Synthesis, structure, and reactivity of 13-vertex carboranes and 14-vertex metallacarboranes

Article abstract of DOI:10.1021/ja0605772

Syntheses, properties, and synthetic applications of 13-vertex closo- and nido-carboranes are reported. Reactions of the nido-carborane salt [(CH ₂)₃C₂B₁₀H₁₀]Na ₂ with dihaloborane reagents afforded 13-vertex closo-carboranes 1,2-(CH₂)₃-3-R-1,2-C₂B₁₀H ₁₀ (R = H (2), Ph (3), Z-EtCH=C(Et) (4), E-^tBuCH= CH (5)). Treatment of the arachno-carborane salt [(CH₂)₃C ₂B₁₀H₁₀]Li₄ with HBBr ₂·SMe₂ gave both the 13-vertex carborane 2 and a 14-vertex closo-carborane (CH₂)₃C₂B ₁₂H¹² (8). On the other hand, the reaction of [C ₆H₄(CH₂)₂C₂B ₁₀H₁₀]Li₄ with HBBr₂·SMe ₂ generated only a 13-vertex closo-carborane 1,2-C₆H ₄(CH₂)₂-1,2-C₂B₁₁H ₁₁ (9). Electrophilic substitution reactions of 2 with excess Mel, Br₂, or I₂ in the presence of a catalytic amount of AlCl₃ produced the hexa-substituted 13-vertex carboranes 8,9,10,11,12,13-X₆-1,2-(CH₂)₃-1,2-C ₂B₁₁H₅ (X = Me (10), Br (11), I (12)). The halogenated products 11 and 12 displayed unexpected instability toward moisture. The 13-vertex closo-carboranes were readily reduced by groups 1 and 2 metals. Accordingly, several 13-vertex nido-carborane dianionic salts {nido-1,2-(CH ₂)₃-1,2-C₂B₁₁H₁₁}{Li ₂(DME)₂-(THF)₂} (13), [{nido-1,2-(CH ₂)₃-1,2-C₂B₁₁H₁₁}{Na ₂(THF)₄}]_n (13a), [{nido-1,2-(CH ₂)₃-3-Ph-1,2-C₂B₁₁H ₁₀}-{Na₂(THF)₄}]_n (14), [{nido-1,2-C₆H₄(CH₂)₂-1,2-C ₂B₁₁H₁₁}{Na₂(THF)₄}] _n (15), and {nido-1,2-(CH₂)₃-1,2-C ₂B₁₁H₁₁}{M(THF)₅} (M = Mg (16), Ca (17)) were prepared in good yields. These carbon-atom-adjacent nido-carboranes were not further reduced to the corresponding arachno species by lithium metal. On the other hand, like other nido-carborane dianions, they were useful synthons for the production of super-carboranes and supra-icosahedral metallacarboranes. Interactions of 13a with HBBr₂·SMe₂, (dppe)NiCl₂, and (dppen)NiCl₂ gave the 14-vertex carborane 8 and nickelacarboranes [η⁵-(CH₂)₃C ₂B₁₁H₁₁]Ni(dppe) (18) and [η⁵- (CH₂)₃C₂B₁₁H¹¹]Ni(dppen) (19), respectively. All complexes were fully characterized by various spectroscopic techniques and elemental analyses. Some were further confirmed by single-crystal X-ray diffraction studies.

Full text of DOI:10.1021/ja0605772

Published on Web 03/24/2006
Synthesis, Structure, and Reactivity of 13-Vertex Carboranes
and 14-Vertex Metallacarboranes
Liang Deng, Hoi-Shan Chan, and Zuowei Xie*
Contribution from the Department of Chemistry, The Chinese UniVersity of Hong Kong,
Shatin, New Territories, Hong Kong, China
Received January 31, 2006; E-mail: zxie@cuhk.edu.hk
Abstract: Syntheses, properties, and synthetic applications of 13-vertex closo- and nido-carboranes are
reported. Reactions of the nido-carborane salt [(CH2)3C2B10H10]Na2 with dihaloborane reagents afforded
13-vertex closo-carboranes 1,2-(CH2)3-3-R-1,2-C2B11H10 (R ) H (2), Ph (3), Z-EtCHdC(Et) (4), E-tBuCHd
CH (5)). Treatment of the arachno-carborane salt [(CH2)3C2B10H10]Li4 with HBBr2‚SMe2 gave both the 13-
vertex carborane 2 and a 14-vertex closo-carborane (CH2)3C2B12H12 (8). On the other hand, the reaction
of [C6H4(CH2)2C2B10H10]Li4 with HBBr2‚SMe2 generated only a 13-vertex closo-carborane 1,2-C6H4(CH2)2-
1,2-C2B11H11 (9). Electrophilic substitution reactions of 2 with excess MeI, Br2, or I2 in the presence of a
catalytic amount of AlCl3 produced the hexa-substituted 13-vertex carboranes 8,9,10,11,12,13-X6-1,2-(CH2)3-
1,2-C2B11H5 (X ) Me (10), Br (11), I (12)). The halogenated products 11 and 12 displayed unexpected
instability toward moisture. The 13-vertex closo-carboranes were readily reduced by groups 1 and 2 metals.
Accordingly, several 13-vertex nido-carborane dianionic salts {nido-1,2-(CH2)3-1,2-C2B11H11}{Li2(DME)2-
(THF)2} (13), [{nido-1,2-(CH2)3-1,2-C2B11H11}{Na2(THF)4}]n (13a), [{nido-1,2-(CH2)3-3-Ph-1,2-C2B11H10}-
{Na2(THF)4}]n (14), [{nido-1,2-C6H4(CH2)2-1,2-C2B11H11}{Na2(THF)4}]n (15), and {nido-1,2-(CH2)3-1,2-
C2B11H11}{M(THF)5} (M ) Mg (16), Ca (17)) were prepared in good yields. These carbon-atom-adjacent
nido-carboranes were not further reduced to the corresponding arachno species by lithium metal. On the
other hand, like other nido-carborane dianions, they were useful synthons for the production of super-
carboranes and supra-icosahedral metallacarboranes. Interactions of 13a with HBBr2‚SMe2, (dppe)NiCl2,
and (dppen)NiCl2 gave the 14-vertex carborane 8 and nickelacarboranes [η5-(CH2)3C2B11H11]Ni(dppe) (18)
and [η5-(CH2)3C2B11H11]Ni(dppen) (19), respectively. All complexes were fully characterized by various
spectroscopic techniques and elemental analyses. Some were further confirmed by single-crystal X-ray
diffraction studies.
carboranes is also well developed.1,5 In sharp contrast, super-
Introduction
carboranes with more than 12 vertices (C2BnHn+2 with n > 10)
Icosahedral carboranes constitute a class of structurally unique
molecules with exceptional thermal and chemical stabilities and
with the ability to hold various substituents.1 These properties
have made them useful basic units for weakly coordinating
anions,2 boron neutron capture therapy (BNCT) drugs,3 and
supramolecular design.4 The chemistry of sub-icosahedral
were totally unknown until the first 13-vertex carborane 1,2-
C6H4(CH2)2-3-Ph-1,2-C2B11H10 was reported in 2003.6 Subse-
quently, the first 14-vertex carborane 1,2-(CH2)3-1,2-C2B12H12
was successfully synthesized in 2005.7 The use of CAd (carbon-
atom-adjacent) carborane anions as starting materials is the key
to accomplishing such a breakthrough.6-8
(1) (a) Grimes, R. N. Carboranes; Academic Press: New York, 1970. (b) Onak,
T. Polyhedral Carbaboranes. In ComprehensiVe Organometallic Chemistry
II; Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds. Pergamon: New York,
1995; Vol. 1, pp 217-255. (c) Grimes, R. N. Metallacarboranes.
In ComprehensiVe Organometallic Chemistry II; Abel, E. W., Stone,
F. G. A., Wilkinson, G., Eds.; Pergamon: New York, 1995; Vol. 1,
pp 373-430. (d) Davidson, M.; Hughes, A. K.; Marder, T. B.; Wade, K.
Contemporary Boron Chemistry; Royal Society of Chemistry: Cam-
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of the 21st Century; Russian Academy of Sciences: Moscow, Russia,
2002.
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Cancer Res. 1990, 50, 1061-1070. (b) Yamamoto, Y. Pure. Appl. Chem.
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Schaffer, P.; Sogbein, O. O.; Stephenson, K. A. Coord. Chem. ReV. 2002,
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(4) (a) Yang, X.; Jiang, W.; Knobler, C. B.; Hawthorne, M. F. J. Am. Chem.
Soc. 1992, 114, 9719-9722. (b) Andrews, P. C.; Hardie, M. J.; Raston, C.
L. Coord. Chem. ReV. 1999, 189, 169-198. (c) Schwab, P. F. H.; Levin,
M. D.; Michl, J. Chem. ReV. 1999, 99, 1863-1934. (d) Wedge, T. J.;
Hawthorne, M. F. Coord. Chem. ReV. 2003, 240, 111-128. (e) Vicente,
J.; Chicote, M.-T.; Alvarez-Falco´n, M. M. Organometallics 2003, 22,
4792-4797. (f) Jude, H.; Disteldorf, H.; Fischer, S.; Wedge, T.; Hawkridge,
A. M.; Arif, A. M.; Hawthorne, M. F.; Muddiman, D. C.; Stang, P. J. J.
Am. Chem. Soc. 2005, 127, 12131-12139. (g) Ma, L.; Hamdi, J.; Huang,
J.; Hawthorne, M. F. Inorg. Chem. 2005, 44, 7249-7258. (h) Herzog, A.;
Jalisatgi, S. S.; Knobler, C. B.; Wedge, T. J.; Hawthorne, M. F. Chem.s
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(5) (a) Sˇt´ıbr, B. Chem. ReV. 1992, 92, 225-250. (b) Siebert, W.; Maier, C.-J.;
Maier, A.; Greiwe, P.; Bayer, M. J.; Hofmann, M.; Pritzkow, H. Pure Appl.
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75, 1211-1218. (d) Hosmane, N. S.; Maguire, J. A. Organometallics 2005,
24, 1356-1389.
(6) Burke, A.; Ellis, D.; Giles, B. T.; Hodson, B. E.; MacGregor, S. A.; Rosair,
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2131.
9
10.1021/ja0605772 CCC: $33.50 © 2006 American Chemical Society
J. AM. CHEM. SOC. 2006, 128, 5219-5230
5219

A R T I C L E S
Deng et al.
Scheme 1. Preparation of 13-Vertex Carboranes from nido
These achievements open up possibilities for the development
of new chemistry of super-carboranes and a new generation of
BNCT drugs having a higher boron content.9 This virtually
unexplored area of research is especially attractive in view of
the flourish chemistry displayed by their icosahedral cousins.1-4,10
Herein, we would like to present our detailed study on the
synthesis, structure, and reactivity of 13-vertex carboranes.
Effects of the C, C′-linkages and RBX2 reagents on the
formation and reactivity of 13-vertex carboranes will be
discussed, and the similarities and differences between the 12-
and 13-vertex carboranes will also be addressed. Supra-
icosahedral metallacarboranes derived from 13-vertex species
will be described.
Species
Results and Discussion
Synthesis and Structure of 13-Vertex closo-Carboranes.
Our previous work showed that the linkages between the two
cage carbon atoms of o-carboranes can control the relative
positions of the cage carbon atoms during the reactions with
group 1 metals.8 Recent results indicated that these bridges may
also play a role in stabilizing super-carboranes.6,7 Considering
the rigidity and relatively small size of the (CH2)3 unit, which
may facilitate the capitation reaction with RBX2, 1,2-(CH2)3-
1,2-C2B10H10 (1)7 was chosen as the starting material. Reduction
of 1 with excess finely cut sodium metal in THF at room
temperature gave presumably a nido-carborane salt {1,2-(CH2)3-
1,2-C2B10H10}{Na2(THF)x}. Treatment of this salt with 2 equiv
of dihaloborane reagents in toluene from -78 to 25 °C afforded,
after column chromographic separation, 13-vertex carboranes
1,2-(CH2)3-3-R-1,2-C2B11H10 (R ) H (2), Ph (3), Z-EtCHd
C(Et) (4), E-tBuCHdCH (5)) in 20-37% isolated yields
(Scheme 1). A small amount of 1 (3-6%) and a mixture of
other boron-containing compounds were obtained in all cases.
Many attempts to separate these boron-containing species failed.
The control experiments indicated that the use of 2 equiv of
dihaloborane reagents offered the highest isolated yield of 13-
vertex carboranes. It was assumed that some boranes might be
consumed by side reactions. More than 2 equiv of boranes were
not necessary, which resulted in difficulty in separation. Donor
solvents such as THF, DME, and Et2O led to a much lower
yield.
Scheme 2. Preparation of 13- and 14-Vertex Carboranes from
arachno Species
carborane 1,2-(CH2)3-1,2-C2B12H12 (8) in 32% and 7% yields,7
respectively. However, treatment of the arachno-carborane salt
[{1,2-C6H4(CH2)2-1,2-C2B10H10}{Li4(THF)6}]2 (7)8a with 5.0
equiv of HBBr2‚SMe2 afforded only a 13-vertex carborane 1,2-
C6H4(CH2)2-1,2-C2B11H11 (9), and no 14-vertex species was
detected (Scheme 2). These results suggested that the linkage
played an important role in the preparation of super-carboranes.
Single-crystal structures of 6 and 7 may offer some insight into
these differences. The o-xylyl moiety in 7 folds toward the C2B3
face,8a which may limit the access of the borane reagents to the
open pentagonal bonding face. On the other hand, the trimeth-
ylene group has no interaction with the hexagonal C2B4 or
pentagonal C2B3 face.8d
Compounds 2-5, 8, and 9 are quite stable in air and soluble
in common organic solvents such as hexane, toluene, and THF.
They were fully characterized by 1H, 13C, and 11B NMR
spectroscopic techniques as well as high-resolution mass
spectrometry. Both the 11B NMR spectra of 2 and 9 displayed
a 1:5:5 splitting pattern, whereas those of 3, 4, and 5 showed
the 1:1:3:2:4, 1:1:4:2:3, and 1:1:6:3 splitting patterns, respec-
tively.
In view of the isolated yield of 20% for 3 versus 6% for
1,2-C6H4(CH2)2-3-Ph-1,2-C2B11H10,6 it was suggested that 1 was
a much better starting material than 1,2-C6H4(CH2)2-1,2-
C2B10H10. Such differences could be ascribed to the presence
of the more sterically demanding o-xylyl bridge. This assump-
tion was supported by the following experiments. Reaction of
the arachno-carborane salt [{1,2-(CH2)3-1,2-C2B10H10}{Li4-
(THF)5}]2 (6) with 5.0 equiv of HBBr2‚SMe2 gave both the 13-
vertex carborane 1,2-(CH2)3-1,2-C2B11H11 (2) and a 14-vertex
(8) For CAd carborane anions, see: (a) Zi, G.; Li, H.-W.; Xie, Z. Organo-
metallics 2001, 20, 3836-3838. (b) Zi, G.; Li, H.-W.; Xie, Z. Chem.
Commun. 2001, 1110-1111. (c) Zi, G.; Li, H.-W.; Xie, Z. Organometallics
2002, 21, 5415-5427. (d) Deng, L.; Cheung, M.-S.; Chan, H.-S.; Xie, Z.
Organometallics 2005, 24, 6244-6249. (e) Xie, Z. Pure Appl. Chem. 2003,
75, 1335-1341.
(9) Grimes, R. N. Angew. Chem., Int. Ed. 2003, 42, 1198-1200.
(10) For reviews, see: (a) Saxena, A. K.; Hosmane, N. S. Chem. ReV. 1993,
93, 1081-1124. (b) Saxena, A. K.; Maguire, J. A.; Hosmane, N. S. Chem.
ReV. 1997, 97, 2421-2462. (c) Grimes, R. N. Coord. Chem. ReV. 2000,
200/202, 773-811. (d) Xie, Z. Pure Appl. Chem. 2001, 73, 361-365. (e)
Kang, S. O.; Ko, J. AdV. Organomet. Chem. 2001, 47, 61-99. (f) Xie, Z.
Acc. Chem. Res. 2003, 36, 1-9. (g) Xie, Z. Coord. Chem. ReV. 2002, 231,
23-46. (h) Xie, Z. Coord. Chem. ReV. 2006, 250, 259-272.
Single-crystal X-ray analyses revealed there are four and two
crystallographically independent molecules, respectively, in the
unit cells of 3 and 9. Their representative structures are shown
9
5220 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006

13-Vertex Carboranes and 14-Vertex Metallacarboranes
A R T I C L E S
implying a small activation barrier.6 These results suggest that
the tethering group has a large effect on the connectivity around
the cage carbon atoms.
Methylation and Halogenation of 13-Vertex closo-Carbo-
ranes. Very rich electrophilic substitution reactions on icosa-
hedral boranes12 and carboranes13,14 prompted us to examine
the chemical properties of 13-vertex carboranes. Compound 2
was chosen for this purpose for its simplicity. Reaction of 2
with excess iodomethane in the presence of a catalytic amount
of AlCl3 at room temperature for 2 days gave a hexamethylated
13-vertex carborane 8,9,10,11,12,13-(CH3)6-1,2-(CH2)3-1,2-
C2B11H5 (10) in 85% isolated yield (Scheme 3). This reaction
was closely monitored by 11B NMR spectroscopy as 2 and 10
have distinct splitting patterns. Prolonged reaction did not lead
to the complete methylation product but rather a mixture of
polymethylated products as indicated by the 11B NMR spectra.
The hexahalogenated products 8,9,10,11,12,13-X6-1,2-(CH2)3-
1,2-C2B11H5 (X ) Br (11), I (12)) were obtained in 22% and
25% isolated yields by treatment of 2 with excess bromine and
iodine in CH2Cl2 at room temperature in the presence of a
catalytic amount of AlCl3, respectively (Scheme 3). Higher
halogenation products were not observed even under forced
reaction conditions. Interaction of 2 with H2O2 led to a complete
degradation of the cage, resulting in the formation of B(OH)3,
which differed significantly from its icosahedral analogues.14h
Figure 1. Molecular structure of 1,2-(CH2)3-3-Ph-1,2-C2B11H10 (3), show-
ing one of the four crystallographically independent molecules in the unit
cell.
Compound 10 is very stable in air and moisture and quite
soluble in common organic solvents. However, 11 and 12 are
hygroscopic and decomposed slowly in moist air. Such a process
sped up in a basic media as indicated by the 11B NMR. These
results are very different from those obtained for their icosa-
hedral cousins,12-14 which might be ascribed to the joint effects
of the substituents and the more open trapezoidal faces presented
in these 13-vertex carboranes. The low stability of 11 and 12
(12) For B12H122-, see: (a) Peymann, T.; Knobler, C. B.; Hawthorne, M. F. J.
Am. Chem. Soc. 1999, 121, 5601-5602. (b) Peymann, T.; Knobler, C. B.;
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Am. Chem. Soc. 2001, 123, 2182-2185. (d) Sivaev, I. B.; Bregadze, V. I.;
Sjoberg, S. Collect. Czech. Chem. Commun. 2002, 67, 679-727. (e) Farha,
O. K.; Julius, R. L.; Lee, M. W.; Huertas, R. E.; Knobler, C. B.; Hawthorne,
M. F. J. Am. Chem. Soc. 2005, 127, 18243-18251.
(13) For CB11H12-, see: (a) Jelinek, T.; Plesˇek, J.; Heˇrma´neck, S.; Sˇt´ıbr, B.
Collect. Czech. Chem. Commun. 1986, 51, 819-829. (b) Jelinek, T.;
Baldwin, P.; Scheidt, W. R.; Reed, C. A. Inorg. Chem. 1993, 32, 1982-
1990. (c) Xie, Z.; Jelinek, T.; Bau, R.; Reed, C. A. J. Am. Chem. Soc.
1994, 116, 1907-1913. (d) King, B. T.; Janousek, Z.; Gruener, B.;
Trammell, M.; Noll, B. C.; Michl, J. J. Am. Chem. Soc. 1996, 118, 3313-
3314. (e) Xie, Z.; Manning, J.; Reed, R. W.; Mathur, R.; Boyd, P. D. W.;
Benesi, A.; Reed, C. A. J. Am. Chem. Soc. 1996, 118, 2922-2928. (f)
Xie, Z.; Tsang, C. W.; Xue, F.; Mak, T. C. W. Inorg. Chem. 1997, 36,
2246-2247. (g) Ivanov, S. V.; Rockwell, J. J.; Polyakov, O. G.; Gaudinski,
C. M.; Anderson, O. P.; Solntsev, K. A.; Strauss, S. H. J. Am. Chem. Soc.
1998, 120, 4224-4225. (h) Xie, Z.; Tsang, C. W.; Sze, E. T. P.; Yang. Q.;
Chan, D. T. W.; Mak, T. C. W. Inorg. Chem. 1998, 37, 6444-6451. (i)
Tsang, C. W.; Xie, Z. Chem. Commun. 2000, 1839-1840. (j) Clarke, A.
J.; Ingleson, M. J.; Kociok-Ko¨hn, G.; Mahon, M. F.; Patmore, N. J.; Rourke,
J. P.; Ruggiero, G. D.; Weller, A. S. J. Am. Chem. Soc. 2004, 126, 1503-
1517.
Figure 2. Molecular structure of 1,2-C6H4(CH2)2-1,2-C2B11H11 (9), showing
one of the two crystallographically independent molecules in the unit cell.
in Figures 1 and 2. Selected bond distances are listed in Table
1. In view of the molecular structures of 3, 9, and 1,2-C6H4-
(CH2)2-3-Ph-1,2-C2B11H10 (9Ph),6 it is found that the connectiv-
ity of the cage carbon atoms in 3 is significantly different from
those observed in 9 and 9Ph. Chart 1 illustrates the connectivity
of the C(cage)-C(cage) unit with its lower layered five boron
atoms. The four independent molecules in 3 occur as two pairs
of similar molecules, and each of them are related by an
approximate translation. One pair (3a, b) bears two trapezoidal
faces with the others being triangulated, giving one five- and
one four-coordinate cage carbon atoms, respectively. The other
(3c, d) possesses one trapezoidal face and one bent pentagonal
face, resulting in the formation of two four-coordinate cage
carbon atoms. It is noted that in solution only one set of peaks
(14) For C2B10H12, see: (a) Potenza, J. A.; Lipscomb, W. N. Inorg. Chem. 1966,
5, 1483-1488. (b) Bregadze, V. I. Chem. ReV. 1992, 92, 209-224. (c)
Jiang, W.; Knobler, C. B.; Mortimer, M. D.; Hawthorne, M. F. Angew.
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Herzog, A.; Knobler, C. B.; Hawthorne, M. F. Angew. Chem., Int. Ed. 1998,
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B.; Hawthorne, M. F. Chem.sEur. J. 1999, 5, 1212-1217. (g) Herzog,
A.; Callahan, R. P.; Macdonald, C. L. B.; Lynch, V. M.; Hawthorne, M.
F.; Lagow, R. J. Angew. Chem., Int. Ed. 2001, 40, 2121-2123. (h) Herzog,
A.; Knobler, C. B.; Hawthorne, M. F. J. Am. Chem. Soc. 2001, 123, 12791-
12797. (i) Barbera`, G.; Teixidor, F.; Vin˜as, C.; Sillanpa¨a¨, R.; Kiveka¨s, R.
Eur. J. Inorg. Chem. 2003, 8, 1511-1513. (j) Teixidor, F.; Barbera`, G.;
Vaca, A.; Kiveka¨s, R.; Sillanpa¨a¨, R.; Oliva, J.; Vin˜as, C. J. Am. Chem.
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1
was observed in the H and 11B NMR spectra of 3, indicating
a fast diamond-square-diamond process.11 Low-temperature
NMR experiments were not able to arrest this transformation,
(11) Lipscomb, W. Science 1966, 153, 373-378.
9
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A R T I C L E S
Deng et al.
Table 1. Selected Bond Distances (Å) in 13-Vertex Carboranes
3a
3b
3c
3d
9a
9b
9Pha
10
11
C(1)-B(3)
C(1)-B(4)
C(1)-B(5)
C(1)-B(6)
C(2)-B(3)
C(2)-B(5)
C(2)-B(6)
C(2)-B(7)
av B-Xb
2.139(3)
1.635(3)
1.663(3)
2.173(3)
1.958(3)
2.588(3)
1.779(3)
1.539(3)
2.109(3)
1.631(3)
1.687(3)
2.139(3)
1.877(2)
2.629(3)
1.803(3)
1.518(3)
1.994(3)
1.567(3)
1.764(3)
2.382(3)
1.993(3)
2.470(3)
1.748(3)
1.539(3)
2.102(3)
1.596(3)
1.681(3)
2.264(3)
1.978(3)
2.513(3)
1.774(3)
1.528(3)
1.915(2)
1.622(2)
1.799(2)
2.404(2)
1.870(2)
2.526(2)
1.821(2)
1.591(2)
1.907(2)
1.615(2)
1.799(2)
2.440(2)
1.867(2)
2.498(2)
1.820(2)
1.592(2)
1.840(3)
1.569(3)
1.898(3)
2.373(3)
1.917(3)
2.587(3)
1.766(2)
1.632(3)
2.167(9)
1.627(7)
1.627(7)
2.167(9)
1.860(9)
2.604(9)
1.860(9)
1.465(7)
1.587(9)
2.11(2)
1.60(2)
1.67(2)
2.24(2)
1.85(3)
2.56(2)
1.86(3)
1.53(2)
1.94(1)
a See ref 6. b For 10, X ) Me; for 11, X ) Br.
Chart 1. Connectivity of the C(cage)-C(cage) Unit with Boron
Atoms in 13-Vertex Carboranesa
a The distance of 1.96 Å was arbitrarily chosen as the cutoff point for
the representation of connectivities between the cage carbon and boron
atoms.
Scheme 3. Methylation/Halogenation of 13-Vertex Carborane
Figure 3. Stick representation of the chemical shifts and relative intensities
in the 11B{1H} spectra of 1,2-(CH3)2-1,2-C2B11H5X6. The blue and black
lines represent the BH and BX vertices, respectively.
toward water especially basic solutions led to poor isolated
yields, although they were formed quantitatively in the reactions
according to the 11B NMR analyses since the basic solutions
were used to remove excess halogen reagents during the workup
process.
The electronic effects of the substituents on the cage are
significant as shown in Figure 3. According to the 11B NMR
chemical shifts of the B-Me, B-Br, and B-I vertices, it might
be best described that both Me and Br are more electron-
withdrawing14j and I is more electron-donating than the H atom
in the 13-vertex cages. A similar phenomenon was observed in
Figure 4. Molecular structure of 8,9,10,11,12,13-(CH3)6-1,2-(CH2)3-1,2-
C2B11H5 (10).
to those of 1.58 (1) Å in 4,5,7,8,9,10,11,12-(CH3)8-1,2-
C2B10H4,14b 1.60 (1) Å in 9-X-12-Y-3,4,5,6,7,8,9,10-(CH3)8-
1,2-C2B10H4 (X, Y ) Cl, I),14j and 1.95 (1) Å in 9,10,11,12-
Br4-1,2-(CH3)2-1,2-C2B10H6.14a
Reactions of 13-Vertex closo-Carboranes with Groups 1
and 2 Metals. Synthesis and Structure of 13-Vertex nido-
Carborane Salts. It is well documented that o-R2C2B10H10 can
be reduced by group 1 metals to form [nido-R2C2B10H10]M2 or
[arachno-R2C2B10H10]Li4 (R2 ) linkages) salts.8,15 They are very
useful synthons for the synthesis of metallacarboranes of p-,
d-, and f-block elements and super-carboranes with 13 and 14
vertices.6,7,10,16 Treatment of 13-vertex closo-carboranes 2, 3,
a 7,8,9,10,11,12-X6-CB11H6 system.13e
-
The molecular structures of both 10 and 11 were further
confirmed by single-crystal X-ray analyses and shown in Figures
4 and 5, respectively. The geometry of the cage and the
connectivity around the cage carbon atoms in 10 and 11 are
very similar to those of 3b (Table 1). All six methyl or bromo
substituents are bound to the cage boron atoms that are the
farthest away from the cage carbons because these boron vertices
are the most electron-rich ones. The average B-X bond
distances of 1.587(9) Å in 10 and 1.94(1) Å in 11 are very close
9
5222 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006

13-Vertex Carboranes and 14-Vertex Metallacarboranes
A R T I C L E S
Figure 6. Molecular structure of {1,2-(CH2)3-1,2-C2B11H11}{Li2(DME)2-
(THF)2} (13).
Figure 5. Molecular structure of 8,9,10,11,12,13-Br6-1,2-(CH2)3-1,2-
C2B11H5 (11).
tallization of 15 from a dioxane solution afforded a nido-
carborane salt of dioxane solvation [{nido-1,2-C6H4(CH2)2-1,2-
C2B11H11}{Na2(dioxane)0.5(THF)4}]n (15a).
Scheme 4. Preparation of Group 1 Metal Complexes of 13-Vertex
nido-Carboranes
Significantly different from 1, the reaction of 2 with excess
finely cut lithium metal in THF gave, after recrystallization from
DME, {nido-1,2-(CH2)3-1,2-C2B11H11}{Li2(THF)2(DME)2} (13)
in 83% isolated yield. No arachno species was detected. This
result indicates that the Li metal is unable to reduce the 13-
vertex nido-carborane although Li can readily reduce the 12-
vertex nido-carborane to the corresponding arachno-species.8
It may be concluded that the 13-vertex nido-carborane is a
stronger reductant (or a weaker oxidant) than the 12-vertex nido-
carborane in the above redox reactions. This may be one of the
reasons why 14-vertex carboranes are less accessible than the
13-vertex species.
The 1H NMR spectra supported a ratio of two THF and two
DME molecules per cage in 13, four THF molecules per cage
in 13a, 14, and 15 and four THF and a half dioxane molecules
per cage in 15a, respectively. The 11B NMR spectra displayed
a 1:5:5 splitting pattern in the range -9 to -25 ppm for 13,
13a, 15, and 15a and a 1:1:2:3:2:1:1 splitting pattern within
-5 to -28 ppm for 14. Their compositions were confirmed by
elemental analyses. The molecular structures were subject to
single-crystal X-ray diffraction studies.
Except for the monomeric structure of 13 that consists of
well-separated, alternating layers of cations [Li(THF)(DME)]+
and dianions [nido-(CH2)3C2B11H11]2- shown in Figure 6, others
are coordination polymers in which sodium ions link the nido-
carborane cages via either Na‚‚‚H-B interactions in 14 (Figure
7) and 15 (Figure 8) or Na‚‚‚O(dioxane) bonding interactions
and 9 with excess finely cut Na metal in THF at room
temperature gave the corresponding 13-vertex nido-carborane
salts [{nido-1,2-(CH2)3-1,2-C2B11H11}{Na2(THF)4}]n (13a), [{ni-
do-1,2-(CH2)3-3-Ph-1,2-C2B11H10}{Na2(THF)4}]n (14), and [{nido-
1,2-(C6H4)(CH2)2-1,2-C2B11H11}{Na2(THF)4}]n (15) in 80-85%
yields (Scheme 4). It was noteworthy that these reactions
proceeded much faster than those of icosahedral cages and
naphthalene was not required, indicating that 13-vertex carbo-
ranes were more reactive than the 12-vertex ones.8,15 Recrys-
(16) (a) Wilson, N. M. M.; Ellis, D.; Buoyd, A. S. F.; Giles, B. T.; Macgregor,
S. A.; Rosair, G. M.; Welch, A. J. Chem. Commun. 2002, 464-465. (b)
Wang, S.; Wang, Y.; Cheung, M.-S.; Chan, H.-S.; Xie, Z. Tetrahedron
2003, 59, 10373-10380. (c) Laguna, M. A.; Ellis, D.; Rosair, G. M.; Welch,
A. J. Inorg. Chim. Acta 2003, 347, 161-167. (d) Wang, S.; Li, H.-W.;
Xie, Z. Organometallics 2004, 23, 3780-3787. (e) Wang, S.; Li, H.-W.;
Xie, Z. Organometallics 2004, 23, 2469-2478. (f) Cheung, M.-S.; Chan,
H.-S.; Xie, Z. Organometallics 2004, 23, 517-526. (g) Hodson, B. E.;
McGrath, T. D.; Stone, F. G. A. Organometallics 2005, 24, 1638-1646.
(h) Burke, A.; Ellis, D.; Ferrer, D.; Ormsby, D. L.; Rosair, G. M.; Welch,
A. J. Dalton Trans. 2005, 1716-1721. (i) Cheung, M.-S.; Chan, H.-S.;
Xie, Z. Organometallics 2005, 24, 4468-4474. (j) Cheung, M.-S.; Chan,
H.-S.; Bi, S.; Lin, Z.; Xie, Z. Organometallics 2005, 24, 4333-4336.
(15) For examples, see: (a) Dunks, G. B.; Wiersema, R. J.; Hawthorne, M. F.
J. Am. Chem. Soc. 1973, 95, 3174-3179. (b) Tolpin, E. I.; Lipscomb, W.
N. Inorg. Chem. 1973, 12, 2257-2262. (c) Churchill, M. R.; DeBoer, B.
G. Inorg. Chem. 1973, 12, 2674-2682. (d) Getman, T. D.; Knobler, C.
B.; Hawthorne, M. F. J. Am. Chem. Soc. 1990, 112, 4593-4594. (e) Chui,
K.; Li, H.-W.; Xie, Z. Organometallics 2000, 19, 5447-5453.
9
J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006 5223

A R T I C L E S
Deng et al.
Figure 7. (Top) A portion of the infinite polymeric chains in [{1,2-(CH2)3-3-Ph-1,2-C2B11H10}{Na2(THF)4}]n (14). (Bottom) Structure of the anion in 14.
in 15a (Figure 9) to form infinite zigzag polymeric chains. A
common 13-vertex nido-carborane structural motif bearing
an open five-membered face (C(1)C(2)B(3)B(4)B(8)) with a
B(3)‚‚‚B(4) separation of about 2.64 Å is observed in all
structures. Selected bond distances are compiled in Table 2 for
comparison. The out-of-plane (C(1)C(2)B(3)B(4)) displacement
of the B(8) atom ranges from 0.68 to 0.72 Å, which is larger
than those observed in 12-vertex arachno-carborane tetraanions
(0.60 to 0.63 Å).8d The data in Table 2 indicate that the C, C′-
linkages do not have significant effects on the geometry of the
open five-membered ring in 13-vertex nido-carboranes.
To the best of our knowledge, there is no report on the
reduction of boron-substituted o-carboranes.17 Although it is not
possible to determine which bond breaks first in the reduction
of 13-vertex carboranes since complexes 13-15 are all ther-
modynamic products as indicated by the 11B NMR spectroscopy
(i.e., they do not isomerize upon heating), the formation of 14
suggests that the electron-withdrawing phenyl group favors the
BPh vertex to be on the open five-membered face. Careful
examination of the cage structures of 3 and 14 can conclude
that this transformation clearly involves several bond-forming
and bond-breaking processes.
powder in THF at room temperature gave the alkaline earth
metal complexes {(CH2)3C2B11H11}{M(THF)5} (M ) Mg (16),
Ca (17)) in ∼70% yield (Scheme 5). Their 11B NMR spectra
were identical with that of 13 and 13a, indicating that they
should have the same nido-carborane dianion. The H NMR
spectra supported a ratio of five THF molecules per cage for
1
both 16 and 17.
An X-ray diffraction study revealed that 17 is a monomeric
structure, consisting of a 13-vertex [nido-(CH2)3C2B11H11]2-
dianion and a pseudo-octahedral complex cation as shown
in Figure 10. The Ca2+ ion does not bond to the bent penta-
gonal face but rather interacts with the anion via one set of two
Ca‚‚‚H-B bondings. This is different from that of [η6-C2B10H12]-
Ca(MeCN)4 in which the nido-carboranyl ligand is η6-bound
to the Ca atom.18a As shown in Table 2, the structural parameters
of the anions are very close to those observed in 13.
Synthesis and Structure of 14-Vertex Metallacarboranes.
Polyhedral expansion, a method originated by Hawthorne,19 has
been widely used in the preparation of supra-icosahedral
metallacarboranes.10,16,18,20 This prompted us to explore the
(18) (a) Khattar, R.; Knobler, C. B.; Hawthorne, M. F. J. Am. Chem. Soc. 1990,
112, 4962-4963. (b) Khattar, R.; Knobler, C. B.; Hawthorne, M. F. Inorg.
Chem. 1990, 29, 2191-2192. (c) Hosmane, N. S. J. Organomet. Chem.
1999, 581, 13-27. (d) Hosmane, N. S.; Zhang, H.; Maguire, J. A.; Wang,
Y.; Demissie, T.; Colacot, T. J.; Ezhova, M. B.; Lu, K.-J.; Zhu, D.; Gray,
T. G.; Helfert, S. C.; Hosmane, S. N.; Collins, J. D.; Baumann, F.; Kaim,
W.; Lipscomb, W. N. Organometallics 2000, 19, 497-508. (e) Vin˜as, C.;
Barbera`, G.; Teixidor, F. J. Organomet. Chem. 2002, 642, 16-19. (f)
Laromaine, A.; Teixidor, F.; Vin˜as, C. Angew. Chem., Int. Ed. 2005, 44,
2220-2222.
It is reported that carboranes can be reduced by group 2
metals to form metallacarboranes.18 As a more reactive species,
13-vertex closo-carboranes are readily reduced by alkaline earth
metals. Treatment of 2 with excess activated Mg or Ca metal
(17) The reduction of boron-substituted 12-vertex nido-carboranes (Me3-
Si)4C4B7H7(BMe) and (Me3Si)4C4B7H7(BSiMe3) with Mg was reported,
see: ref 18d.
(19) Dunks, G. B.; McKown, M. M.; Hawthorne, M. F. J. Am. Chem. Soc. 1971,
93, 2541-2543.
9
5224 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006

13-Vertex Carboranes and 14-Vertex Metallacarboranes
A R T I C L E S
Figure 8. (Top) A portion of the infinite polymeric chains in [{1,2-C6H4(CH2)2-1,2-C2B11H11}{Na2(THF)4}]n (15). (Bottom) Structure of the anion in 15.
Figure 9. A portion of the infinite polymeric chains in [{1,2-C6H4(CH2)2-1,2-C2B11H11}{Na2(dioxane)0.5(THF)4}]n (15a).
applications of 13-vertex nido-carborane salts in the preparation
of 14-vertex carboranes and metallacarboranes. Very recently
we reported our preliminary results on the synthesis of a 14-
vertex carborane 1,2-(CH2)3-1,2-C2B12H12 from the reaction of
13a with HBBr2‚SMe2 in toluene.7 Accordingly, we examined
a series of reactions of 13a with different kinds of metal salts
such as SnCl2, ZrCl4, (Ph3P)2NiCl2, (Ph3P)2PdCl2, (Ph3P)2PtCl2,
and (Ph3P)3RuCl2 in attempts to prepare 14-vertex metallacar-
boranes. The results showed that the neutral 13-vertex carborane
2 was generated quantitatively according to the 11B NMR
analyses and was recovered in more than 90% yield after workup
in the reactions with SnCl2, ZrCl4, (Ph3P)2PdCl2, and (Ph3P)2-
PtCl2. It was clear that the redox reactions proceeded because
(20) For M2C4B8 clusters, see: (a) Maxwell, W. M.; Bryan, R. F.; Sinn, E.;
Grimes, R. N. J. Am. Chem. Soc. 1977, 99, 4016-4029. (b) Pipal, J. R.;
Grimes, R. N. Inorg. Chem. 1978, 17, 6-10. (c) Maxwell, W. M.; Bryan,
R. F.; Sinn, E.; Grimes, R. N. J. Am. Chem. Soc. 1977, 99, 4008-4015.
For M2C2B10 clusters, see: (d) Ellis, D.; Lopez, M. E.; McIntosh, R.; Rosair,
G. M.; Welch, A. J. Chem. Commun. 2005, 1917-1919. (e) Evans, W. J.;
Hawthorne, M. F. J. Chem. Soc., Chem. Commun. 1974, 38-39.
9
J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006 5225

A R T I C L E S
Deng et al.
Table 2. Selected Bond Distances (Å) for 13, 13a, 14, 15, 15a, and 17-19
13a
13a
14
15
15a
17
18
19
C(1)-C(2)
C(1)-B(4)
C(2)-B(3)
B(4)-B(8)
B(3)-B(8)
B(3)‚‚‚B(4)
db
1.503(10)
[1.552(9)]
1.578(11)
[1.557(11)]
1.573(12)
[1.596(12)]
1.874(12)
[1.844(11)]
1.850(12)
[1.894(11)]
2.628(18)
[2.657(18)]
0.691
1.529(8)
1.552(6)
1.553(5)
1.547(6)
1.541(5)
1.491(6)
1.512(9)
1.557(6)
1.557(6)
1.903(6)
1.903(6)
2.677(6)
0.679
1.572(7)
1.580 (7)
1.859(7)
1.893(7)
2.653(9)
0.705
1.562(7)
1.560(6)
1.864(7)
1.854(7)
2.584(8)
0.721
1.570(8)
1.561(8)
1.860(8)
1.866(8)
2.614(10)
0.682
1.565(5)
1.572(6)
1.862(5)
1.879(6)
2.650(6)
0.701
1.739(6)
1.730(6)
1.914(7)
1.925(7)
2.854(7)
0.631
1.738(11)
1.714(11)
1.947(12)
1.946(12)
2.869(12)
0.620
[0.695]
Ni(1)-C(1)
Ni(1)-C(2)
Ni(1)-B(3)
Ni(1)-B(4)
Ni(1)-B(8)
2.216(4)
2.158(4)
2.061(5)
2.062(5)
2.469(5)
2.205(7)
2.195(7)
2.051(8)
2.058(8)
2.451(8)
a Distances in brankets are those of a second molecule. b Displacement of B(8) to the C(1)C(2)B(3)B(4) plane.
Scheme 5. Preparation of Group 2 Metal Complexes of 13-Vertex
nido-Carboranes
Scheme 6. Preparation of 14-Vertex Nickelacarboranes
of the very strong reducing power of 13-vertex nido-carborane
anions. In the case of (Ph3P)2NiCl2 and (Ph3P)3RuCl2, the 11B
NMR spectra indicated the formation of new products in
addition to 2. Many attempts to isolate a pure 14-vertex species
from the reaction mixtures failed.
The above results suggested that prevention of the redox
reactions is crucial for the preparation of 14-vertex metalla-
carboranes. After screening a number of metal halides, it was
found that (dppe)NiCl2 and (dppen)NiCl2 (dppe ) 1,2-bis-
(diphenylphosphino)ethane, dppen ) cis-1,2-bis(diphenylphos-
phino)ethene) were suitable metal salts. They were treated with
1 equiv of 13a in THF to afford the desired 14-vertex
nickelacarboranes [η5-(CH2)3C2B11H11]Ni(dppe) (18) and [η5-
(CH2)3C2B11H11]Ni(dppen) (19) in 34% and 45% yields,
respectively (Scheme 6). Complexes 18 and 19 were very
Figure 10. Molecular structure of {1,2-(CH2)3-1,2-C2B11H11}{Ca(THF)5}
(17).
21
22
sensitive to air and moisture. They decomposed slowly at room
temperature in solution to generate 2 and presumably Ni(dppe)2
or Ni(dppen)2 as indicated by 11B and 31P NMR. It was noted
that 18 and 19 did not dissolve in common organic solvents
such as THF and CH2Cl2 once crystallized out, which made
NMR characterization infeasible. The 1H NMR spectra of their
hydrolysis products showed a ratio of one dppe or dppen and
three THF molecules per cage.
(21) Booth, G.; Chatt, J. J. Chem. Soc. 1965, 3238-3241.
(22) Bomfim, J. A. S.; de Souza, F. P.; Filgueiras, C. A. L.; de Sousa, A. G.;
Gambardella, M. T. P. Polyhedron 2003, 22, 1567-1573.
Single-crystal X-ray analyses revealed that 18 and 19 are
isomorphous and isostructural with three THFs of solvation, as
9
5226 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006

13-Vertex Carboranes and 14-Vertex Metallacarboranes
A R T I C L E S
C2B4H4]Ni(TMEDA).24 Complexes 18 and 19 are best described
as 18e- species, in which nido-carboranyl acts as a 6e- π ligand.
Conclusion
This paper reports in detail the syntheses, properties, and
synthetic applications of 13-vertex closo- and nido-carboranes.
The results show that the capitation reactions of CAd 12-vertex
nido-carborane dianionic salts with dihaloboranes are generally
a good method for the preparation of 13-vertex carboranes. The
C, C′-linkages of the cages have a large effect on the formation
of 13-vertex carboranes. Less sterically demanding linkages and
dihaloboranes usually offer higher synthetic yields. These super-
carboranes have more diverse structures than their icosahedral
cousins. Different isomers are observed in the solid-state
structures of 13-vertex species with various connectivity patterns
of the cage carbon atoms.
Electrophilic substitution of BH vertices on 13-vertex closo-
carborane has been achieved. Hexamethylated and hexahalo-
genated 13-vertex closo-carboranes have been prepared. Sur-
prisingly, the latter decomposes slowly upon exposure to
moisture, whereas the polyhalogenated icosahedral carboranes
are very stable to water.
Figure 11. Molecular structure of [η5-(CH2)3C2B11H11]Ni(dppe) (18).
13-Vertex closo-carboranes are readily reduced by groups 1
and 2 metals, affording CAd 13-vertex nido-carborane dianions
with a bent pentagonal face. These CAd dianions are inert
toward Li metal, which is significantly different from their 12-
vertex analogues. No CAd 13-vertex arachno-carborane tet-
raanions are observed.
Although CAd 13-vertex carborane dianions are stronger
reducing reagents than the corresponding 12-vertex ones as
evidenced by the reaction with Li metal, they are new π ligands
for transition metals. The isolation and structural characterization
of the 14-vertex carborane and nickelacarboranes clearly show
that CAd 13-vertex nido-carborane dianions are useful synthons
for the production of super-carboranes and -heteroboranes. It
is anticipated that a new class of 14-vertex heterocarboranes
derived from 13-vertex carboranes would be prepared in the
foreseeable future.
Figure 12. Molecular structure of [η5-(CH2)3C2B11H11]Ni(dppen) (19).
Experimental Section
shown in Figures 11 and 12, respectively. Selected bond lengths
are summarized in Table 2. The geometry of the 14-vertex
metallacarborane is a distorted-bicapped-hexagonal antiprism
with two seven-coordinate boron vertices, which is similar to
the 14-vertex carborane.7 Different from 13- and 14-vertex
metallacarboranes of the C2B10 systems20a,d in which the metal
is often bound to the carborane cage in an η6 fashion, the Ni
atom in 18 and 19 is bound to the bent open face (C(1)C(2)-
B(3)B(4)B(8)) in an η5 fashion with relatively long Ni(1)-B(8)
bond distances of 2.469(5) Å in 18 and 2.451(1) Å in 19,
respectively. The open pentagonal bonding faces in 18 and 19
are much larger than those observed in 13-15a and 17 as
indicated by the bond distances (Table 2). On the other hand,
the out-of-plane displacement of the B(8) atom is significantly
smaller than that found in groups 1 and 2 metal salts of the
13-vertex [nido-(CH2)3C2B11H11]2-. These changes imply that
the open bonding face in 13-vertex nido-carborane dianion is
quite flexible. Except for the Ni(1)-B(8) bond, other Ni-C,
Ni-B, and Ni-P bond distances in 18 and 19 (Table 2) are
very close to those observed in the known nickelacarboranes
such as [η5-Ph2C2B9H9]Ni(dppe) 23 and [η5-2,4-(SiMe3)2-2,4-
General Procedures. All experiments were performed under an
atmosphere of dry dinitrogen with the rigid exclusion of air and moisture
using standard Schlenk or cannula techniques or in a glovebox. All
organic solvents were freshly distilled from sodium benzophenone ketyl
immediately prior to use. 1,2-(CH2)3-1,2-C2B10H10 (1),7 [{1,2-(CH2)3-
1,2-C2B10H10}{Li4(THF)5}]2 (6),7 [{1,2-C6H4(CH2)2-1,2-C2B10H10}{Li4-
(THF)6}]2 (7),8a Z-EtCHdCEtBBr2‚SMe2,25 E-tBuCHdCHBBr2‚SMe2,25
activated Mg and Ca powder,26 (dppe)NiCl2,21 and (dppen)NiCl222 were
prepared according to the literature methods. All other chemicals were
purchased from either Aldrich or Acros Chemical Co. and used as
received unless otherwise noted. Infrared spectra were obtained from
KBr pellets prepared in the glovebox on a Perkin-Elmer 1600 Fourier
1
transform spectrometer. H and 13C NMR spectra were recorded on a
Bruker DPX 300 spectrometer at 300.13 and 75.47 MHz, respectively.
11B NMR spectra were recorded on a Varian Inova 400 spectrometer
at 128.32 MHz. All chemical shifts were reported in δ units with
(23) Garrioch, R. M.; Kuballa, P.; Low, K. S.; Rosair, G. M.; Welch, A. J. J.
Organomet. Chem. 1999, 575, 57-62.
(24) Zhang, H.; Wang, Y.; Saxena, A. K.; Oki, A. R.; Maguire, J. A.; Hosmane,
N. S. Organometallics 1993, 12, 3933-3944.
(25) Brown, H. C.; Campbell, J. B., Jr. J. Org. Chem. 1980, 45, 389-395.
(26) Rieke, R. D.; Li, P. T.-J.; Burns, T. P.; Uhm, S. T. J. Org. Chem. 1981,
46, 4323-4324.
9
J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006 5227

A R T I C L E S
Deng et al.
references to the residual protons of the deuterated solvents for proton
and carbon chemical shifts and to external BF3‚OEt2 (0.00 ppm) for
boron chemical shifts. Mass spectra were recorded on a Thermo
Finnigan MAT 95 XL spectrometer. Elemental analyses were performed
by MEDAC Ltd., Middlesex, U.K.
(d, JBH ) 128 Hz, 3B, BH). IR (KBr, cm-1): νBH 2564 (vs). HRMS
m/z calcd for C11H27B11+: 278.3204. Found: 278.3200.
Preparation of 1,2-(CH2)3-1,2-C2B12H12 (8). To a toluene (50 mL)
suspension of [{1,2-(CH2)3-1,2-C2B10H10}{Li4(THF)5}]2 (6; 8.60 g, 15.0
mmol) was slowly added HBBr2‚SMe2 (75.0 mL of 1.0 M in
dichloromethane, 75.0 mmol) at -78 °C, and the mixture was stirred
at this temperature for 1 h and then at room temperature for 6 h.
Removal of the precipitate and solvents gave a brownish sticky solid.
Chromatographic separation (SiO2, 300-400 mesh, n-hexane as elute)
afforded 1 (0.12 g, 2%), 2 (1.88 g, 32%), and 8 (0.44 g, 7%),
respectively, all as a white solid. Mp 88-90 °C. 1H NMR (CDCl3): δ
3.15 (m, 4H, CH2CH2CH2), 2.31 (m, 2H, CH2CH2CH2). 13C{1H} NMR
(CDCl3): δ 40.73 (CH2CH2CH2), 25.88 (CH2CH2CH2); the cage
carbons were not observed. 11B NMR (CDCl3): δ 7.80 (d, JBH ) 154
Hz, 1B, BH), 5.64 (d, JBH ) 154 Hz, 2B, BH), 2.87 (d, JBH ) 160 Hz,
2B, BH), -4.23 (d, JBH ) 180 Hz, 1B, BH), -6.39 (d, JBH ) 151 Hz,
2B, BH), -9.29 (d, JBH ) 168 Hz, 1B, BH), -12.34 (d, JBH ) 159 Hz,
Preparation of 1,2-(CH2)3-1,2-C2B11H11 (2). To a THF (30 mL)
solution of 1,2-(CH2)3-1,2-C2B10H10 (1; 1.84 g, 10.0 mmol) was added
finely cut Na metal (0.50 g, 21.7 mmol) and a catalytic amount of
naphthalene (0.10 g, 0.78 mmol), and the mixture was stirred at room
temperature for 4 days, giving a deep green solution. Removal of THF
afforded a brown solid, presumably [nido-(CH2)3C2B10H10][Na2(THF)x].
Toluene (30 mL) was then added, giving a yellow suspension. HBBr2‚
SMe2 (20.0 mL of 1.0 M in dichloromethane, 20.0 mmol) was slowly
added to the suspension at -78 °C, and the mixture was stirred at this
temperature for 1 h and then at room temperature for 6 h. Chromato-
graphic separation (SiO2, 300-400 mesh, n-hexane as elute) afforded
1 (0.06 g, 3%) and 2 (0.73 g, 37%) both as a white solid. Mp 60-61
°C. 1H NMR (CDCl3): δ 3.26 (t, J ) 7.5 Hz, 4H, CH2CH2CH2), 2.18
(m, 2H, CH2CH2CH2). 13C{1H} NMR (CDCl3): δ 49.11 (CH2CH2CH2),
25.55 (CH2CH2CH2); the cage carbons were not observed. 11B NMR
(CDCl3): δ 3.52 (d, JBH ) 186 Hz, 1B, BH), 0.96 (d, JBH ) 186 Hz,
5B, BH), -1.19 (d, JBH ) 186 Hz, 5B, BH). IR (KBr, cm-1): νBH
2570 (vs). HRMS m/z calcd for C5H17B11+: 195.2457. Found: 195.2455.
Preparation of 1,2-(CH2)3-3-Ph-1,2-C2B11H10 (3). Following the
procedures described for 2, PhBCl2 (2.60 mL, 20.0 mmol) was reacted
with a suspension of [nido-(CH2)3C2B10H10][Na2(THF)x] (10.0 mmol)
in toluene (30 mL). Compounds 1 (0.12 g, 6%) and 3 (0.54 g, 20%)
were obtained as a white solid. X-ray-quality crystals of 3 were grown
from a saturated n-hexane solution at room temperature. Mp 97-98
°C. 1H NMR (CDCl3): δ 7.42 (d, J ) 6.9 Hz, 2H, C6H5), 7.32 (m, 3H,
C6H5), 3.05 (t, J ) 7.2 Hz, 4H, CH2CH2CH2), 1.84 (m, 2H, CH2CH2-
CH2). 13C{1H} NMR (CDCl3): δ 134.1, 129.6, 128.1 (C6H5), 47.56
(CH2CH2CH2), 25.57 (CH2CH2CH2); the CB and cage carbons were
2B, BH), -24.73 (d, JBH ) 145 Hz, 1B, BH). IR (KBr, cm-1): νBH
+
2566 (vs). HRMS: m/z calcd for C5H18B12
: 208.2592. Found:
208.2583.
Preparation of 1,2-C6H4(CH2)2-1,2-C2B11H11 (9). Following the
procedures described for 8. HBBr2‚SMe2 (25.0 mL of 1.0 M in
dichloromethane, 25.0 mmol) was reacted with [{1,2-C6H4(CH2)2-1,2-
C2B10H10}{Li4(THF)6}]2 (7; 7.20 g, 5.0 mmol) in toluene (30 mL). 1,2-
C6H4(CH2)2-1,2-C2B10H10 (0.21 g, 8%) and 9 (0.42 g, 17%) were
obtained both as a white solid. X-ray-quality crystals of 9 were grown
from a saturated n-hexane solution at room temperature. Mp 106-108
1
°C. H NMR (CDCl3): δ 7.53 (m, 2H, C6H4), 7.45 (m, 2H, C6H4),
4.35 (s, 4H, CH2). 13C{1H} NMR (CDCl3): δ 130.8, 128.5, 126.6
(C6H4), 50.81 (CH2); the cage carbons were not observed. 11B NMR
(CDCl3): δ 4.98 (d, JBH ) 128 Hz, 1B, BH), 2.11 (d, JBH ) 128 Hz,
5B, BH), -0.10 (d, JBH ) 146 Hz, 5B, BH). IR (KBr, cm-1): νBH
+
2566 (vs). HRMS m/z calcd for C10H19B11
: 256.2421. Found:
not observed. 11B NMR (CDCl3): δ 3.31 (s, 1B, BPh), 1.18 (d, JBH
186 Hz, 1B, BH), -2.32 (d, JBH ) 146 Hz, 3B, BH), -3.30 (d, JBH
)
)
256.2424.
Preparation of 8,9,10,11,12,13-(CH3)6-1,2-(CH2)3-1,2-C2B11H5 (10).
To an iodomethane (10 mL) solution of 2 (196 mg, 1.00 mmol) was
added a catalytic amount of AlCl3 (33 mg, 0.25 mmol), and the mixture
was stirred at room temperature for 2 days to give a red-brown turbid
solution. After filtration, the solid was washed with n-hexane (10 mL
× 2). The combined organic solution was treated with a saturated
NaHCO3 solution to remove acid and then with an aqueous Na2S2O3
solution. After drying with MgSO4, removal of the solvent yielded a
pale yellow oil. Flash chromatographic separation (SiO2, 300-400
mesh, n-hexane as elute) afforded 10 (234 mg, 85%) as a white solid.
X-ray-quality crystals were grown from a saturated n-hexane solution
128 Hz, 2B, BH), -7.06 (d, JBH ) 166 Hz, 4B, BH). IR (KBr, cm-1):
νBH 2566 (vs). HRMS m/z calcd for C11H21B11+: 270.2578. Found:
270.2581.
Preparation of 1,2-(CH2)3-3-(Z-EtCHdCEt)-1,2-C2B11H10 (4).
Following the procedures described for 2, Z-EtCHdCEtBBr2‚SMe2
(20.0 mmol in 20 mL of CH2Cl2) was reacted with a suspension of
[nido-(CH2)3C2B10H10][Na2(THF)x] (10.0 mmol) in toluene (30 mL).
Compound 4 (0.72 g, 26%) was obtained as a colorless oil with the
recovery of 1 (0.10 g, 5%). 1H NMR (CDCl3): δ 5.73 (t, J ) 7.2 Hz,
1H, CHdC), 3.15 (m, 4H, CH2CH2CH2), 2.04 (m, 6H, CH2CH3
+
CH2CH2CH2), 0.97 (t, J ) 7.5 Hz, 3H, CH2CH3), 0.88 (t, J ) 7.5 Hz,
3H, CH2CH3). 13C{1H} NMR (CDCl3): δ 146.4, 139.2 (vinyl carbon),
47.36 (CH2CH2CH2), 25.02 (CH2CH2CH2), 22.42 (CH2CH3), 22.19
(CH2CH3), 14.37 (CH2CH3), 13.98 (CH2CH3), the cage carbons were
1
at room temperature. Mp 125-128 °C. H NMR (CDCl3): δ 3.10 (t,
J ) 6.0 Hz, 4H, CH2CH2CH2), 2.06 (m, 2H, CH2CH2CH2), 0.17 (br,
15H, CH3), -0.12 (br, 3H, CH3). 13C{1H} NMR (CDCl3): δ 124.4
not observed. 11B NMR (CDCl3): δ 10.24 (s, 1B, BC), 5.70 (d, JBH
)
(cage carbon), 47.97 (CH
2CH2CH2), 25.23 (CH2CH2CH2), 0.92 (br,
CH3). 11B NMR (CDCl3): δ 7.11 (s, 1B, BMe), 5.19 (s, 5B, BMe),
-9.41 (d, JBH ) 146 Hz, 5B, BH). IR (KBr, cm-1): νBH 2557 (s).
HRMS m/z calcd for C11H29B11+: 279.3282. Found: 279.3280.
145 Hz, 1B, BH), 2.43 (d, JBH ) 151 Hz, 4B, BH), 0.31 (d, JBH ) 130
Hz, 2B, BH), -3.18 (d, JBH ) 153 Hz, 3B, BH). IR (KBr, cm-1): νBH
+
2565 (vs). HRMS m/z calcd for C11H27B11
: 278.3204. Found:
278.3204.
Preparation of 8,9,10,11,12,13-Br6-1,2-(CH2)3-1,2-C2B11H5 (11).
To a CH2Cl2 (10 mL) solution of 2 (196 mg, 1.00 mmol) was added
excess bromine (1.58 g, 10.0 mmol) and a catalytic amount of AlCl3
(33 mg, 0.25 mmol), and the mixture was stirred at room temperature
for 12 h to give a deep red turbid solution. After filtration, the solid
was washed with CH2Cl2 (10 mL × 2). The combined organic solution
was treated with a cold saturated NaHCO3 aqueous solution and dried
with MgSO4. Removal of the solvent yielded a brown solid. Recrys-
tallization from dry CH2Cl2 afforded 11 (168 mg, 25%) as yellow
Preparation of 1,2-(CH2)3-3-(E-tBuCHdCH)-1,2-C2B11H10 (5).
Following the procedures described for 2, E-tBuCHdCHBBr2‚SMe2
(20.0 mmol in 20 mL of CH2Cl2) was reacted with a suspension of
[nido-(CH2)3C2B10H10][Na2(THF)x] (10.0 mmol) in toluene (30 mL).
Compound 5 (0.83 g, 30%) was obtained as a colorless oil with the
1
recovery of 1 (0.10 g, 5%). H NMR (CDCl3): δ 6.14 (d, J ) 17.7
Hz, 1H, tBuCHdCH), 5.28 (d, J ) 17.7 Hz, 1H, tBuCHdCH), 3.15 (t,
J ) 7.5 Hz, 4H, CH2CH2CH2), 2.05 (m, 2H, CH2CH2CH2), 0.99 (s,
9H, C(CH3)3). 13C{1H} NMR (CDCl3): δ 137.0, 128.2 (vinyl carbon),
47.32 (CH2CH2CH2), 34.90 (C(CH3)3), 28.86 (C(CH3)3), 25.76 (CH2CH2-
CH2); the cage carbons were not observed. 11B NMR (CDCl3): δ 7.03
(s, 1B, BC), 3.12 (d, JBH ) 186 Hz, 1B, BH), 0.54 (m, 6B, BH), -3.90
1
crystals. Mp. 181 °C (dec). H NMR (CDCl3): δ 3.30 (t, J ) 7.5 Hz,
4H, CH2CH2CH2), 2.34 (m, 2H, CH2CH2CH2). 13C{1H} NMR
(CDCl3): δ 122.5 (cage carbon), 48.93 (CH2CH2CH2), 25.47 (CH2CH2-
CH2). 11B NMR (CDCl3): δ 7.34 (s, 1B, BBr), 1.14 (s, 5B, BBr), -7.91
9
5228 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006

13-Vertex Carboranes and 14-Vertex Metallacarboranes
A R T I C L E S
(d, JBH ) 169 Hz, 5B, BH). IR (KBr, cm-1): νBH 2592 (s). HRMS:
m/z calcd for C5H11B11Br6+: 669.6990. Found: 669.6964.
(5). IR (KBr, cm-1): νBH 2524 (vs). Anal. Calcd for C22H43B11Na2O3
(15 - THF): C, 50.77; H, 8.33. Found: C, 51.11; H, 8.48.
Preparation of [{1,2-C6H4(CH2)2-1,2-C2B11H11}{Na2(dioxane)0.5
-
Preparation of 8,9,10,11,12,13-I6-1,2-(CH2)3-1,2-C2B11H5 (12). To
a CH2Cl2 (10 mL) solution of 2 (196 mg, 1.00 mmol) was added excess
iodine (2.54 g, 10.0 mmol) and a catalytic amount of AlCl3 (33 mg,
0.25 mmol), and the mixture was stirred at room temperature for 3
days to give a deep red turbid solution. After filtration, the solid was
washed with CH2Cl2 (10 mL × 2). The combined organic solution was
treated with saturated NaHCO3 solution and then an aqueous Na2S2O3
solution and dried with MgSO4. Removal of the solvent yielded a dark
red solid. Recrystallization from dry CH2Cl2 afforded 12 (210 mg, 22%)
as deep red crystals. Mp 230 °C (dec). 1H NMR (CDCl3): δ 3.01 (t, J
) 7.2 Hz, 4H, CH2CH2CH2), 2.30 (m, 2H, CH2CH2CH2). The 13C NMR
spectrum was not obtained for the very poor solubility of 12 in CDCl3.
11B NMR (CDCl3): δ 2.90 (s, 1B, BI), -1.92 (d, JBH ) 176 Hz, 5B,
BH), -8.73 (s, 5B, BI). IR (KBr, cm-1): νBH 2592 (w). HRMS: m/z
calcd for C5H11B11I6+: 951.6220. Found: 951.6220.
(THF)4}]n (15a). This compound was prepared from the recrystalli-
zation of 15 (593 mg, 1.00 mmol) in dioxane: yield 540 mg (85%).
1H NMR (pyridine-d5): δ 7.26 (m, 2H, C6H4), 7.14 (m, 2H, C6H4),
3.65 (m, 16H, THF), 3.62 (m, 4H, dioxane), 3.37 (s, 4H, CH2), 1.60
(m, 16H, THF). 13C{1H} NMR (pyridine-d5): δ 142.6, 126.1, 124.7
(C6H4), 67.18, 25.14 (THF), 66.51 (dioxane), 46.55 (CH2); the cage
carbons were not observed. 11B{1H} NMR (pyridine-d5): δ -6.77 (1),
-12.55 (5), -23.38 (5). IR (KBr, cm-1): νBH 2515 (vs). Anal. Calcd
for C24H45B11Na2O4 (15a - THF): C, 51.25; H, 8.06. Found: C, 51.33;
H, 8.55.
Preparation of {1,2-(CH2)3-1,2-C2B11H11}{Mg(THF)5} (16). This
complex was prepared as a white powder using the same procedures
described for 13 from 1,2-(CH2)3-1,2-C2B11H11 (2; 196 mg, 1.00 mmol)
and freshly prepared Mg powder (48 mg, 2.00 mmol) in THF (25
1
mL): yield 448 mg (77%). H NMR (pyridine-d5): δ 3.65 (m, 20H,
Preparation of {1,2-(CH2)3-1,2-C2B11H11}{Li2(DME)2(THF)2}
(13). To a THF (10 mL) solution of 1,2-(CH2)3-1,2-C2B11H11 (2; 196
mg, 1.00 mmol) was added finely cut Li metal (90.0 mg, 10.0 mmol),
and the mixture was stirred at room temperature for 1 day to give a
red solution. Removal of excess Li and THF yielded a pale yellow
solid. Recrystallization from DME afforded 13 as colorless crystals
THF), 2.43 (m, 4H, CH2CH2CH2), 2.26 (m, 2H, CH2CH2CH2), 1.62
(m, 20H, THF). 13C{1H} NMR (pyridine-d5): δ 67.18, 25.14 (THF),
42.69 (CH2CH2CH2), 29.33 (CH2CH2CH2); the cage carbons were not
observed. 11B{1H} NMR (pyridine-d5): δ -9.00 (1), -14.62 (5),
-24.62 (5). IR (KBr, cm-1): νBH 2488 (vs), 2448 (vs), 2348 (s). Anal.
Calcd for C7H21B11MgO0.5 (16 - 4.5 THF): C, 32.78; H, 8.25. Found:
C, 32.69; H, 8.62.
1
(443 mg, 83%). H NMR (pyridine-d5): δ 3.66 (m, 8H, THF), 3.50
(m, 8H, DME), 3.28 (m, 12H, DME), 2.40 (m, 4H, CH2CH2CH2), 2.21
(m, 2H, CH2CH2CH2), 1.65 (m, 8H, THF). 13C{1H} NMR (pyridine-
d5): δ 71.44, 58.05 (DME), 67.32, 25.25 (THF), 43.21 (CH2CH2CH2),
29.26 (CH2CH2CH2); the cage carbons were not observed. 11B{1H}
NMR (pyridine-d5): δ -8.67 (1), -14.36 (5), -24.56 (5). IR (KBr,
cm-1): νBH 2427 (vs). Anal. Calcd for C19H49B11Li2O10.5 (13 - 0.5
THF): C, 45.79; H, 9.91. Found: C, 45.79; H, 9.96.
Preparation of {1,2-(CH2)3-1,2-C2B11H11}{Ca(THF)5} (17). This
complex was prepared as colorless crystals using the same procedures
described for 13 from 1,2-(CH2)3-1,2-C2B11H11 (2; 196 mg, 1.00 mmol)
and freshly prepared Ca powder (80 mg, 2.00 mmol) in THF (25 mL):
1
yield 436 mg (73%). H NMR (pyridine-d5): δ 3.65 (m, 20H, THF),
2.47 (m, 6H, CH2), 1.61 (m, 20H, THF). 13C{1H} NMR (pyridine-d5):
δ 67.15, 25.12 (THF), 42.75 (CH2CH2CH2), 29.34 (CH2CH2CH2); the
cage carbons were not observed. 11B{1H} NMR (pyridine-d5): δ -11.00
(1), -15.86 (5), -26.10 (5). IR (KBr, cm-1): νBH 2499 (vs), 2464
(vs). Anal. Calcd for C21H49B11CaO4 (17 - THF): C, 48.08; H, 9.41.
Found: C, 47.69; H, 9.03.
Preparation of [{1,2-(CH2)3-1,2-C2B11H11}{Na2(THF)4}]n (13a).
This complex was prepared as colorless crystals using the same
procedures described for 13 from 1,2-(CH2)3-1,2-C2B11H11 (2; 196 mg,
1.00 mmol) and finely cut Na metal (230 mg, 10.0 mmol) in THF (25
1
mL): yield 425 mg (80%). H NMR (pyridine-d5): δ 3.63 (m, 16H,
Preparation of [η5-(CH2)3C2B11H11]Ni(dppe) (18). To a THF (10
mL) suspension of (dppe)NiCl2 (528 mg, 1.00 mmol) was slowly added
a THF (10 mL) solution of 13a (563 mg, 1.00 mmol) at -78 °C, and
the mixture was then stirred at room temperature for 6 h to give a
deep red solution. After filtration, the resulting red solution was
concentrated to about 10 mL. Complex 18‚3THF was obtained as dark
red crystals after this solution stood at room temperature for 1 day
(296 mg, 34%). NMR data were not obtainable as this complex did
not redissolve in common organic solvents. IR (KBr, cm-1): νBH 2529
(vs). Anal. Calcd for C35H49B11NiOP2 (18 + THF): C, 57.96; H, 6.81.
Found: C, 58.22; H, 7.12.
Preparation of [η5-(CH2)3C2B11H11]Ni(dppen) (19). To a THF (10
mL) suspension of (dppen)NiCl2 (526 mg, 1.00 mmol) was slowly
added a THF (10 mL) solution of 13a (563 mg, 1.00 mmol) at -78
°C, and the mixture was then stirred at room temperature for 6 h to
give a deep red solution. After filtration, the resulting red solution was
concentrated to about 10 mL. Complex 19‚3THF was obtained as dark
red crystals after this solution stood at room temperature for 1 day
(390 mg, 45%). NMR data were not obtainable as this complex did
not redissolve in common organic solvents. IR (KBr, cm-1): νBH 2532
(vs). Anal. Calcd for C31H39B11NiP2 (19): C, 57.18; H, 6.04. Found:
C, 57.52; H, 6.39.
THF), 2.46 (t, J ) 6.3 Hz, 4H, CH2CH2CH2), 2.25 (m, 2H, CH2CH2-
CH2), 1.59 (m, 16H, THF). 13C{1H} NMR (pyridine-d5): δ 67.15, 25.11
(THF), 42.93 (CH2CH2CH2), 29.24 (CH2CH2CH2), the cage carbons
were not observed. 11B{1H} NMR (pyridine-d5): δ -9.01 (1), -14.67
(5), -24.64 (5). IR (KBr, cm-1): νBH 2501 (vs). Anal. Calcd for
C17H41B11Na2O3 (13a - THF): C, 44.54; H, 9.02. Found: C, 44.20;
H, 9.03.
Preparation of [{1,2-(CH2)3-3-Ph-1,2-C2B11H10}{Na2(THF)4}]n
(14). This complex was prepared as colorless crystals using the same
procedures described for 13 from 1,2-(CH2)3-3-Ph-1,2-C2B11H10 (3; 272
mg, 1.00 mmol) and finely cut Na metal (230 mg, 10.0 mmol) in THF
(25 mL): yield 515 mg (85%). 1H NMR (pyridine-d5): δ 8.40 (d, J )
6.9 Hz, 2H, C6H5), 7.24 (m, 2H, C6H5), 7.13 (m, 1H, C6H5), 3.65 (m,
16H, THF), 2.38 (m, 4H, CH2CH2CH2), 2.20 (m, 2H, CH2CH2CH2),
1.61 (m, 16H, THF). 13C{1H} NMR (pyridine-d5): δ 134.3, 125.7
(C6H5), 67.18, 25.14 (THF), 41.07 (CH2CH2CH2), 29.22 (CH2CH2CH2);
the CB and cage carbons were not observed. 11B{1H} NMR (pyridine-
d5): δ -5.51 (1), -8.92 (1), -11.68 (2), -17.61 (3), -22.26 (2),
-26.08 (1), -27.22 (1). IR (KBr, cm-1): νBH 2596 (vs). Anal. Calcd
for C19H39B11Na2O2 (14 - 2THF): C, 49.14; H, 8.46. Found: C, 49.20;
H, 8.43.
Preparation of [{1,2-C6H4(CH2)2-1,2-C2B11H11}{Na2(THF)4}]n
(15). This complex was prepared as colorless crystals using the same
procedures described for 13 from 1,2-C6H4(CH2)2-1,2-C2B11H11 (9; 258
mg, 1.00 mmol) and finely cut Na metal (230 mg, 10.0 mmol) in THF
X-ray Structure Determination. Except for 3, 9, and 10, all single
crystals were immersed in Paraton-N oil and sealed under N2 in thin-
walled glass capillaries. Data were collected at 293 K on a Bruker
SMART 1000 CCD diffractometer using Mo KR radiation. An
empirical absorption correction was applied using the SADABS
program.27 All structures were solved by direct methods and subsequent
Fourier difference techniques and refined anisotropically for all non-
hydrogen atoms by full-matrix least squares calculations on F2 using
1
(25 mL): yield 504 mg (85%). H NMR (pyridine-d5): δ 7.26 (m,
2H, C6H4), 7.14 (m, 2H, C6H4), 3.65 (m, 16H, THF), 3.37 (s, 4H, CH2),
1.60 (m, 16H, THF). 13C{1H} NMR (pyridine-d5): δ 142.6, 126.1, 124.7
(C6H4), 67.18, 25.14 (THF), 46.55 (CH2); the cage carbons were not
observed. 11B{1H} NMR (pyridine-d5): -6.77 (1), -12.55 (5), -23.38
9
J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006 5229

A R T I C L E S
Deng et al.
Table 3. Crystal Data and Summary of Data Collection and Refinement for 3, 9, 10, 11, and 13
3
9
10
11
13
formula
C11H21B11
0.40 × 0.30 × 0.10
272.2
C10H19B11
0.50 × 0.40 × 0.20
258.2
C11H29B11
0.50 × 0.40 × 0.30
280.3
C5H11B11Br6
0.30 × 0.20 × 0.10
669.5
C42H106B22Li4O12
0.20 × 0.20 × 0.15
1068.9
crystal size (mm3)
fw
crystal system
space group
a, Å
orthorhombic
Pca21
orthorhombic
Pca21
orthorhombic
Pnma
orthorhombic
Pbca
orthorhombic
Pca21
17.164(1)
12.497(1)
30.441(2)
6529.3(7)
16
29.984(2)
6.958(1)
14.805(1)
3088.5(3)
8
13.549(12)
10.789(9)
12.519(11)
1830(3)
4
12.435(2)
17.434(3)
17.516(3)
3797.3(10)
8
26.847(2)
11.269(1)
22.190(2)
6713.4(9)
4
b, Å
c, Å
V, Å3
Z
D
calcd, Mg/m3
1.108
1.110
1.017
2.398
1.058
radiation (λ), Å
2θ range, deg
µ, mm-1
Mo KR (0.710 73)
2.6 to 52.0
0.052
Mo KR (0.710 73)
2.7 to 56.0
0.052
Mo KR (0.710 73)
5.0 to 48.0
0.047
Mo KR (0.710 73)
4.6 to 50.0
12.670
Mo KR (0.710 73)
3.4 to 48.0
0.065
F(000)
2272
1072
600
2448
2304
no. of obsd reflns
no. of params refnd
goodness of fit
R1
10 488
795
0.960
0.066
7358
380
0.994
0.060
1523
136
1.610
0.092
3344
199
1.017
0.062
10 527
722
0.994
0.090
wR2
0.155
0.135
0.311
0.156
0.222
Table 4. Crystal Data and Summary of Data Collection and Refinement for 14, 15, 15a, 17, 18‚3THF, and 19‚3THF
14
15
15a
17
18
‚3THF
19‚3THF
formula
crystal size
(mm3)
fw
crystal system
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C27H53B11Na2O4
0.50 × 0.40 × 0.30
C52H102B22Na4O8
0.30 × 0.20 × 0.10
C28H53B11Na2O5
0.50 × 0.30 × 0.20
C25H57B11CaO5
0.25 × 0.20 × 0.15
C43H65B11NiO3P2
0.30 × 0.30 × 0.20
C43H63B11NiO3P2
0.30 × 0.20 × 0.10
606.6
monoclinic
P21/n
15.322(5)
11.640(4)
20.559(7)
90
96.73(1)
90
1185.1
orthorhombic
Pbca
11.734(1)
24.069(1)
24.633(1)
90
90
90
6956.7(6)
8
1.132
634.6
monoclinic
P21/n
10.662(1)
28.285(2)
12.822(1)
90
100.73(1)
90
596.7
monoclinic
P21/c
9.824(1)
19.279(2)
18.281(2)
90
92.97(1)
90
869.5
triclinic
P1h
867.5
triclinic
P1h
11.002(1)
11.663(1)
20.388(2)
81.85(1)
77.99(1)
68.84(1)
2380.1(4)
2
10.961(2)
11.703(2)
20.509(3)
82.87(1)
80.04(1)
67.55(1)
2389.9(7)
2
3641(2)
4
1.106
3799.1(5)
4
1.109
3457.9(5)
4
1.146
Z
D
calcd, Mg/m3
1.213
1.205
radiation (λ), Å
2θ range, deg
µ, mm-1
F(000)
Mo KR (0.710 73)
3.2 to 50.0
0.085
Mo KR (0.710 73)
3.4 to 50.0
0.088
Mo KR (0.710 73)
2.9 to 48.0
0.087
Mo KR (0.710 73)
4.2 to 50.0
0.214
Mo KR (0.710 73)
3.8 to 50.0
0.512
Mo KR (0.710 73)
2.0 to 48.0
0.510
1296
2528
1352
1288
920
916
no. of obsd
6394
6117
5966
6090
8281
7514
reflns
no. of params
refnd
397
432
459
380
541
541
goodness of fit
R1
wR2
1.014
0.088
0.245
1.062
0.080
0.221
1.040
0.098
0.274
1.023
0.058
0.150
1.012
0.064
0.175
1.019
0.079
0.203
the SHELXTL program package.28 All hydrogen atoms were geo-
metrically fixed using the riding model. There were four crystallo-
graphically independent molecules in the unit cell of 3 and two in 9
and 13, respectively. The molecular structures of 18 and 19 contained
three THFs of solvation. Crystal data and details of data collection
and structure refinements were given in Tables 3 and 4.
Acknowledgment. The work described in this paper was
supported by a grant from the Research Grants Council of the
Hong Kong Special Administration Region (Project No. 403805).
Supporting Information Available: Crystallographic data in
CIF format for complexes 3, 9, 10, 11, 13, 14, 15, 15a, and
17-19. This material is available free of charge via the Internet
at http://pubs.acs.org.
(27) Sheldrick, G. M. SADABS: Program for Empirical Absorption Correction
of Area Detector Data. University of Go¨ttingen: Germany, 1996.
(28) Sheldrick, G. M. SHELXTL 5.10 for Windows NT: Structure Determination
Software Programs. Bruker Analytical X-ray Systems, Inc.: Madison,
Wisconsin, USA, 1997.
JA0605772
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5230 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006