Reaction scope and mechanism of sterically induced ruthenium-mediated intramolecular coupling of o-carboranyl with cyclopentadienyl. Synthesis and structure of ruthenium complexes incorporating doubly linked cyclopentadienyl-carboranyl ligands

Article abstract of DOI:10.1021/om0604122

Reactions of [Me(R¹)A(C₅H₃R ²)(C₂B₁₀H₁₀)]Li₂ (A = C, Si; R¹ = H, Me; R² = H, Me) with 1 equiv of RuCl ₂(PPh₃)₃ in THF afforded the corresponding doubly linked cyclopentadienyl-carboranyl ruthenium-(II) hydride complexes [η-Me₂C(C₅H₃)(C₂B ₁₀H₁₀)]RuH(PPh₃)₂ (6), [η ⁵-MeHC(C₅H₃)(C₂B₁₀H ₁₀)]RuH-(PPh₃)₂ (7), [η⁵-Me ₂C(5-Me-C₅H₂)(C₂B₁₀H ₁₀)]RuH(PPh₃)₂ (8), [η⁵-Me ₂C(3/4-Me-C₅H₂)(C₂B ₁₀H₁₀)]RuH-(PPh₃)₂ (9a/9b), and [η⁵-Me₂Si(C₅H₃)(C ₂B₁₀H₁₀)]RuH(PPh₃)₂ (10) in 72-85% isolated yields. On the other hand, interaction of [Me ₂C(C₅H₄)(C₂B₁₀H ₁₀)]Li₂ with 1 equiv of RuCl₂[PPh ₂(OEt)]₃ produced only [η⁵:σ-Me ₂C(C₅H₄)((C₂B₁₀H ₁₀)]Ru[PPh₂(OEt)]₂ (14). An equimolar reaction of [Me₂C(C₅H₄)(C₂B ₁₀H₁₀)]-Li₂ with RuCl₂(PPh ₃)₃ in the presence of dppe (dppe = 1,2-bis(diphenylphosphino)ethane) generated [η⁵:σ-Me ₂C(C₅H₄)(C₂B₁₀H ₁₀)]Ru(dppe) (15). No ruthenium hydride complexes were detected in the latter two cases. Treatment of [η⁵-Me₂C(C ₅H₃)(C₂B₁₀H ₁₀)]RuH(PPh₃)₂ (6) with excess HBF ₄·OEt₂ in toluene gave the neutral ligand Me ₂C(C₅H₄)(C₂B₁₀H ₁₀) (12). This work showed that such intramolecular coupling reactions were driven by steric factors. A possible reaction mechanism was proposed to account for these ruthenium-mediated coupling reactions. All new complexes were fully characterized by multinuclear NMR techniques and elemental analyses. Molecular structures of 6, 7, and 8 were further confirmed by single-crystal X-ray analyses.

Full text of DOI:10.1021/om0604122

4188
Organometallics 2006, 25, 4188-4195
Reaction Scope and Mechanism of Sterically Induced
Ruthenium-Mediated Intramolecular Coupling of o-Carboranyl with
Cyclopentadienyl. Synthesis and Structure of Ruthenium Complexes
Incorporating Doubly Linked Cyclopentadienyl-Carboranyl
Ligands
Yi Sun, Hoi-Shan Chan, and Zuowei Xie*
Department of Chemistry, The Chinese UniVersity of Hong Kong, Shatin, New Territories,
Hong Kong, China
ReceiVed May 15, 2006
Reactions of [Me(R1)A(C5H3R2)(C2B10H10)]Li2 (A ) C, Si; R1 ) H, Me; R2 ) H, Me) with 1 equiv
of RuCl2(PPh3)3 in THF afforded the corresponding doubly linked cyclopentadienyl-carboranyl ruthenium-
(II) hydride complexes [η5-Me2C(C5H3)(C2B10H10)]RuH(PPh3)2 (6), [η5-MeHC(C5H3)(C2B10H10)]RuH-
(PPh3)2 (7), [η5-Me2C(5-Me-C5H2)(C2B10H10)]RuH(PPh3)2 (8), [η5-Me2C(3/4-Me-C5H2)(C2B10H10)]RuH-
(PPh3)2 (9a/9b), and [η5-Me2Si(C5H3)(C2B10H10)]RuH(PPh3)2 (10) in 72-85% isolated yields. On the
other hand, interaction of [Me2C(C5H4)(C2B10H10)]Li2 with 1 equiv of RuCl2[PPh2(OEt)]3 produced only
[η5:σ-Me2C(C5H4)(C2B10H10)]Ru[PPh2(OEt)]2 (14). An equimolar reaction of [Me2C(C5H4)(C2B10H10)]-
Li2 with RuCl2(PPh3)3 in the presence of dppe (dppe ) 1,2-bis(diphenylphosphino)ethane) generated
[η5:σ-Me2C(C5H4)(C2B10H10)]Ru(dppe) (15). No ruthenium hydride complexes were detected in the latter
two cases. Treatment of [η5-Me2C(C5H3)(C2B10H10)]RuH(PPh3)2 (6) with excess HBF4‚OEt2 in toluene
gave the neutral ligand Me2C(C5H4)(C2B10H10) (12). This work showed that such intramolecular coupling
reactions were driven by steric factors. A possible reaction mechanism was proposed to account for
these ruthenium-mediated coupling reactions. All new complexes were fully characterized by multinuclear
NMR techniques and elemental analyses. Molecular structures of 6, 7, and 8 were further confirmed by
single-crystal X-ray analyses.
(C2B10H11) (A′′ ) H2C,8 Me2Si9), have been developed. These
ligands are finding many applications in organometallic
Introduction
chemistry.1-10 Experimental results show that the bridging atom
significantly influences the chemical and physical properties of
the resulting organometallic complexes.10 In this connection,
we are interested in a doubly linked ligand system incorporating
both carboranyl and cyclic π ligands.
A general method for the preparation of doubly bridged
biscyclopentadienes is the reaction of [Me2A(C5H4)2]Li2 with
Me2SiCl2.11 This methodology is, however, not applicable to
the proposed system. For example, treatment of [Me2A(C5H4)-
(C2B10H10)]M2 (A ) C, Si; M ) Li, Na, K) with 1 equiv of
Me2SiCl2 under various reaction conditions afforded a mixture
of inseparable products. On the other hand, attempts to prepare
[η5:σ-Me2C(C5H4)(C2B10H10)]Ru(PPh3)2 from the reaction of
[Me2C(C5H4)(C2B10H10)]Li2 with RuCl2(PPh3)3 under various
conditions failed; instead, an unprecedented ruthenium hydride
Ligands are an essential part of organometallic compounds.
They impose a dominant control over both the chemical and
the physical properties of the resulting metal complexes.1 By
taking the unique property of the carborane unit and the
advantage of cyclic π ligands, a series of single-atom-bridged
cyclopentadienyl-, indenyl-, and fluorenyl-carboranyl ligands,
A(C5H5)(C2B10H11) (A ) Me2C,2 Me2Si3), A′(C9H7)(C2B10H11)
(A′ ) Me2C,4 Me2Si,5 iPr2NB,6 iPr2NP7), and A′′(C13H9)-
* To whom correspondence should be addressed. Fax: (852)26035057.
Tel: (852)26096269. E-mail: zxie@cuhk.edu.hk.
(1) Xie, Z. Acc. Chem. Res. 2003, 36, 1.
(2) (a) Hong, E.; Kim, Y.; Do, Y. Organometallics 1998, 17, 2933. (b)
Chui, K.; Yang, Q.; Mak, T. C. W.; Xie, Z. Organometallics 2000, 19,
1391. (c) Wang, H.; Wang, Y.; Li, H.-W.; Xie, Z. Organometallics 2001,
20, 5110. (d) Wang, H.; Chan, H.-S.; Xie, Z. Organometallics 2005, 24,
3772.
(3) (a) Xie, Z.; Wang, S.; Zhou, Z.-Y.; Xue, F.; Mak, T. C. W.
Organometallics 1998, 17, 489. (b) Xie, Z.; Wang, S.; Zhou, Z.-Y.; Mak,
T. C. W. Organometallics 1998, 17, 1907. (c) Xie, Z.; Wang, S.; Zhou,
Z.-Y.; Mak, T. C. W. Organometallics 1999, 18, 1641. (d) Lee, M. H.;
Hwang, J.-W.; Kim, Y.; Han, Y.; Do, Y. Organometallics 2000, 19, 5514.
(e) Zi, G.; Yang, Q.; Mak, T. C. W.; Xie, Z. Organometallics 2001, 20,
2359.
(6) (a) Zi, G.; Li, H.-W.; Xie, Z. Organometallics 2002, 21, 1136. (b)
Zi, G.; Li, H.-W.; Xie, Z. Organometallics 2002, 21, 3850.
(7) (a) Wang, H.; Wang, H.; Li, H.-W.; Xie, Z. Organometallics 2004,
23, 875. (b) Wang, H.; Chan, H.-S.; Okuda, J.; Xie, Z. Organometallics
2005, 24, 3118.
(8) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. Organometallics 2004,
23, 5864.
(9) Wang, S.; Li, H.-W.; Xie, Z. Organometallics 2001, 20, 3842.
(10) (a) Xie, Z. Coord. Chem. ReV. 2002, 231, 23. (b) Xie, Z. Coord.
Chem. ReV. 2006, 250, 259.
(11) (a) Nifant’ev, I. E.; Yarnykh, V. L.; Borzov, M. V.; Mazurchik, B.
A.; Mstislavskii, V. I.; Roznyatovskii, V. A.; Ustynyuk, Yu. A. Organo-
metallics 1991, 10, 3739. (b) Brandow, C. G.; Mendiratta, A.; Bercaw, J.
E. Organometallics 2001, 20, 4253. (c) Siemeling, U.; Jutzi, P.; Neumann,
B.; Stammler, H. G.; Hursthouse, M. B. Organometallics 1992, 11, 1328.
(4) Wang, S.; Yang, Q.; Mak, T. C. W.; Xie, Z. Organometallics 2000,
19, 334.
(5) (a) Xie, Z.; Wang, S.; Yang, Q.; Mak, T. C. W. Organometallics
1999, 18, 2420. (b) Wang, S.; Yang, Q.; Mak, T. C. W.; Xie, Z.
Organometallics 1999, 18, 4478. (c) Wang, S.; Wang, Y.; Cheung, M.-S.;
Chan, H.-S.; Xie, Z. Tetrahedron 2003, 59, 10373. (d) Wang, S.; Li, H.-
W.; Xie, Z. Organometallics 2004, 23, 2469. (e) Wang, S.; Li, H.-W.; Xie,
Z. Organometallics 2004, 23, 3780. (f) Wang, S.; Li, H.-W.; Xie, Z.
Organometallics 2001, 20, 3624.
10.1021/om0604122 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 07/21/2006

Ru Complexes with Cyclopentadienyl-Carboranyl Ligands
Organometallics, Vol. 25, No. 17, 2006 4189
Scheme 1
Scheme 2
complex, [η5-Me2C(C5H3)(C2B10H10)]RuH(PPh3)2, containing
the doubly linked ligand [Me2C(C5H3)(C2B10H10)]- was isolated
in 80% yield.12 This result indicates that such an intramolecular
coupling reaction is very efficient. An independent work was
published soon after our communication,13 in which the
ruthenium complex [η5-(C5H4)(MeC2B10H10)]RuH(PPh3)2 bear-
ing a [(C5H4)(MeC2B10H10)]- ligand was prepared in 74% yield
from the reaction of CpRuCl(PPh3)2 with LiMeC2B10H10 in
toluene. A metal-assisted nucleophilic attack on the Cp ring was
proposed as a reaction pathway. These results prompted us to
investigate the reaction scope and possible mechanism of
ruthenium-mediated intramolecular coupling reaction of an
o-carboranyl with a cyclopentadienyl. We report here a full
account of our study on this subject.
[η5-Me(R1)A(C5H2R2)(C2B10H10)]Ru(H)(PPh3)2. The above
carbon-bridged cyclopentadienyl-carboranyl ligands were easily
converted into the corresponding dilithium salts [Me(R1)C-
(C5H3R2)(C2B10H10)]Li2 by reaction with 2 equiv of n-BuLi.
Treatment of these salts with 1 equiv of RuCl2(PPh3)3 at room
temperature in THF afforded, respectively, the ruthenium(II)
hydride complexes [η5-Me2C(C5H3)(C2B10H10)]RuH(PPh3)2 (6),12
[η5-MeHC(C5H3)(C2B10H10)]RuH(PPh3)2 (7), [η5-Me2C(5-Me-
C5H2)(C2B10H10)]RuH(PPh3)2 (8), and [η5-Me2C(3/4-Me-C5H2)-
(C2B10H10)]RuH(PPh3)2 (9a/b) as yellow crystals in 63-80%
isolated yields (Scheme 2). A Me2Si-linked analogue, [η5-Me2-
Si(C5H3)(C2B10H10)]RuH(PPh3)2 (10), was also prepared as
yellow crystals in 67% isolated yield by the reaction of [Me2-
Si(C5H4)(C2B10H10)]Li2 with 1 equiv of RuCl2(PPh3)3 in THF.
Surprisingly, a few red crystals identified as the dinitrogen
complex [{η5:σ-Me2Si(C5H4)(C2B10H10)}Ru(PPh3)]2(µ-N2) (11)
by single-crystal X-ray analyses (vide infra) were obtained from
the mother liquor of the above reaction. Its spectroscopic data
were not obtainable due to insufficient amount of materials
(Scheme 3). It is noted that 9a and 9b were isolated as a 1:1
mixture, as shown by the 1H NMR, which were inseparable by
recrystallization. On the other hand, reaction of [Me2A(C9H6)-
(C2B10H10)]Li2 (A ) C, Si) with 1 equiv of RuCl2(PPh3)3
generated a mixture of inseparable products that did not contain
any ruthenium hydride species, as indicated by the absence of
Results and Discussion
Ligands. To study the reaction scope of the coupling
reactions, several new carbon-bridged cyclopentadienyl-car-
boranyl ligands, MeHC(C5H5)(C2B10H11) (2), Me2C(2-Me-
C5H4)(C2B10H11) (3), and Me2C(3-Me-C5H4)(C2B10H11) (4),
were synthesized from the reaction of Li2C2B10H10 with 1.1
equiv of 6-methylfulvene, 2,6,6-trimethylfulvene, or 3,6,6-
trimethylfulvene in toluene/ether (2:1), followed by hydrolysis
with a saturated NH4Cl aqueous solution. They were isolated
as a pale yellow solid in 80-90% yields (Scheme 1).
1
The H NMR spectra showed that 2-4 are all mixtures of
different isomers, with the linkage being bonded to either a sp2-
or sp3-C of the five-membered ring. Several multiplets in the
range 5.92-6.61 ppm attributable to the vinyl protons of
cyclopentadiene, a broad singlet at about 3.4 ppm assignable
to the cage CH proton, and several multiplets at about 3.0 ppm
corresponding to the sp3-CH2 and sp3-CH protons of the
cyclopentadiene were observed. In addition, the linkage and
1
methyl substituent on the Cp ring were also found in the H
NMR spectra of 2-4. Their 13C{1H} NMR spectra were
consistent with the 1H NMR data. The 11B{1H} NMR spectrum
of 2 displayed a 1:1:2:1:2:3 pattern, whereas those of 3 and 4
exhibited a 1:1:2:2:4 pattern. Compounds 2-4 were further
characterized by high-resolution mass spectrometry.
1
the unique Ru-H resonance in the H NMR spectra.
Complexes 6-10 are very soluble in polar organic solvents
such as THF, CH2Cl2, CHCl3, and toluene and barely soluble
in hot n-hexane. They are stable for a few minutes in dry air in
the solid state, but decompose in moist air.
(12) For a preliminary communication, see: Sun, Y.; Chan, H.-S.;
Dixneuf, P. H.; Xie, Z. Chem. Commun. 2004, 2588.
(13) Basato, M.; Biffis, A.; Tubaro, C.; Graiff, C.; Tiripicchio, A. Dalton
Trans. 2004, 4092.

4190 Organometallics, Vol. 25, No. 17, 2006
Sun et al.
Scheme 3
1
The H NMR spectra of 6-10 showed a unique doublet of
doublets at about -10 ppm with 2JHP ≈ 30 and 40 Hz assignable
to the Ru-H proton, several multiplets of aromatic protons in
the range 7.65-6.81 ppm, and two singlets of Me2C or Me2Si
methyl protons (or a doublet of MeHC methyl protons in 7). In
addition, the CH and CMe protons of the five-membered ring
were also observed in the 1H NMR spectra. The 11B{1H} NMR
spectra exhibited a 1:2:1:1 pattern for 6-10. Two singlets at
about 70 and 65 ppm were found in the 31P{1H} NMR spectra
of 6-10, indicating the presence of planar chirality in all those
ruthenium hydride complexes. Their solid-state IR spectra all
displayed a characteristic terminal B-H absorption at around
2550 cm-1 and the frequency of a Ru-H stretch at around 1970
Figure 1. Molecular structure of [η5-MeHC(C5H3)(C2B10H10)]RuH-
(PPh3)2 (7).
cm-1 14
. The composition of 6-10 was confirmed by elemental
analyses. The presence of 9a,b isomers was supported by the
existence of two sets of NMR data (except for 11B{1H} NMR),
in particular, two doublets of doublets of two Ru-H protons
and two singlets and two doublets of the Cp protons corre-
1
sponding to 9a and 9b, respectively, observed in the H NMR
spectrum and four singlets found in the 31P{1H} NMR. It is
noted that, except for the Cp protons, a full assignment of the
resonances to 9a,b is not possible. The ratio of 9a,b did not
change as shown by the 1H NMR even after heating the NMR
solution at 80 °C for 4 h.
The molecular structures of 6-8 were further confirmed by
single-crystal X-ray analyses. Figures 1 and 2 show the
representative structures of 7 and 8, respectively. Selected bond
distances and angles are listed in Table 1 for comparison. They
have similar solid-state structures in which the Ru(II) ion is
η5-bound to a cyclopentadienyl ring and σ-bound to a hydrogen
atom and coordinated to two phosphorus atoms in a three-legged
piano stool geometry. The Ru-Cent distances of 1.910 Å in 6,
1.916 Å in 7, and 1.922 Å in 8 are close to that of 1.907 Å in
[η5-C5D4-(MeC2B10H10)]RuD(PPh3)2,13 but are longer than that
of 1.889 Å in CpRuH(PPh3)2,15 1.847 Å in CpRuCl(PPh3)2,16
and 1.848 Å in CpRuBr(PPh3)2.17 The P(1)-Ru-P(2) angle of
96.0(1)° in 6, 97.6(1)° in 7, and 97.2(1)° in 8 are almost the
Figure 2. Molecular structure of [η5-Me2C(5-Me-C5H2)(C2B10H10)]-
RuH(PPh3)2 (8).
same as that of 97.4(1)° in [η5-C5D4-(MeC2B10H10)]RuD-
(PPh3)2,13 but are significantly smaller than that of 101.4(1)° in
CpRuH(PPh3)2,15 104.0(1)° in CpRuCl(PPh3)2,16 and 103.2(1)°
in CpRuBr(PPh3)2,17 indicating the steric effect of the carboranyl
moiety. The Ru-P distances in 6-8 are very similar to those
observed in CpRuX(PPh3)2 (X ) Cl, Br, H).15-17 The Ru-H
distances of 1.54(1) Å in 6, 1.53(5) Å in 7, and 1.54(3) Å in 8
are within the range reported for other Ru-H complexes, for
example, 1.55(3) Å in (C5H4CH2CH2NMe2)RuH(PPh3)2,14a 1.52-
(4) Å in [(η6-cot)Ru((-)-Me-DuPHOS)(H)][BF4] (cot ) 1,3,5-
cyclooctatriene, (-)-Me-DuPHOS ) (-)-1,2-bis((2R,5R)-2,5-
dimethylphospholanyl)benzene),14d and 1.51(4) Å in CpRuH-
(PPh3)2.15 The C(2)-C(15) distances of 1.490(2) Å in 6, 1.495-
(6) Å in 7, and 1.486(4) Å in 8 are very close to the
corresponding values found in directly linked cyclopentadienyl-
carboranes, for example, 1.492(2) Å in [η5-C5D4-(MeC2B10H10)]-
RuD(PPh3)2,13 1.491(5) Å in 1-(4-C7H7)-12-[C5H3-3,4-(CH3)2]-
C2B10H10,18 and 1.489(2) Å in 2-(o-carboranyl)indene.19 The
newly formed five-membered rings (C(2)C(1)C(11)C(14)C(15))
(14) (a) Ayllon, J. A.; Sayers, S. F.; Sabo-Etienne, S.; Donnadieu, B.;
Chaudret, B.; Clot, E. Organometallics 1999, 18, 3981. (b) Jia, G.; Morris,
R. H. J. Am. Chem. Soc. 1991, 113, 3, 875. (c) Basallote, M. G.; Dura´n, J.;
Ferna´ndez-Trujillo, M. J.; Ma´n˜ez, M. A. Organometallics 2000, 19, 695.
(d) Wiles, J. A.; Bergens, S. H.; Vanhessche, K. P. M.; Dobbs, D. A.;
Rautenstrauch, V. Angew. Chem., Int. Ed. 2001, 40, 914.
(15) Smith, K.-T.; Rømming, C.; Tilset, M. J. Am. Chem. Soc. 1993,
115, 8681.
(16) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J. Chem.
Soc., Dalton Trans. 1981, 1398.
(17) Bruce, M. I.; Low, P. J.; Skelton, B. W.; Tiekink, E. R. T.; Werth,
A.; White, A. H. Aust. J. Chem. 1995, 48, 1887.

Ru Complexes with Cyclopentadienyl-Carboranyl Ligands
Organometallics, Vol. 25, No. 17, 2006 4191
Table 1. Selected Bond Distances (Å) and Angles (deg) for
6, 7, and 8a
Scheme 4
6‚0.5THFb
7
8
Ru-H
1.54(1)
2.263(2) [2.266(2)]
1.910
1.53(5)
2.262(5)
1.916
1.54(3)
2.269(3)
1.922
av Ru-Cring
Ru-Cent
Ru-P(1)
2.291(1) [2.289(1)]
2.282(1) [2.283(1)]
1.671(2) [1.674(2)]
1.490(2) [1.482(2)]
1.442(2) [1.422(2)]
1.516(2) [1.539(2)]
1.571(2) [1.569(2)]
96.0(1) [96.5(1)]
101.1(1) [101.0(1)]
102.5(1) [102.5(1)]
109.1(1) [108.7(1)]
2.279(1)
2.261(1)
1.679(6)
1.495(6)
1.412(6)
1.527(6)
1.543(6)
97.6(1)
2.280(1)
2.280(1)
1.652(4)
1.486(4)
1.416(4)
1.534(4)
1.560(4)
97.2(1)
Ru-P(2)
C(1)-C(2)
C(2)-C(15)
C(15)-C(14)
C(14)-C(11)
C(11)-C(1)
P(1)-Ru-P(2)
C(1)-C(11)-C(14)
C(15)-C(2)-C(1)
C(2)-C(1)-C(11)
102.7(3)
103.0(3)
107.6(4)
101.6(2)
103.0(2)
108.7(2)
a Cent: the centroid of the five-membered ring. b Distances and angles
in brackets are those of a second molecule.
(PCP ) [2,6-(CH2PBut2)2C6H3]-),20b and 1.119(4) and 1.965-
(4) Å in [(PNP)RuCl2]2(µ-N2) (PNP ) 2,6-bis-(di-tert-butyl-
phosphinomethyl)pyridine).20c The dinitrogen molecule in 11
just serves as a bridging donor, and its triple bond character
remains unchanged. The Ru-C(cage) and Ru-C (ring) dis-
tances are very close to those observed in [η5:σ-Me2C(C5H4)-
(C2B10H10)]Ru(L2) (L ) Lewis bases) complexes.21
Doubly Linked Compound Me2C(C5H4)(C2B10H10). Com-
plexes 6-10 contain doubly linked cyclopentadienyl-carbo-
ranyl ligands. We wondered whether the free ligands could be
released from these ruthenium complexes. In general, the Cp-
Ru π bonds are very strong and rather inert, which remain intact
in catalysis.22 There is no method to effectively break the Cp-
Ru π bonds. We attempted to reduce the Ru(II) to Ru(0) using
group 1 metals in the hope of releasing the free ligands. This
reduction was unfortunately coupled with cage-opening, leading
to a mixture of products. To our surprise, a free ligand was
isolated during the protonation of 6. Treatment of 6 with excess
HBF4‚OEt2 in toluene at -78 °C gave, after quenching with a
saturated NaHCO3 aqueous solution, a doubly linked compound,
Me2C(C5H4)(C2B10H10) (12), as a white solid in 65% isolated
yield (Scheme 4).
Figure 3. Molecular structure of [{η5:σ-Me2Si(C5H4)(C2B10H10)}-
Ru(PPh3)]2(µ-N2) (11). Selected distances [Å] and angles [deg]:
Ru1-C2 ) 2.165(6), Ru1-C13 ) 2.224(7), Ru1-C14 ) 2.241-
(7), Ru1-C15 ) 2.253(7), Ru1-C16 ) 2.205(7), Ru1-C17 )
2.173(7), Ru1-P1 ) 2.331(2), Ru1-Cent ) 1.860, Ru1-N1 )
2.014(5), N1-N1A ) 1.099(10), C13-Si1-C1 ) 103.2(3), Ru1-
N1-N1A ) 167.2(2).
in 6-8 are almost coplanar. The B-B, B-C, and C-C
distances of the cage are very comparable to those observed in
other carboranyl complexes.10
A single-crystal X-ray diffraction study revealed that 11 is a
centrosymmetrical dinuclear complex in which the two [η5:σ-
Me2Si(C5H4)(C2B10H10)]Ru(PPh3) moieties are connected by a
dinitrogen molecule, as shown in Figure 3. The crystallographic
center of symmetry lies at the midpoint of the NtN bond, and
each ruthenium atom adopts the typical three-legged piano stool
geometry. The bridging N-N distance of 1.099(10) Å and the
Ru-N distance of 2.014(5) Å can be compared to the corre-
sponding values found in other ruthenium dinitrogen complexes,
for example, 1.110(3) and 1.955(2) Å in [mer,trans-RuCl2-
(NN′N)]2(µ-N2) (NN′N ) 2,6-bis[(dimethylamino)methyl]-
pyridine),20a 1.134(6) and 2.038(4) Å in [RuH(PCP)]2(µ-N2)
The mechanism of this process is not clear. But the 1H NMR
experiments in C6D6 suggested the presence of a cationic
ruthenium dihydride intermediate, as deduced from the observa-
tion of a triplet at -6.50 ppm (2JHP ) 23.4 Hz) assignable to
the RuH2 protons and three multiplets at 6.76, 4.36, and 3.33
ppm corresponding to the Cp protons in the 1H NMR spectrum
and only one singlet at 59.3 ppm in the 31P{1H} NMR spectrum.
These characteristic NMR data are very similar to those
(21) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. J. Organomet. Chem.
2006, 691, 3071.
(22) (a) Naota, T.; Takaya, H.; Murahashi, S.-I. Chem. ReV. 1998, 98,
2599. (b) Trost, B. M.; Toste, F. D.; Pinkerton, A. B. Chem. ReV. 2001,
101, 2067. (c) Ritleng, V.; Sirlin, C.; Pfeffer, M. Chem. ReV. 2002, 102,
1731. (d) Trost, B. M. Acc. Chem. Res. 2002, 35, 695. (e) Bruneau, C.;
Dixneuf, P. H. Ruthenium Catalysts and Fine Chemistry; Springer: Berlin,
2004. (f) Trost, B. M.; Frederiksen, M. U.; Rudd, M. T. Angew. Chem.,
Int. Ed. 2005, 44, 6630. (g) Bruneau, C.; Dixneuf, P. H. Angew. Chem. Int.
Ed. 2006, 45, 2176. (h) Fischmeister, C.; Bruneau, C.; Dixneuf, P. H. In
Ruthenium in Organic Synthesis; Murahashi, S.-I., Ed.; Wiley-VCH:
Weinheim, Germany, 2004; p 309.
(18) Taylor, J.; Caruso, J.; Newlon, A.; Englich, U.; Ruhlandt-Senge,
K.; Spencer, J. T. Inorg. Chem. 2001, 40, 3381.
(19) Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25, 2617.
(20) (a) Abbenhuis, R. A. T. M.; del R´ıo, I.; Bergshoef, M. M.; Boersma,
J.; Veldman, N.; Spek, A. L.; van Koten, G. Inorg. Chem. 1998, 37, 1749.
(b) Gusev, D. G.; Dolgushin, F. M.; Antipin, M. Yu. Organometallics 2000,
19, 3429. (c) Zhang, J.; Gandelman, M.; Shimon, L. J. W.; Rozenberg, H.;
Milstein, D. Organometallics 2004, 23, 4026.

4192 Organometallics, Vol. 25, No. 17, 2006
Sun et al.
Scheme 5
Scheme 6
observed in [(Cp-NH)RuH2(PPh3)2][PF6]2 (Cp-NH ) C5H4CH2-
CH2NHMe2),14a [Cp*RuH2(dppm)][BF4] (dppm ) bis(diphenyl-
phosphino)methane),14b and [CpRuH2(PPh3)2][BF4].14c Hence,
it is proposed that [{η5-Me2C(C5H3)(C2B10H10)}RuH2(PPh3)2]-
[BF4] might serve as an intermediate, followed by reductive
elimination to generate 12, as shown in Scheme 4.
1
The H NMR spectrum of 12 showed two multiplets of the
vinyl protons at 6.04 and 5.91 ppm, one multiplet of sp3-CH2
protons of the cyclopentadiene at 3.30 ppm, and one singlet of
the two methyl protons at 1.53 ppm. Its 13C{1H} NMR spectrum
was consistent with the H NMR data. The 11B{1H} NMR
1
elimination, leading to the formation of the intermediate B
with a new C(cage)-C(ring) bond. Oxidative addition pro-
duces the species C, followed by the dissociation of PPh3
and haptotropic shift from η1 to η5 to yield the final product.
This proposed mechanism can also explain why no ruthenium
hydride complexes were detected from the reaction of [Me2A-
(C9H6)(C2B10H10)]Li2 (A ) C, Si) with RuCl2(PPh3)3. For
indenyl, the rearrangement of the double bonds within the C5
ring can destroy the aromaticity, which is energically highly
unfavorable.
spectrum exhibited a 1:1:2:2:4 pattern. Its composition was
further confirmed by high-resolution mass spectrometry. Com-
pound 12 was conveniently converted into the monolithium salt
by reacting with 1 equiv of n-BuLi in THF. Interaction of this
salt with 0.5 equiv of [RuCl2(COD)]x in THF afforded, after
workup, the ruthenocene [η5-Me2C(C5H3)(C2B10H10)]2Ru (13)
in 42% isolated yield. It was fully characterized spectroscopi-
cally.
Mechanism. The above results clearly show that the coupling
reaction of the cyclopentadienyl with an o-carboranyl proceeds
efficiently to form a new C(cage)-C(ring) bond as long as there
is no substituent on one of the R-carbon atoms of the Cp ring.
The unprecedented isolation of 11 indicates the importance of
the steric factors. If the coupling reactions were induced by the
steric forces, phosphines with smaller cone angles would
disfavor the coupling reactions. In fact, reaction of [Me2C-
(C5H4)(C2B10H10)]Li2 with 1 equiv of RuCl2[PPh2(OEt)]3 (cone
angles are 133° for PPh2(OEt) and 145° for PPh3)23 in THF
gave the salt metathesis product [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru[PPh2(OEt)]2 (14) in 55% isolated yield (Scheme 5). In the
presence of dppe, the complex [η5:σ-Me2C(C5H4)(C2B10H10)]-
Ru(dppe) (15) was isolated in 62% yield from the reaction of
[Me2C(C5H4)(C2B10H10)]Li2 with 1 equiv of RuCl2(PPh3)3
(Scheme 5). No ruthenium hydride complex was isolated from
the above two reactions. These results further support the
argument of a sterically induced coupling reaction.24 The
presence of PPh3 in the reaction system is essential for such a
coupling reaction.
Conclusion
This work shows that intramolecular couplings of a cyclo-
pentadienyl with an o-carboranyl unit are driven by steric factors.
Both carboranyl and phosphines with large cone angles are
crucial components for such coupling reactions. Sterically less
demanding phosphines such as PPh2(OEt) and dppe lead to the
formation of [η5:σ-Me2C(C5H4)(C2B10H10)]RuL2 (L2 ) [PPh2-
(OEt)]2, dppe), rather than ruthenium hydride complexes.
The doubly linked cyclopentadienyl-carboranyl compound
can be prepared by treatment of the corresponding ruthenium
hydride complexes with excess HBF4‚OEt2, followed by hy-
drolysis. These ligands are not accessible by any other known
methods.
Experimental Section
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. THF, toluene, diethyl ether, and n-hexane were freshly
distilled from sodium benzophenone ketyl immediately prior to use.
CH2Cl2 was freshly distilled from CaH2 and P2O5, respectively,
immediately prior to use. 6-Methylfulvene,25 2,6,6-trimethylful-
vene,26 3,6,6-trimethylfulvene,27 Me2C(C5H5)(C2B10H11),2b Me2Si-
(C5H5)(C2B10H11),3c RuCl2(PPh3)3,28 RuCl2[P(OEt)Ph2]3,29 and [RuCl2-
Therefore, a possible reaction pathway for the formation
of 6-10 is proposed and shown in Scheme 6. Reaction of
[Me(R1)A(C5H4)(C2B10H10)]Li2 with RuCl2(PPh3)3 gives the
first intermediate, A. Coordination of PPh3 induces reductive
(23) Hirano, M.; Asakawa, R.; Nagata, C.; Miyasaka, T.; Komine, N.;
Komiya, S. Organometallics 2003, 22, 2378.
(24) For examples of sterically induced haptotropic shift from η5 to η1,
see: (a) Tanabe, M.; Bourke, S. C.; Herbert, D. E.; Lough, A. J.; Manners,
I. Angew. Chem., Int. Ed. 2005, 44, 5886. (b) Evans, W. J.; Davis, B. L.
Chem. ReV. 2002, 102, 2119.
(25) Macomber, D. W.; Spink, W. C.; Rausch, M. D. J. Organomet.
Chem. 1983, 250, 311.

Ru Complexes with Cyclopentadienyl-Carboranyl Ligands
Organometallics, Vol. 25, No. 17, 2006 4193
(COD)]x30 were prepared according to 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
yield 1.53 g (79%). 1H NMR (CDCl3): δ 6.11-5.98 (m, 2H, vinyl
H), 3.44 (br s, 1H, CH of cage), 2.89 (m, 2H, sp3-CH2 in C5H4),
2.05 (s, 3H, CH3-C5H4), 1.50 (s, 6H, C(CH3)2). 13C{1H} NMR
(CDCl3): δ 150.4, 146.9, 127.2, 126.9 (C5H4), 84.7 (cage C), 64.0
(sp3-C in C5H4), 44.5 (CH3-C5H4), 41.2 (C(CH3)2), 30.9 (C(CH3)2).
11B{1H} NMR (CDCl3): δ -4.1 (2B), -9.2 (2B), -11.7 (2B),
-13.9 (4B). IR (KBr, cm-1): ν 2588 (vs) (B-H). HRMS: m/z calcd
1
Perkin-Elmer 1600 Fourier transform spectrometer. H and 13C-
{1H} NMR spectra were recorded on a Bruker DPX 300 spec-
trometer at 300 and 75 MHz, respectively. 11B{1H} and 31P{1H}
NMR spectra were recorded on a Varian Inova 400 spectrometer
at 128 and 162 MHz, respectively. All chemical shifts were reported
in δ units with references to the residual solvent resonance of the
deuterated solvents for proton and carbon chemical shifts, to external
BF3‚OEt2 (0.0 ppm) for boron chemical shifts, and to external 85%
H3PO4 (0.0 ppm) for phosphorus chemical shifts. Mass spectra were
obtained on a ThermoFinnigan MAT 95 XL mass spectrometer.
Elemental analyses were performed by either MEDAC Ltd. U.K.
or Shanghai Institute of Organic Chemistry, CAS, China. Melting
points were determined on an Electrothermal digital melting point
apparatus M-IA9100 and were uncorrected.
Preparation of MeHC(C5H5)(C2B10H11) (2). To a solution of
o-C2B10H12 (1.00 g, 6.90 mmol) in a dry toluene/diethyl ether (2:
1, 15 mL) mixture was added dropwise a 1.60 M solution of n-BuLi
in n-hexane (8.70 mL, 13.90 mmol) at -78 °C with stirring, and
the mixture was warmed to room temperature and stirred for 3 h.
The resulting solution (Li2C2B10H10) was then cooled to 0 °C, and
a solution of 6-methylfulvene (0.70 g, 7.60 mmol) in a toluene/
diethyl ether (2:1, 15 mL) mixture was slowly added. The reaction
mixture was stirred at 80 °C overnight, quenched with 20 mL of a
saturated NH4Cl aqueous solution at 0 °C, transferred to a separatory
funnel, and then diluted with 30 mL of diethyl ether. The organic
layer was separated, and the aqueous layer was extracted with Et2O
(3 × 15 mL). The combined ether solutions were dried over
anhydrous Na2SO4 and concentrated to give a crude yellow solid,
which was purified by column chromatography (SiO2, hexane) to
yield 2 as a pale yellow solid (1.47 g, 90%). 1H NMR (CDCl3): δ
6.51-6.19 (m, 3H, vinyl H), 3.57 (m, 1H, CHCH3), 3.39 (br s,
1H, CH of cage), 3.02 (m, 2H, sp3-CH2 in C5H5), 1.41 (d, 3J ) 7.2
Hz, 3H, CHCH3). 13C{1H} NMR (CDCl3): δ 145.6, 135.4, 131.8,
130.8 (C5H4), 79.2 (cage C), 60.8 (sp3-C in C5H5), 41.2 (CHCH3),
20.7 (CHCH3). 11B{1H} NMR (CDCl3): δ -3.1 (1B), -5.1 (1B),
-9.2 (2B), -11.1 (1B), -11.9 (2B), -13.7 (3B). IR (KBr, cm-1):
ν 2574 (vs) (B-H). HRMS: m/z calcd for C9H2011B810B2+ 236.2563,
found 236.2563.
+
for C11H2411B810B2 264.2876, found 264.2872.
Preparation of [η5-Me2C(C5H3)(C2B10H10)]RuH(PPh3)2‚0.5THF
(6‚0.5THF). A 1.60 M solution of n-BuLi in n-hexane (1.25 mL,
2.00 mmol) was slowly added to a THF solution (15 mL) of Me2C-
(C5H5)(C2B10H11) (0.25 g, 1.00 mmol) at -78 °C with stirring. The
mixture was warmed to room temperature and stirred for 3 h. The
powder of RuCl2(PPh3)3 (0.96 g, 1.00 mmol) was added to the
resulting solution, and the mixture was stirred at room temperature
for 24 h. After removal of the solvent and addition of CH2Cl2 (20
mL), the precipitate was filtered off, and the solvent was removed
under vacuum. The resulting red solid was recrystallized from a
THF solution to give 6‚0.5THF as yellow crystals (0.73 g, 80%),
1
mp 156-157 °C. H NMR (C6D6): δ 7.60-6.81 (m, 30H, aryl
H), 4.83 (m, 1H, C5H3), 3.71 (m, 1H, C5H3), 3.65 (m, 1H, C5H3),
3.55 (m, 2H, THF), 1.42 (m, 2H, THF), 1.14 (s, 3H, C(CH3)2),
2
0.92 (s, 3H, C(CH3)2), -10.14 (dd, JHP ) 39.3 and 31.5 Hz, 1H,
1
Ru-H). 13C{1H} NMR (C6D6): δ 140.6 (d, JCP ) 40.0 Hz, aryl
1
2
C), 140.0 (d, JCP ) 40.0 Hz, aryl C), 134.4 (d, JCP ) 10.8 Hz,
aryl C), 134.2 (d, 2JCP ) 10.8 Hz, aryl C), 128.5 (d, 3JCP ) 6.5 Hz,
aryl C), 127.4 (d, 4JCP ) 3.6 Hz, aryl C), 127.3 (d, 4JCP ) 3.6 Hz,
aryl C), 98.9, 89.9, 82.8, 82.1, 75.8 (C5H3), 67.8 (THF), 42.2
(C(CH3)2), 36.2 (C(CH3)2), 30.0 (C(CH3)2), 25.8 (THF), cage
carbons were not observed. 31P{1H} NMR (C6D6): δ 71.9, 65.2.
11B{1H} NMR (C6D6): δ -5.4 (2B), -7.7 (4B), -10.1 (2B), -14.1
(2B). IR (KBr, cm-1): ν 2568 (vs) (B-H), 1970 (s) (Ru-H). Anal.
Calcd for C46H50B10P2Ru (6): C, 63.21; H, 5.77. Found: C, 63.00;
H, 5.80.
Preparation of [η5-MeHC(C5H3)(C2B10H10)]RuH(PPh3)2 (7).
This complex was prepared as yellow crystals from MeHC(C5H5)-
(C2B10H11) (0.24 g, 1.00 mmol), n-BuLi in n-hexane (1.60 M, 1.25
mL, 2.00 mmol), and RuCl2(PPh3)3 (0.96 g, 1.00 mmol) in THF
using the identical procedures reported for 6: yield 0.67 g (78%),
1
mp 145-146 °C. H NMR (C6D6): δ 7.53-6.89 (m, 30H, aryl
H), 4.29 (m, 1H, C5H3), 4.18 (m, 1H, C5H3), 3.78 (m, 1H, C5H3),
2.10 (m, 1H, CHCH3), 0.63 (d, 3J ) 6.9 Hz, 3H, CHCH3), -10.43
Preparation of Me2C(2-Me-C5H4)(C2B10H11) (3). This com-
pound was prepared as a pale yellow solid from o-C2B10H12 (1.00
g, 6.90 mmol), n-BuLi in n-hexane (1.60 M, 8.70 mL, 13.90 mmol),
and 2,6,6-trimethylfulvene (0.91 g, 7.60 mmol) in a toluene/diethyl
ether (2:1) mixture using the identical procedures reported for 2:
yield 1.55 g (80%). 1H NMR (CDCl3): δ 6.61-6.42 (m, 2H, vinyl
H), 3.44 (br s, 1H, CH of cage), 3.03 (m, 2H, sp3-CH2 in C5H4),
2.15 (s, 3H, CH3-C5H4), 1.61 (s, 6H, C(CH3)2). 13C{1H} NMR
(CDCl3): δ 135.1, 134.6, 130.5, 129.9 (C5H4), 86.0 (cage C), 63.7
(sp3-C in C5H4), 46.1 (CH3-C5H4), 42.5 (C(CH3)2), 32.7 (C(CH3)2).
11B{1H} NMR (CDCl3): δ -4.1 (2B), -9.2 (2B), -11.7 (2B),
-13.9 (4B). IR (KBr, cm-1): ν 2587 (vs) (B-H). HRMS: m/z calcd
2
(dd, JHP ) 35.7 Hz, 1H, Ru-H). 13C{1H} NMR (C6D6): δ 140.3
1
1
(d, JCP ) 40.0 Hz, aryl C), 139.5 (d, JCP ) 40.0 Hz, aryl C),
2
2
134.1 (d, JCP ) 11.0 Hz, aryl C), 133.9 (d, JCP ) 11.0 Hz, aryl
C), 127.5 (d, 3JCP ) 6.0 Hz, aryl C), 127.3 (d, 3JCP ) 6.0 Hz, aryl
C), 110.3 (d, 4JCP ) 3.6 Hz, aryl C), 108.6 (d, 4JCP ) 3.6 Hz, aryl
C), 94.9, 83.1, 82.9, 82.3, 77.8 (C5H3), 38.6 (CHCH3), 19.2
(CHCH3), cage carbons were not observed. 31P{1H} NMR (C6D6):
δ 69.6, 64.6. 11B{1H} NMR (C6D6): δ -4.3 (2B), -5.4 (4B), -8.5
(2B), -11.7 (2B). IR (KBr, cm-1): ν 2584 (vs) (B-H), 1944 (s)
(Ru-H). Anal. Calcd for C45H48B10P2Ru: C, 62.85; H, 5.63.
Found: C, 63.13; H, 5.68.
Preparation of [η5-Me2C(5-Me-C5H2)(C2B10H10)]RuH(PPh3)2
(8). This complex was prepared as yellow crystals from Me2C(2-
Me-C5H4)(C2B10H11) (0.26 g, 1.00 mmol), n-BuLi in n-hexane (1.60
M, 1.25 mL, 2.00 mmol), and RuCl2(PPh3)3 (0.96 g, 1.00 mmol)
in THF using the identical procedures reported for 6: yield 0.56 g
(63%), mp 168-170 °C. 1H NMR (C6D6): δ 7.65-6.85 (m, 30H,
aryl H), 4.85 (d, 3J ) 2.1 Hz, 1H, C5H2), 3.45 (d, 3J ) 2.1 Hz, 1H,
C5H2), 2.11 (s, 3H, CH3-C5H2), 1.18 (s, 3H, C(CH3)2), 0.97 (s,
+
for C11H2411B810B2 264.2876, found 264.2870.
Preparation of Me2C(3-Me-C5H4)(C2B10H11) (4). This com-
pound was prepared as a pale yellow solid from o-C2B10H12 (1.00
g, 6.90 mmol), n-BuLi in n-hexane (1.60 M, 8.70 mL, 13.90 mmol),
and 3,6,6-trimethylfulvene (0.91 g, 7.60 mmol) in a toluene/diethyl
ether (2:1) mixture using the identical procedures reported for 2:
(26) Smith, W. B.; Biesemeier, S.; Deavenport, D. L. J. Org. Chem.
1971, 36, 2853.
(27) Miller, S. A.; Bercaw, J. E. Organometallics 2002, 21, 934.
(28) La Placa, S. J.; Ibers, J. A. Inorg. Chem. 1965, 4, 778.
(29) Sime, W. J.; Stephenson, T. A. J. Organomet. Chem. 1978, 161,
245.
2
3H, C(CH3)2), -10.04 (dd, JHP ) 42.3 and 29.1 Hz, 1H, Ru-H).
13C{1H} NMR (C6D6): δ 140.7 (d, 1JCP ) 40.0 Hz, aryl C), 138.7
1
2
(d, JCP ) 40.0 Hz, aryl C), 134.9 (d, JCP ) 10.8 Hz, aryl C),
134.5 (d, 2JCP ) 10.8 Hz, aryl C), 127.4 (d, 3JCP ) 6.5 Hz, aryl C),
127.2 (d, 4JCP ) 3.6 Hz, aryl C), 93.5, 82.6, 82.1, 76.4, 75.9 (C5H2),
43.2 (CH3-C5H2), 41.6 (C(CH3)2), 32.9 (C(CH3)2), 29.4 (C(CH3)2),
(30) Albers, M. O.; Ashworth, T. V.; Oosthuizen, H. E.; Singleton, E.
Inorg. Synth. 1989, 26, 68.

4194 Organometallics, Vol. 25, No. 17, 2006
Sun et al.
cage carbons were not observed. 31P{1H} NMR (C6D6): δ 69.7,
66.5. 11B{1H} NMR (C6D6): δ -5.4 (2B), -7.2 (4B), -9.8 (2B),
-13.8 (2B). IR (KBr, cm-1): ν 2576 (vs) (BH), 1928 (s) (Ru-H).
Anal. Calcd for C47H52B10P2Ru: C, 63.57; H, 5.90. Found: C,
63.36; H, 5.93.
(4B). IR (KBr, cm-1): ν 2588 (vs) (B-H). HRMS: m/z calcd for
+
C10H2011B810B2 248.2563, found 248.2561.
Preparation of [η5-Me2C(C5H3)(C2B10H10)]2Ru (13). A 1.60
M solution of n-BuLi in n-hexane (63 µL, 0.10 mmol) was slowly
added to a THF solution (5 mL) of Me2C(C5H4)(C2B10H10) (12; 25
mg, 0.10 mmol) at -78 °C with stirring, and the mixture was
warmed to room temperature and stirred for 2 h. The powder of
[RuCl2(COD)]x (14 mg, 0.05 mmol) was added to the resulting
solution, and the mixture was stirred at room temperature for 12 h.
After removal of the solvent, the resulting yellow solid was
recrystallized from an ether solution to give 13 as a pale yellow
Preparation of [η5-Me2C(3/4-Me-C5H2)(C2B10H10)]RuH(PPh3)2
(9a/b). These mixtures of complexes were prepared as yellow
crystals from Me2C(3-Me-C5H4)(C2B10H11) (0.26 g, 1.00 mmol),
n-BuLi in n-hexane (1.60 M, 1.25 mL, 2.00 mmol), and RuCl2-
(PPh3)3 (0.96 g, 1.00 mmol) in THF using the identical procedures
1
reported for 6: yield 0.64 g (72%), mp 195 °C dec. H NMR
1
(C6D6): δ 7.60-6.81 (m, 60H, aryl H), 4.82 (d, 3J ) 2.1 Hz, 1H,
solid (13 mg, 42%). H NMR (CDCl3): δ 4.57 (m, 2H, C5H3),
3
3.45 (m, 2H, C5H3), 3.29 (m, 2H, C5H3), 1.40 (s, 6H, C(CH3)2),
1.38 (s, 6H, C(CH3)2). 13C{1H} NMR (CDCl3): δ 102.1, 85.8, 76.6,
65.2 (C5H3), 37.7 (C(CH3)2), 30.6, 29.9 (C(CH3)2), cage carbons
were not observed. 11B{1H} NMR (CDCl3): δ -4.5 (4B), -9.5
C5H2), 3.67 (s, 1H, C5H2), 3.41 (s, 1H, C5H2), 3.45 (d, J ) 2.1
Hz, 1H, C5H2), 2.11 (s, 3H, CH3-C5H2), 2.08 (s, 3H, CH3-C5H2),
1.36 (s, 3H, C(CH3)2), 1.17 (s, 6H, C(CH3)2), 1.02 (s, 3H, C(CH3)2),
2
-10.41 (dd, JHP ) 37.2 and 32.7 Hz, 1H, Ru-H), -10.62 (dd,
(8B), -11.5 (4B), -13.7 (4B). IR (KBr, cm-1): ν 2562 (vs) (B-
2JHP ) 39.6 and 31.7 Hz, 1H, Ru-H). 13C{1H} NMR (C6D6): δ
11
1
1
H). HRMS: m/z calcd for C20H38
B
10B4Ru+ 596.4018, found
16
140.3 (d, JCP ) 40.0 Hz, aryl C), 139.0 (d, JCP ) 40.0 Hz, aryl
596.4019.
2
2
C), 135.0 (d, JCP ) 12.2 Hz, aryl C), 134.7 (d, JCP ) 12.2 Hz,
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru[PPh2(OEt)]2
(14). This complex was prepared as yellow crystals from Me2C-
(C5H5)(C2B10H11) (0.25 g, 1.00 mmol), n-BuLi in n-hexane (1.60
M, 1.25 mL, 2.00 mmol), and RuCl2[PPh2(OEt)]3 (0.86 g, 1.00
mmol) in THF using the identical procedures reported for 6: yield
aryl C), 128.0 (d, 3JCP ) 6.6 Hz, aryl C), 127.4 (d, 3JCP ) 6.6 Hz,
4
aryl C), 110.2 (d, JCP ) 4.0 Hz, aryl C), 99.1, 98.7, 91.8, 90.7,
89.3, 88.0, 86.7, 84.3, 82.4, 77.0 (C5H2), 42.6, 42.0 (CH3-C5H2),
41.3, 41.1 (C(CH3)2), 32.4, 31.9, 30.1, 30.0 (C(CH3)2), cage carbons
were not observed. 11B{1H} NMR (C6D6): δ -4.5 (2B), -6.6 (4B),
-8.6 (2B), -13.1 (2B). 31P{1H} NMR (C6D6): δ 69.9, 69.2, 66.8,
63.5. IR (KBr, cm-1): ν 2576 (s) (B-H), 1940 (vs) (Ru-H). Anal.
Calcd for C47H52B10P2Ru: C, 63.57; H, 5.90. Found: C, 63.70; H,
6.42.
1
0.45 g (55%), mp 269-270 °C. H NMR (C6D6): δ 7.56-7.03
(m, 20H, aryl H), 4.13 (m, 2H, C5H4), 3.72 (m, 2H, C5H4), 3.23
(m, 2H, OCH2), 3.07 (m, 2H, OCH2), 1.32 (s, 6H, C(CH3)2), 0.99
3
(t, J ) 6.9 Hz, 6H, CH2CH3). 13C{1H} NMR (C6D6): δ 139.3,
139.1, 136.3, 133.2, 132.3, 129.9, 129.7, 127.4 (aryl C), 84.2, 77.0
(C5H4), 63.8 (OCH2), 39.7 (C(CH3)2), 31.7 (C(CH3)2), 16.1
(CH2CH3), cage carbons were not observed. 31P{1H} NMR
(C6D6): δ 135.4. 11B{1H} NMR (C6D6): δ -3.4 (2B), -7.3 (8B).
IR (KBr, cm-1): ν 2584 (vs) (B-H). These data were identical with
those reported in the literature.21
Preparation of [η5-Me2Si(C5H3)(C2B10H10)]RuH(PPh3)2 (10)
and [{η5:σ-Me2Si(C5H4)(C2B10H10)}Ru(PPh3)]2(µ-N2) (11). Com-
plex 10 was prepared as yellow crystals from Me2Si(C5H5)-
(C2B10H11) (0.27 g, 1.00 mmol), n-BuLi in n-hexane (1.60 M, 1.25
mL, 2.00 mmol), and RuCl2(PPh3)3 (0.96 g, 1.00 mmol) in THF
using the identical procedures reported for 6: yield 0.60 g (67%),
mp 204 °C dec. Slow evaporation of the mother liquor at room
Preparation of [η5:σ-Me2C(C5H4)(C2B10H10)]Ru(dppe) (15).
A 1.60 M solution of n-BuLi in n-hexane (1.25 mL, 2.00 mmol)
was slowly added to a THF solution (15 mL) of Me2C(C5H5)-
(C2B10H11) (0.25 g, 1.00 mmol) at -78 °C with stirring, the mixture
was warmed to room temperature. To the resulting solution was
slowly added a THF solution (10 mL) containing dppe (0.40 g,
1.00 mmol) and RuCl2(PPh3)3 (0.96 g, 1.00 mmol), and the mixture
was stirred at room temperature for 24 h. After removal of the
solvent and addition of CH2Cl2 (20 mL), the precipitate was filtered
off. The clear solution was concentrated to dryness. The resulting
yellow solid was recrystallized from a CH2Cl2 solution to give 15
as yellow crystals (0.46 g, 62%), mp 162-163 °C. 1H NMR
(CDCl3): δ 7.92-6.74 (m, 20H, aryl H), 5.32 (m, 2H, C5H4), 4.30
1
temperature gave a few red crystals identified as 11. For 10, H
NMR (C6D6): δ 7.59-6.82 (m, 30H, aryl H), 4.97 (m, 1H, C5H3),
4.11 (m, 1H, C5H3), 3.79 (m, 1H, C5H3), 0.13 (s, 3H, Si(CH3)2),
2
0.05 (s, 3H, Si(CH3)2), -9.97 (dd, JHP ) 37.0 and 32.2 Hz, 1H,
1
Ru-H). 13C{1H} NMR (C6D6): δ 140.7 (d, JCP ) 40.0 Hz, aryl
1
2
C), 140.3 (d, JCP ) 40.0 Hz, aryl C), 134.3 (d, JCP ) 10.8 Hz,
aryl C), 134.2 (d, 2JCP ) 10.8 Hz, aryl C), 127.3 (d, 3JCP ) 9.6 Hz,
aryl C), 111.1 (d, JCP ) 4.4 Hz, aryl C), 93.1, 92.0, 81.3, 80.0,
4
78.3 (C5H3), 0.1 (CH3), -2.8 (CH3), cage carbons were not
observed. 31P{1H} NMR (C6D6): δ 71.6, 64.1. 11B{1H} NMR
(C6D6): δ -4.3 (2B), -8.9 (4B), -10.8 (2B), -13.8 (2B). IR
(KBr, cm-1): ν 2572 (vs) (B-H), 1975 (s) (Ru-H). Anal. Calcd
for C45H50B10P2RuSi: C, 60.72; H, 5.66. Found: C, 61.24; H,
6.11.
3
3
(m, 2H, C5H4), 2.87 (t, J ) 9.0 Hz, 2H, CH2), 2.48 (t, J ) 9.0
Hz, 2H, CH2), 1.48 (s, 6H, CH3). 13C{1H} NMR (CDCl3): δ 132.4,
131.6, 130.8, 129.5, 128.9, 128.4, 128.0, 127.6 (aryl C), 82.7, 74.6
(C5H4), 39.8 (C(CH3)2), 31.6 (CH3), 24.6 (d, JCP ) 21.2 Hz,
PCH2CH2P), cage carbons were not observed. 11B{1H} NMR
(CDCl3): δ -4.2 (2B), -7.5 (4B), -9.6 (4B). 31P{1H} NMR
(CDCl3): δ 81.1. IR (KBr, cm-1): ν 2563 (s) (B-H). These data
were identical with those reported in the literature.8
Preparation of Me2C(C5H4)(C2B10H10) (12). A solution of
HBF4 in diethyl ether (54% wt, 0.10 mL, 1.00 mmol) was slowly
added to a toluene solution (5 mL) of 6 (0.15 g, 0.17 mmol) at
-78 °C with stirring, and the mixture was warmed to room
temperature and stirred for 3 h. Then the reaction was quenched
with 10 mL of a saturated NaHCO3 aqueous solution, transferred
to a separatory funnel, and diluted with 10 mL of diethyl ether.
The organic layer was separated, and the aqueous layer was
extracted with Et2O (3 × 5 mL). The combined ether solutions
were dried over anhydrous Na2SO4. Removal of solvent gave a
crude brown solid, which was purified by column chromatography
(SiO2, hexane) to yield 12 as a white solid (0.027 g, 65%). 1H NMR
(CDCl3): δ 6.04 (m, 1H, vinyl H), 5.91 (m, 1H, vinyl H), 3.30 (m,
2H, sp3-CH2 in C5H4), 1.53 (s, 6H, C(CH3)2). 13C{1H} NMR
(CDCl3): δ 180.5, 162.4, 123.1, 120.3 (C5H4), 96.4 (cage C), 46.7
(sp3-C in C5H4), 43.3 (C(CH3)2), 30.1 (C(CH3)2). 11B{1H} NMR
(CDCl3): δ -5.5 (1B), -6.1 (1B), -7.7 (2B), -9.1 (2B), -12.5
X-ray Structure Determination. 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 absorp-
tion correction was applied using the SADABS program.31 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
(31) Sheldrick, G. M. SADABS: Program for Empirical Absorp-
tion Correction of Area Detector Data, University of Go¨ttingen: Germany,
1996.

Ru Complexes with Cyclopentadienyl-Carboranyl Ligands
Organometallics, Vol. 25, No. 17, 2006 4195
Table 2. Crystal Data and Summary of Data Collection and Refinement for 6-8 and 11
6‚0.5THF
7
8
11
formula
cryst size (mm)
fw
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C48H54B10O0.5P2Ru
0.30 × 0.20 × 0.10
910.0
triclinic
P1h
13.317(3)
16.389(3)
23.527(5)
93.51(3)
100.28(3)
109.95(3)
4708(2)
4
C45H48B10P2Ru
0.30 × 0.20 × 0.20
860.0
triclinic
P1h
10.335(1)
12.577(2)
16.789(2)
81.82(1)
81.23(1)
84.43(1)
2128.4(5)
2
C47H52B10P2Ru
0.40 × 0.40 × 0.20
888.0
monoclinic
P21/c
17.534(1)
12.296(1)
21.374(1)
90
102.50(1)
90
C54H70B20N2P2Ru2Si2
0.25 × 0.20 × 0.10
1283.6
tetragonal
P43212
14.762(2)
14.762(2)
31.863(3)
90
90
90
6943.1(9)
4
1.228
4499.1(4)
4
1.311
Z
D
calcd, Mg/m3
1.284
1.342
radiation (λ), Å
2θ max, deg
µ, mm-1
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
50.0
50.0
50.0
50.0
0.436
1880
0.477
884
0.453
1832
0.551
2616
F(000)
no. of obsd reflns
no. of params refnd
goodness of fit
R1
13 317
1116
1.035
0.048
7463
527
1.007
0.052
7916
545
1.001
0.033
6117
371
1.134
0.046
wR2
0.131
0.111
0.081
0.135
the SHELXTL program package.32 For the noncentrosymmetric
structure of 11, the appropriate enantiomorph was chosen by
refining Flack’s parameter x toward zero.33 All hydrogen atoms
were geometrically fixed using the riding model. Crystal data and
details of data collection and structure refinements are given in
Table 2.
Acknowledgment. This work was supported by grants from
the Research Grants Council of The Hong Kong Special
Administration Region (Project No. 403103) and Mainline
Research Scheme of The Chinese University of Hong Kong
(Project No. MR01/002).
Supporting Information Available: X-ray crystallographic data
in CIF format for 6, 7, 8, and 11. This material is available free of
charge via the Internet at http://pubs.acs.org.
(32) Sheldrick, G. M. SHELXTL 5.10 for Windows NT: Structure
Determination Software Programs; Bruker Analytical X-ray Systems,
Inc.: Madison, WI, 1997.
(33) Flack, H. D. Acta Crystallogr. 1983, A39, 876.
OM0604122