Synthesis and reactivity of 1,2-bis(chlorodimethylgermyl)carborane and 1,2-bis(bromodimethylstannyl)carborane

Article abstract of DOI:10.1021/ic0110878

The 1,2-bis(chlorogermyl)-(1) and 1,2-bis(bromostannyl)carborane (2) have been prepared by the reaction of dilithio-o-carborane with Me₂GeCl₂ and Me₂SnBr₂, respectively. Compounds 1 and 2 are found to be good precursors for the synthesis of a variety of cyclization compounds. The Wurtz-type coupling reaction of 1 and 2 using sodium metal afforded the four-membered digerma compound 3 and five-membered tristanna compound 4, respectively. The salt elimination reactions of 1 and 2 using Li₂N^tBu and Li₂PC₆H₅ afforded the cyclic products (Me₂)M(C₂B₁₀H₁₀) M(Me₂)E (5, M = Ge, E = N^tBu; 6, M = Sn, E = N^tBu; 7, M = Ge, E = PC₆H₅; 8, M = Sn, E = PC₆H₅). The 1,2-bis(dimethylgermyl)carborane 9 and 1,2-bis(dimethylstannyl)carborane 10 were prepared by the reaction of 1 and 2 with sodium cyanoborohydride. The reactions of 9 and 10 with Pd(PPh₃)₄ afforded the bis(germyl)palladium 12 and bis(stannyl)palladium 13 complexes, respectively.

Full text of DOI:10.1021/ic0110878

Inorg. Chem. 2002, 41, 3084−3090
Synthesis and Reactivity of 1,2-Bis(chlorodimethylgermyl)carborane and
1,2-Bis(bromodimethylstannyl)carborane
,†
,†
Chongchan Lee,† Junghyun Lee,† Soon W. Lee,‡ Sang Ook Kang,* and Jaejung Ko*
Departments of Chemistry, Korea UniVersity, Chochiwon, Chungnam 339-700, Korea, and
Sungkyunkwan UniVersity, Natural Science Campus, Suwon 440-746, Korea
Received October 22, 2001
The 1,2-bis(chlorogermyl)- (1) and 1,2-bis(bromostannyl)carborane (2) have been prepared by the reaction of dilithio-
o-carborane with Me2GeCl2 and Me2SnBr2, respectively. Compounds 1 and 2 are found to be good precursors for
the synthesis of a variety of cyclization compounds. The Wurtz-type coupling reaction of 1 and 2 using sodium
metal afforded the four-membered digerma compound 3 and five-membered tristanna compound 4, respectively.
t
The salt elimination reactions of 1 and 2 using Li2NBu and Li2PC H afforded the cyclic products (Me2)M(C B H )-
6
5
2 10 10
t
t
M(Me2)E (5, M ) Ge, E ) NBu; 6, M ) Sn, E ) NBu; 7, M ) Ge, E ) PC H ; 8, M ) Sn, E ) PC H ). The
6
5
6 5
1,2-bis(dimethylgermyl)carborane 9 and 1,2-bis(dimethylstannyl)carborane 10 were prepared by the reaction of 1
and 2 with sodium cyanoborohydride. The reactions of 9 and 10 with Pd(PPh3)4 afforded the bis(germyl)palladium
12 and bis(stannyl)palladium 13 complexes, respectively.
Introduction
bromide to the tin hydride. This fact prompted us to
synthesize the 1,2-bis(halogermyl)- (1) and 1,2-bis(halostan-
nyl)carborane (2) following the synthetic procedure of 1,2-
bis(chlorosilyl)carboranes prepared by Heying et al.6 Com-
pounds 1 and 2 are also found to be good precursors for the
synthesis of a variety of cyclization compounds. In this paper,
we describe (i) the facile synthesis of 1,2-bis(chlorogermyl)-
(1) and 1,2-bis(bromostannyl)carborane (2); (ii) the Wurtz-
type coupling reaction of 1 and 2 with sodium metal; (iii)
the isolation of the 1,2-bis(digermylazanyl)- (5) and 1,2-bis-
Organogermanium and organotin compounds have at-
tracted considerable interest because of their potential
applications such as electric conduction, nonlinear optics,
and photoresists.1 However, their chemistry is not well
developed as compared with organosilicon chemistry due to
the synthetic limitations available for these compounds. For
example, the double-silylation reaction has been well docu-
mented.2 On the other hand, the double-germylation and
-stannylation reactions have sporadically appeared.3 Recently,
we4 reported the double-silylation reactions of a P2PtSi2
complex using 1,2-bis(dimethylsilyl)carborane. Therefore, it
was of interest to investigate the possibility of synthesizing
the 1,2-bis(dimethylgermyl)carborane and 1,2-bis(dimeth-
ylstannyl)carborane for the double-germylation and -stan-
nylation reactions. In fact, we could not prepare such
compounds by a one-step reaction due to the inaccessibility
of the starting materials. Previously, we5 found that sodium
cyanoborohydride was effective in the conversion of the tin
(3) (a) Herberhold, M.; Steffl, U.; Milius, W.; Wrackmeyer, B. Angew.
Chem., Int. Ed. Engl. 1997, 36, 1508. (b) Mitchell, T. N.; Amamria,
A.; Killing, H.; Rutschow, D. J. Organomet. Chem. 1983, 241, C45.
(c) Mitchell, T. N.; Schneider, U. J. Organomet. Chem. 1991, 407,
319. (d) Piers, E.; Skerlj, R. T. J. Chem. Soc., Chem. Commun. 1986,
626. (e) Casson, S.; Kocienski, P.; Reid, G.; Smith, N.; Street, J. M.;
Webster, M. Synthesis 1994, 1301. (f) Tsuji, Y.; Kakehi, T.; J. Chem.
Soc., Chem. Commun. 1992, 1000. (g) Mitchell, T. N.; Killing, A. A.
H.; Rutschow, D. J. Organomet. Chem. 1986, 304, 257. (h) Tsumuraya,
T.; Ando, W. Organometallics 1989, 8, 2286. (i) Komoriya, H.; Kako,
M.; Nakadaira, Y.; Mochida, K. Organometallics 1996, 15, 2014. (j)
Hayashi, T.; Yamashita, H.; Sakakura, T.; Uchimaru, Y.; Tanaka, M.
Chem. Lett. 1991, 245. (k) Mochida, K.; Hodota, C.; Yamashita, H.;
Tanaka, M. Chem. Lett. 1992, 1635. (l) Komoriya, H.; Kako, M.;
Nakadaira, Y.; Mochida, K. J. Organomet. Chem. 2000, 611, 420.
(m) Barrau, J.; Rima, G.; Cassano, V.; Satge´, J. Organometallics 1995,
14, 5700.
* Authors to whom correspondence should be addressed. E-mail:
jko@tiger.korea.ac.kr (J.K.).
† Korea University.
‡ Sungkyunkwan University.
(1) (a) Ban, H.; Deguchi, K.; Tanaka, A. J. Appl. Polym. Sci. 1989, 37,
1589. (b) Baumert, J. C.; Bjorklund, G. C.; Jundt, D. H.; Jurich, M.
C.; Looser, H.; Miller, R. D.; Twieg, R. J. Appl. Phys. Lett. 1988, 53,
1147.
(4) (a) Kang, Y.; Kang, S. O.; Ko, J. Organometallics 2000, 19, 1216 (b)
Kang, Y.; Lee, J.; Kong, Y. K.; Kang, S. O.; Ko, J. Chem. Commun.
1998, 2343.
(5) Lee, T.; Lee, S. W.; Jang, H. G.; Kang, S. O.; Ko, J. Organometallics
2001, 20, 741.
(2) (a) Beletskaya, I.; Moberg, C. Chem. ReV. 1999, 99, 3435. (b) Sharma,
H. K.; Pannell, K. H. Chem. ReV. 1995, 95, 1351.
(6) Papetti, S.; Heying, T. L. Inorg. Chem. 1963, 2, 1405.
3084 Inorganic Chemistry, Vol. 41, No. 12, 2002
10.1021/ic0110878 CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/14/2002

1,2-Bis(chlorogermyl)- and -(bromostannyl)carboranes
(distannazanyl)carborane (6) by the salt elimination reaction;
(iv) the synthesis of 1,2-bis(2-phenyl-1,1,3,3-tetramethyldi-
germylphosphide)carborane (7) by the reaction of 1 and Li2-
PPh; and (v) the synthesis of the bis(germyl)- (12) and
bis(stannyl)palladium (13) complexes by the oxidative ad-
dition reaction of 9 and 10 with a zerovalent palladium
compound.
Results and Discussion
Synthesis of 1,2-Bis(chlorogermyl)carborane (1) and
1,2-Bis(bromostannyl)carborane (2). Previously, the syn-
thesis of 1,2-bis(chlorosilyl)carborane was carried out by salt
elimination reaction of 1,2-Li2C2B10H10 and 2 equiv of Me2-
SiCl2 by Heying.6 The utilization of the same preparative
procedures has proven satisfactory for the preparation of 1,2-
bis(chlorogermyl)carborane (1) and 1,2-bis(bromostannyl)-
carborane (2), which were found to be good precursors for
the synthesis of cyclization compounds. Thus, compound 1
was prepared as a colorless solid by the reaction of
1,2-Li2C2B10H10 with 2 equiv of Me2GeCl2 according to eq
Figure 1. X-ray cystal structure of 3 with 50% probability thermal
ellipsoids depicted. Selected bond lengths (Å) and angles (deg): Ge-Ge-
(A) 2.4416(6), Ge-C(1) 2.012(3), C(1)-C(1A) 1.698(5), C(1)-Ge-Ge-
(A) 79.35(7), C(1A)-C(1)-Ge 100.65(7).
1
1. Compound 1 is soluble in toluene and THF. The H and
and 13C NMR, mass spectrum, and elemental analysis. The
structure of 3 was determined from its X-ray crystal structure.
The ORTEP view of 3 is shown in Figure 1. The C(1)-
C(1A) bond length (1.698(5) Å) is typical for o-carborane
(1.63-1.72 Å).7 The Ge-Ge bond distance (2.4416(6) Å)
is within known values of Ge-Ge bond lengths in analogous
compounds.8 The small Ge(A)-Ge-C(1) bond angle
(79.35(7)°) demonstrates that 3 is highly strained. Such a
geometry was observed in a similar silicon compound.9
13C NMR, mass spectrometry, and elemental analysis for 1
support the proposed structure. The initial indication of the
formulation for 1 stemmed from the observation of a parent
ion in the mass spectrum at m/z 418. In the 1H and 13C NMR
spectra of 1, the methyl group on Ge gives rise to one signal
at 0.55 and 6.44 ppm, respectively, which is significantly
upfield shifted from that of Me2GeCl2 (1.22 and 15.34 ppm).
A similar reaction of 1,2-Li2C2B10H10 with Me2SnBr2 gave
the 1,2-bis(bromostannyl)carborane (2) (eq 2). The 1H NMR
Synthesis of the 4,5-Carboranylene-1,1,2,2,3,3-hexam-
ethyl-1,2,3-tristannacyclopentane (4). The Wurtz-type cou-
pling reaction of 2 using sodium metal in refluxing toluene
afforded the unexpected product, 4, in 28% yield (eq 4). The
structure of 4 is consistent with its 1H, 13C, and 119Sn NMR
1
spectra. H NMR signals in 4 ascribable to the SnMe were
signal of 2 ascribable to the SnMe2 moiety was observed at
0.16 ppm. In particular, the 119Sn NMR signal had clearly
shifted from 70 ppm for Me2SnBr2 to 103 ppm for 2.
Synthesis of the 3,4-Carboranylene-1,1,2,2-tetramethyl-
1,2-digermacyclobutane (3). The Wurtz-type coupling reac-
tion of 1 using sodium metal afforded the strained four-
membered digerma compound 3 (eq 3). Compound 3 is
2
2
119Sn
117Sn
observed at 0.59 (s, JH-
) 52.8 Hz, JH-
) 50.4
3
2
119Sn
Hz, JH-Sn ) 24.0 Hz) and 0.49 (s, JH-
) 49.2 Hz,
3
2JH-
) 46.8 Hz, JH-Sn ) 10.2 Hz) ppm, which are
117Sn
indicative of two kinds of methyl groups on the Sn atoms in
a 1:2 ratio. The 13C NMR spectrum of 4 exhibits the expected
two resonances at -5.2 and -12.5 ppm. Of particular interest
is the 119Sn NMR spectrum, which shows two resonances at
-116.9 and -181.4 ppm with a typical 117Sn satellite signal
of 1J
Sn ) 3426.6 Hz and 2J
Sn ) 670.8 Hz. The
119Sn-117
119Sn-117
(7) Yang, X.; Knobler, C. B.; Zheng, Z.; Hawthorne, M. F. J. Am. Chem.
Soc. 1994, 116, 7142.
(8) Mochida, K.; Shibayama, N.; Goto, M. Chem. Lett. 1998, 339.
(9) de Rege, F. M.; Kasselbaum, J. D.; Scott, B. L.; Abney, K. D.; Balaich,
G. J. Inorg. Chem. 1999, 38, 486.
readily soluble in CH2Cl2 and toluene and is relatively stable
in air. The identity of compound 3 was confirmed by its 1H
Inorganic Chemistry, Vol. 41, No. 12, 2002 3085

Lee et al.
Reaction of 1 and 2 with Dilithio-tert-butylamine. The
compounds 5 and 6 can be prepared either by reacting 1 or
2 with tert-butylamine in the presence of NEt3, as in the
preparative method of 1,3-disilaisoindoline,13 or by reacting
1 or 2 with dilithio-tert-butylamine as in the synthesis of
hexa-tert-butyldistannaazane.14 Because the former procedure
may in some cases result in cleavage of the C(carborane)-M
(M ) Ge; Sn) bond, the latter procedure is preferred. Thus,
1,2-bis(digermylazanyl)carborane (5) was prepared as a
colorless solid by the reaction of 1 with a stoichiometric
amount of dilithio-tert-butylamine (eq 5). When 1,2-bis-
Figure 2. X-ray cystal structure of 4 with 50% probability thermal
ellipsoids depicted. Selected bond lengths (Å) and angles (deg): Sn(1)-
C(1) 2.215(4), Sn(1)-Sn(2) 2.7571(4), C(1)-C(1a) 1.701(6), C(1)-Sn-
(1)-Sn(2) 98.89(9), Sn(1)-Sn(2)-Sn(1a) 93.187(16), C(1a)-C(1)-Sn(1)
121.36(9).
(bromodimethylstannyl)carborane was treated with dilithio-
tert-butylamine, a similar reaction occurred to give the cyclic
distannaazane 6. Initially, we attempted the substitution
reaction of 1,2-bis(chlorostannyl)carborane with dilithio-tert-
butylamine, but no reaction occurred, probably due to the
strong bond of Sn-Cl. After many attempts, we found that
1,2-bis(bromostannyl)carborane 2 served well for the conver-
sion of Sn-Br to the cyclic distannaazane without any
cleavage of the Sn-C(carborane) bond. Compounds 5 and
6 were purified by low-temperature recrystallization from
toluene as colorless crystals. Satisfactory elemental analyses
values strongly resemble the literature ones for 1,2,3-
tristanna[3]ferrocenophane.10
The assignment of 4 was further confirmed by an X-ray
diffraction study. The molecular structure of 4 is shown in
Figure 2. The X-ray study revealed 4 to be a five-membered
cyclization product. The five-membered ring of 4 is slightly
puckered with the dihedral angle between Sn(1)-C(1)-
C(1a)-Sn(1a) and Sn(1)-Sn(2)-Sn(1a) being 10.2(3)°. The
Sn(1)-Sn(2) bond length of 2.7571(4) Å is comparable to
that observed for distanna[2]ferrocenophane.10
A reasonable mechanism for the formation of 4 involves
the initial insertion of the radical intermediate (A) into the
Sn-Sn bond (B) formed during the Wurtz-type coupling
reaction, followed by cyclization to 4. In order to trap the
were obtained for both compounds, and the 1H, 13C, and 119
-
Sn NMR spectral data are consistent with the presence of
the cyclic azanyl carborane. The signal at -0.15 ppm for
Sn-CH3 in the 1H NMR spectrum for 6 locates at a higher
field than that for 2. The 119Sn NMR chemical shift of 84.6
ppm resembles the literature value for distannylamine
compounds.15
Reaction of 1 and 2 with Dilithiophenylphosphine.
Although the synthesis of the organogermylphosphine and
organostannylphosphine16 was well established by reaction
of the corresponding halides and primary phosphine in the
presence of NEt3, Couret17 and Schumann18 reported that the
digerma-2,5-phospholane and cyclic bis(triorganogermyl)-
phosphine could be prepared by the reaction of dilithium
alkylphosphide and alkylgermanium dihalide. 2,5-Distanna-
phospholane was also prepared from the reaction of distan-
nachloride 2 and RPLi2.19 This preparative method is
(12) Komoriya, H.; Kako, M.; Nakadaira, Y. Organometallics 1996, 15,
2014.
(13) (a) Schro¨ck, R.; Dreiha¨upl, K.-H.; Sladek, A.; Schmidbaur, H. J. Chem.
Soc., Dalton Trans. 1996, 4193. (b) Tamao, K.; Sun, G.-R.; Kawach,
A. J. Chem. Soc., Chem. Commun. 1995, 2079.
(14) Puff, H.; Ha¨nssgen, D.; Beckermann, N.; Roloff, A,; Schuh, W. J.
Organomet. Chem. 1989, 373, 37.
(15) Diemer, S.; No¨th, H.; Polborn, K.; Storch, W. Chem. Ber. 1992, 125,
389.
intermediate D, we carried out the Wurtz-type reaction using
dimethylphenylsilane and diphenylacetylene as trapping
agents. While the expected stannylene trapped product was
not obtained, product 4 was obtained in 34% yield. Similar
results were observed in the thermolysis of the four-
membered phenylene disilacycle11 and digermacycle.12
(16) (a) Schumann, H.; Benda, H. Chem. Ber. 1971, 104, 333 (b) Schumann,
H,; Benda, H. Angew. Chem. 1968, 80, 845.
(10) Herberhold, M.; Steffl, U.; Milius, W.; Wrackmeyer, B. Angew. Chem.,
Int. Ed. Engl. 1996, 35, 1803.
(11) Naka, A.; Hayashi, M.; Okazaki, S.; Ishikawa, M. Organometallics
1994, 13, 4994.
(17) Couret, C,; Stage´, J.; Escudie, J.; Andriamizaka, J. D. J. Organomet.
Chem. 1977, 132, C5.
(18) (a) Schumann, H.; Benda, H. Angew. Chem. 1968, 80, 846. (b)
Schumann, H.; Benda, H. Angew. Chem. 1969, 81, 1049.
3086 Inorganic Chemistry, Vol. 41, No. 12, 2002

1,2-Bis(chlorogermyl)- and -(bromostannyl)carboranes
Table 1. Crystal Data of 3, 4, 8, and 11
3
4
8
11
empirical formula
mol wt
C6H22B10Ge2
347.52
C8H28B10Sn3
588.47
C12H27B10PSn2
547.79
C8H32B20Ge2
489.72
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
P2/n
orthorhombic
Pnma
15.5491(7)
11.7044(5)
11.4205(5)
90
2078.45(16)
4
1.881
orthorhombic
Pnma
16.2836(14)
10.9236(9)
12.3182(9)
90
2191.1(3)
4
1.661
monoclinic
P21/c
7.0027(6)
8.7871(8)
13.0248(11)
94.267(2)
799.18(12)
2
9.8685(8)
9.6393(7)
13.1644(10)
107.349(6)
1195.3(2)
2
â (deg)
V, Å3
Z value
D
calcd, (g cm-3
)
1.444
1.361
cryst size, mm3
0.20 × 0.30 × 0.40
0.16 × 0.30 × 0.30
0.42 × 0.10 × 0.12
0.32 × 0.24 × 0.10
F(000)
344
1104
1056
488
µ (mm-1
)
3.731
3.561
2.346
2.511
2θ range (deg)
2.32-28.27
ω
1930
0.0357
0.0893
1.061
2.21-28.32
ω
2705
0.0331
0.0856
1.173
2.07-25.00
ω
2018
0.0519
0.1201
1.039
3.5-50
scan type
ω
no. of reflns with I > 2σ(I)
1782
R
0.0313
0.0758
1.065
wR2a
GOF
2
2
2
a wR2 ) ∑[w(Fo - Fc )2]/∑[w(Fo )2]1/2
.
C5, C7, C8,and C9 atoms. As the dihedral angle between
the two planes (C1, C1a, Sn1, Sn1a and P1, Sn1, Sn1a) is
137.27° and the bond angle of P1-Sn1-C1 is 100.68(14)°,
the coordination environment about Sn(1) may be described
as a distorted tetrahedral configuration. The Sn(1)-P(1) bond
distance (2.518(2) Å) is comparable to that observed for a
few known Sn-P bond lengths (2.52 Å).20
1
The H, 13C, 31P, and 119Sn NMR spectra of 8 were
consistent with the structure determined by X-ray crystal-
1
lography. The H NMR signals ascribable to Sn-Me for 8
were observed as two doublets at 0.28 (d, JH-P ) 3.0 Hz,
Figure 3. X-ray cystal structure of 8 with 50% probability thermal
ellipsoids depicted. Selected bond lengths (Å) and angles (deg): Sn(1)-
C(2) 2.119(5), Sn(1)-C(3) 2.128(9), Sn(1)-C(1) 2.189(5), Sn(1)-P(1)
2.518(2), C(2)-Sn(1)-C(3) 115.0(3), C(2)-Sn(1)-C(1) 105.3(2), C(3)-
Sn(1)-C(1) 105.4(3), C(1)-Sn(1)-P(1) 100.68(14), C(4)-P(1)-Sn(1)
100.8(4), C(4)-P(1)-Sn(1a) 95.58(11).
119
117
JH-
) 56.4 Hz, JH-
) 54.6 Hz, anti to the lone pair
Sn
Sn
119
on phosphorus) and 0.08 (d, JH-P ) 0.9 Hz, JH- Sn ) 54.6
117
Hz, JH- Sn ) 52.8 Hz, syn to the lone pair on phosphorus).
The 31P NMR signal appeared at 77.2 ppm with high
119
117
coupling constants of JP- Sn ) 934.3 Hz and JP- Sn ) 892.8
Hz. The chemical shift is very close to that of 2,5-
distannaphospholane (77.2 ppm).17
applicable for the synthesis of our compounds. Thus, 4,5-
carboranylene-2-phenyl-1,1,3,3-tetramethyl-2-phospha-1,3-
digermacyclopentane 7 was readily prepared in high yield
by the reaction of dilithiophenylphosphine with 1 (eq 6).
Compound 8 was also prepared using the same synthetic
method as 7. Compounds 7 and 8 are moderately soluble in
Reaction of 1 and 2 with Sodium Cyanoborohydride.
o-Bis(dimethylsilyl)carborane was found to be a good
precursor for the double silylation reaction.21 However, its
congeners, the germanium and tin chemistry, are not
developed because synthetic methods available for such
compounds are not accessible. Recently, we6 prepared the
triorganotin hydride, (CabC,P)SnMe2H (CabC,P ) 1-PPh2-1,2-
C2B10H10), by the reaction of (CabC,P)SnMe2Br with sodium
cyanoborohydride as a reducing agent. This preparative
procedure was also effective for the synthesis of 1,2-bis-
(dimethylgermyl)carborane (9) and 1,2-bis(dimethylstannyl)-
carborane (10). Thus, compounds 9 and 10 were prepared
by the reaction of compounds 1 and 2 with sodium
cyanoborohydride (eq 7). Compounds 9 and 10 are crystalline
solids that are relatively stable in air and to brief heating to
toluene and THF. The structure of 8, unambiguously
established by the single-crystal X-ray analysis, is shown in
Figure 3. The crystallographic data and processing parameters
are given in Table 1. The plane of symmetry of the molecule
coincides with the crystallographic plane of symmetry. This
is why the compound has a Z value of 4 instead of 8. The
plane of symmetry passes through the P1, B1, B2, B6, C4,
(20) (a) Mathiasch, B. J. Organomet. Chem. 1979, 165, 295. (b) Dra¨ger,
M.; Mathiasch, B. Angew. Chem. 1981, 93, 1079.
(21) (a) Kang, Y.; Lee, J.; Kong, Y, K.; Kang, S. O.; Ko, J.Organometallics
2000, 19, 1722. (b) Kang, Y.; Kim, J.; Kong, Y. K.; Lee, J.; Lee, S.
W.; Kang, S. O.; Ko, J. Organometallics 2000, 19, 5026.
(19) Andriamizaka, J. D.; Couret, C.; Escudie´, J.; Satge´, J. Phosphorus
Sulfur 1982, 12, 265.
Inorganic Chemistry, Vol. 41, No. 12, 2002 3087

Lee et al.
100-110 °C. Compounds 9 and 10 are moderately soluble
in toluene and THF.
1
The H and 13C spectra of 10 were consistent with the
1
proposed structure. The H NMR signals ascribable to the
SnMe2 and SnH were observed at 0.07 (d, JH-H ) 1.80 Hz,
119
117
JH- Sn ) 60.6 Hz, JH- Sn ) 57.6 Hz) and 5.57 (sept, JH-Sn
) 2058.4 Hz, JH-H ) 1.80 Hz) ppm, respectively. The
infrared spectrum of 10 shows the stretching mode of ν-
(SnH) at 1913 cm-1. The mass spectrum of 10 showed a
molecular ion at m/z 441.
Reaction of 1 with 1,2-Dilithio-o-carborane. The reaction
of 1 with 1,2-dilithio-o-carborane in ether affords the 2,3,5,6-
dicarboranylene-1,1,4,4-tetramethyl-1,4-digermacyclohex-
ane 11 (eq 8). The structure of 11 was determined by spectral
Figure 4. X-ray cystal structure of 11 with 50% probability thermal
ellipsoids depicted. Selected bond lengths (Å) and angles (deg): Ge(1)-
C(3) 1.930(4), Ge(1)-C(4) 1.933(4), Ge(1)-C(1) 1.982(3), Ge(1)-C(2)
1.986(3), C(1)-Ge(1)-C(2) 110.90(12).
chose compounds 9 and 10 as good candidates for the bis-
(germyl)- and bis(stannyl)metal complexes because an
analogous system, 1,2-bis(dimethylsilyl)carborane, was known
to react with metal compounds to give the cyclic bis(silyl)-
metal complexes.4 Moreover, Nakadaira and co-workers26
reported that the reaction of 1,2-bis(diethylgermyl)benzene
with Pd(PPh3)4 underwent dehydrocoupling to give the cyclic
digermylapallada complex. Thus, treatment of compounds
9 and 10 with Pd(PPh3)4 in toluene resulted in the oxidative
addition of M-H (M ) Ge, Sn) to the palladium to afford
the bis(germyl)palladium (12) and bis(stannyl)palladium
complexes (13) as yellow crystals in high yield (eq 9).
data and confirmed by X-ray structural analysis. The structure
is given in Figure 4 with selected bond lengths and angles.
The central six-membered ring has a boat conformation, and
the tricyclic framework has a butterfly conformation with a
dihedral angle of 158°, which is comparable to that of 9,-
10-dihydro-9,10-digermylanthracene.22 Since the ORTEP
diagram of 11 shows that each germanium has pseudoaxial
and pseudoequatorial methyl groups, its 1H NMR spectrum
is expected to show two signals for the nonequivalent methyl
groups. However, a singlet at 0.65 ppm due to the methyl
groups did not change in the temperature range from 25 to
-50 °C. Therefore, it is reasonable to assume that a boat to
boat inversion occurs in solution as observed in the 9,10-
dihydro-9,10-distannaanthracene.22 The tin analogue of 11
has been reported by Zakharkin et al.23
Synthesis of the Bis(germyl)palladium (12) and Bis-
(stannyl)palladium Complexes (13). Bis(germyl)palladi-
um24 and bis(stannyl)palladium25 complexes have been
implicated as key intermediates in the double germylation
and stannylation of alkynes, 1,3-dienes, and allenes. How-
ever, only a few bis(germyl)- and bis(stannyl)palladium
complexes have been characterized due to the synthetic
limitation on organogermanium and tin compounds. We
Compounds 12 and 13 are stable in an inert-gas environment
and showed slow decomposition when in contact with air.
They are readily soluble in organic solvents such as toluene
and THF.
1
The H, 13C, and 31P NMR spectra of 13 were consistent
1
with the proposed formulation. The H NMR spectrum of
13 shows one peak at -0.16 (JH-Sn ) 41.1 Hz; peaks due to
117Sn and 119Sn were not resolved) ppm due to the hydrogen
atoms of the Sn-Me groups. The 31P{1H} NMR spectrum
of 13 showed a resonance centered at 24.0 ppm with satellite
peaks due to 2JP-Sn(transoid) (2JP- Sn ) 1442.5 Hz, 2JP-
)
119
117
Sn
2
1401.4 Hz) and JP-Sn(cisoid) (154.8 Hz), which is consistent
with the cis configuration of 13.25a,27
In summary, we have prepared 1,2-bis(chlorogermyl)-
carborane (1) and 1,2-bis(bromostannyl)carborane (2). The
two compounds were effective reactants in the cyclization
reaction. The two starting compounds, 1 and 2, readily
(22) Saito, M.; Nitta, M.; Yoshioka, M. Organometallics 2001, 20, 749.
(23) Zakharkin, L. I.; Bregadze, V. I.; Okhlobystin, O. Y. J. Organomet.
Chem. 1965, 4, 211.
(24) (a) Barrau, J.; Rima, G.; Cassano, V.; Satge, J. Inorg. Chim. Acta.
1992, 198, 461. (b) Yamashita, H.; Kobayashi, T.; Tanaka, M.;
Samuels, J. A.; Streib, W. E. Organometallics 1992, 11, 2330.
(25) (a) Tsuji, Y.; Nishiyama, K.; Hori, S.; Ebihara, M.; Kawamura, T.
Organometallics 1998, 17, 507. (b) Mu¨ller, C.; Schubert, V. Chem.
Ber. 1991, 124, 2181. (c) Obora, Y.; Tsuji, Y.; Nishiyama, K.; Ebihara,
M.; Kawamura, T. J. Am. Chem. Soc. 1996, 118, 10922.
(26) (a) Komoriya, H.; Kako, M.; Nakadaira, Y.; Mochida, K. Organo-
metallics 1996, 15, 2014. (b) Komoriya, H.; Kako, M.; Nakadaira,
Y.; Mochida, K. J. Organomet. Chem. 2000, 611, 420.
(27) Ebsworth, E. A.; Maganian, V. M.; Reed, F. T. S.; Group, R. O. J.
Chem. Soc., Dalton Trans. 1978, 1167.
3088 Inorganic Chemistry, Vol. 41, No. 12, 2002

1,2-Bis(chlorogermyl)- and -(bromostannyl)carboranes
undergo a substitution reaction with Li2NtBu and Li2PPh to
afford new classes of heterocycles. Compounds 1 and 2 also
react with sodium cyanoborohydride, generating a new class
of hydride compounds. 1,2-Bis(dimethygermyl)carborane (9)
and 1,2-bis(dimethylstannyl)carborane (10) were found to
be good precursors for the synthesis of the bis(germyl)-
palladium (12) and bis(stannyl)palladium complexes (13),
which are implicated as important active catalyst species in
a number of transition-metal-catalyzed germylation and
stannylation reactions. This potential has been further
exploited in a series of novel chemical transformations with
this system.
Synthesis of 3,4-Carboranylene-1,1,2,2-tetramethyl-1,2-di-
germacyclobutane (3). Sodium (0.027 g, 1.18 mmol) was added
to a solution of 1 (0.20 g, 0.48 mmol) in toluene. The mixture was
heated under reflux for 72 h, and solvent was removed under
reduced pressure. The residue was extracted with hexane (20 mL).
Reduction of the volume (10 mL) and cooling of the solution
afforded 3 as colorless crystals in 35% yield. Mp: 231-235 °C.
1H NMR (C6D6): δ 0.21 (Ge-CH3). 13C{1H} NMR (C6D6): δ -0.2
(Ge-CH3). MS(EI): m/z 348 [M+]. Anal.Calcd for C6H22B10Ge2:
C, 20.73; H, 6.33. Found: C, 20.31; H, 6.18.
Synthesis of 4,5-Carboranylene-1,1,2,2,3,3-hexamethyl-1,2,3-
tristannacyclopentane (4). This complex was prepared as described
for the synthesis of 3 and was crystallized from toluene at -10 °C
1
to give 4 in 28% yield. Mp: 205-210 °C. H NMR (C6D6): δ
Experimental Section
2
2
3
119Sn
117Sn
119
0.59 (s, 6H, JH-
) 52.8 Hz, JH-
) 50.4 Hz, JH-Sn
Sn
)
2
2
117Sn
24.0 Hz, SnSnMe2Sn), 0.49 (s, 12H, JH-
) 49.2 Hz, JH-
All experiments were performed under a dry nitrogen atmosphere
in a Vacuum Atmospheres drybox or by standard Schlenk tech-
niques. Diethyl ether, toluene, and THF were freshly distilled from
sodium benzophenone. Hexane was dried and distilled from CaH2
) 46.8 Hz, JH-Sn ) 10.2 Hz, SnMe2). 13C{1H} NMR (C6D6): δ
3
-5.2 (1J
-
) 286.3 Hz, J
) 64.8 Hz), -12.5 (1J
13C -119Sn
2
13C -119Sn
13C
2
119
13C -119
117Sn
Sn ) 208.6 Hz, J
Sn ) 42.6 Hz). 119Sn{1H} NMR (C6D6):
δ -116.9 (1J
) 3426.6 Hz, J
) 670.8 Hz),
2
119Sn
-
119Sn 117Sn
-
1
and chloroform from CaCl2. H, 13C, 31P, and 119Sn NMR spectra
-181.4 (J ) 3428.4 Hz). Anal.Calcd for C8H28B10Sn3: C, 16.32;
H, 4.75. Found: C, 16.69; H, 4.52.
were recorded on a Varian Mercury 300 spectrometer operating at
300.00, 75.44, 121.44, and 111.82 MHz, respectively. Chemical
shifts were referenced to TMS (1H), benzene-d6 (1H, δ 7.156; 13C-
{1H}, δ 128.00), H3PO4 (31P), and Me4Sn (119Sn). IR spectra were
recorded on a Biorad FTS-165 spectrometer. Elemental analyses
were performed with a Carlo Erba Instruments CHNS-O EA 1108
analyzer.
o-Carborane was purchased from KATCHEM Ltd. and used
without purification. The starting materials Me2GeCl2, Me2SnBr2,
PhPH2, and Na2PdCl4 were purchased from Strem Chemical and
NaBH3(CN) from Aldrich. Pd(PPh3)428 and Li2PPh29 were prepared
according to the literature.
Synthesis of 4,5-Carboranylene-2-tert-butyl-1,1,3,3-tetram-
ethyl-2-aza-1,3-digermacyclopentane (5). n-BuLi (4.76 mmol, 1.6
M in hexane) was slowly added to a stirred solution of tert-
butylamine (0.2 mL, 1.90 mmol) dissolved in triethylamine (1 mL)
and ethyl ether (8 mL) at -78 °C. The solution was warmed to
room temperature and stirred for 12 h. The precipitated product
was filtered and dried. Li2NtC4H9 (0.014 g, 0.167 mmol) in THF
(10 mL) was added to a THF (10 mL) solution of 1 (0.07 g, 0.167
mmol) at -78 °C. The solution was refluxed for 6 h and evaporated
to dryness under vacuum. The residue was recrystallized from
toluene (30 mL) to yield colorless crystals in 70% yield. Mp: 145-
Synthesis of o-Bis(chlorodimethylgermyl)carbarane (1). n-
BuLi (3.10 mmol, 1.6 M in hexane) was slowly added to a stirred
solution of o-carborane (0.20 g, 1.40 mmol) in toluene (15 mL) at
-78 °C. The solution was warmed to room temperature and stirred
for 12 h. To that solution was added GeMe2Cl2 (0.60 g, 3.47 mmol)
in toluene (15 mL) at -78 °C. The solution was warmed to room
temperature and stirred for 12 h. The solution was evaporated under
vacuum and washed with hexane (3 mL). The residue was
recrystallized from toluene (20 mL) to yield colorless crystals in
1
t
150 °C. H NMR (C6D6): δ 1.22 (s, 9H, Bu), 0.60 (s, 12H, Ge-
CH3). 13C{1H} NMR (C6D6): δ 71.4, 35.0 (C-CH3), 4.7 (C-CH3),
1.3 (Ge-CH3). MS(EI): m/z 418 [M+]. Anal. Calcd for C10H31B10-
NGe2: C, 28.68; H, 7.45. Found: C, 28.34; H, 7.21.
Synthesis of 4,5-Carboranylene-2-tert-butyl-1,1,3,3-tetram-
ethyl-2-aza-1,3-distannacyclopentane (6). Compound 6 was pre-
pared using the same procedure as described for 5. Yield: 75%.
1
t
Mp: 160-164 °C. H NMR (C6D6): δ 0.98 (s, 9H, Bu), -0.15
1
(s, 12H, JH- Sn ) 56.7 Hz, JH- Sn ) 54.6 Hz, Sn-CH3). 13C{1H}
NMR (C6D6): δ 30.5 (C-CH3), 5.2 (C-CH3), 0.6 (Sn-CH3).
119Sn{1H} NMR(C6D6): δ 84.6. MS(EI): m/z 510 [M+]. Anal.
Calcd for C10H31B10NSn2: C, 23.51; H, 6.11. Found: C, 23.24; H,
5.98.
82% yield. Mp: 108-110 °C. H NMR (C6D6): δ 0.55 (s, 12H,
119
117
Ge-CH3). 13C{1H} NMR (C6D6): δ 73.6 (carborane C), 6.4 (Ge-
CH3). MS(EI): m/z 418 [M+]. Anal. Calcd for C6H22B10Cl2Ge2:
C, 17.22; H, 5. 29. Found: C, 16.86; H, 5.04.
Synthesis of o-Bis(bromodimethylstannyl)carborane (2). n-
BuLi (4.17 mmol, 1.6 M in hexane) was slowly added to a stirred
solution of o-carborane (0.30 g, 2.08 mmol) in THF (20 mL) at
-78 °C. The solution was warmed to room temperature and stirred
for 12 h. This solution was added to SnMe2Br2 (1.20 g, 4.17 mmol)
in THF (60 mL) at -78 °C and warmed to room temperature. The
solution was stirred for 12 h at that temperature. The solution was
evaporated under vacuum and washed with hexane (20 mL). The
residue was recrystallized from toluene (30 mL) to yield colorless
crystals in 55% yield. Mp: 355-360 °C. 1H NMR (C6D6): δ 0.16
Synthesis of 4,5-Carboranylene-2-phenyl-1,1,3,3-tetramethyl-
2-phospha-1,3-digermacyclopentane (7). n-BuLi (1.13 mmol, 1.6
M in hexane) was slowly added to a stirred solution of phenylphos-
phide (0.50 g, 0.45 mmol) in Et2O (15 mL) at -78 °C. The solution
was warmed to room temperature and stirred for 12 h. The yellow
precipitate (Li2PPh) was filtered and dried. Li2PPh (0.02 g, 0.167
mmol) in THF (10 mL) was added to a THF (10 mL) solution of
1 (0.07 g, 0.167 mmol) at -78 °C. The solution was stirred for 8
h at room temperature and evaporated to dryness under vacuum.
The residue was recrystallized from hexane (30 mL) to yield
colorless crystals in 85% yield. Mp: 170-173 °C. 1H NMR
(C6D6): δ 7.32-6.95 (m, 5H, Ph), 0.42 (d, 6H, JH-P ) 6.6 Hz,
(s, 12H, JH- Sn ) 61.2 Hz, JH- Sn ) 58.5 Hz, Sn-CH3). 13C{1H}
NMR (C6D6): δ 66.4 (carborane C), -4.8 (Sn-CH3). 119Sn{1H}
NMR (C6D6): δ 103. MS(EI): m/z 599 [M+]. Anal.Calcd for
C6H22B10Br2Sn2: C, 12.01; H, 3.69. Found: C, 11.82; H, 3.46.
119
117
Ge-CH3 anti to the lone pair on phosphorus), 0.18 (d, 6H, JH-P
)
1.2 Hz, Ge-CH3 syn to the lone pair on phosphorus). 13C{1H}
NMR (C6D6): δ 137.0, 136.8, 128.8, 128.7, 128.5 (Ph), 2.7 (JC-P
) 28.9 Hz, Ge-CH3, anti to the lone pair on phosphorus), 0.8
(28) Brauer, G. Handbuch der Pra¨paratiVen Anorganischen Chemie;
Ferdinand Enke Verlag: Stuttgart, 1981; p 2013.
(29) Petrie, M. A.; Power, P. P. Inorg. Chem. 1993, 32, 1309.
Inorganic Chemistry, Vol. 41, No. 12, 2002 3089

Lee et al.
(JC-P ) 4.2 Hz, Ge-CH3, syn to the lone pair on phosphorus).
31P{1H} NMR (C6D6): δ 119.99. MS(EI): m/z 455 [M+]. Anal.
Calcd for C12H27B10PGe2: C, 31.63; H, 5.96. Found: C, 31.28; H,
5.78.
(CDCl3): δ 1.3. MS(EI): m/z 490 [M+]. Anal. Calcd for C8H32B10-
Ge2: C, 19.61; H, 6.58. Found: C, 19.22; H, 6.78.
Synthesis of (Me2)Ge(1,2-C2B10H10)Ge(Me2)Pd(PPh3)2 (12).
To a stirred toluene (20 mL) solution of Pd(PPh3)4 (0.30 g, 0.26
mmol) was added compound 9 (0.10 g, 0.28 mmol) in toluene (10
mL) at -78 °C. The solution was warmed to room temperature
and stirred for 3 h. Purification was achieved by column chroma-
tography (eluent 1:1 benzene/hexane). The second yellow fraction
(Rf ) 0.32) was collected. The resulting yellow powder was dried
in vacuo to give 0.28 g of 12. Yield: 80%. Mp: 130-135 °C. 1H
Synthesis of 4,5-Carboranylene-2-phenyl-1,1,3,3-tetramethyl-
2-phospha-1,3-distannacyclopentane (8). Compound 8 was pre-
pared using the same procedure as described for 7. Yield: 85%.
1
Mp: 201-205 °C. H NMR (C6D6): δ 7.32-6.92 (m, 5H, Ph),
119Sn
117Sn
0.28 (d, 6H, JH-P ) 3.0 Hz, JH-
) 56.4 Hz, JH-
) 54.6
Hz, Sn-CH3, anti to the lone pair on phosphorus), 0.08 (d, 6H,
119
117
JH-P ) 0.9 Hz, JH-
) 54.6 Hz, JH-
) 52.8 Hz, Sn-CH3,
Sn
Sn
NMR (C6D6): δ 7.36-7.04 (m, 30H, Ph), 0.02 (t, 12H, JH-P
)
syn to the lone pair on phosphorus). 13C{1H} NMR (C6D6): δ 138.5,
2.40 Hz, Ge-CH3). 13C{1H} NMR (C6D6): δ 134.4, 134.3, 134.2,
133.2, 132.7, 130.1 (Ph). 7.0 (Ge-CH3). 31P{1H} NMR (C6D6):
δ 21.6. Anal. Calcd for C42H52B10P2Ge2Pd: C, 51.55; H, 5.35.
Found: C, 51.28; H, 5.22.
136.6, 129.1, 127.7, 127.1 (Ph), 73.7, -3.4, -5.0. 31P{1H} NMR
119
117
(C6D6): δ 77.2 (JP- Sn ) 934.3 Hz, JP- Sn ) 892.8 Hz, Sn-P).
119Sn{1H} NMR (C6D6): δ 52 (JSn-P ) 892.1 Hz) MS(EI): m/z
547 [M+]. Anal. Calcd for C12H27B10PSn2: C, 26.30; H, 4.96.
Found: C, 26.72; H, 5.06.
Synthesis of (Me2)Sn(1,2-C2B10H10)Sn(Me2)Pd(PPh3)2 (13).
Compound 13 was prepared using the same procedure as described
for 12 in 92% yield. Mp: 105-110 °C. 1H NMR (C6D6): δ 7.42-
7.04 (m, 30H, Ph), -0.16 (d, 12H, JH-Sn ) 41.1 Hz, Sn-CH3).
13C{1H} NMR (C6D6): δ 139.1, 134.7, 134.6, 132.3, 132.1, 132.0
Synthesis of o-Bis(dimethylgermyl)carborane (9). NaBH3CN
(0.15 g, 2.4 mmol) was added to a stirred solution of 1 (0.10 g,
0.24 mmol) in THF (20 mL) at -78 °C. The solution was warmed
to room temperature and stirred for 12 h at room temperature. The
solution was evaporated to dryness and extracted with hexane (20
(Ph), 4.8 (Sn-CH3). 31P{1H} NMR(C6D6): δ 24.0 (JP-
)
119Sn
117Sn
1442.5 Hz, JP-
) 1401.4 Hz, JP-Sn(cisoid) ) 154.8 Hz). Anal.
1
mL). Yield: 92%. Mp: 184-188 °C. H NMR (C6D6): δ 4.23
Calcd for C42H52B10P2Sn2Pd: C, 47.11; H, 4.89. Found: C, 46.94;
H, 4.96.
(sept, 2H, JH-H ) 3.0 Hz, Ge-H), 0.13 (d, 12H, JH-H ) 3.0 Hz,
Ge-CH3). 31C{1H} NMR (C6D6): -2.5 (Ge-CH3). MS(EI): m/z
349 [M+]. Anal. Calcd for C6H24B10Ge2: C, 20.61; H, 6.91.
Found: C, 20.34; H, 6.72.
X-ray Crystallography. Details of the crystal data and a
summary of the intensity data collection parameters for 3, 4, 8,
and 11 are given in Table 1. Crystals 3, 4, 8, and 11 were grown
from hexane and toluene, respectively. Crystals 3, 4, 8, and 11 were
mounted in thin-walled glass capillaries and sealed under argon.
The data sets for the four crystals 3, 4, 8, and 11 were collected on
an Enraf CAD-4 and a Siemens P4 diffractometer. Mo KR radiation
(λ ) 0.7107 Å) was used for all structures. Each structure was
solved by the application of direct methods using the SHELX-96
program and least-squares refinement using SHELXL-97. All non-
hydrogen atoms in compounds 3, 4, 8, and 11 were anisotropically
refined. All other hydrogen atoms were included in the calculated
positions.
Synthesis of o-Bis(dimethylstannyl)carborane (10). NaBH3-
CN (1.0 mL, 1 M in THF) was added to a stirred solution of 2
(0.10 g, 0.17 mmol) in toluene (30 mL) at 0 °C. The solution was
stirred for 6 h at 90 °C and then refluxed for 1 h. The solution was
evaporated to dryness and extracted with hexane (30 mL). Yield:
32%. Mp: 185-192 °C. 1H NMR (C6D6): δ 5.57 (sept, 2H, JH-Sn
) 2058.4 Hz, JH-H ) 1.80 Hz, Sn-H), 0.07 (d, 12H, JH-H ) 1.80
Hz, JH-
) 60.6 Hz, JH-
) 57.6 Hz, Sn-CH3). 13C{1H}
119Sn
117Sn
NMR (C6D6): δ 67.0, -7.1 (Sn-CH3). 119Sn{1H} NMR (C6D6):
δ -12. MS(EI): m/z 441 [M+]. Anal. Calcd for C6H24B10Sn2: C,
16.31; H, 5.47. Found: C, 16.04; H, 5.32.
Acknowledgment. We are grateful to the Brain Korea
Synthesis of 2,3,5,6-Dicarboranylene-1,1,4,4-tetramethyl-1,4-
digermacyclohexa-2,5-diene (11). o-Bis(chlorodimethylgermyl)-
carborane (0.10 g, 0.24 mmol) in ether (10 mL) was slowly added
to a stirred solution of 1,2-dilithio-o-carborane (0.04 g, 0.24 mmol)
dissolved in ether (20 mL) at -78 °C. The solution was warmed
to room temperature and stirred for 6 h. The solution was filtered
and evaporated under vacuum. The residue was recrystallized from
toluene (5 mL) to yield colorless crystals in 65% yield. Mp: 160-
21 program for the generous financial support.
Supporting Information Available: Tables listing crystal-
lographic information, atomic coordinates and Beq values, aniso-
tropic thermal parameters, and intramolecular bond distances,
angles, and torsion angles for 3, 4, 8, and 11. Crystallographic data
in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
1
162 °C. H NMR (CDCl3): δ 0.65 (Ge-CH3). 13C{1H} NMR
IC0110878
3090 Inorganic Chemistry, Vol. 41, No. 12, 2002