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åÄIä “Nauka

/Interperiodica”0451

Russian Journal of Coordination Chemistry, Vol. 28, No. 7, 2002, pp. 451–453. Translated from Koordinatsionnaya Khimiya, Vol. 28, No. 7, 2002, pp. 483–485.Original Russian Text Copyright © 2002 by Gorobinskii, Solntsev, Kuznetsov.

INTRODUCTION

The polyhedral dodecahydro-

closo

-dodecaborate

anion B

12

is a spatial aromatic system [1, 2]. Thisanion has recently been shown [3] to enter into thenucleophilic substitution reaction with carboxylic acidswith the formation of the corresponding carboxo deriv-atives

B

12

+ RCOOH

B

12

H

11

OC(O)R

2–

,

where R is the organic radical. The synthesis in boilingacetic acid (

T

b

= 118°

C) or boiling propionic acid (

T

b

=141

°

C) gave the monosubstituted derivative. The disub-

stituted derivative B

12

H

10

(

OC

(

O

)

R was formed in aminor amount on prolonged boiling in the acid.

It seemed of interest to study the reactivity of mono-substituted derivatives of the

[

B

12

H

11

X

]

2–

anion, whereX = OC

(

O

)

CH

3

, OH, SCN, and I, toward the nucleo-philic substitution reactions with carboxylic acids athigher temperatures. In this work, we used pentanoicacid (

T

b

= 185.4

°

C) to obtain the following anions:(acetyloxo)(pentanoyloxo)[decahydro-

closo

-dodeca-borate(2–)]

[

B

12

H

10

(

OC

(

O

)

CH

3

){

OC

(

O

)(

CH

2

)

3

CH

3

}]

2–

,(hydroxo)(pentanoyloxo)[decahydro-

closo

-dodecabo-rate(2–)]

[

B

12

H

10

(

OH

){

OC

(

O

)(

CH

2

)

3

CH

3

}]

2–

, (thiocy-anato)(pentanoyloxo)decahydro-

closo

-dodecaborate(2–)]

[

B

12

H

10

(

SCN

){

OC

(

O

)(

CH

2

)

3

CH

3

}]

2–

, and (iodo)(pen-tanoyloxo)decahydro-

closo

-dodecaborate(2–)]

[

B

12

H

10

(

I

){

OC

(

O

)(

CH

2

)

3

CH

3

}]

2–

.

1

1

The authors follow the IUPAC rules for borane derivatives [4].Works proposing more complicated rules for titling compounds,namely, the descriptor system, are known [5, 6].

H122–

H122–

)22–

EXPERIMENTAL

Solvents and reagents (pentanoic (valeric) acid,dichloromethane, carbon tetrachloride, 2-propanol, tol-uene, and 1,2-dichloroethane) were dried according tostandard procedures [7].

Monosubstituted derivatives were synthesized usingknown procedures: Cs

2

B

12

H

11

(

OC

(

O

)

CH

3

)

andCs

2

B

12

H

11

OH [3], Cs

2

B

12

H

11

I [8], andCs

2

B

12

H

11

(

SCN

)

[9].Disubstituted derivatives

[(

C

4

H

9

)

4

N

]

2

B

12

H

10

X

(

OC

(

O

)(

CH

2

)

3

CH

3

)

(X =OC

(

O

)

CH

3

, OH, SCN, and I) were synthesized as fol-lows. Valeric acid (20 ml) was added to

[(

C

4

H9)4N]2B12H11X (2 g), argon was passed throughthe mixture for 20 min, and the mixture was boiled inan argon atmosphere for 4 h. The salt was dissolvedunder heating. After boiling, the solvent was evaporatedto dryness in a vacuum. The oily precipitate that formedwas dissolved upon heating in 2-propanol (15 ml), andthe product was salted out from a hot solution usingcold water (200 ml). The white precipitate that formedwas recrystallized from dichloromethane.

Elemental analysis (Table 1) was carried out on anEA-1108 Carlo Erba H,C,N-analyzer (Italy).

11B{1H} and 11B NMR spectra were recorded on aBruker AC 200 spectrometer with a working frequencyof 64.297 MHz and internal stabilization with respectto deuterium. Chemical shifts (δ) of the 11B nuclei arepresented relative to boron trifluoride etherate used asan external standard.

IR spectra were recorded on a Specord M80 in theregion from 400 to 4000 cm–1 (a suspension in Nujol ora solution in CCl4 in KBr cells).

Preparation of New Derivatives of the closo-Dodecaborate Anion [B12H10(OC(O)CH3){OC(O)(CH2)3CH3}]2–,

[B12H10(OH){OC(O)(CH2)3CH3}]2–, [B12H10(SCN){OC(O)(CH2)3CH3}]2–,and [B12H10(I){OC(O)(CH2)3CH3}]2–

L. V. Gorobinskii, K. A. Solntsev, and N. T. KuznetsovKurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences,

Leninskii pr. 31, Moscow, 119991 RussiaReceived March 5, 2001

Abstract—Nucleophilic substitution reactions of the monosubstituted anions [B12H11X]2–, where X =OC(O)CH3, OH, SCN, and I, with pentanoic acid were studied. The obtained compounds were shown to con-tain the [B12H10X{OC(O)(CH2)3CH3}]2– anions.

452

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 28 No. 7 2002

GOROBINSKII et al.

RESULTS AND DISCUSSION

The following nucleophilic substitution reactions ofthe [B12H11X]2– monosubstituted anions with valericacid were carried out:

[(C4H9)4N]2B12H11X + CH3(CH2)3C(O)OH

[(C4H9)4N]2B12H10X{OC(O)(CH2)3(CH3)}.

The IR spectra of the salts obtained exhibit changes incomparison with the spectra of the initial compounds. Anabsorption band corresponding to vibrations of the C=Obond of the COO group appears at 1696 cm–1 in the spec-tra of [(C4H9)4N]2B12H10(OH){OC(O)(CH2)3CH3},[(C4H9)4N]2B12H10(SCN){OC(O)(CH2)3CH3}, and[(C4H9)4N]2B12H10(I){OC(O)(CH2)3CH3}. The broadband at 2480 cm–1 produced by stretching vibrations ofthe B–H bonds does not change its position in the spectraof the reaction products as compared to its position in thespectra of the initial compounds. The characteristic banddue to the ν(C≡N) vibration of the SCN group in the spec-trum of [(C4H9)4N]2B12H10(SCN){OC(O)(CH2)3CH3} isslightly shifted to the high-frequency region (2430 cm–1)as compared to the corresponding band in the spectrumof Cs2B12H11(SCN) (2424 cm–1) [9]. The band from thestretching vibration ν(O–H) of the hydroxyl group alsoinsignificantly changes its position in the spectrum of[(C4H9)4N]2B12H10(OH){OC(O)(CH2)3CH3} as com-pared to that of Cs2B12H11(OH) (3471 cm–1) [8].

Comparing the NMR spectra of the reaction prod-ucts and initial monosubstituted anions (Table 2), wecan conclude that individual compounds are formed. If

the total intensity of the 11B signals is accepted to be 12from the number of boron atoms in the studied com-pounds, then in the 11B {1H} spectrum ofB12H10(OC(O)CH3){OC(O)(CH2)3CH3}2–, the singletcorresponding to the ipso-boron atom (B–OC(O)R)(δ = 2.64 ppm) has an intensity of 2. This signal isshifted downfield compared to the signal from the ipso-boron atom in the spectrum of B12H11(OC(O)CH3)2–

(δ = 7.9 ppm), whose intensity is equal to unity.The 11B{1H} spectrum of the

B12H10(OH){OC(O)(CH2)3CH3}2– anion has a morecomplicated pattern. The singlet corresponding to theipso-boron atom (B–OH) (δ = 4.45 ppm) exhibits adownfield shift compared to the corresponding signal inthe spectrum of B12H11(OH)2– (δ = 6.9 ppm); in addi-tion, a singlet corresponding to the substitutedB-OC(O)R atom appears at 2.76 ppm in the spectrumof this anion.

Similarly, singlets at 1.54 ppm (B–OC(O)R) and−23.11 ppm (B–I) are observed in the 11B{1H} spec-trum of B12H10(I){OC(O)(CH2)3CH3}2–; the latter isshifted downfield as compared to the signal from theipso-boron atom in the spectrum of [B12H11I]2– (δ =−21.5 ppm).

Singlets with δ = 1.78 ppm (B–OC(O)R) and δ =−11.82 ppm (B–SCN) are observed in the 11B{1H}spectrum of B12H10(SCN){OC(O)(CH2)3CH3}2–. Thelatter signal is shifted upfield as compared to the corre-sponding signal in the spectrum of the [B12H11(SCN)2–

anion (δ = –9.4 ppm).

Table 1. Elemental analysis data for [(C4H9)4N]2B12H10(X){OC(O)(CH2)3CH3}

Complex Molecularformula

Content (found/calculated), % Yield, %C H N S

[(C4H9)4N]2B12H10(OH){OC(O)(CH2)3CH3} C37H92N2B12O3 59.02/59.61 12.98/12.45 3.51/3.76 90

[(C4H9)4N]2B12H10(OC(O)CH3){OC(O)(CH2)3CH3} C39H94N2B12O4 60.04/59.48 11.78/12.04 3.98/3.56 80

[(C4H9)4N]2B12H10(I){OC(O)(CH2)3CH3} C37H91N2B12O2I 50.83/51.95 11.14/10.93 2.63/3.28 90

[(C4H9)4N]2B12H10(SCN){OC(O)(CH2)3CH3} C38H91N3B12O2S 59.02/58.03 12.32/11.67 4.97/5.35 4.15/4.07 85

Table 2. NMR spectra of [B12H10(X){OC(O)(CH2)3CH3}]2– and [B12H11X]2–

AnionChemical shift, ppm (intensity) Refe-

rencesB–OC(O)R B–X [X] B–H

B12H10(OC(O)CH3){OC(O)(CH2)3CH3}2– 2.64 (2) –15.31, –17.12, –19.94 (10)

B12H10(OH){OC(O)(CH2)3CH3}2– 2.76 (1) 4.45 (1) [OH] –16.10, –17.71, –20.96,–23.82 (10)

B12H10(I){OC(O)(CH2)3CH3}2– 1.54 (1) –23.11 (1) [I] –14.093, –15.62, –17.69 (10)B12H10(SCN){OC(O)(CH2)3CH3}2– 1.78 (1) –11.82 (1) [SCN] –14.23, –17.43, –24.31 (10)B12H11(OC(O)CΗ3)

2– 7.9 (1) [OC(O)CH3] –10.7, –12.2, –15.4 (11) [3][B12H11(OH)]2– 6.9 (1) [OH] –14.4, –16.6, –22.7 (11) [3][B12H11I]2– –21.5 (1) [I] –13.3, –14.7, –16.5 (11) [8][B12H11(SCN)]2– –9.4 (1) [SCN] –14.4, –16.5 (11) [9]

RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 28 No. 7 2002

PREPARATION OF NEW DERIVATIVES 453

In the 11B NMR spectra of the obtained compounds, thesignals from the boron atoms of the B–H groups are split.

In the general case, the disubstituted derivatives(B12H10XY)n– (n = 0–2) can exist in three isomers:

Signals from the B(1), B(2), B(3, 6), B(4, 5), B(7,11), B(8, 10), B(9), and B(12) atoms can theoreticallybe observed in the 11B{1H} spectrum for the ortho-iso-mer. For the meta-isomer, signals from B(1), B(7), B(2,3), B(4, 6), B(8, 11), B(9, 10), B(5), and B(12) atomscan be observed, and those from B(1), B(2–6), B(7–11), and B(12) atoms can be observed for the para-iso-mer. Some signals can be overlapped in the actuallyobserved spectra.

We can conclude on the isomeric composition of thereaction products of valeration from the NMR spectra.Three and more signals from nonequivalent nonsubsti-tuted boron atoms are observed in the spectra of[(C4H9)4N]2B12H10X{OC(O)(CH2)3CH3}, whereasonly two signals from nonsubstituted boron atoms canappear in the spectrum of the para-isomer. It wasshown in [10, 11] that the meta-isomers are formed inthe electrophilic substitution reactions

B12 + H2O + HOS(O2)(CH3) 1,7-B12H10(OH)2–,

K2B12H12 + HF 1,7-K2B12H10F2.

No ortho-isomers were observed in the products ofthese reactions. On the basis of the aforesaid, weassume that the [B12H10X{OC(O)(CH2)3CH3}]2– com-pounds are meta-isomers.

ACKNOWLEDGMENTS

This work was supported by the Russian Foundationfor Basic Research (project nos. 99-03-32589 and 00-

15-97394.0) and the 6th Competition of Experts for theBest Scientific Projects of Young Scientists of the RASin 1999 (grant no. 167).

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vol. 37, no. 14, p. 3454.3. Krause, L. and Preetz, W., Z. Anorg. Allg. Chem., 1995,

vol. 621, no. 3, p. 516.4. The Nomenclature of Boron Compounds, Inorg. Chem.,

1968, vol. 7, no. 10, p. 1945.5. Casey, J.B., Evans, W.J., and Powell, W.H., Inorg.

Chem., 1983, vol. 22, no. 16, p. 2228.6. Casey, J.B., Evans, W.J., and Powell, W.H., Inorg.

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organisch-chemischen Praktikum und Forschungslabo-ratorium, Stuttgart: G. Thieme, 1991. Translated underthe title Prepapativnaya organichekaya khimiya, Mos-cow: Mir, 1999, p. 704.

8. Knoth, W.H., Miller, H.C., Sauer, J.C., et al., Inorg.Chem., 1964, vol. 3, no. 2, p. 159.

9. Srebny, H.G. and Preetz, W., Z. Anorg. Allg. Chem.,1984, vol. 514, no. 7, p. 7.

10. Peymann, T., Knobler, G.B., and Hawtorne, M.F., Inorg.Chem., 2000, vol. 39, no. 6, p. 1163.

11. Solntsev, K.A., Zhukova, N.A., Butman, L.A., and Kuz-netsov, N.T., Izv. Akad. Nauk SSSR, Neorg. Mater., 1980,vol. 16, no. 10, p. 1882.

64 3

8 79

12

5 2

1

X

Y

10 11

64 3

8 79

12

5 2

1

X

10 11

Y

64 3

8 79

12

5 2

1

X

10 11

Yortho (1, 2) meta (1, 7) para (1, 12)

H122–