 6 8o o 2 ~ o .0 2 0 0 5 2.1 02 1 1 o - 1 o 61 o . 1 o 0 7 ~a o ~ 0 ~ 2 - 0 , 65 0.1 077 -071

    0 5 0 7 8 - 0 9 ?os 0 8 5 0 8 20 0 6 0 , . 9 - 0 2 , .2 0 6 0 9 ~ - 0 9 9z . 0 6 0 7 1 0 5 86 0 6 0 7 0 0 ? 30 7 0 6 t - 0 7 ,0 7 0 5 7 0 5 ' .o 0 9 0 9 6 - 1 1 1i 0 9 0 6 5 o ? , .* 0 9 0 7 0 0 6 0. 1 1 0 o 8 o r eo 1 2 C - o 1 ~0 1 ~ 0 8 6 0 8 2

    4 l ~ 0 . ~ 9 - 0 6 61 1 7 0 7 T - 0 7 8* . . . . L . - 6 . . . .2 o o 6 1 - 0 6 2i o : . o - 0 7 02 o z 0 5 3 - 0 3 8 o , 0 *6 - 0 5 0, 0 '* 0 6 7 0 6 5' t 0 5 1 0 2 0 9 22 0 6 0 8 2 0 7 52 0 7 0 ' , 2 - 0 ( , 708 0 5 4 - 0 5 ~,, 08 0 5 0 - 0 5 50 9 0 6 . 1 - 0 5 00 9 0 6 7 - 0 7 91 1 0 0 8 8 0 8 5lO 0 *6 -o , . . 1

    1o 0 6 7 - 0 6 65 1 1 0 7 7 0 7 0i 12 0 5 6 - 0 6 0,. 12 056 o~z2 1.1 o5~ -o~91 o7, -o7.1

    I'* 0 " 9 - 0 " 7

    A - F ( C A L I A R E I N E L E C T R O N S . H Y O R OO E N A T O N C O N T R I B U T I O N S AR E N O T I N C L U D E D .B - R E F L E C T I O N H I D D E N O Y T H E B E A M S T O P .C - R E F L E C T I O N O B S C U RE D B Y R A D I A T I O N S T R E A K O R O Y F I L M I H R E R F E C T I O N t

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    J A M E S A . I B E R S A S ID I ~ O B E R T G . S N Y D E R 9

    A t o mR hR h 'C1CI'

    T a b l e 3 . Root-mean -square thermal displacements in J~)*Root -mean-square di splacement

    Max. Int . Min. J_ to Rh , C1 plan e In Rh , C1 plan e0.18 0.17 0.15 isotro pic0.19 0.18 0.16 isotropic0.29 0 18 0 16 0.28 0.17, isotro pic0.27 0.20 0.19 0.27 0-20, isotro pic

    * Est im ated s tanda rd d evia t ions : Rh, 0 .01 /~ ; C1, 0 .02 /~.s i n g u l a r , t I n t h e s u c c e e d i n g r e f i n e m e n t t h e s c a l ef a c t o rs f r o m t h e i s o tr o p i c r e f i n e m e n t w e r e u s e d a n dw e r e n o t v a r ie d . T h e t h e r m a l p a r a m e t e r s o f t h e c a r b o na t o m s f r o m t h e i s o tr o p i c r e f i n e m e n t w e r e h e l d c o n -s t a n t i n th i s r e fi n e m e n t , f o r a t t e m p t s t o v a r y t h e s ew h i l e v a r y i n g t h e t h e r m a l p a r a m e t e r s o f th e h e a v ya t o m s a n i s o t r o p i c a l l y l e d to p h y s i c a l l y u n r e a s o n a b l et h e r m a l p a r a m e t e r s f o r t h e c a r b o n a t o m s . T h ea n i s o t r o p i c r e f i n e m e n t ( 8 4 p a r a m e t e r s ) c o n v e r g e d t oa r e l i a b i l i t y f a c t o r o f 0 .0 9 6 a n d t o a v a l u e o f 6 .8 8 f o rt h e e r ro r o f f it f u n c t io n . T h e f i n a l p a r a m e t e r s f r o m t h i sr e f i n e m e n t ( w i t h c a r b o n a t o m t h e r m a l p a r a m e t e r sf r o m t h e i s o t r o p i c r e f i n e m e n t ) a r e l i s t e d i n T a b l e 1 .T h e v a l u e s o f F c b a s e d o n t h e s e d a t a , t o g e t h e r w i t ht h e v a l u e s o f Fo f o r o b s e r v e d a n d o b s c u r e d r e f l e c t i o n s ,a r e l i s te d i n T a b l e 2 . T h e F c v a l u e s a c c o r d i n g l y d o n o ti n c l u d e t h e c o n t r i b u t i o n s fr o m h y d r o g e n a t o m s . T h eFo v a l u e s h a v e b e e n s c a l e d a b s o l u t e ly w i t h t h e u s eo f t h e s c a l e f a c to r s f r o m t h e i s o t r o p i c r e f i n e m e n t .A c h e c k o f t h e s t r u c t u r e a m p l i t u d e s o f t h e a p p r o x -i m a t e l y 1 4 0 0 u n o b s e r v e d r e f le c t io n s w i t h i n t h e s p h e r e~ -1 s i n 0 < 0 . 55 j ~ - i r e v e a l e d n o n e w h i c h w e d e e m t oe x c e e d s i g n i f i c a n t l y ( 1 0 % l e v e l ) o u r e s t i m a t e s o fF m i n . T h e r e f o r e t h e s e d a t a a r e n o t l i s t e d i n T a b l e 2 .N o n e o f t h e p o s i t i o n a l p a r a m e t e r s f r o m t h e a n is o -t r o p i c r e f i n e m e n t d i f f e r s s i g n i f i c a n t l y (1 5 % l e v e l )f r o m t h e p a r a m e t e r s o b t a i n e d f r o m t h e i s o tr o p i cr e f i n e m e n t . S i m i l a r ly , t h e i m p r o v e m e n t i n t h e r e l i-a b i l i t y f a c t o r i s n o t s i g n i f i c a n t ( H a m i l t o n , 1 9 6 1) .T h e r e a s o n f o r t h i s l a c k o f i m p r o v e m e n t , w h i c h i sc o n t r a r y t o g e n e r a l e x p e r ie n c e , is a p p a r e n t f r o m t h ee l l i p s o id s o f v i b r a t i o n o f t h e h e a v y a t o m s ( T a b l e 3 ).I n a g r e e m e n t w i t h e x p e c t a t i o n s , t h e c h l o ri n e a t o m sa r e v i b r a t i n g w i t h c o n s i d e r a b l y g r e a t e r a m p l i t u d e sn o r m a l to t h e r h o d i u m - c h l o r i n e p l a n a r r i n g t h a n i n i t.H o w e v e r , t h e v i b r a t i o n s o f t h e r h o d i u m a t o m s a r ee s s e n t i a l l y i s o tr o p i c . T h i s w e b e l i e v e i s r e a s o n a b l e o nt h e b a s i s o f t h e m o l e c u l a r s t ru c t u r e . S i n c e t h e r h o d i u ma t o m s a r e v i b r a t i n g i s o t r o p i c a l l y , l i t t l e i m p r o v e m e n ti n a g r e e m e n t b e t w e e n o b s e r v e d a n d c a l c u l a te d s t ru c -t u r e a m p l i t u d e s s h o u l d r e s u l t w h e n t h e h e a v y a t o m sa r e a l l o w e d to v i b r a t e a n i s o t ro p i c a l ly . I n c i d e n t a l l y ,t h e v a l u e s o f t h e r e l i a b i l i t y f a c t o r a n d e r r o r o f fi tf u n c t i o n f o r F c c a l c u l a t e d w i t h o m i s s i o n o f t h e c a r b o n -a t o m c o n t r i b u t i o n s a n d w i t h ( a ) i s o tr o p ic t h e r m a lp a r a m e t e r s a n d (b) a n i s o t ro p i c t h e r m a l p a r a m e t e r s

    t We are indebted to Prof . D. H. T empleton for a discuss ionin which he pointed thi s fac t out to us .

    o n t h e h e a v y a t o m s a r e ( a ) 0 . 1 62 a n d 1 2 .0 9 , a n d 0 . 1 5 7 a n d 1 1 . 8 8 .S i n c e t h e a n i s o t ro p i c t h e r m a l p a r a m e t e r s a r e s es i t i v e t o s y s t e m a t i c e r r o r s i n t h e d a t a , t h e r e s u l t s T a b l e 3 w o u l d s e e m t o i n d i c a t e , i n s o f a r a s t h e y a g rw i t h o u r e x p e c t a t i o n s c o n c e r n i n g th e n a t u r e o f tv i b r a t i o n s o f a to m s i n t h e m o l e c u le , t h a t s y s t e m ae r r o r s in th e d a t a a r e n o t s e r io u s . O n t h e o t h e r h a ns y s t e m a t i c e r ro r s i n th e d a t a m i g h t p o s s i b l y b e te x p l a n a t i o n fo r t h e t h e r m a l p a r a m e t e r o f a to m ( T a b l e 1 ) . (S e e F i g . 1 f o r t h e d e s i g n a t i o n o f a t o mT h e i s o t r o p i c t h e r m a l p a r a m e t e r o f a t o m 4 ' i s sn i f i c a n t l y h i g h e r ( a t t h e 1 % l e v e l) t h a n t h e m ev a l u e o f 4 .3 _+ 1 .4 A e d e r i v e d f r o m t h e i n d i v i d ut h e r m a l p a r a m e t e r s o f t h e o t h e r f i f t e e n c a r b o n a t o m( N o n e o f t h e s e d i f f e r s s i g n i f i c a n t l y f r o m a n o t h eT h e r e i s n o s t r u c t u r a l e x p l a n a t i o n f o r th i s . O f c o u rt h e h i g h t h e r m a l p a r a m e t e r m i g h t i n d i c a te t ha t o m 4 ' is m i s p l a c e d s li g h t l y f r o m m i n i m u m p o s i t i( R o s s m a n n et al., 1 9 59 ). B e c a u s e o f t h i s , a n d b e c a ut h e d a t a o f T a b l e 1 l e a d t o r i n g s w i t h o b v i o u s d i s tot io n s , f u r t h e r r e f i n e m e n t s w e re a t t e m p t e d i n w hp a r t i c u l a r c a r b o n a t o m s , s u c h a s 4 ', o r p a r t i c ug r o u p s o f c a r b o n a t o m s , w e r e d e l i b e r a t e l y d i s p l a cf r o m t h e p o s i t i o n s o f T a b l e 1 t o ' m o r e r e a s o n a bp o s i t i o n s . I n a l l ca s e s a f te r a f e w c y c l e s t h e a t o mp o s i t i o n s w e r e t h o s e o f T a b l e 1 . T h i s r e s u l t , w h i l ep r o v i d e s n o e x p l a n a t i o n f o r t h e h i g h t h e r m a l p a r ae t e r v a l u e f o r 4 ' , i s c o m f o r t i n g , f o r i t m a k e s i t s el i k e l y t h a t t h e r e f i n e m e n t h a s c o n v e r g e d t o a t rm i n i m u m i n m u l t i - d i m e n s i o n a l s p a c e. A c h e c k o f tc o r r e l a t i o n m a t r i x r e v e a l s n o u n u s u a l c o r r e l a t i ob e t w e e n B o f a t o m 4 ' a n d o t h e r v a r i a b l e s. A s m et i o n e d a b o v e s y s t e m a t i c e rr o rs i n t h e d a t a m i g h t t h e e x p l a n a t i o n fo r t h e h i g h t h e r m a l p a r a m e t e r a t o m 4 ' . H o w e v e r , o n th e F o u r i e r m a p , w h i c hb a s e d o n a w e i g h t i n g s c h e m e v e r y d i f f e r e n t f r o m t hu s e d i n t h e l e a s t - s q u a r es c a l c u la t i o n , th e p e a k h e i go f a t o m 4 ' is o n l y a b o u t 7 5 % o f t h e a v e r a g e p eh e i g h t o f t h e c a r b o n a t o m s . T h u s , w e o ff e r n o p o s i tr e a s o n f or t h e h i g h v a l u e o f t h e t h e r m a l p a r a m eo f a t o m 4 ' .

    A s i n d i c a t e d i n th e n e x t s e c ti o n , t h e d a t a o f T a b ll e a d t o r i n g s w h i c h a r e d i s t o r t e d , a l t h o u g h t h e dt o r t io n s a r e n o t s i g n i f i c a n t w h e n a c c o u n t i s t a k e nt h e u n c e r t a i n t i e s i n t h e p o s i t i o n s o f i n d i v i d u a l c a r ba t o m s . A l t h o u g h i t w o u l d b e o f g r e a t i n t e r e s t t o c op a r e t h e p r e s e n t r e s u l t s w i t h t h o s e b a s e d o n a m o di n w h i c h t h e r i n g s w e r e c o n s t r a i n e d t o h a v e c e r t

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    928 STRUCTURE OF THE DIMER OF RHODIUM CHLORIDE 1 , 5 - C Y C L O O C T A D I E N Edimensions, the present case was not deemed to bea favorable one for a refinement with constraints.Such a refinement would be sensible (although itwould involve much labor) for a problem in whichthe data were more reliable than here and in whichthe contributions of the atoms in the rings to thestructure amplitudes were greater than they are here.

    e s c r i p t i o n o f t h e s t r u c t u r eThe structure defined by the parameters of Table 1and by the equivalent positions of the space groupis one in which individual molecules of (RhCl(CsH12))2of conformation depicted in Fig. 1 pack togethertightly, with a given cyclooctadiene ring in contactwith rings from three or four adjacent molecules.The cyclooctadiene rings have the boat configuration.Each rhodium atom is in an approximately square-planar configuration, being bonded to two chlorineatoms and to the double-bond centers of a cyclo-octadiene ring (Fig. 2). The closest approaches ofcarbon atoms from other molecules to a given rhodiumato m are 3.79, 4.03, and 4.07 A_ in directions notnormal to the plane of the double-bond centers,chlorine atoms, and rhodium atoms. Thus there isno evidence for a configuration other than d s p 2 forthe rhodium atoms. This configuration is markedlydifferent from that found by Dahl et al. (1961) forthe rhodium a toms i n (RhCl(CO)2)2. The proper tiesand reactions of these two compounds are similar,and thus one is reminded that it is often difficult tocorrelate molecular structure with physical properties.

    7

    3

    6Rh C I~ 1 , ~ ~ 8 , 7

    2 , ~ 4 '3'

    F i g . 1 . S k e t c h o f t h e R h C l - l , 5 - c y c l o o c t a d i e n e ) 2 m o l e c u l e .T h e r h o d i u m s , c h l or in e s , a n d d o u b l e - b o n d c e n t e r s a r e n e a r l yc o p l a n a r .There are two imperfections in the square-planararrangement of the rhodium atoms. First, a givenrhodium atom is closer to the double-bond centers(2.00 /~) th an to the chlorine atoms (2.38 /~), but thebond angles are only slightly different from 90 (Fig. 2). Second, the double-bond centers, chlorineatoms and rhodium atoms do not lie exactly in aplane. In Table 4 the equation of the formal (unitweight) least-squares plane is given, together with the

    deviations of the individual atoms and double-bondcenters from this plane. Only the deviations of thecMorine atoms are significant (at the 1% level);the two rhodium atoms and four double-bond centersdo not deviate significantly from the plane. Thedouble bonds are normal to this plane, within theaccuracy with which their directions are determinedin this study.

    C1

    90o _ .

    c1F i g . 2 . P r i n c i p a l b o n d d i s t a n c e s ( A ) a n d a n g l e s b e t w e e n t h eR h , C 1, a n d d o u b l e - b o n d c e n t e r s ( s y m b o l i z e d b y O ) .

    The packing of the molecules is tight. There is oneC-C intermolecular contact (between symmetry re-lated 5' atoms) which is 3.3 A; all other C-C inter-molecular contacts are 3-7/~ or longer. There are someC1-C intermolecular contacts as short as 3-65 A. Suchclose packing may be the explanation for the devia-tions of the chlorine atoms from the least-squaresplane.Table 4. Dev ia t ions i n A) o f a toms and double-bondcenters f ro m least-squares plane

    A t o m o r A t o m o rc e n t e r D e v i a t i o n c e n t e r D e v i a t i o nR h - - 0 . 0 1 0 1 - 2 0 - 12Rh' -- 0.003 5-6 0.04C] -- 0.16 1 -2 0.08Cl' --0.19 5--6 0.I1

    Equation of unit normal to the formal (unit weight)least-squares plane ism ---- - - 4 .5 89 b~ - t- 19.381 b 2 - - 2-8 05 b3

    ~vV " ~h e r ~ t h e b i s a re t h e r e c i p r o c a l l a t r i n e v e c t o r s . T h e o r i g i nt o p l a n e d i s t a n c e i s 3 .3 5 5 A . L e a s t - s q u a r e s p l a n e w a s b a s e do n e q u a t i o n ( 11 ) o f S c h o m a k e r e t a l . ( 1959) .

    Table 5 lists selected intramolecular bond distancesand angles. These have been computed with the helpo~ the Busi ng- Levy (1959b) error function programfrom the final least-squares output tape. The standarddeviations attached to individual distances and anglesare those derived in this way from the completeinverse error matrix and so include the effects ofcorrelation between variables. In Table 5 there arealso given for a given set of distances or angles,mean bond distances or mean b o n d an g l e s t o g e t h e rwith the standard deviation of an individual memberof the set on the assumption of equivalence. Thereare no significant deviations (5% level) of membersof a given set from the mean of the set, and so theensuing discussion is limited to mean distances andangles. Similarly, the distances and angles depictedin Fig. 2 are mean values.

    The Rh-C1 distance of 2.38 + 0.01 A is within t herange of 2-32 to 2.41 /~ tabulat-ed by Baenziger et al.(1961) for Pt-C1 and Pd-C1 distances. The distancealso compares well with the Rh-C1 distances of 2.33

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    J A M E S A . I B E R S A N DT a b l e 5 . Selected in tramoIecular bond d is tancesin t~) and angles

    D i s t a nc e A - BA - B d A - B ) a d A - B ))

    R h- R h ' 3 .498 0 -005Rh -C1 2.37 0.01Rh -C I ' 2 .38 0 .01Rh' -C 1 2 .39 0 .01Rh ' -C I ' 2 .39 0 .01

    2.38 0.01R h- 1 2 . 10 0 . 06R h- 2 2 . 07 0 . 04R h- 5 2 . 18 0 - 05R h- 6 2 . 10 0 . 05R h ' - l ' 2 .1 3 0 .0 5R h ' - 2 ' 2 . 13 0 . 06R h ' - 5 ' 2 . 14 0 . 05R h ' - 6 ' 2 . 14 0 . 05

    A- B d A-B) a d A-B) )Cl-CI 3.22 0.02Rh-3 3 .09 0-06R h- 4 2 . 98 0 . 06Rh-7 3 .12 0 .05R h- 8 3 . 04 0 . 05R h ' - 3 ' 3 . 10 0 . 06R h ' - 4 ' 3 .05 0 . 10R h ' - 7 ' 3 .07 0 -06R h ' - 8 ' 2 . 84 0 . 06

    3.04 0.091-2 1.52 0.075-6 1-42 0.071 ' -2 ' 1 .36 0 .075 ' -6 ' 1 .44 0 .06

    2-12 0.03 1.44 0.072-3 1 .54 0 .04 1-6 2 .69 0 .083-4 1.43 0-09 2-5 2.81 0.074-5 1 .59 0 .09 1 ' -6 ' 2 .82 0-076-7 1.63 0.07 2' -5 ' 2.95 0.087-8 1-39 0.07 2-82 0.108-1 1.46 0.072 ' -3 ' 1 .61 0 .08 3-8 3 .21 0 .083 -4' 1.61 0.12 4-7 3.14 0.084 ' -5 ' 1 .58 0 .10 3 ' -8 ' 2 .95 0 .096' - 7' 1.50 0.07 4 ' -7 ' 3.27 0.117 ' -8 ' 1 .36 0 .088--1 ' 1-48 0.08 3.14 0.14

    1-52 0.09A ng l e s A - B - C

    A - B - C /_ A - B - C ) a / A - B - C ) )1-2-3 132 44 - 5 - 6 118 55-6- 7 125 48-1 -2 117 41 ' - 2 ' - 3 ' 119 54 ' - 5 ' - 6 ' 123 55- -6 ' -7 ' 130 58 ' - 1 ' - 2 ' 122 5

    123 62-3 -4 105 53-4-5 125 56-7 -8 110 47-8-1 118 52 -3' -4 113 53 ' - 4 ' - 5 ' 116 76 ' - 7 ' - 8 ' 106 57 ' - 8 ' - 1 ' 133 5

    116 10CI ' -R h-C 1 85 3 0- 4CI ' -Rh ' -C1 84.7 0 .4R h - C 1 - R h ' 94 .4 0 .5R h - C I ' - R h ' 9 4. 5 0 .5

    a n d 2 . 38 f o u n d b y D a M et al. ( 1961 ) i n ( l Z hC l ( C O ) e ) 9 .T h e l ~ h - R h d i s t a n c e o f 3 . 4 98 + _ 0 0 0 5 /~ m a y b ec o m p a r e d w i t h t h a t o f 3 -3 1 /~ i n th e c a r b o n y l a n d

    R O B E R T G . S N Y D E R 9 2w i t h a P d - P d d i s t a n c e o f 3 . 4 6 A i n ( s t y r e n e - P d C l 2 ) 2( g o l d e n B a e n z i g e r , 1 9 5 5 ) a n d i n ( E t P d C l e ) 2 ( D e m p -s e y B a e n z i g e r , 1 9 5 5 ) . T h e d o u b l e - b o n d c e n t e r tr h o d i u m d i s t a n c e o f 2 . 0 0 i 0 . 0 4 / ~ c o m p a r e s w e l l w i t ht h e d o u b l e - b o n d c e n t e r t o p a l l a d i u m d i s t a n c e o2 . 0 4 ~ i n n o r b o r n a d i e n e d i c h l o r o p a l l a d i u m ( I I ) ( B a e nz i g e r e t a l . 1 9 6 1 ) .E v e n t h o u g h a c c o u n t h a s b e e n t a k e n o f t h e a n i s ot r o p i c n a t u r e o f t h e h e a v y a t o m v i b r a t i o n s t h e r i ng e o m e t r y i s n o t w e l l d e f i n e d . T h e s i n g l e b o n d s c a n n ob e d i s t i n g u i s h e d f r o m t h e ' d o u b l e ' b o n d s o n t h e b a s io f l e n g t h . O n t h e b a s i s o f t h e i r p o s i t i o n s r e l a t i v e tt h e r h o d i u m a t o m s t h e y c a n b e . T h e t w e l v e s i n gb o n d s a v e r a g e 1 . 5 2 0 - 0 9 ~ , w i t h n o i n d i v i d u as i g n i f i c a n t v a r i a t i o n s ( 5 % l e v el ) f r o m t h i s m e a n . T hf o u r d o u b l e b o n d s a v e r a g e 1 . 4 4 __ 0 . 0 7 - ~ w i t h ns i g n i f ic a n t v a r i a t io n s . T h i s v a l u e m a y b e c o m p a r ew i t h 1 .4 6 +_ 0 - 0 4 / ~ i n n o r b o r n a d i e n e d i c h l o r o - p a l l a d i u( I I ) a n d w i t h 1 . 4 3 _ +0 1 5 / ~ i n ( s t y r e n e - P d C 1 2 )( B a e n z i g e r et al. , 1 9 6 1) . T h e 9 5 % f i d u c i a l li m i t s ft h i s m e a n a n d s t a n d a r d d e v i a t i o n a r e 1 -3 5 a n d 1 . 5 3 /a n d s o t h e r e is a b o u t a 2 % c h a n c e t h a t t h e m e a n 1 . 44 ~ w i t h a s t a n d a r d d e v i a t i o n o f 0 . 0 7 J~, b a s eo n a s a m p l e s iz e o f f o u r , c a n b e f r o m a n o r m a l p o p u l at i o n w h o s e m e a n i s 1 . 34 J~ , t h e n o r m a l d o u b l e - b o nl e n g t h . I t i s t h u s l i k e l y t h a t t h e d o u b l e b o n d s 1 ,5 . cyc looc tad iene h a v e l e n g t h e n e d u p o n b e i ng b o n d et o th e r h o d i u m a t o m .A c o m p a r i s o n o f t h e i n f r a r e d s p e c t r u m ( R hC l (C s H 19 . )) 2 w i t h t h a t o f 1 , 5 - c y c l o o c t a d i e n e p r o v i dc o r r o b o r a t iv e e v i d e n c e fo r a w e a k e r d o u b l e - b o n d t h e c o m p l e x . A b a n d a t 1 6 57 c m . - 1, w h i c h o c c u r s t h e s p e c t r u m o f 1,5-cycIooctadiene a n d w h i c h a s s o c i a t e d w i t h C = C s t r e t c h i n g , d o e s n o t o c c u r i n ts p e c t r u m o f t h e c o m p l e x a t a f r e q u e n c y h i g h e r t h a1 47 5 c m . -1 , w h e r e t h e m e t h y l e n e d e f o r m a t i o n b a no c c u r s. W e w e r e u n a b l e t o i d e n t i f y t h e C = C s t r e t c h ib a n d i n th e s p e c t r u m o f t h e c o m p l e x , a n d i t i s p o s s ibt h a t i t oc c u rs a t a f r e q u e n c y c o n s i d e r a b l y l o w e r th1 4 7 5 cm . - 1 . * N o t a b l e a m o n g o t h e r d i f f e re n c e s b e t w et h e s p e c t r a i s a s h i f t in t h e f r e q u e n c y o f t h e o l e f ih y d r o g e n o u t - o f- p l a n e b e n d i n g m o d e . I n t h e s p e co f 1 , 5 cyc looc tad iene a n d o f m o s t o t h e r cis-o left h i s m o d e a p p e a r s a s a s t r o n g i n f r a re d b a n d n e6 7 5 c m . - 1. I n t h e c o m p l e x t h i s b a n d i s d i s p l a c e d h i g h e r f r e q u e n c ie s ( > 7 7 5 c m . -1 ) t o w a r d t h e r e g io f h y d r o g e n b e n d i n g f r e q u e n c i e s i n s a t u r a t e d m oc u l e s ( > 1 0 0 0 c m . - 1 ) .

    U n f o r t u n a t e l y i t i s n o t p o s s i b l e , o n t h e b a s i s o f i n f r a r e d d a t a , t o e s t i m a t e w i t h c o n f id e n c e t h e e x t eo f t h e l e n g t h e n i n g o f th e d o u b l e b o n d s i n t h e c o m p lT h e r e is a b o u t a 9 5 % c h a n c e th a t t h e d o u b l e b om e a n i s l es s t h a n t h e s i n g l e b o n d m e a n , t h a t i s, t ht h e d o u b l e b o n d s a n d s i ng l e b o n d s a r e fr o m d i f f erp o p u l a t i o n s . M o r e o v e r , t h e r e is a b o u t a 9 5 % c h a nt h a t t h e C - C - C a n g l e i s g r e a t e r t h a n t h e C - C

    * Fo r c om pa r i s on a C - C s i ng l e bond s t r e t c h i ng f r e quei s i n the r egion 1100-1000 cm. -1 .

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    930 S T R U C T U R E O F T H E D I M E R O F R H O D I U M C H L O R I D E 1 , 5 - C Y C L O O C T A D I E N Ea n g l e . I t s e e m s l i k e l y t h e n t h a t t h e ' d o u b l e ' b o n d si n t h e c o m p l e x a r e i n t e r m e d i a t e i n le n g t h t o a n o r m a ls i n g le a n d a n o r m a l d o u b l e b o n d .W e f e e l t h a t w e h a v e o b t a i n e d a l l o f t h e i n f o r m a t i o no n t h e r i n g g e o m e t r y w h i c h i s p o s s ib l e w i t h t h e p r e s e n tv i s u a l i n t e n s i t y d a t a . W e a g r e e w i t h B a e n z i g e r et al.( 19 6 1) t h a t i n t h is t y p e o f p r o b l e m b e t t e r d a t a a r ep r o b a b l y r e q u i r e d i f s ig n i f i c a n t i n f o r m a t i o n o n r i n gg e o m e t r y i s t o b e o b t a i n e d .

    R e f e r e n c e sBAENZIGER, N. C. , DO YLE , J . R. , RICHARD S, G. F .CARPENTER, C. L . (1961) . Advances in the Chemistryof Coordination Compounds, p . 1 3 1 . . N e w Y o r k : M a c -m i l l a n .B u s r ~ G , W . R . L E V Y , H . A . ( 1 95 9 a ). O a k R i d g e: N a t io n a l L a b o r a t o r y R e p o r t 5 9 -4 -3 7 .B us I N G , W. R . LEVY, H . A . ( 1959b). O ak R i dg e: N a ti o n a l L a b o r a t o r y R e p o r t 5 9 -1 2 -3 .Cm~TT, J . VENANZI, L . M. (1957) . J. Chem. Soc.p. 4735.

    DAHL, L. F . , MARTELL, C . WAr~-PT.ER, D. L. (196 1).J. Amer. Chem. Soc. 83, 1761.DAWSON, B. (1960). Acta Cryst. 13, 403.DEMPSEY, J. :N. BAENZIQER, N. C. (1955). J. Amer.Chem. Soc. 77, 4984.H A MIL TO N , W. C . (1961). Pa pe r H - 5 , A m er . C r ys t . A ssn .M e e t i n g , B o u l d e r , C o l o r a d o , J u l y 3 1 - A u g u s t 4 .HOERNI, J . A. IBERS, J . A. (1954) . Acta Cryst. 7, 744.HOT,DEN, J . R . BAEN ZmER , N. C. (1955) . J. Amer.Chem. Soc. 77 , 4987 .HUGHES, E . W . (1941) . J. Amer. Chem. Soc. 63, 1737.IBERS, J . A. (1956) . Acta Cryst. 9, 652.IBE~S, J . A. CRO~ER, D. T . (1958) . Acta Cryst. 1 1 , 7 9 4 .IBERS, J. A. S~-YDER, R. G. (1962). J. Amer. Chem. Soc.84, 495.ROSSMANN, M. G. , JACOBSON, R. A. , Hn~SHFELD, F. L .LIPSCOMB, W . N . (1959). Acta Cryst. 12, 530.SCHOMAKER, V., W ASER, J . , MA RSH, R . E . BERGM_AN, G.(1959). Acta Cryst. 12, 600.SHOEMAKER, D. P. DONOHUE J . , SCHOMAKER, V.COREY, R. B. (1950). J. Amer. Chem. Soc. 72 , 2328 .TEMPLETON, D . H. (1962). International Tables for X rayCrystallography. Vol . 3 , Sect ion 3.3 .2 .THOMAS, L . H. UMEDA, K. (1957) . J. Chem. Phys. 2 6 ,293.

    Acts Cryst. (1962) . 15, 930T h e r y s t a l S t r u c t u r e o f I r o n P e n t a c a r b o n y l

    B Y A . W . HANSONDivision of Pure Physics, National Research Council, Ottawa, Canada

    Received 4 December 1961)I r o n p e n t a c a r b o n y l a t - 8 0 C . i s m o n o c l in i c , p r o b a b l y Cc, w i t h

    a = 1 1 . 7 1, b = 6 . 8 0 , c = 9 . 2 8 A ; f l= 1 0 7 .6 ; Z = 4 .I n t e n s i t i e s w e r e c o l l e c te d f o r t h e t h r e e z o n e s [ 0 10 ], [ 0 0 1] , a n d [ 11 0 ] a t t e m p e r a t u r e s r a n g i n g f r o m- - 7 0 to - - 1 1 0 C . T h e c r y s t a l s tr u c t u r e w a s d e t e r m i n e d b y h e a v y - a t o m m e t h o d s , a n d r e f i n e d w i t ht h e a i d o f tw o - d i m e n s i o n a l F o u r i e r s y n t h e s e s . T h e m o l e c u l e h a s t h e e x p e c t e d f o r m o f a t r i g o n a lb i p y r a m i d , b u t i s s l i g h t l y d i s t o r t e d i n s u c h a w a y a s t o a l l o w c l o se r p a c k i n g .

    I n t r o d u c t i o nE w e n s L i s t e r ( 19 3 9) h a v e s h o w n b y e l e c t ro n -d i f f r a c t i o n s t u d i e s o f t h e g a s t h a t t h e m o l e c u l e o f i r o npentacarb0ny l Fe C0)s) has the f0 rm 0f a tr ig0nalb i p y r a m i d . H o w e v e r , r e c e n t i n v e s t i g a t io n s i n t h eD i v i s i o n o f P u r e C h e m i s t r y h a v e m a d e i t d e s i ra b l et o c o n f i r m t h i s i m p o r t a n t r e s u l t b y c r y s t a l - s t ru c t u r ea n a l y s i s .

    E x p e r i m e n t a l d e t a i l sI r o n p e n t a c a r b o n y l i s a s t ra w - c o l o u r e d l i q u i d w h i c hf re e z es a t - 2 0 C. T h e X - r a y d a t a w e r e o b t a i n e df r o m p r e c e ss i o n a n d W e i s s e n b e r g p h o t o g r a p h s t a k e n

    a t t e m p e r a t u r e s r a n g i n g fr o m - - 7 0 to - - 1 1 0 C.D i s t i l l e d m a t e r i a l w a s s e a l e d i n a th i n - w a l l e d g l a s sc a p i l l a r y o f a b o u t 0 . 4 r a m . d i a m e t e r , a n d s i n g l e c r y s t a l sw e r e g r o w n b y a l t e r n a t e s lo w f re e z i n g a n d p a r t i u lm e l t i n g o f t h e s a m p l e . S u i t a b l e c r y s t a l s w e r e e a s yt o g ro w , b u t w h e n c o o le d to t h e w o r k i n g t e m p e r a t u r et h e y i n v a r i a b l y s p l it in t o t w o o r m o r e f r a g m e n t s .S o m e t i m e s t h e d a m a g e t o t h e c r y s t a l w as c o m p a r a -t i v e l y s li g h t, a n d t h e p h o t o g r a p h s w e r e u s a b le . A l lt h e X - r a y d a t a h a v e b e e n o b t a i n e d f r o m s u c h p h ot o -g r a p h s . M o K ~ r a d i a t i o n w a s u s e d t h r o u g h o u t .

    T h e c r y s t a l d a t a a t - 8 0 C. ( o b t a i n e d fr o m p r e c es -s i o n p h o t o g r a p h s ) a r e