Synthesis of mono- and dihalogenated derivatives of (Me2S)2B12H10 and palladium-catalyzed boron-carbon cross-coupling reactions of the iodides with grignard reagents

Article abstract of DOI:10.1021/ic020600u

Two series of compounds, 9-X-1,7-(Me₂S)₂B₁₂H₉ and 9,10-X₂-1,7-(Me₂S)₂B₁₂ H₈ (X = Cl, Br, I), have been synthesized from reactions of 1,7-(Me₂S)₂B₁₂H₁₀ with various halogenating reagents. In addition, reactions of 1,7-(Me₂S)₂B₁₂H₁₀ with 2,4-(NO₂)₂C₆H₃SCl and PhSeBr resulted in 9-(2′,4′-(NO₂)₂C₆ H₃S)-1,7-(Me₂S)₂B₁₂H₉ and 9,10-(PhSe)₂-1,7(Me₂S)₂B₁₂ H₈, respectively. X-ray studies of the dibromo, monoiodo, and aryl thioether derivatives show that electrophilic substitution in 1,7-(Me₂S)₂B₁₂H₁₀ takes place at positions 9 and 10, as in the case of the metacarborane 1,7-C₂B₁₀H₁₂. From 1,12-(Me₂S)₂B₁₂H₁₀ the halides (X = Br, I) were prepared. For both 1,7- and 1,12-(Me₂S)₂B₁₂H₁₀ the best iodination results were obtained using iodine monochloride in refluxing acetonitrile. In the presence of 5 mol % (PPh₃)₂PdCl₂ the iodides 9-l-1,7-(Me₂S)₂B₁₂H₉, and 9,10-l₂-1,7-(Me₂S)₂B₁₂ H₈ react with RMgX (R = Me, Ph, Bn; X = Cl, Br) in THF to yield the corresponding B-alkyland B-aryl-substituted products in good yields without using Cul as a cocatalyst. The bromo derivative 9-Br-1,7(Me₂S)₂B₁₂H₉ did not react under similar conditions. No interference from the nearby Me₂S substituent was observed in palladium-catalyzed substitution of iodide in 2-1-1,12- (Me₂S)₂B₁₂H₉. Presumably due to the intramolecular activation of an aryl C-H bond of the benzyl substituent in the inermediate palladium complex, the yield of 9,10-Bn₂-1,7(Me₂S)₂B₁₂ H₈ was significantly lower than those of the dimethyl and diphenyl derivatives. The molecular structures of 9-R-1,7-(Me₂S)₂B₁₂H₉ (R = Ph, Bn) and 2-Bn-1,12-(Me₂S)₂B₁₂H₉ were obtained by single-crystal X-ray analysis.

Full text of DOI:10.1021/ic020600u

Inorg. Chem. 2003, 42, 3199−3207
Synthesis of Mono- and Dihalogenated Derivatives of (Me2S)2B12H10 and
Palladium-Catalyzed Boron−Carbon Cross-Coupling Reactions of the
Iodides with Grignard Reagents
Roman G. Kultyshev, Shengming Liu, Hoitung T. Leung, Jianping Liu, and Sheldon G. Shore*
Department of Chemistry, The Ohio State UniVersity, Columbus, Ohio 43210
Received October 7, 2002
Two series of compounds, 9-X-1,7-(Me S)2B H and 9,10-X -1,7-(Me S)2B H (X ) Cl, Br, I), have been synthesized
2
12
9
2
2
12 8
from reactions of 1,7-(Me2S)2B H with various halogenating reagents. In addition, reactions of 1,7-(Me2S)2B H
12 10
12 10
with 2,4-(NO ) C H SCl and PhSeBr resulted in 9-(2′,4′-(NO ) C H S)-1,7-(Me2S)2B H and 9,10-(PhSe)2-1,7-
2 2
6
3
2 2
6
3
12 9
(Me2S)2B H , respectively. X-ray studies of the dibromo, monoiodo, and aryl thioether derivatives show that
12
8
electrophilic substitution in 1,7-(Me2S)2B H takes place at positions 9 and 10, as in the case of the meta-
12 10
carborane 1,7-C B H . From 1,12-(Me2S)2B H the halides 2-X-1,12-(Me2S)2B H (X ) Br, I) were prepared.
2
10 12
12 10
12 9
For both 1,7- and 1,12-(Me2S)2B H the best iodination results were obtained using iodine monochloride in refluxing
12 10
acetonitrile. In the presence of 5 mol % (PPh3)2PdCl2 the iodides 9-I-1,7-(Me2S)2B H , 2-I-1,12-(Me2S)2B H , and
12
9
12 9
9,10-I2-1,7-(Me2S)2B H react with RMgX (R ) Me, Ph, Bn; X ) Cl, Br) in THF to yield the corresponding B-alkyl-
12
8
and B-aryl-substituted products in good yields without using CuI as a cocatalyst. The bromo derivative 9-Br-1,7-
(Me2S)2B H did not react under similar conditions. No interference from the nearby Me2S substituent was observed
12
9
in palladium-catalyzed substitution of iodide in 2-I-1,12-(Me S)2B H . Presumably due to the intramolecular activation
2
12 9
of an aryl C−H bond of the benzyl substituent in the inermediate palladium complex, the yield of 9,10-Bn2-1,7-
(Me2S)2B H was significantly lower than those of the dimethyl and diphenyl derivatives. The molecular structures
12
8
of 9-R-1,7-(Me2S)2B H (R ) Ph, Bn) and 2-Bn-1,12-(Me2S)2B H were obtained by single-crystal X-ray analysis.
12
9
12 9
Introduction
iodine in 3-I-1,2-C2B10H11 and 2-I-1,12-C2B10H11, respec-
tively, by various aryl groups. Palladium-catalyzed substitu-
tion has been also extended to monocarborane derivatives
[12-ICB11H11]- and [1-R-12-ICB11H10]- (R ) Me, Ph).6 In
the [B12H12]2- series Gru¨ner and co-workers7 successfully
used [(Bn2NH)B12H10I]- as a cross-coupling substrate, while
Construction of carbon-carbon bonds via the palladium-
catalyzed cross-coupling reactions of organic halides and
triflates with organometallic reagents, in particular using
Suzuki and Stille protocols, has become a routine synthetic
tool of modern organic synthesis.1 On the other hand,
examples of substitution in carborane and borane clusters
based on similar boron-carbon cross-coupling reactions are
still scarce. Zakharkin and co-workers2 were the first to apply
this methodology to iodocarboranes in 1982. It was further
developed by Jones3 and Hawthorne.4 Most recently Vinas
et al.5a and Eriksson et al.5b reported on the substitution of
(4) (a) Zheng, Z.; Jiang, W.; Zinn, A.; Knobler, C. B.; Hawthorne, M. F.
Inorg. Chem. 1995, 34, 2095-2100. (b) Jiang, W.; Knobler, C. B.;
Curtis, C. E.; Mortimer, M. D.; Hawthorne, M. F. Inorg. Chem. 1995,
34, 3491-3498. (c) Jiang, W.; Harwell, D. E.; Mortimer, M. D.;
Knobler, C. B.; Hawthorne, M. F. Inorg. Chem. 1996, 35, 4355-
4359. (d) Harakas, G.; Vu, T.; Knobler, C. B.; Hawthorne, M. F. J.
Am. Chem. Soc. 1998, 120, 6405-6406.
(5) (a) Vinas, C.; Barbera, G.; Oliva, J.; Texidor, F.; Welch, A. J.; Rosair,
G. M. Inorg. Chem. 2001, 40, 6555-6562. (b) Eriksson, L.; Be-
letskaya, I. P.; Bregadze, V. I.; Sivaev, I. B.; Sjoberg, S. J. Organomet.
Chem. 2002, 657, 267-272.
* To whom correspondence should be addressed. E-mail: shore@
chemistry.ohio-state.edu.
(1) Metal-Catalyzed Cross-Coupling Reactions; Diederich, F., Stang, P.
J., Eds.; Wiley-VCH: Weinheim, Germany, 1998.
(2) Zakharkin, L. I.; Kovredov, A. I.; Ol’shevskaya, V. A.; Shaugum-
bekova, Zh. S. J. Organomet. Chem. 1982, 226, 217-222.
(3) Li, J.; Logan, C. F.; Jones, M., Jr. Inorg. Chem. 1991, 30, 4866-
4868.
(6) (a) Morris, J. H.; Henderson, K. W.; Ol’shevskaya, V. A. J. Chem.
Soc., Dalton Trans. 1998, 1951-1959. (b) Gru¨ner, B.; Janousˇek, Z.;
King, B. T.; Woodford, J. N.; Wang, C. H.; Vsˇetecˇka, V.; Michl, J. J.
Am. Chem. Soc. 1999, 121, 3122-3126. (c) Franken, A.; Kilner, C.
A.; Thornton-Pett, M.; Kennedy, J. D. J. Organomet. Chem. 2002,
657, 176-179.
10.1021/ic020600u CCC: $25.00 © 2003 American Chemical Society
Published on Web 04/12/2003
Inorganic Chemistry, Vol. 42, No. 10, 2003 3199

Kultyshev et al.
Hawthorne and co-workers8 replaced the iodine in [B12H11I]2-
with methyl, n-octadecyl, and phenyl groups.
We are interested in the application of this methodology
to halogenated derivatives of 1,2-, 1,7-, and 1,12-(Me2S)2-
B12H10 (1-3).9 In this paper we describe their synthesis and
characterization as well as reactions of iodides with Grignard
reagents leading to B-alkyl and -aryl derivatives that are
difficult to obtain by other methods. While among the
isomers of carborane 1,2-C2B10H12 is the easiest and 1,12-
C2B10H12 is the most difficult isomer to prepare, in the
(Me2S)2B12H10 series it is the 1,2-isomer that can only be
obtained in very small quantities.9b For this reason halogena-
tion of 2 and 3, received most of our attention. Nevertheless,
some preliminary information on the bromination and
iodination of 1 was also obtained.
Figure 1. Molecular structure of 9,10-Br2-1,7-(Me2S)2B12H8 (5).
1) revealed that substitution indeed occurred at positions 9
and 10, similar to the bromination of 1,7-C2B10H12.11b
Judging from the rate of disappearance of bromine color,
reaction of 3 for which only one monohalogenated isomer
is possible with 1 equiv of bromine in dichloromethane is
much slower than that of 2. This is expected on the basis of
the behavior of 1,12-C2B10H12 that is known to be less
reactive toward electrophilic reagents than other isomers due
to a lower negative charge on its 10 equiv boron atoms. The
11B NMR of the product (160.5 MHz) displays only 6 signals
instead of the expected 8 due to the accidental overlap of
two signals due to nonequivalent ipso-boron atoms 1 and
12 and another overlap of two signals of intensity 2. Due to
signal overlaps, 11B-11B{1H} COSY was not helpful in
Results and Discussion
Bromination.10 The distribution of charges among the
boron atoms of 1-3 and, therefore, their behavior toward
electrophilic substitution is expected to be similar to that of
1,2-, 1,7-, and 1,12-C2B10H12 due to their similarities in
structure and polarization of the ipso-boron atoms by
formally positively charged sulfur atoms. To test the validity
of this analogy we attempted the preparation, isolation, and
characterization of mono- and dibrominated derivatives of
1-3. Unlike the bromination of 1,7-C2B10H12, which requires
AlCl3 as a catalyst,11a mono- and dibromination of 2 by Br2
in CH2Cl2 take place at room temperature without AlCl3.
The 11B NMR spectrum of the monobrominated product
contains 8 signals. The two most downfield signals of
1
signal assignment. The H NMR spectrum of 2-Br-1,12-
1
(Me2S)2B12H9 (6) has two methyl resonances at 2.58 and 2.49
ppm. The former probably belongs to the Me2S group at
B(1), which is in close proximity of the electron-withdrawing
bromine substituent. The 13C{1H} NMR spectrum also
reveals two different methyl signals. No attempt was made
to synthesize the corresponding dibromo derivative because
a mixture of several isomers, with no particular isomer
predominating, was previously obtained from 1,12-C2B10H12.4b
Iodination. Iodine slowly reacts with 2 upon prolonged
reflux in acetonitrile. However, addition of a stoichiometric
amount of AlCl3 to a solution of 2 and iodine (1:1) in CH2-
Cl2 at room temperature results in quick fading of iodine
color. The 11B NMR spectrum of the isolated iododerivative
displays a pattern of 8 signals, similar to that of 9-Br-1,7-
(Me2S)2B12H9 (4), except for the chemical shift of the iodine-
substituted boron, which moves upfield drastically (-24.8
ppm compared to -8.7 ppm for the bromoderivative).
Similar upfield signals were observed for the iodine-
substituted boron atoms in other iodinated boranes and
intensities 1 and 2 are singlets. The H NMR spectrum of
the product (500 MHz, CD3CN) revealed only one signal at
2.51 ppm suggesting that substitution occurred at either
position 9(10) or 2(3). In CD2Cl2, the splitting of the methyl
signal into a set of two closely spaced resonances is observed,
in agreement with the expected diastereotopicity of two
methyl groups attached to the same sulfur atom in either
9(10)- or 2(3)-brominated product. 11B-11B{1H} COSY did
not provide a definite answer due to some overlap of the
singlets. A good quality crystal for X-ray diffraction study
could not be obtained. However, addition of 2 equiv of
bromine to a solution of 2 in dichloromethane produced
mostly dibrominated product, although it required more time
for completion. The 11B NMR spectrum of the product
displayed a high-symmetry 2:2:2:4:2 pattern. This is con-
sistent with bromination of boron verticies related by a plane
of symmetry, namely either 9 and 10 or 2 and 3. The X-ray
structure of 9,10-Br2-1,7-(Me2S)2B12H8 (5) (Figure 1, Table
1
carboranes.12 As in the case of 4, the H NMR spectrum of
(7) Gru¨ner B.; Bonnetot, B.; Mongeot, H. Collect. Czech. Chem. Commun.
1997, 62, 1185-1204.
(8) Peymann, T.; Knobler, C. B.; Hawthorne, M. F. Inorg. Chem. 1998,
37, 1544-1548.
(9) (a) Hamilton, E. J. M.; Jordan, G. T., IV; Meyers, E. A.; Shore, S. G.
Inorg. Chem. 1996, 35, 5335-5341. (b) Kultyshev, R. G.; Liu, J.;
Meyers, E. A.; Shore, S. G. Inorg. Chem. 1999, 38, 4913-4915.
(10) (Me2S)2B12Br2H8 (presumably, a mixture of isomers) has been
previously isolated from the reaction between bromine and (Me2S)2-
B12H10, and characterized by the elemental analysis. See: Miller, H.
C.; Hertler, W. R.; Muetterties, E. L.; Knoth, W. H.; Miller, N. E.
Inorg. Chem. 1965, 4, 1216-1221.
the iododerivative in CD2Cl2 has two closely spaced methyl
resonances. The molecular structure of 9-I-1,7-(Me2S)2B12H9
(7) determined by single-crystal X-ray diffraction established
that substitution took place at the 9(10) position (Figure 2,
(11) (a) Smith, H. D.; Knowles, T. A.; Schroeder, H. Inorg. Chem. 1965,
4, 107-110. (b) Beall, H.; Lipscomb, W. N. Inorg. Chem. 1967, 6,
874-879.
(12) Hermanek, S. Chem. ReV. 1992, 92, 325-362.
3200 Inorganic Chemistry, Vol. 42, No. 10, 2003

Halogenated DeriWatiWes of (Me2S)2B12H10
Table 1. Crystallographic Data for 9,10-Br2-1,7-(Me2S)2B12H8 (5), 9-I-1,7-(Me2S)2B12H9 (7), and 9-(2′,4′-(NO2)2C6H3S)-1,7-(Me2S)2B12H9 (12)
5
7
12
chem formula
fw
C4H20B12Br2S2
421.86
C4H21B12IS2
389.95
C10H24B12N2O4S3
462.21
space group
a, Å
b, Å
P212121
9.599(3)
9.699(2)
19.070(6)
90
P21/n
P21/c
9.6936(10)
13.8905(10)
13.0341(10)
108.923(10)
1660.2(2)
4
7.9282(16)
23.867(5)
12.364(3)
91.080(10)
2288.3(8)
4
c, Å
â, deg
V, Å3
1775.5(8)
4
Z
F(calcd), g cm-3
cryst size, mm
temp, °C
radiatn (λ, Å)
µ, mm-1
R1a [I > 2σ(I)]
wR2b (all data)
1.578
1.560
1.342
0.3 × 0.3 × 0.4
0.42 × 0.38 × 0.31
0.38 × 0.12 × 0.08
-60
-73
-73
Mo KR (0.710 73)
4.776
Mo KR (0.710 73)
2.152
Mo KR (0.710 73)
0.345
0.0629
0.1669
0.0175
0.0441
0.0599
0.1855
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
2
2
2
Scheme 1
Figure 2. Molecular structure of 9-I-1,7-(Me2S)2B12H9 (7).
products (Scheme 1). Contrary to the iodination of 1,7-
C2B10H12,4a no catalyst is necessary.
Table 1).
Iodination of 2 by 2 equiv of I2-AlCl3 results in 9,10-I2-
1,7-(Me2S)2B12H8 (8). The 11B NMR spectrum of 8 is very
similar to that of the bromine analogue except for the upfield
chemical shift of the iodine-substituted boron atoms. A 11B-
11B{1H} COSY experiment assisted in unambiguous assign-
ment of all signals and indirectly supported the substitution
at positions 9 and 10 as no cross-coupling could be seen
between the signal of B(1,7) and that of the iodine-substituted
boron atoms (see the Supporting Information). Both mono-
and diiodinated derivatives of 2 obtained via the I2-AlCl3
route were contaminated by an unknown impurity. Although
double recrystallization of 7 from ethyl acetate considerably
reduced the amount of impurity, it only led to 30% recovery
of the product. We encountered the same problem upon
attempted purification of 8. It seems that impurities form
upon reaction of the iododerivatives with aluminum trichlo-
ride, as the 11B NMR spectrum of 7 changed upon stirring
with AlCl3 in CH2Cl2. Obviously, a much cleaner synthesis
of 7 and 8 was in demand. Fortunately, iodination of 2 by 1
or 2 equiv of iodine monochloride in acetonitrile upon reflux
provided the above derivatives essentially free of side
Similarly, 2-I-1,12-(Me2S)2B12H9 (9) can be obtained either
from the reaction of 3 with I2-AlCl3 in CH2Cl2 at room
temperature or with ICl in CH3CN upon reflux. As in the
case of 2, the former reagent produces side products, which
cannot be easily removed, and ICl is a better choice for the
synthesis of 9. Its 11B NMR spectrum has fewer signals than
expected due to the accidental overlap of two signals of
intensity 2. The iodine-substituted boron atom appears at
-24.9 ppm, almost 15 ppm upfield from the corresponding
signal of the bromine-substituted compound. The remainder
of the signals was assigned using 11B-11B{1H} COSY (see
the Supporting Information). There are two methyl reso-
1
nances in the H NMR and 13C{1H} NMR spectra of 9 due
to the presence of two nonequivalent dimethyl sulfide groups.
The synthesis of diiodo derivatives was not attempted for
the same reason as in the case of bromination.
Bromination and Iodination of 1. Attempted synthesis
of the mono- and dihalogenated derivatives of 1 using Br2
and I2-AlCl3 resulted in mixtures of isomers. It seems that
these isomers are 9- and 8-X-1,2-(Me2S)2B12H9 in the former
case and 9,12- and 8,10-X2-1,2-(Me2S)2B12H8 in the latter
Inorganic Chemistry, Vol. 42, No. 10, 2003 3201

Kultyshev et al.
Scheme 2
case. The isomers formed in approximately equal amounts.
This is contrary to the halogenation of 1,2-C2B10H12, which
results in preferential substitution at boron atoms 9 and 12.
Such behavior might be due to a smaller difference in
negative charge between positions 9,12 and 8,10 in 1
compared to that in 1,2-C2B10H12. All attempts to separate
the isomers failed.
Chlorination of 2. The synthesis of analogous chlorinated
derivatives of 1-3 was not planned initially due to the
expected lack of reactivity of resulting B-Cl bonds toward
substitution. However, serendipitous chlorination of 2 was
observed upon stirring with methanesulfonyl chloride (2
equiv) in dichloromethane in the presence of AlCl3 (no
reaction occurs without AlCl3). From a mixture of 9-Cl-1,7-
(Me2S)2B12H9 (10) and 9,10-Cl2-1,7-(Me2S)2B12H8 (11) the
latter was isolated by column chromatography. There was
no evidence for the formation of a CH3SO2-substituted boron
product. This is in agreement with the results of Schaffer
and Gabel, who found that closo-[B12H12]2- reacts with acyl
chlorides in the presence of AlCl3 yielding B-chlorinated
derivatives rather than Friedel-Crafts acylation products.13
The monochloride 10 was independently prepared from the
reaction of 2 with N-chlorosuccinimide (1:1). In the 11B NMR
spectra of 9-X-1,7-(Me2S)2B12H9 (X ) Cl, Br, I) the signal
of the halogen-substituted boron atom appears further down-
field as the substituent is changed from iodine to chlorine.
The rest of the pattern essentially does not change. The same
is true for the spectra of 9,10-X2-1,7-(Me2S)2B12H8 (see the
Supporting Information).
Reactions of 2 with Sulfenyl and Selenenyl Halides.
Although [(CH3S)3B12H9]2- was obtained by Muetterties and
co-workers from the reaction of [B12H12]2- with methyl
disulfide under acidic conditions,14 the yield was only 15%,
and a mixture of isomers was most likely produced. To
explore the possibility of the synthesis of polythiosubstituted
compounds via reactions of 1-3 with sulfur electrophiles,
commercially available (2,4-dinitrophenyl)sulfenyl chloride
was used. It did not react with 2 in CH2Cl2 at room
temperature. Addition of AlCl3 resulted in substitution, but
the reaction was not clean. Reflux of 2 with 2 equiv of the
sulfenyl chloride in acetonitrile for 24 h resulted in formation
Figure 3. Molecular structure of 9-(2′,4′-(NO2)2C6H3S)-1,7-(Me2S)2B12H9
(12).
of 9-(2′,4′-(NO2)2C6H3S)-1,7-(Me2S)2B12H9 (12) as a main
product (Scheme 2). This is in agreement with the combined
directive effect of the two Me2S groups previously estab-
lished for halogenation. Prolonged reflux resulted in forma-
tion of disulfide (2,4-(NO2)2C6H3S)2 as dark-brown crystals
without any sign of 9,10-(2′,4′-(NO2)2C6H3S)2-1,7-(Me2S)2-
B12H8. The absence of the latter product is presumably due
to insufficient electrophilicity of the sulfenyl chloride toward
position 10, which is expected to possess only a very small
negative charge in the trisubstituted boron cage. The mo-
lecular structure of 12 was determined by single-crystal X-ray
diffraction analysis (Figure 3, Table 1).
Unlike 2,4-(NO2)2C6H3SCl, PhSeBr generated in situ from
phenyl diselenide and bromine (1:1) in acetonitrile reacted
with 2 upon reflux yielding mostly a diselenosubstituted
product, 9,10-(PhSe)2-1,7-(Me2S)2B12H8 (13) (Scheme 2).
Presumably, this difference in behavior is due to the greater
electrophilicity of the selenenyl bromide. A monoseleno
derivative also formed as a minor product complicating the
isolation of 13. After two chromatographic procedures we
were able to isolate 13 in 38% yield. The 11B NMR spectrum
of this compound is similar to that of 5, but the signal of the
selenium-substituted boron atoms is much sharper. A sele-
nocyanate derivative [(NCSe)B12H11]2- was previously syn-
thesized from [B12H12]2- using both chemical15a and
electrochemical15b conditions.
Palladium-Catalyzed Boron-Carbon Cross-Coupling
Reactions of Iodo Derivatives of 1,7- and 1,12-(Me2S)2-
B12H10 with Grignard Reagents. A reaction of 7 and CH3-
(13) (a) Schaffer, S.; Gabel, D. In AdVances in Neutron Capture Therapy;
Larsson, B., Crawford, J., Weinreich, R., Eds.; Elsevier: New York,
1997; Vol. II, pp 38-41. (b) Gabel, D.; Mai, S.; Perleberg, O. J.
Organomet. Chem. 1999, 581, 45-50.
(14) Knoth, W. H.; Sauer, J. C.; England, D. C.; Hertler, W. R.; Muetterties,
E. L. J. Am. Chem. Soc. 1964, 86, 3973-3983.
(15) (a) Nachtigal, C.; Steuer, B.; Preetz, W. Chem. Ber. 1996, 129, 1531-
1534. (b) Morris, J. H.; Brattsev, V. A.; Gaines, D. F. In AdVances In
Boron Chemistry; Siebert, W.; Ed.; The Royal Society of Chemistry:
Cambridge, U.K., 1997; pp 434-437.
3202 Inorganic Chemistry, Vol. 42, No. 10, 2003

Halogenated DeriWatiWes of (Me2S)2B12H10
Scheme 3
Figure 4. Molecular structure of 9-Ph-1,7-(Me2S)2B12H9 (15).
similar difference was observed between the chemical shifts
of the ipso-boron atoms in [CH3B12H11]2- and [PhB12H11]2-.8
Crystals of 15 suitable for X-ray study were obtained from
the NMR sample in CD3CN. The molecular structure is
shown in Figure 4, and the relevant crystallographic data
can be found in Table 2.
MgBr (4 equiv) in THF at 45 °C in the presence of 5 mol %
of (PPh3)2PdCl2 resulted in complete iodide substitution after
18 h (Scheme 3). It could be easily monitored by 11B{1H}
NMR. As the B-I singlet of the starting material at -24.8
ppm is replaced by a new singlet at -4.5 ppm, the rest of
the pattern essentially does not change. At the end no signals
other than those of 9-CH3-1,7-(Me2S)2B12H9 (14) can be seen
in the spectrum of the reaction mixture. There are two signals
Similar to MeMgBr and PhMgBr, benzylmagnesium
chloride yielded 9-Bn-1,7-(Me2S)2B12H9 (16) upon reaction
with 7. By 11B NMR the benzyl-substituted derivative was
found to be the main product of the reaction after 22 h of
heating. In the 1H NMR spectrum benzylic protons give rise
to a broad singlet at 2.19 ppm, about 2 ppm downfield from
the methyl signal in 14. This broad signal becomes sharp
upon broad-band boron decoupling. Although the benzylic
carbon cannot be observed by routine 13C{1H} NMR, it can
1
in the H NMR spectrum of 14, one at 2.51 ppm due to
Me2S groups and another at 0.17 ppm (CD2Cl2) due to the
methyl group on boron. Both location and broadness of the
latter peak are in agreement with the data reported earlier
by Hawthorne and co-workers8 for the 1H NMR for
[CH3B12H11]2-. This conversion was achieved without use
of CuI as a cocatalyst. The latter was reported to be essential
for the reaction to succeed in the case of iodocarboranes.4a,b
Similarly, CuI was used in the synthesis of [(naphthyl)-
(Bn2NH)B12H10]- from [(Bn2NH)B12H10I]- and [RB12H11]2-
(R ) Me, Ph) from [B12H11I]2-.7,8 Interestingly, no reaction
occurred when (PPh3)2PdCl2 was replaced by (dppf)PdCl2
(dppf ) 1,1′-bis(diphenylphosphino)ferrocene).
1
be detected indirectly in the H-13C HMQC spectrum at
about 30 ppm in CD2Cl2 (see the Supporting Information).
X-ray-quality crystals of this product were obtained by
layering its solution in dichloromethane with hexane. The
molecular structure is shown in Figure 5 (see Table 2 for
crystallographic data). Attempts to use allylmagnesium
bromide in a similar reaction produced no trace of the
substitution product.
As judged by 11B NMR, very little conversion occurred
when 4 was treated with MeMgBr under similar conditions.
This result is analogous to the carbon-carbon cross-coupling
reactions where bromides are known to be less reactive than
iodides due to a weaker tendency of a C-Br bond to undergo
oxidative addition to Pd(0).
Using phenylmagnesium bromide instead of methylmag-
nesium bromide under the conditions described above, 9-Ph-
1,7-(Me2S)2B12H9 (15) was prepared. The 11B NMR spectrum
of the reaction mixture, although not as clean as in the case
of MeMgBr, was essentially that of the product and indicated
complete conversion (no residual B-I signal). The signal
of the phenyl substituted boron atom is shifted downfield
from that of the methyl substituted boron by 1.2 ppm. A
It was of interest to explore cross-coupling reactions of 9
possessing a Me2S substituent on the boron vertex next to
the iodine-substituted boron atom. It seems that the dimethyl
sulfide group does not interfere as the yields of 17-19
synthesized from 9 were comparable to those of 14-16
1
prepared from 7 (Scheme 3). The H NMR spectrum of 19
reveals two different Me2S signals, one of them being shifted
upfield substantially compared to the Me2S signal in the
parent compound 3 (about 0.2 ppm). Since only the upfield
signal correlated with that of the aromatic protons 2 and 6
in the NOESY experiment (see the Supporting Information),
we assigned it to the Me2S group on B(1). Crystals of 19
were grown by slow evaporation of dichloromethane from
Inorganic Chemistry, Vol. 42, No. 10, 2003 3203

Kultyshev et al.
Table 2. Crystallographic Data for 9-Ph-1,7-(Me2S)2B12H9 (15), 9-Bn-1,7-(Me2S)2B12H9 (16), and 2-Bn-1,12-(Me2S)2B12H9 (19)
15
16
19
chem formula
fw
C10H26B12S2
340.15
C11H28B12S2
354.17
C11H28B12S2
354.17
space group
a, Å
b, Å
Pbca
P21/c
P1h
13.3469(10)
11.8991(10)
23.7024(10)
13.1588(10)
9.4695(10)
16.8791(10)
7.9365(10)
10.3822(10)
12.5820(10)
95.078(10)
98.175(10)
101.251(10)
999.24(18)
2
c, Å
R, deg
â, deg
98.039(10)
γ, deg
V, Å3
3764.3(5)
8
2082.6(3)
4
Z
F(calcd), g cm-3
cryst size, mm
temp, °C
radiatn (λ, Å)
µ, mm-1
R1a [I > 2σ(I)]
wR2b (all data)
1.200
1.130
1.177
0.38 × 0.38 × 0.19
0.35 × 0.35 × 0.12
0.46 × 0.31 × 0.31
-123
-73
-123
Mo KR (0.710 73)
0.271
Mo KR (0.710 73)
0.247
Mo KR (0.710 73)
0.258
0.0362
0.0939
0.0349
0.0998
0.0303
0.0823
a R1 ) Σ||Fo| - |Fc||/Σ|Fo|. b wR2 ) {Σ[w(Fo - Fc )2]/Σ[w(Fo )2]}1/2
.
2
2
2
Figure 6. Molecular structure of 2-Bn-1,12-(Me2S)2B12H9 (19).
Figure 5. Molecular structure of 9-Bn-1,7-(Me2S)2B12H9 (16).
isolated in a significantly lower yield compared to those of
20 and 21. As expected, 22 displayed five signals in its 11
B
the NMR sample. Its molecular structure is shown in Figure
6, and the relevant crystallographic data can be found in
Table 2.
NMR spectrum. The first minor product, which is separable
from 22, possesses eight signals in its 11B NMR spectrum.
Three of them are singlets including the highest upfield signal
indicating the presence of iodine in the molecule (see the
Supporting Information); therefore, it is most likely to be
9-Bn-10-I-1,7-(Me2S)2B12H8. The second minor product,
which could not be separated from 22, displayed two singlets
in the downfield region of the 11B NMR spectrum (see the
Supporting Information). The intramolecular activation of a
C-H bond of the benzyl substituent in a σ-(10-dodecabo-
ranyl)palladium iodide complex resulting from 9-Bn-10-I-
1,7-(Me2S)2B12H8 could be responsible for its formation.16
Similarly, when reacted with MeMgBr, diiodide 8 pro-
duced 9,10-Me2-1,7-(Me2S)2B12H8 (20). The methyl carbon
atoms cannot be observed by routine 13C{1H} NMR but can
1
be detected indirectly in the H-13C HMQC spectrum at
about 3 ppm in CD3CN (see the Supporting Information).
Reaction of 8 with excess PhMgBr under similar conditions
produced the expected 9,10-Ph2-1,7-(Me2S)2B12H8 (21) in
67% yield after chromatography. The 11B NMR spectrum
of this compound has only four signals instead of the
expected five due to the accidental overlap of the signal of
intensity 4 and one of the signals of intensity 2. Interestingly,
a similar reaction with excess benzylmagnesium chloride
resulted in a mixture of three boron products. The major
product identified as 9,10-Bn2-1,7-(Me2S)2B12H8 (22) was
(16) Intramolecular C-H activation leading to ortho-palladation via Pd-
(IV) intermediates has been reported in the literature. For example,
see: Alsters, P. L.; Engel, P. F.; Hogerheide, M. P.; Copijn, M.; Spek,
A. L.; van Koten, G. Organometallics 1993, 12, 1831-1844.
3204 Inorganic Chemistry, Vol. 42, No. 10, 2003

Halogenated DeriWatiWes of (Me2S)2B12H10
SHELXTL97 (difference electron density calculation, full-matrix
least-squares refinements) structure solution package.21 Data merg-
ing was performed using the data preparation program supplied by
SHELXTL97. All non-hydrogen atoms were located and refined
anisotropically. All hydrogens on boron atoms are located and
refined isotropically. Hydrogen atoms on carbons are calculated
assuming standard C-H geometries. For data collected on the
CAD4 diffractometer, unit cell parameters were obtained by a least-
squares refinement of the angular settings from 25 reflections, well
distributed in reciprocal space and lying in the 2θ range of 24-
30°. Diffraction data were corrected for Lorentz and polarization
effects and empirical absorption (empirically from ψ scan data).
There are no unusual structural features or distances and angles in
these molecular structures that require discussion.
The palladium-catalyzed substitution of iodine by an alkyl
or aryl group in iodocarboranes and boranes is likely to take
place via a mechanism8 similar to the one generally accepted
for the palladium-catalyzed carbon-carbon cross-coupling
reactions. However, no boron cage intermediates have been
isolated as yet.17 The 11B NMR spectrum of a solution
containing equimolar amounts of 7 and Pd(PPh3)4 in THF
did not change after stirring for 1 day at room temperature.
The spectrum of the same solution taken 3 months later
revealed a new singlet at -2 ppm, which grew at the expense
of the B-I signal of the starting borane, along with other
new signals. Heating resulted in further increase in intensity
of the former signal at the expense of the latter. The signal
at -2 ppm might be due to the formation of the (σ-
dodecaboranyl)palladium iodide complex, although its isola-
tion was not attempted. The 31P NMR spectrum of the
solution after heating showed two major signals at 24.2 and
24.0 ppm, which fall within the expected range for the above
intermediate (for comparison, the chemical shift of (PPh3)2-
Pd(Ph)(I) is 22.3 ppm18).
9-Br-1,7-(Me2S)2B12H9 (4). A 50 mL round-bottomed flask
equipped with a magnetic stirbar was charged with 0.2807 g of 2
(1.063 mmol) and 15 mL of dichloromethane. To the resulting
solution, 5.6 mL of 0.192 M solution of Br2 in CH2Cl2 (1.075 mmol)
was added within 15 min. After the addition the volatile materials
were removed under reduced pressure leaving behind a yellowish
solid. Upon recrystallization from 1-propanol, 0.3126 g (86%) of
1
the product was obtained as white needlelike crystals. H NMR
(CD2Cl2, 300 MHz): δ 2.541 and 2.536 (2 s, S(CH3)2). 13C{1H}
NMR (CD2Cl2, 75.5 MHz): δ 26.2. 11B NMR (CD3CN, 160.5
MHz): δ -8.7 (s, B(9)), -10.2 (s, B(1,7)), -12.6 (d, B(10)), -13.9
(d, B(5,12) or B(4,8)), -14.3 (d, B(4,8) or B(5,12)), -15.9 (d, JBH
) 144, B(6,11)), -17.2 (d, B(3)), -20.0 (d, JBH ) 145, B(2)). MS
Experimental Section
General Data. Chromatography was performed on Selecto silica
gel (230-400 mesh). Fractions obtained after chromatography were
analyzed by TLC using the palladium dichloride stain. H NMR
1
11
(EI): calcd for C4H2110B2 B10S279Br, m/z ) 342.1458; obsd, m/z
spectra were obtained on Bruker DRX-500, DPX-400, and AC-
300 spectrometers at 500.1, 400.1, and 300.1 MHz, respectively,
and referenced to TMS using residual proton signals of deuterated
solvents. 13C NMR spectra were obtained on Bruker DRX-500,
DPX-400, AC-300, and DPX-250 spectrometers operating at 125.8,
100.6, 75.5, and 62.9 MHz, respectively, and referenced to TMS
using deuterated solvent signals. 11B spectra were obtained on the
Bruker DRX-500 spectrometer at 160.5 MHz and referenced
externally to BF3‚OEt2 in C6D6 (δ ) 0.00 ppm). Coupling constants
are reported in hertz. The mass spectra were recorded on Micromass
QTOF Electrospray (ESI) and VG-70 (EI) mass spectrometers.
X-ray Structure Determinations. Single-crystal X-ray diffrac-
tion data were collected on a Nonius Kappa CCD diffractometer
for compounds 7, 12, 15, 16, and 19. An Enraf-Nonius CAD4
diffractometer was employed for compound 5. Both instruments
employ graphite-monochromated Mo KR radiation. For data
collected on the CCD system, a single crystal was mounted on the
tip of a glass fiber coated with Fomblin oil (a pentafluoro polyether).
Unit cell parameters were obtained by indexing the peaks in the
first 10 frames and refined by employing the whole data set. All
frames were integrated and corrected for Lorentz and polarization
effects using the Denzo-SMN package (Nonius BV, 1999).19
Absorption correction was applied using the SORTAV program.20
Structures were solved by direct methods and refined using
) 342.1452 (M+).
9,10-Br2-1,7-(Me2S)2B12H8 (5).22 A 50 mL round-bottomed flask
equipped with a magnetic stirbar was charged with 0.1316 g of
9-Br-1,7-(Me2S)2B12H9 (0.384 mmol) and 15 mL of dichlo-
romethane. To the resulting solution 1.0 mL of a 0.396 M solution
of Br2 in CH2Cl2 (0.396 mmol) was added. After the solution was
stirred overnight, the volatile materials were removed under reduced
pressure. The crude product was recrystallized from 1-propanol
twice to yield 0.0804 g of the title compound as a white solid (50%).
1H{11B} NMR (CD3CN, 500 MHz): δ 2.52 (s, 12H, S(CH3)2), 2.02
(br s, 2H, H(5,12)), 1.90 (br s, 4H, H(4,6,8,11), 1.66 (br s, 2H,
H(2,3)). 13C{1H} NMR (CD3CN, 125.8 MHz): δ 26.0. 11B NMR
(CD3CN, 160.5 MHz): δ -8.6 (s, B(9,10)), -9.9 (s, B(1,7)), -11.0
(d, JBH ) 144, B(5,12)), -14.7 (d, JBH ) 144, B(4,6,8,11)), -19.9
11
79
(d, JBH ) 142, B(2,3)). MS (EI): calcd for C4H2010B2 B10S2
-
Br81Br, m/z ) 422.0543; obsd, m/z ) 422.0534 (M+).
2-Br-1,12-(Me2S)2B12H9 (6).23 A 50 mL round-bottomed flask
equipped with a magnetic stirbar was charged with 0.3286 g of 3
(1.244 mmol) and 0.280 g of Br2-dimethyl sulfide complex (1.261
mmol). Dichloromethane (25 mL) was added, and the solution was
stirred overnight. A second portion of Br2SMe2 was added to the
solution (0.200 g, 0.901 mmol), and stirring was continued for an
additional 1 day followed by addition of a third portion of Br2-
SMe2 (0.080 g, 0.360 mmol). After an additional 2 days of stirring,
the 11B NMR spectrum indicated that the reaction was complete.
(17) Recently Grushin et al.18 attempted to observe intermediates of boron-
carbon cross-coupling reactions of 9-iodo-meta-carborane. No sub-
stantial change in the 31P spectrum of the toluene-d8 solution containing
9-iodo-meta-carborane and (PPh3)4Pd (ratio 10:1) was detected even
after 3 h of heating at 70 °C. Unfortunately, this was not complemented
by observation of 11B NMR of the same solution. It was concluded
that the equilibrium constant for the oxidative addition of the
carboranyl boron-iodine bond to a zerovalent palladium is very
unfavorable.
(20) (a) Blessing, R. H. Acta Crystallogr. 1995, A51, 33-38. (b) Blessing,
R. H. J. Appl. Crystallogr. 1997, 30, 421-426.
(21) SHELXTL, version 5.10; Bruker Analytical X-ray Systems: Madison,
WI, 1997.
(22) Although the procedure below uses 4 as a starting material, 5 can be
prepared directly from 2 using 2 equiv of bromine.
(18) Marshall, W. J.; Young, R. J.; Jr., Grushin, V. V. Organometallics
2001, 20, 523-533.
(19) Otwinowsky, Z.; Minor, W. In Methods in Enzymology, Vol. 276:
Macromolecular Crystallography; Carter, C. W., Jr., Sweet, R. M.,
Eds.; Academic Press: New York, 1997; Part A, pp 307-326.
(23) Bromine-dimethyl sulfide complex is used in this procedure solely
due to the convenience of handling a solid reagent. For its preparation
see Olah, G. A.; Vankar, Y. D.; Arvanaghi, M.; Prakash, G. K. S.
Synthesis 1979, 701-721. Bromine can be used instead as described
above for the synthesis of 4.
Inorganic Chemistry, Vol. 42, No. 10, 2003 3205

Kultyshev et al.
The resulting solution was washed with aqueous Na2S2O3 and dried
over MgSO4. After removal of the solvent under reduced pressure,
the crude product was recrystallized from 1-propanol yielding
160.5 MHz): δ -2.4 (s, B(9)), -10.7 (s, B(1,7)), -13.5 (d, B(10)),
-14.9 (d, B(5,12)), -15.4 (d, B(4,8)), -17.2 (d, B(6,11)), -18.6
(d, B(3)), -21.9 (d, JBH ) 139, B(2)). MS (ESI): calcd for
C4H2110B2 B10S235ClNa, m/z ) 321.1860; obsd, m/z ) 321.1871
1
11
0.2958 g of 6 as white crystals (69%). H NMR (CD3CN, 500
MHz): δ 2.58 and 2.49 (2 s, S(CH3)2). 13C{1H} NMR (CD3CN,
62.9 MHz): δ 26.0, 25.4. 11B NMR (CD3CN, 160.5 MHz): δ -8.6
(s, 2B), -10.9 (s, 1B), -14.5 (d, 4B), -16.6 (d, 2B), -17.3 (d,
[(M + Na)+].
9,10-Cl2-1,7-(Me2S)2B12H8 (11). A 50 mL round-bottomed flask
equipped with a magnetic stirbar was charged with 0.1104 g of 2
(0.418 mmol). Dichloromethane (10 mL), mesyl chloride (0.070
mL, 0.90 mol), and aluminum trichloride (0.2086 g, 1.560 mmol)
were added under nitrogen, and the mixture was stirred overnight.
The resulting solution was washed with aqueous 1 M HCl and
water. After drying over MgSO4, the solvent was removed under
reduced pressure. The crude product, containing both mono- and
dichlorosubstituted derivatives, was chromatographed on silica gel
using CH2Cl2 as an eluent. The title compound (lower spot on TLC)
was isolated as a white crystalline material, but the yield was not
11
2B), -19.0 (d, 1B). MS (EI): calcd for C4H2110B2 B10S279Br, m/z
) 342.1458; obsd, m/z ) 342.1459 (M+).
General Procedure for Synthesis of Iodo-Substituted Boranes.
A 250 mL three-necked round-bottomed three-neck flask equipped
with a condenser, magnetic stirbar, and a rubber septum was charged
with (Me2S)2B12H10 (4.2-4.6 mmol) and 80-100 mL of acetoni-
trile. Under nitrogen a calculated volume of 0.77 M solution of
iodine monochloride in dichloromethane required for either mono-
or diiodination was added by syringe. The resulting solution was
refluxed for 2-2.5 h (sand bath) in the case of monoiodination
and overnight (10-11 h) in the case of diiodination. The volatile
materials were removed under reduced pressure followed by
dissolution of a residue in CH2Cl2. The resulting solution was
washed with aqueous Na2S2O3 and dried over MgSO4. After
removal of the solvent under reduced pressure, the crude product
was recrystallized form EtOH (95%) (7, 9) or acetone-EtOH (95%)
(8).
1
determined. H{11B} NMR (CD3CN, 500 MHz): δ 2.51 (s, 12H,
S(CH3)2), 1.89 (br s, 2H, H(5,12)), 1.78 (br s, 4H, H(4,6,8,11),
1.45 (br s, 2H, H(2,3)). 13C{1H} NMR (CD3CN, 125.8 MHz): δ
26.0. 11B NMR (CD3CN, 160.5 MHz): δ -2.5 (s, B(9,10)), -11.2
(s, B(1,7)), -13.5 (d, JBH ) 141, B(5,12)), -15.5 (d, JBH ) 142,
B(4,6,8,11)), -21.5 (d, JBH ) 141, B(2,3)). MS (EI): calcd for
11
C4H2010B2 B10S235Cl2, m/z ) 332.1575; obsd, m/z ) 332.1583
(M+).
9-I-1,7-(Me2S)2B12H9 (7). From the reaction of 2 (1.1705 g,
4.432 mmol) with 4.44 mmol of ICl, 1.5730 g of 7 was isolated as
9-(2′,4′-(NO2)2C6H3S)-1,7-(Me2S)2B12H9 (12). A solution of 2
(1.0169 g, 3.851 mmol) and (2,4-dinitrophenyl)sulfenyl (1.8833 g,
7.706 mmol) in 100 mL of acetonitrile was placed in a 250 mL
three-necked round-bottomed flask equipped with a condenser and
stirbar and refluxed for 24 h under nitrogen. The resulting solution
was filtered, and the volatile materials were removed under reduced
pressure. Dichloromethane (200 mL) was added to the residue, and
the mixture was stirred overnight. After filtration the solvent was
removed under reduced pressure, and the crude product was
chromatographed on silica gel using CH2Cl2 as an eluent. The
product was further purified by recrystallization from ethanol (95%)
yielding three crops of orange crystals having the identical NMR
1
white crystals (91%). H NMR (CD2Cl2, 400 MHz): δ 2.55 and
2.54 (2s, S(CH3)2). 13C{1H} NMR (CD2Cl2, 100.6 MHz): δ 26.2.
11B NMR (CD2Cl2, 160.5 MHz): δ -9.4 (s, B(1,7)), -12.3 (d,
1B), -13.7 (d, 2B), -14.2 (d, 2B), -15.6 (d, 2B, JBH ) 147),
-16.9 (d, 1B), -18.6 (d, 1B, JBH ) 141), -24.8 (s, B(9)). MS
11
(ESI): calcd for C4H21 B12S2INa, m/z ) 415.1145; obsd, m/z )
415.1144 [(M + Na)+].
9,10-I2-1,7-(Me2S)2B12H8 (8). From the reaction of 2 (1.1117
g, 4.210 mmol) with 8.47 mmol of ICl, 1.6169 g of the title
1
compound was isolated as white crystals (75%). H{11B} NMR
1
(CD3CN, 500 MHz): δ 2.53 (s, 12H, S(CH3)2), 2.19 (br s, 2H,
H(5,12)), 2.08 (br s, 4H, H(4,6,8,11), 1.99 (br s, 2H, H(2,3)). 13C-
{1H} NMR (CD3CN, 125.8 MHz): δ 26.0. 11B NMR (CD3CN,
160.5 MHz): δ -8.1 (s, B(1,7)), -11.4 (d, B(5,12)), -13.3 (d,
B(4,6,8,11)), -17.2 (d, B(2,3)), -22.3 (s, B(9,10)). MS (ESI): calcd
spectra. Those were combined to give 1.1857 g of 12 (67%). H
4
NMR (CD2Cl2, 500 MHz): δ 8.54 (d, 1H, JHH ) 2.5, H3), 8.43
(d, 1H, 3JHH ) 8.9, H6), 8.14 (d, 1H, 3JHH ) 8.9; 4JHH ) 2.5, H5),
2.55 (s, 6H, S(CH3)2). 13C{1H} NMR (CD2Cl2, 125.8 MHz): δ
149.8, 147.8, 144.0, 135.0, 125.1, 120.1, 26.2. 11B NMR (CD2Cl2,
160.5 MHz): δ -6.5 (s, B(9)), -9.6 (s, B(1,7)), -13.7 (d, 1B),
-14.4 (d, 2B), -15.1 (d, 2B), -15.8 (d, 2B), -17.2 (d, 1B), -18.0
11
for C4H2010B2 B10S2I2Na, m/z ) 539.0187; obsd, m/z ) 539.0179
[(M + Na)+].
11
(d, 1B). MS (ESI): calcd for C10H24O4N2 B12S3Na, m/z )
2-I-1,12-(Me2S)2B12H9 (9). From the reaction of 3 (1.2209 g,
4.623 mmol) with 4.62 mmol of ICl, 1.6300 g of 9 was isolated as
487.1913; obsd, m/z ) 487.1909 [(M + Na)+].
1
a white powder (90%). H NMR (CD2Cl2, 500 MHz): δ 2.61 (s,
9,10-(PhSe)2-1,7-(Me2S)2B12H8 (13). A 50 mL three-necked
round-bottomed three-neck flask equipped with a condenser,
magnetic stirbar, and a rubber septum was charged with 0.3880 g
of 98% phenyl diselenide (1.218 mmol) and 15 mL of acetonitrile.
Under nitrogen 8.0 mL of 0.149 M solution of bromine in
acetonitrile was added by syringe, and the resulting mixture was
stirred in the dark for 1 h. After the addition of 0.3217 g of 2 (1.218
mmol) the solution was refluxed for 21 h. The volatile materials
were removed under reduced pressure followed by the addition of
dichloromethane to the residue. The resulting solution was fitered,
washed with aqueous NaCl, and dried over MgSO4. After removal
of the solvent, an oily residue left which crystallized upon trituration
with ethanol (95%). The crude product was chromatographed twice
on silica gel using dichloromethane as an eluent yielding 0.2566 g
6H, B(1)S(CH3)2), 2.52 (s, 6H, B(12)S(CH3)2). 13C{1H} NMR (CD2-
Cl2, 125.8 MHz): δ 26.1, 25.7. 11B NMR (CD2Cl2, 160.5 MHz):
δ -7.8 and - 8.1 (2s, B(1) and B(12)), -13.5 (d, B(3,6)), -13.8
(d, B(7,11)), -16.0 (d, B(4,5) and B(8,10)), -16.9 (d, B(9)), -25.8
11
(s, B(2)). MS (ESI): calcd for C4H2110B2 B10S2INa, m/z )
413.1221; obsd, m/z ) 413.1232 [(M + Na)+].
9-Cl-1,7-(Me2S)2B12H9 (10). A 25 mL round-bottomed flask
equipped with a magnetic stirbar was charged with 0.2640 g of 2
(1.000 mmol), 0.1337 g of N-chlorosuccinimide (1.001 mmol) and
10 mL of acetonotrile. The resulting solution was refluxed for 1 h
followed by solvent removal in vacuo. The residue was partitioned
between dichloromethane (10 mL) and water (10 mL). The organic
phase was washed twice with water and dried with MgSO4. After
solvent removal the crude product was obtained as a white powder
(0.2778 g, 93% yield) and purified by column chromatography.
1H NMR (CD2Cl2, 500 MHz): δ 2.54 and 2.53 (2s, S(CH3)2). 13C-
{1H} NMR (CD2Cl2, 125.8 MHz): δ 25.9. 11B NMR (CH2Cl2,
1
of the product as a yellowish powder (38%). H NMR (CD3CN,
500 MHz): δ 7.63-7.61 (m, 4H, Ph2,6), 7.17-7.13 (m, 6H, Ph3,4,5),
2.45 (s, 12H, S(CH3)2). 13C{1H} NMR (CD3CN, 125.8 MHz): δ
136.5, 133.4, 129.0, 126.6, 25.9. 11B NMR (CD3CN, 160.5 MHz):
3206 Inorganic Chemistry, Vol. 42, No. 10, 2003

Halogenated DeriWatiWes of (Me2S)2B12H10
δ -7.0 (s, B(9,10)), -9.0 (s, B(1,7)), -12.7 (d, B(5,12)), -14.2
(d, JBH ) 143, B(4,6,8,11)), -17.8 (d, JBH ) 139, B(2,3)). MS
{1H} NMR (CD3CN, 125.8 MHz): δ 134.7, 128.1, 126.9, 26.0,
25.3. 11B NMR (CD3CN, 160.5 MHz): δ -4.7 (s, B(2)), -6.6 (s,
B(1,12)), -13.5 (d, 2B), -14.6 (d, 2B), -15.3 (d, 2B), -16.1 (d,
11
(ESI): calcd for C16H3010B2 B10S278Se80SeNa, m/z ) 597.1216;
11
obsd, m/z ) 597.1232 [(M + Na)+].
2B), -16.8 (d, B(9)). MS (ESI): calcd for C10H2610B2 B10S2Na,
General Procedure for Synthesis of B-Monoalkyl and B-
Monoaryl Derivatives of 2 and 3. In a typical experiment a 50
mL three-necked round-bottomed flask equipped with a condenser
and magnetic stirbar was charged with 0.5 mmol of iodide 7 or 9
and 4-5 mol % of (PPh3)2PdCl2. Dry THF was condensed (15-
20 mL), and the resulting solution was placed in ice-water bath.
After 30 min of stirring, a Grignard reagent (2 mmol, solution in
ether) was added by a syringe, and the ice-water bath was replaced
by an oil bath at 40-45 °C. Heating was continued for 1-2 days
depending on the completeness of reaction, which was checked by
11B NMR. Methanol was added to destroy an excess Grignard
reagent followed by filtration and solvent removal in vacuo. The
residue was partitioned between dichloromethane-aqueous HCl (1
M), and the organic phase was washed with distilled water, dried
over MgSO4, and filtered. After solvent removal under reduced
pressure, the crude product was purified by chromatography.
m/z ) 363.2571; obsd, m/z ) 363.2578 [(M + Na)+].
2-Bn-1,12-(Me2S)2B12H9 (19). Yield: 74%. 1H NMR (CD2Cl2,
500 MHz): 7.17-7.10 (m, 4H, Ph), 7.02-6.99 (m, 1H, Ph), 2.46
(s, 6H, B(12)S(CH3)2), 2.33 (s, 6H, B(1)S(CH3)2), 2.27 (br s, 2H,
BCH2). 13C{1H} NMR (CD2Cl2, 125.8 MHz): δ 147.4, 129.5,
128.0, 124.0, 26.1, 26.0. 11B NMR (CD2Cl2, 160.5 MHz): δ -5.2
(s, B(2)), -7.9 (s, B(1), B(12)), -14.7 (d, JBH ) 141, B(3,6), B(7,-
11)), -16.7 (d, JBH ) 139, B(4,5), B(8,10)), -19.0 (d, JBH ) 137,
11
B(9)). MS (ESI): calcd for C11H2810B2 B10S2Na, m/z ) 377.2728;
obsd, m/z ) 377.2706 [(M + Na)+].
Preparation of B-Dialkyl and B-Diaryl Derivatives of 2. The
procedure was analogous to that for the preparation of the
monoalkyl and monoaryl derivatives except diiodide 8 was used
as a starting material.
9,10-Me2-1,7-(Me2S)2B12H8 (20). Yield: 64%. 1H NMR (CD3-
CN, 500 MHz): δ 2.46 (s, 12H, S(CH3)2), 0.08 (s, 6H, BCH3).
13C{1H} NMR (CD2Cl2, 125.8 MHz): δ 26.1. 11B NMR (CD3CN,
160.5 MHz): δ - 4.4 (s, B(9,10)), -9.9 (s, B(1,7)), -12.2 (d, JBH
) 134, B(5,12)), -14.3 (d, J ) 135, B(4,6,8,11)), -20.2 (d, JBH
1
9-Me-1,7-(Me2S)2B12H9 (14). Yield: 80%. H NMR (CD2Cl2,
500 MHz): δ 2.51 (s, 12H, S(CH3)2), 0.17 (br s, 3H, BCH3). 11B
NMR (CD2Cl2, 160.5 MHz): δ -4.8 (s, B(9)), -10.0 (s, B(1,7)),
-12.7 (d, B(10)), -14.0 (d, B(5,12) or B(4,8)), -14.7 (d, B(4,8)
11
) 137, B(2,3)). MS (ESI): calcd for C6H2610B2 B10S2Na, m/z )
or B(5,12)), -16.4 (d, B(6,11)), -17.7 (d, B(3)), -21.1 (d, JBH
)
315.2568; obsd, m/z ) 315.2580 [(M + Na)+].
9,10-Ph2-1,7-(Me2S)2B12H8 (21). Yield: 67%. H NMR (CD2-
11
138, B(2)). MS (ESI): calcd for C5H2410B2 B10S2Na, m/z )
1
301.2411; obsd, m/z ) 301.2417 [(M + Na)+].
Cl2, 500 MHz): δ 7.39-7.37 (m, 4H, Ph), 7.03-6.99 (m, 6H, Ph),
2.56 (s, 12H, S(CH3)2). 13C{1H} NMR (CD2Cl2, 125.8 MHz): δ
134.2, 126.9, 125.6, 26.2. 11B NMR (CH2Cl2, 160.5 MHz): δ -3.5
(s, B(9,10)), -10.4 (s, B(1,7)), -14.8 (d, JBH ) 135, B(5,12),
B(4,6,8,11)), -18.9 (d, JBH ) 142, B(2,3)). MS (ESI): calcd for
1
9-Ph-1,7-(Me2S)2B12H9 (15). Yield: 70%. H NMR (CD3CN,
3
500 MHz): δ 7.47 (d, 2H, JHH ) 7.1, H2, H6), 7.09 (dd, 2H, H3,
H5), 7.05 (tt, 1H, H4), 2.52 (s, 12H, S(CH3)2). 13C{1H} NMR (CD3-
CN, 125.8 MHz): δ 134.2, 127.6, 126.1, 26.1. 11B NMR (CD3CN,
160.5 MHz): δ -3.3 (s, B(9)), -8.7 (s, B(1,7)), -12.6 (d, B(10)),
-13.7 (d, 2B), -14.3 (d, 2B), -15.3 (d, 2B), -16.6 (d, B(3)),
-18.5 (d, JBH ) 138, B(2)).
11
C16H3010B2 B10S2Na, m/z ) 439.2887; obsd, m/z ) 439.2899 [(M
+ Na)+].
1
9,10-Bn2-1,7-(Me2S)2B12H8 (22). Yield: 33%. H NMR (CD2-
1
9-Bn-1,7-(Me2S)2B12H9 (16). Yield: 63%. H NMR (CD2Cl2,
Cl2, 500 MHz): 7.16-7.11 (m, 8H, Ph), 6.99-6.96 (m, 2H, Ph),
2.40 (s, 12H, S(CH3)2), 2.26 (br s, 4H, BCH2). 13C{1H} NMR (CD2-
Cl2, 125.8 MHz): δ 148.7, 129.5, 127.7, 123.3, 26.1. 11B NMR
(CD2Cl2, 160.5 MHz): δ -3.5 (s, B(9,10)), -10.8 (s, B(1,7)),
-13.7 (d, JBH ) 135, B(5,12)), -15.8 (d, J ) 136, B(4,6,8,11)),
-20.6 (d, JBH ) 135, B(2,3)). MS (ESI): calcd for C18H3410B211B10S2-
Na, m/z ) 467.3202; obsd, m/z ) 467.3196 [(M + Na)+].
500 MHz): 7.13 (m, 2H, Ph), 7.06 (m, 2H, Ph), 6.96 (dd, 1H, Ph),
2.47 (s, 12H, S(CH3)2), 2.19 (br s, 2H, BCH2). 13C{1H} NMR (CD2-
Cl2, 125.8 MHz): δ 148.7, 129.2, 127.7, 123.3, 26.2. 11B NMR
(CD2Cl2, 160.5 MHz): δ -3.3 (s, B(9)), -10.0 (s, B(1,7)), -13.3
(d, B(10)), -14.4 (d, 2B), -15.2 (d, 2B), -16.4 (d, 2B), -17.8
(d, B(3)), -20.4 (d, JBH ) 137, B(2)). MS (ESI): calcd for
11
C11H28 B12S2Na, m/z ) 379.2647; obsd, m/z ) 379.2654 [(M +
Na)+].
Acknowledgment. We thank Ms. Christine Plecˇnik for
helpful suggestions. Support from the Charles H. Kimberly
Chair of Chemistry Endowment is greatly appreciated.
2-Me-1,12-(Me2S)2B12H9 (17). Yield: 75%. 1H NMR (CD2Cl2,
500 MHz): δ 2.50 (s, 6H, S(CH3)2), 2.49 (s, 6H, S(CH3)2), 0.20
(br s, 3H, BCH3). 13C{1H} NMR (CD3CN, 125.8 MHz): δ 26.1,
25.7. 11B NMR (CD2Cl2, 160.5 MHz): δ -6.6 (s, B(2)), -7.8 (s,
B(1), B(12)), -14.2 (d, J ) 136, B(3,6), B(7,11)), -16.7 (d, J )
132, B(4,5), B(8,10)), -19.5 (d, J ) 138, B(9)). MS (ESI): calcd
Supporting Information Available: Six crystallographic files
in CIF format, 11B-11B{1H} COSY spectra of 8 and 9, 11B{1H}
NMR spectra of 4, 5, 7, 8, 10, 11, and both minor products from
the reaction of 8 with excess BnMgCl, 1H-13C HMQC spectra of
16 and 20, and the NOESY spectrum of 19. This material is
available free of charge via the Internet at http://pubs.acs.org.
11
for C5H2410B2 B10S2Na, m/z ) 301.2411; obsd, m/z ) 301.2433
[(M + Na)+].
2-Ph-1,12-(Me2S)2B12H9 (18). Yield: 70%. 1H NMR (CD3CN,
3
500 MHz): δ 7.52 (br d, 2H, JHH ) 6.5, H2, H6), 7.18-7.12 (m,
3H, H3, H5, H4), 2.48 (s, 6H, S(CH3)2), 2.28 (s, 6H, S(CH3)2). 13C-
IC020600U
Inorganic Chemistry, Vol. 42, No. 10, 2003 3207