Indian Journal o f Chemi stry VoL 44A. August 2005. pp. 1576- 158 1 - .-

Magnetic and spectroscopic characterization of copper(II) chlorobenzoate adducts with substituted piperidir;es

B S Manhasa, S B Kaliab.* , A K Sardanaa & G Kaushal b

"Department of Chemi stry" punj~i Uni \lS rsity, Pati ala 147002. Indi a "Dcpartment o f Chemistry. Himachal Pradesh University. Shimla 171 OOs:Tridi a

Email: shashibalakali a@redifTmail .co m

Received 17 Janlla ry 2005: revised 25 Mal' 2005

Copper(ll ) chlorobenzoates react with substituted piperidines in an organic medium to give solid compl exes havi ng gencral formula ICu(OOCRh( L)] (R = 2-.3- or 4-CIC6H~ and L = I-methyl. I-c thyl and 2.6-dimethylpipe rid inc). All the complexes with copper(ll ) chlo robenzoates are of I : I stoichio metry irrespecti ve o f the a mount o f the ligand added and have been shown by phys ico-chemi cal methods to be binuclear. containing bidentate bridging carboxylate gmup except ICu(OOCC6H4CI -4 h (2.6-M e2 Pipd)] fo r which po lymeric square pyramidal structure has been proposed . All the compl exes show anti ferro magnetic behavio ur with the exception o f [Cu(OOCC6H4CI-4h(2.6-Me2Pipd)] which is paramagnetic. The spin exchange parameter. -21, fo r two o f the compl exes has been evaluated from magneti c suscepti bility measurements at diffe renttcmperatures. which corresponds to ax ial binuclear copper(ll ) compl exes with S = I.

(PC Code Int. CI 7 C07 FI/08

Copper(II) carboxylates generally form I : I , I :2, 1:3 or 1:4 complexes with unidentate ligands, while with the bidentate ligand they commonly form L:0.5, 1: I or 1:2 complexes. Different poss ible coordination characteristics of the carboxylate group lead to the exi stence of mononuclear, binuclear Oir polynuclear structures of complexes. Literature survey of copper(U) carboxylates and saturated heterocyc lic bases show that very fe w attempts have been made to study the comple xation propelties of these bases with copper( lI) arylcarboxylates. In continuation of our earlier publi shed work I , the present in vestiga tion on the complexes of rC u(OOCRhCL)] (R = 2-,3- or 4-ClC6H4) with saturated monoheterocyclic bases (L)

such as I-methyl piperidine ( I-M ePipd ), I-ethyl­piperidi ne (l-EtPipd). and 2,6-dimethylpiperidine (2,6-Me2Pipd ) has been undertaken to see the role of pK" of the parent carboxylic acid in structure determination and the effect of steric and e lectronic properties o f the bases on the sto ichiometry, magnetic behav iour and structure of the complexes. Such a study with pyridine type li gands has earli er been the subject of syste matic in vesti ga ti ons2

.

Materials and Methods T he bases , I-MePipd, l-EtPipd . and 2.6-Me2Pipd

(A ldrich C hemical s or K and K laboratories) were

dried by refiu xing over sodium hydroxide beads. The colourless liquids obtained afte r d istillati on were stored over sodium hydroxide beads.

Preparation of Copper(lI) chlorobenzoates (0-, 111- aud po)

To the solution of 0-, 111- or p- chlorobenzoic ac id (Si sco) (5 g, 3 1.92 mmol ) in the mini mum quantity o f acetone (30 mL), a solution of sodium hydroxide 0 .277 g, 31.92 mmol) in distilled water (8 mL) was added dropwi se with stirring at room te mpe rature. The pH of the resulting solution of sodium chl orobenzoale was then adjusted to 5 by adding an appropriate amount of chlorobenzoic ac id. A filtered solution of copper(II) sulphate pentahydrate (3.987 g, 15 .96 mmol) in di stilled wa ter (28 mL) was then added to the stirred solution of sodium chlorobenzoate . The prec ipitate, thus obtained, was filtered . washed with distilled water and dried in air. It was then d ried at 140°C fo r 3 h.

Preparation of the complexes Copper(U) chl orobenzoate (l g, 2.67 mmol) was

suspended in e ther (30 mL) in a round bottom fl ask. A solution of stoichiornetJ;c amount or 50% excess (Table I) of heterocycli c base in the same solvent ( 15 mL) wa s added dropwise after success ive interva ls of 10 min in a total peri od of about 2.5 h to the conti nuously stilTed suspension of copper(II) chlorobenzoate. S ince copper(lf)

M AN HAS el al.: CHA RACT ERIZ AT ION OF COPPER(I1) CHLOROBENZOATE ADDUCTS 1577

Table I-Elemental analys is, colour and parti culars of the method of preparati on 0" the complexes

Compd Yield Found (Calc.) % Colour *S. A .I Decomp

(Comp) [Formu la weight] ('Yo) Cu C

rCu(OOCC6H.jCI-4h( I -MePipd)J 80 13.0S SO.S6 (C2oH21 N0 4CI2Cu) [473 .S] ( 13.4 1 ) (SO 70) rCu(OOCCr,H4CI-4h( I -EtPipd) J 8S 12.91 SI .45 (ClI H,3N0 4C12CU) 1487.SI ( 13.03) (51.70) [Cu(OOCC6H4CI-4l2(2.6-Mez Pipd) I 70 13.28 SI.54 (CzI H2:\NO.jClzlu) [487.SJ ( 13.03) (S I 70) I Cu(OOCC6H4CI-3h( I -MePi pd) ] 80 13.37 50.28 (C2oHzIN0 4C1 ICU) [473.5 ] ( 134 1) (50.70) [Cu(OOCCr,H4CI-3h( I -EtPipd) I 80 1275 5 1.90 (C1I H13NO.jCll CU) 1487 .5] ( 13.03) (5 1.70) I Cu(OOCC6H.jC I-3h(2,6- Mc2 Pipdl 70 13.5 1 5 1.48 (C1I H23NO.jCIICU) 1487.S] ( 13.03) (5 1 70) ICu(OOCC6H4CI-2)z( I -MePipd)] 8S 1332 50.88 (CloHzIN0 4CI2CU) [473.5 J ( 134 1) (SO.70) [Cu(OOCC6H4CI-2lz( I -EtPipd) I 80 12.96 5 1.47 (C2I Hz3N0 4CI2Cu) [487.5] ( 13 03) (S I .70) [Cu(OOCC6H4CI-2h(2.6-Mcz Pipd)] 70 12.97 5 1.95 (CII Hn N0 4C1zCu) [487.51 ( 13.03) (5 1.70)

*Soichiomctri c amount (S.A. ) or in excess

ch lorobenzoate has been take n as its suspe nsIOn III

ether (and not its solution), the drop-w ise additi on of the base soluti on in ethe r is do ne in order to e nsure comp letion of the reacti on. The coloured adducts of the bases (Table I ) separated afte r the conte nts had been stirred for another 2 h. The separated produc t was filtered in a G4 f iltrat ion unit, washed with diethyl ether, dr ied under vac uum and placed in a des iccator conta ining anhydrous calcium ch loride .

Elemental analyses and physical measurements Copper in the complexes was dete rmined by E DT A

ti trali on using xy leno l o range as indicator. Carbon, hydrogen analyses were pe rfo rmed on an auto matic Coleman-33 anal yze r, w hi le nitrogen was estimated by Kj e ldahl's method in the departmenta l mi croanalytica l laboratory. Chl oride content was determined by Vol hard's method .

rR of copper(IJ) chlo robenzoate (0- and In-) complexes with hete rocyclic bases and the ir anhydrous sodium chl orobenzoates were recorded as KBr pellets on Pye-U nicam SP3-300 infrared spec trophotometer in 4000-200 cm-I region. whi le IR o f the p -c hl orobenzoate complexes were recorded on Nicole t 5DX infrared spec trophoto mete r in 4000-200 cm·1 reg ion. E lec tro nic re nectancc spec tra of the complexes (sa mples were e ithe r neat or di luted with MgC0 3) were recorded o n U ni cam SP-700 U.V . vis ib le spec trophoto mete r hav ing SP-735 diffuse re nec tance attac hment (range: 50 ,000-4.000 em-I). The X-band EPR meas urements (9.439-9.442 GHz)

H N CI Excess (0C)

4.23 3.2 1 14.46 Blui sh Excess 240 (4.47) (2 .96) ( 14.96) green S.04 3.35 14. 11 Blui sh Excess 245

(4.7S) (2.87) ( 14.S3) green S. 14 32 1 14.23 Light S.A 200

(47S) (287) ( 14.53) violet 4.8 1 3. 12 15 .04 Green Excess 235

(44 7) (2.96) ( 14.96) 4.7 1 2.93 14.12 L ight Excess 240

(4.75) (2.87) ( 14.53 ) green 4.64 2.69 14.42 Light SA 195

(4.75) (2.87) ( 14.53) bl ue 4.97 3. 11 14.56 Light Exccss 220

(4 .47) (2.96) ( 14.96) green 4.28 3. 01 14.08 Greenish Excess 220

(4.75) (2.87) ( 14.S3) blue 4.77 3.25 14.24 Sky blue SA 190

(4. 75) (2.87) ( 14.53)

of powdered materi a ls at room te mperature were made o n a JES-FE3 XG e lectron paramagnetic resonance spec tromete r. Diphenylpicry lhydrazy l (DPPH) was used as ca librant.

Room-te mperature magne tic susceptibi I ity of a ll the compl exes was measured on a Go uy balance using Hg[Co(NCS) .. ] as ca librant. The magnetic susceptibi lity of two of the complexes at diffe rent te mpe ratures was measured on Vibra ting Sample Magneto mete r PA R -155 with vari able-temperature c ryos tat. The meas ured susceptibili ty was corrected for the di amagnetic suscepti bi lity of the I igands. T he correcti on for te mperature independent

pa ra magnet ism was take n as 60x 10-6 cgs units per gra m ato m of copper(II) ions.

Results and Discussion Copper(II) chlorobenzoates were prepared by

reacting aqueous solut ion of copper(II) sulfate with sto ichi o metric amo unts of sodium sa lts of the corresponding chl orobenzoic ac id in J: J water­acetone mi xture . Synthes is of the adduc ts of copper(IO c hlo robe nzoates with substit uted piperidines was perfo rmed by reac ting the ir ethe r soluti ons in swichio metric amounts and 50% excess o f sto ic hi o metric amo unts of the bases, whereby onl y comp lexes o f the I : 1 sto ichiometry were obta ined by the equati ons:

HOOC R + NaOH -> aOOCR + H20 . . . ( I )

15 78 INDIAN J CHEM. SEC A, AUGUST 2005

2(NaOOCR) + CuS04.5 H}0 ->

Cu(OOCRh + Na2S04 + 5H20

Cu(OOCR h + L -> ICu(OOCRh L]

.. (2 )

. (3 )

(R = 2-. 3- or 4-CiC(,H-I and L = I-M ePi pd . I-EtPipd and 2.6-Me2Pipd )

The comp lexes are in soluble in o rganic solvents and do not me lt. but decompose aro und 250°C. C hem ical formulae based upon e le mental analyses, colour and particulars of the me thod of preparati on of complex es are li sted in Table I .

IR studies

The structural possibi I ities and stoichi o metry of the comp lexes [C u(OOCR h LI depe nd upon the mode of coordination of the carboxylate g roup and the monoheterocyc I ic bases, the substituted pi peridi nes. IR studies are quite useful in de termining the mode of coordination of these ligands. On crit ically exa mining the position and direction of the shifts of the v,,(OCO) and vl OCO) of the carboxylate g roup in the complexes, as compared to the ir position s in the sodium salts of the respective ac ids, the bridging bidentate mode of coordination can be suggested for

all the complexes' (Tabl e 2). A shift to th l" lower ene rgy reg ion (-40 cm· l

) of the band due to v(N-H) vi bration in the complexes re lati ve to those in the free bases (-3300 cm· l

) indicates the coordination of the bases throug h nitrogen atom of thei r .\I-H bond -l·). Additional bands in the complexes . by co mpari son with the IR spectra of uncompl exed co ppe r( ll ) c hl o ro benzoates and free bases in the reg io ns 415-465 c m· 1 and 275-305 cm· l

• te ntative ly have I:)ecn assigned to v(Cu-O) and v(Cu-N ) modes, respec tivel/'('.

Elcctronic rellcctance spectral studies

Tabl e 3 shows thaI monohe terocyc lic ba scs. substituted pipe ridines form anti f 'rromag ne ti c complexes w ith copper(I1) chlorobenzoates but w ith the exception of ICu(00CC6H4Ci-4)2(2,6-Me2Pipd )]. For the anti ferromagnetic compl exes , two absorptions , one as a broad band in the region 12,500-13,890 cm-I (band J) and the other as a shoulder around 33.900-37,000 cm· 1 (band II ) are observed. Band I ma y be due to absorption corresponding to the dxy ---+ dx'2./· and dxz,dyz ---+ d/ .y2 e lectronic transitions

for the copper(lI) ion in tetragonal envi ronments7. The

band (II) can be assigned to the 2Prr(0 )---+(dx2.y2)*

Tahle 2-Some coordinativc ly diagnostic reatures or thc IR spcctra (c m-I) or sodium salts or chlorobcnzcatcs

and thcir copper(lI ) complexes

Comp. v(N-Hl va(OCO) v/OCO) v(Cu·O) v(Cu-N) Suggestcd modc or bi ndi ng

4·CIC(,H.COONa 1540 1400 3-C1C6H4COONa 1550 1390 2-CICuH_ICOONa 1575 1385 ICu(00CC(,H.CI-4)z( I -MePipd)1 1580 1395 468 300 Bridging bidentate ICu(00CCuH4CI-4M I-EtPipdl] 155 1 1402 460 303 Bridgi ng bidentatc I Cu(00CC6H4C1·4h(2.6-MeL Pipd)] 155 1 1395 468 300 Bridging bideillatc rC u(00CC(,H4CI-3)1( I·McPipd)] 1550 1392 430 290 Bridging bidcntate I Cu(00CCuH4CI-3)!C I -EtPipd)J 1580 1390 450 300 Bridging bidentate I Cu(00CC(,H4CI -3)2(2.6·Me2Pipd) I 3 160 1585 1395 415 290 Bridging hidcntate ICu(00CC6H4CI ·2h ( I ·McPipd)l 1595 1395 430 275 Bridgmg bidcntal.c ICu(00CCc,H4CI-2)2( I -EtPipd)] 1580 1405 420 305 Bridgmg bidentatc ICu(00CC(,H.CI·2h (2.6· Mc2Pi pd)1 3235 1565 1400 420 305 Bridging hidclllate

Tablc 3 - Electronic rell cctancc spectral data (cm-I) and room-tcmperaturc ~df valucs or thc magnetically dilute and antilc rromagnctic adducts or coppcr(l l) chlorobcnzoates with substituted piperidines.

Compo

I Cu(00CC6H-lCI·4)1(2 .6-Mc2Pipd)J rCu(00CC6H4CI·4h( I -McPipd)J rCu(00CC6H-lCI·4hC I-EtPipd)] IClI(00CC6 f-1 -lC I-3)1( I -MePipd) I rClI (00CC6H4CI-3)2( I -EtPipd)] ICu(00CC61 LICI ·3M2,6-Me2Pipd)] IClI(00CC6H-lCI·2h( I·MePipd)l [ClI(00CCuH4CI·2h( I·EtPipd)J [Cu(00CC6H4C1-2h(2,6-MelPipd)]

Absorpti on I (d·d trans itions)

14.925: 19.800 13,515 13. 160 12.660 13.425 13.335 12.500 12,820 13.890

Absorption II (Ligand ->ml.:tal charge transfer transition:;)

37.035

33.335 35,715 35.7 15 35,7 15 35.7 15 33.900

Ileff (B.M .)

2098 1.64 1.41 1.65 1.63 1.66 1.54 1.48 1.62

M ANH AS el al. CHARACTERIZATION OF COPPER(II) CHLOROBENZOATE A DDUCTS 1579

Table 4 - EPR spectral parametcrs. spin exchange parameter [-21 (cm·I) ] of anti ferromagnetic copper(II ) complexes and pK. or axial li gand and carboxylic acid.

Compo gil g"" IDI(cm-l) Carboxylic Axial l igand M agnetic

susceptibi l i ty (-21)

[Cu(OOCC6H4C1-4)2 2. 127 1 2.464 1 2.2394 ( I-McPipd)] [CIJ(OOCC6H4C1-4h 2. 1246 2.4639 2.2377 ( I -EtPipd)] /Cu(OOCC6H4CI-3)2 2. 11 86 2.4529 2.2300 ( I -McPipd)] [Cu(OOCC6H4CI-3h 2.11 84 2.409 1 2.2 153 ( I -EtPipd)] [Cu(OOCC6H4CI-3h 2. 11 58 2.4644 2.2320 (2.6-M c2Pipd)] rClI(OOCC6H4CI-2h 2. 1369 2 3878 2.2205 ( I -MePipd)] rClI(OOCC6H4CI-2h 2.0789 2.4 199 2.1 926 ( I -EtPipd)] [Cu(OOCC6H4CI-2)2 2. 11 80 2.52 19 2.2526 (2.6-Mc2Pipd) I

charge-transfer transition , the appearance of thi s band is considered to be characte ri sti c of the dimeric structure for the copper(TT) carboxylate complexes7

-9

. The magnetically dilute complex, viz. , [Cu(OOCC,~CI-

4h(2,6-Me2Pipd)] exhibits the splitting of the d-d band resulting in the appearance of two bands at 19,800 cm' l and 14,925 c m' l. Here, the di ffe re nce be tween the two 'd-d' trans itions is apparently large r. The splitting of the band due to 2T 2g ~ 2E g transitio n into two bands has been attributed to the l ahn-Telle r effect in copper(l!) compl exes. Moreover, in the present case , the complexes are bound to be di storted due to the large di fference in the li gand fi e ld strengths o f carboxylate ligand and the bases.

ESR studies The X-band EPR c urve of powdered materia l for

the magnetically dilute copper(II) complex, Cu(OOCC6H.jCl -4M2.6-Me2Pipd), at room-temperature is consistent wi th axial symmetry of the complex . The magnitude of 8 11 (2 .2681) and 8.1(2.0437) obtained from the EPR spectrum of the

compl ex is consistent (g il > 8.1 > 2.04) with an

e longated tetragonal type structure , which agrees with the results obtained from e lectron absorptio n studies lo.ll . The observed value o f g il is in confo rmity with the Cu04N2 chromophore of the complex 12. The X-band EPR spectra at roo m te mperature for powdered samples of anti fe rro magnetic compl exes (Table 4) under present di sc ussion contain absorption lines at fi e ld strengths of 600 (Hz l ) , 4700 (H.i) and

6100 (Hd, whi ch are characte ri stic features of ax ially

acid pl(, pK"

0.3754

0.3753

0.4009

0.37 12

0.38 12 3.824 11 .070 230

0.3568

0_3743

0.4033 2.922 11 .070 239

symmetric binuc lear copper(Il) spec ies and correspond to the spin triplet state (5 = 1) with D > hv (D , the zero-fie ld splitting parameter for the triplet state) and E = 0 13.14. The range of gil or 8z (2.38-2.52), 8.1

(2.08-2.13) and D (0.37-0.40 cm' l) e valuated from the EPR spec tra are comparable with the earlie r reported values for binuclear copper(II) ary l carboxy late complexes2. 15.IG.

Magnetic susceptibility studies .-' With the exception of [Cu(OOCC6H4C I-4h

(2,6-Me2Pipd)] (J.4rr = 2.098 ly ing above the spin only value of 1.73 B .M . and hence magneticall y dilute) , the room-te mperature Pd f values for a ll other copper(II) complexes li e in the range 1.41-1.66 B. M . (T able 3) which is less than the spin-onl y va lue for one unpaired e lectron ( 1.73). These values are, however, close to the values reported for dinuclear or po lynuc lear copper(II) carboxylate complexes in which the carboxy late gro up is ac ting as a bridge between two metal ionsl ),IG. and spin-spin inte racti ons ex ist. T wo of the co mplexes, have a lso been characte ri zed by magnetic susceptibility measurements at di f fe rent temperatures. The magnetic moment values fo r these complexes decrease with te mperature thus confirming the ir anti fe rromagnetic behaviour. The spin-exchange parameter (-21) from the magnetic susceptibility da ta at diffe rent tempe ratures for the comple xes, VIZ .,

[C u(OOCC6H4C I-n)2 (2,6-Me2Pipd)] (n = 3 and 2) Xc" x 106 at 294 K ; 160 K; 100 K ; 80 K = 11 80; 1167; 1665; 1336 and 18 17 ; 156 1; 2090; 1673 forn = 3 'and

1580 INDI AN J CHEM . SEC A. AUGUST 2005

2 respect ive ly) has been evaluated (Table 4) using the foll ow ing modified equation based upo n 13 leaney and Bower's mode l '7.

,J Nji2p" (I _ x) -3j=_ 2JI

l { (J. ./3x ' I k T k7 Xr - --- N J

\ ~ " T /I

.(4)

or 1111 F - 3) = - :! .IlkT

T he unknown quantities in Eq.(4) were ta ken as follows' s: the value of g was determ ined from EPR

measurements and the va lue of Na was taken to be 60x 10-6 cgs units. The value of x (in the above express ion), the mole fraction of the paramagnetic impurity was so chosen as to fit in well with the above express ion . The va lue of 21 has been dete rmined from the slope of I 21/k] of the strai ght line obtained from a pl ot of InCF-3) vs J/T. Inspite of the high basicities of the bases used ( pk" = 8-9 ), the range of va lues of 21 is comparab le to that for the ea rl ie r reported copper(II) carboxylate complexes with te rminal ligands of low basicity, e.g., py, etc. and no consistent trend of the variation o f -21 with pk,, 's of the acids or ligands is obtained. This result is disappo intil,g. But in view of the earli e r repol1s, it is not surpri sing.

In the present study, for the complexes obtained in I: I sto ic hio metry of the type IC u(OOCRh LI , I-MePipd and I-EtPipd form anti ferromagnetic complexes with all copper(Il) chlorobenzoaets used. While with (2,6-Me2Pipd). the complex with copper(H) 4-chlorobenzoate has been found to be magnet ically dilute. On the bas is of a ll the studies, for the antiferromagnetic complexes of 1: 1 stoichiometry, binuclear copper(II) ;1Cetate monohydrate like structure (Fig. la) where carboxy late group acts as a syn-syn bridging bidentate li gand is ass igned. For the complex [Cu(00CC6H4C I-4M2,6-Me2Pipd)]. poly­meric sq uare pyramidal structure (Fig:. I b) where carboxylate group acts as a bridg ing biclentate ligand is assi gned.

T he study of anti ferromagnetic inte rac tions in copper(II ) arylcarb0xy late complexes had been considered to be of spec ia l inte rest since predic table vanatlon in the e lec tron donor properties of arylcarboxylate group can be effected much more easily by vary ing the substituent and its position on the a ry l ring. However. attempts at arri ving at a finn corre lat ion between -21 valiles and the donor ability of the arylcarboxy late ani on or pk" of the paren t ac id

L=

Fig. l a - Proposed structure lo r thc complcx I(CuOOCRh L I (R = 2-: 3-: or 4-CIC(,l-IJ : L= I-Mcthylpipelidineor I-Bhylpipc:idinc: RI= CHI orC2H,: R2 = R, = ~ = Rs = Ru= H and =2.6-Dimcth ylpipcridinc : R2 = Rc. = CH, : RI = R, = R4 = Rs = 1-/ ).

Fig. I b - Proposcd structure rCu(OOCCr,H4CI-4h (2.6-Mc2Pipd)1.

have been frustrating2• Thi s is partly because, 111

gene ral , the -21 va lues for arylcarboxyl ates are lower than in a lkylcarboxy lates and data for certa in reasons are imprec ise2. Conseque ntly , the va ri ation in them is small and often unre li ab le; the diffe rences may well be of the order of experimental e rror. T he gene ral lack of correlation between the exte nt of an ti fe rro magnet ic inte raction and the pk,,'s and the donor strength of the li gands (te rminal ligand and bridging carboxy late) has been explained earli er too ' .

Conclusions

Our interest in the present study on the complexes of rCu(OOCR)z(L)] (R = 2-,3- or 4·ClC6H4) , with saturated he te rocyc lic bases, piperidines, was to see the role of pk" of the parent carboxy lic ac id in struc ture determination and the effect of steric and e lec tronic propel1ies of the bases on the stoichiometry, magnetic behaviour and structure of complexes. The present results show that o nly complexes with I : 1 sto ichi ometry irrespective of the amount of the ligand added were o btained. All the complexes have been fo und to be ami ferromagnet ic with the exception of rCu(00CC6H4C I-4)2 (2,6-Me2Pipd) l. whic h is paramagnetic. Binuclear

MANHAS el al.: CHARACTERIZATION OF COPPER(II) C HLOROBENZOATE ADDUCTS 1581

copper(II) acetate monohydrate like structure where carboxylate group acts as a syn-syn bridging bidentate ligand has been proposed for all the antifelTomagnetic complexes while polymeric square pyramidal structure where carboxylate group acts as a bridging bidentate I igand has been assigned to the magnetically dilute complex.

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