Synthesis, structural characterization, and reactivity of group 4 metal complexes derived from 1-indenyl-1,2-carborane

Article abstract of DOI:10.1021/om701108v

Treatment of 1-indenyl-1,2-carborane with 1 equiv of M(NMe ₂)₄ (M = Zr, Hf) in toluene gave [η⁵- (C₂B₁₀H₁₁)C₉H₆]M(NMe ₂)₃ (2), which were converted to [η⁵- (C₉H₇)C₂B₉H₁₀]M(NMe ₂)₂(HNMe₂) (3) in the presence of HNMe ₂. Complexes 3 were also prepared from an equimolar reaction of [Me₃NH] [7-C₉H₇-7,8-C₂B ₉H₁₁] (4) with M(NMe₂)₄. Dissolving 2 or 3 in polar solvents led to the isolation of structurally unique complexes [σ:η⁵-(C₉H₆)C₂B ₉H₁₀]M(NMe₂)(L)_n (M = Ti, L = DME, n = 1 (5a); M = Zr, L = DME, n = 1 (5b), L = Py, n = 2 (5b′), L = THF, n = 2 (5b″)). Interaction of 3 with 1 or 2 equiv of diisopropylcarbodiimide yielded the monoguanidinate complex [η⁵-(C₉H ₇)C₂B₉H₁₀]Zr(NMe₂) [η²-(PrⁱN)₂C(NMe₂)] (9) or diguanidinate complex [η⁵-(C₉H₇)C ₂B₉H₁₀]Zr[η²-(Pr ⁱN)₂C(NMe₂)]₂ (10). Heating 9 in toluene gave a C-N bond cleavage product, [η¹:σ: η⁵-{[2-C=NPrⁱ(NHPrⁱ)]C₉H ₅}C₂B₉H₁₀]Zr[η²- (PrⁱN)₂C(NMe₂)] (11a). Triguanidinate complexes [{η²-(PrⁱN)₂C(NR₂)} ₃M][(C₉H₇)C₂B₉H ₁₁] (8) (M = Ti, Zr, Hf; NR₂ = NMe₂, NEt ₂, N(CH₂)₄) were prepared from reactions of 3 or 5b with 3 equiv of guanidines in refluxing THF. Treatment of 5b with 1 equiv of diphenylketene generated [σ:η⁵-{[3-C(=CPh ₂)-O]C₉H₆}C₂B₉H ₁₀]Zr(NMe₂)(THF)₂ (14). These complexes were fully characterized by various spectroscopic techniques and elemental analyses. Some were further confirmed by single-crystal X-ray analyses.

Full text of DOI:10.1021/om701108v

Organometallics 2008, 27, 1157–1168
1157
Synthesis, Structural Characterization, and Reactivity of Group 4
Metal Complexes Derived from 1-Indenyl-1,2-carborane
Hao Shen, Hoi-Shan Chan, and Zuowei Xie*
Department of Chemistry and Center of NoVel Functional Molecules, The Chinese UniVersity of Hong
Kong, Shatin, New Territories, Hong Kong, People’s Republic of China
ReceiVed NoVember 3, 2007
Treatment of 1-indenyl-1,2-carborane with 1 equiv of M(NMe2)4 (M ) Zr, Hf) in toluene gave [η5-
(C2B10H11)C9H6]M(NMe2)3 (2), which were converted to [η5-(C9H7)C2B9H10]M(NMe2)2(HNMe2) (3) in
the presence of HNMe2. Complexes 3 were also prepared from an equimolar reaction of [Me3NH][7-
C9H7-7,8-C2B9H11] (4) with M(NMe2)4. Dissolving 2 or 3 in polar solvents led to the isolation of structurally
unique complexes [σ:η5-(C9H6)C2B9H10]M(NMe2)(L)n (M ) Ti, L ) DME, n ) 1 (5a); M ) Zr, L )
DME, n ) 1 (5b), L ) Py, n ) 2 (5b′), L ) THF, n ) 2 (5b′′)). Interaction of 3 with 1 or 2 equiv of
diisopropylcarbodiimide yielded the monoguanidinate complex [η5-(C9H7)C2B9H10]Zr(NMe2)[η2-
(PriN)2C(NMe2)] (9) or diguanidinate complex [η5-(C9H7)C2B9H10]Zr[η2-(PriN)2C(NMe2)]2 (10). Heating
9 in toluene gave a C-N bond cleavage product, [η1:σ:η5-{[2-CdNPri(NHPri)]C9H5}C2B9H10]Zr[η2-
(PriN)2C(NMe2)] (11a). Triguanidinate complexes [{η2-(PriN)2C(NR2)}3M][(C9H7)C2B9H11] (8) (M )
Ti, Zr, Hf; NR2 ) NMe2, NEt2, N(CH2)4) were prepared from reactions of 3 or 5b with 3 equiv of
guanidines in refluxing THF. Treatment of 5b with 1 equiv of diphenylketene generated [σ:η5-{[3-
C(dCPh2)-O]C9H6}C2B9H10]Zr(NMe2)(THF)2 (14). These complexes were fully characterized by various
spectroscopic techniques and elemental analyses. Some were further confirmed by single-crystal X-ray
analyses.
Me2C,4 Me2Si,5 Pri2NB,6 Pri2NP7), and A′′(C13H9)(C2B10H11)
(A′′ ) H2C,8 Me2Si9) have been developed. These ligands are
finding many applications in organometallic chemistry, and the
results show that the bridging atom significantly influences
properties of the resulting organometallic complexes.1g–j,2–9
It is anticipated that the interactions between a cyclic organic
moiety and a carboranyl group would be largely enhanced if
there is no linkage in between. A recently reported compound,
1-indenyl-1,2-carborane, exhibits an interesting property.10 Its
trianion [7-C9H6-7,9-C2B10H11]3- and penta-anion [7-C9H6-7,10-
C2B10H11]5- have demonstrated a very similar coordination
mode to that of [C6H5(C5H4)]- in lanthanide chemistry, which
favors the formation of “metal-bridged” complexes.10 One
would expect that reaction of group 4 metal amides M(NMe2)4
with 1-indenyl-1,2-carborane or 7-indenyl-7,8-dicarbollide would
most likely afford the same type of “metal-bridged” dinuclear
amide complexes. To our surprise, the dicarbollide derivative
[7-C9H6-7,8-C2B9H10]3- is able to form an unprecedented highly
constrained-geometry metal complex [σ:η5-(C9H6)C2B9H10]-
Introduction
Ligands impose a dominant control over both chemical and
physical properties of the resulting metal complexes. Ligand
design has thus become a central theme in the development of
the chemistry of organometallic compounds.1 It is expected that
incorporation of a carboranyl fragment into the ligand frame-
work would provide new metal/charge combinations, which
would have an impact on the properties of metal complexes. In
this connection, a series of single-atom-bridged cyclopentadi-
enyl-, indenyl-, and fluorenyl-carboranyl ligands A(C5H5)-
(C2B10H11) (A ) Me2C,2 Me2Si3), A′(C9H7)(C2B10H11) (A′ )
* Corresponding author. Fax: (852)26035057. Tel: (852)26096269.
E-mail: zxie@cuhk.edu.hk.
(1) (a) Knowles, W. S. Angew. Chem., Int. Ed. 2002, 41, 1998. (b)
Noyori, R. Angew. Chem., Int. Ed. 2002, 41, 2008. (c) Sharpless, K. B.
Angew. Chem., Int. Ed. 2002, 41, 2024. (d) Gladysz, J. A. Guest Editor.
Special Issue on Frontiers in Metal-Catalyzed Polymerization. Chem. ReV
2000, 100, 1167. (e) Hosmane, N. S., Maguire, J. A. In ComprehensiVe
Organometallic Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.;
Elsevier: Oxford, 2007; Vol. 4, Chapter 3.05, p 175. (f) Kang, S. O.; Ko,
J. AdV. Organomet. Chem. 2001, 47, 61. (g) Xie, Z. Coord. Chem. ReV.
2002, 231, 23. (h) Xie, Z. Acc. Chem. Res. 2003, 36, 1. (i) Xie, Z. Coord.
Chem. ReV. 2006, 250, 259. (j) Deng, L.; Xie, Z. Coord. Chem. ReV. 2007,
251, 2452.
(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.
(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. (e) Sun, Y.; Chan, H.-S.; Dixneuf, P. H.; Xie, Z. Chem. Commun
2004, 2588. (f) Wang, Y.; Wang, H.; Wang, H.; Chan, H.-S.; Xie, Z. J.
Organomet. Chem. 2003, 683, 39.
(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.
(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.
(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) Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25, 2617.
10.1021/om701108v CCC: $40.75
2008 American Chemical Society
Publication on Web 02/19/2008

1158 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
Scheme 1
Scheme 2
assignable to the Zr(N(CH3)2)3 unit was observed in the 13C
NMR spectrum besides the indenyl and cage carbon signals.
Its 11B NMR exhibited a 1:1:4:4 pattern. Similar spectroscopic
features were also observed in the NMR spectra of 2c. The
compositions of 2b,c were further confirmed by elemental
analyses.
Zr(NMe2)(DME), which exhibits unique chemical properties.11
We then extended our research to include the Ti and Hf
chemistry. This article reports a full account on the reactions
of M(NMe2)4 with 1-indenyl-1,2-carborane and 7-indenyl-7,8-
dicarbollide, the interconversions among different types of amide
complexes, and their reactivities.
Complexes 2b,c are very stable in toluene, and no amine
elimination was observed even at refluxing temperature. Pro-
longed reaction of 1 with 1 equiv of Zr(NMe2)4 in a sealed NMR
tube, however, led to the formation of a 1:1 mixture of 2b and
an unidentified species as indicated by 1H NMR. The 11B NMR
showed a characteristic resonance at 29 ppm assignable to
HB(NMe2)2,13a,b suggesting that a deboration reaction occurred.
It was assumed that this new species might be formed from the
reaction of 2b with HNMe2 generated in situ in the reaction
mixture.13c–j In fact, treatment of 2b or 2c with 2.2 equiv of
HNMe2 in toluene yielded almost quantitatively complexes [η5-
(C9H7)C2B9H10]M(NMe2)2(HNMe2) (M ) Zr (3b), Hf (3c))
(Scheme 1).
Results and Discussion
Synthesis of Amide Complexes. Our previous work showed
that interaction of group 4 metal amides M(NMe2)4 (M ) Ti,
Zr, Hf) with A(C5H5)(C2B10H11) (A ) Me2C, Me2Si)2c or
A′(C9H7)(C2B10H11) (A′ ) Me2C,2c Me2Si,2c Pri2NB,6b Pri2NP7b)
led to the clean formation of the corresponding constrained-
geometry metal complexes [η5:σ-A(C5H4)C2B10H10]M(NMe2)2
or [η5:σ-A′(C9H6)C2B10H10]M(NMe2)2, respectively.1i It is
anticipated that the two acidic protons in 1-C9H7-1,2-C2B10H11
(1) would allow similar amine elimination reaction to occur.
However, treatment of 1 with 1 equiv of Zr(NMe2)4 in toluene
at room temperature produced only the monodeprotonated
complex [η5-(C2B10H11)C9H6]Zr(NMe2)3 (2b) in quantitative
yield. On the other hand, reaction of 1 with Hf(NMe2)4 at room
temperature gave a mixture of products. Complex [η5-
(C2B10H11)C9H6]Hf(NMe2)3 (2c) was finally isolated in quantita-
tive yield from an equimolar reaction of 1 with Hf(NMe2)4 in
toluene at -30 °C (Scheme 1). It is noted that the HNMe2
generated in the reactions must be immediately removed;
otherwise, a mixture of products would be formed. Under similar
reaction conditions, reaction of 1 with Ti(NMe2)4 did not lead
to the isolation of any pure products. The 1H NMR experiments
indicated that only about 20% of 1 was consumed, even after
the reaction mixture of Ti(NMe2)4 and 1 equiv of 1 in benzene-
d6 stood at room temperature for 4 weeks. Its 1H NMR spectrum
became very complicated upon heating. Such reactivity differ-
ences among group 4 metal complexes were reported in the
literature and is probably due to the size effect.12
The above results clearly showed that amines can serve as
deboration agents. Therefore, an aqueous solution of Me3N
(45%) was then used as the reagent to convert 1 to [Me3NH][7-
C9H7-7,8-C2B9H11] (4) in 99% yield in refluxing methanol. An
equimolar reaction of 4 with M(NMe2)4 (M ) Ti, Zr, Hf) in
toluene at room temperature afforded [η5-(C9H7)C2B9H10]-
Ti(NMe2)2(HNMe2) (3a) in 62% yield or 3b,c in >95% yields
(Scheme 2). Complex 3b is barely soluble in toluene, while 3c
is insoluble. Both are slightly soluble in DME and soluble in
THF and pyridine, whereas complexes 2b,c are soluble in most
organic solvents, which facilitates the purification of 3b,c.
Complex 3a is slightly soluble in toluene and soluble in THF,
DME, and pyridine.
1
The H NMR spectrum of 3b in benzene-d6 displayed two
doublets at 1.99 and 1.73 ppm with J ) 6.0 Hz corresponding
to the coordinated dimethyl amine, two singlets at 2.55 and 2.06
ppm attributable to the Zr(N(CH3)2)2 protons, a singlet of indenyl
1
The H NMR spectrum of 2b in benzene-d6 showed two
(13) (a) Nöth, H.; Vahrenkamp, H. Chem. Ber 1966, 99, 1049. (b)
Fussstetter, H.; Nöth, H.; Wrackmeyer, B.; McFarlane, W. Chem. Ber 1977,
110, 3172. (c) Lee, Y.-J.; Lee, J.-D.; Ko, J.; Kim, S.-H.; Kang, S. O. Chem.
Commun. 2003, 1364. (d) Gao, M.; Tang, Y.; Xie, M.; Qian, C.; Xie, Z.
Organometallics 2006, 25, 2578. (e) Wise, S. D.; Au, W.-S.; Getman, T. D.
Main Group Met. Chem. 2002, 25, 411. (f) Brockman, R.; Challis, K.;
Froehner, G.; Getman, T. D. Main Group Met. Chem. 2002, 25, 629. (g)
Batsanov, A. S.; Goeta, A. E.; Howard, J. A. K.; Hughes, A. K.; Malget,
J. M. Dalton Trans. 2001, 1820. (h) Teixidor, F.; Viñas, C.; Benakki, R.;
Kevekäs, R.; Sillanpää, R. Inorg. Chem. 1997, 36, 1719. (i) Laromaine,
A.; Teixidor, F.; Kevekäs, R.; Sillanpää, R.; Benakki, R.; Grüner, B.; Viñas,
C. Dalton Trans. 2005, 1785. (j) Teixidor, F.; Gómez., M. L.; Viñas, C.;
Sillanpää, R.; Kevekäs, R. Organometallics 1997, 16, 1278.
doublets at 6.47 and 5.99 ppm with J ) 3.6 Hz assignable to
the C5 ring protons of the indenyl, a broad singlet at 3.29 ppm
attributable to the cage CH proton, and a singlet at 2.58 ppm
corresponding to the N(CH3)2 group, in addition to the aromatic
protons in the range 7.9–6.8 ppm. One singlet at 43.7 ppm
(11) For the preliminary communication, see: Shen, H.; Chan, H.-S.;
Xie, Z. J. Am. Chem. Soc. 2007, 129, 12934.
(12) (a) Chandra, G.; Lappert, M. F. J. Chem. Soc. A 1968, 1940. (b)
Diamond, G. M.; Jordan, R. F. Organometallics 1996, 15, 4030. (c) Shen,
H.; Chan, H.-S.; Xie, Z. Organometallics 2007, 26, 2694.

Group 4 Metal Complexes from 1-Indenyl-1,2-carborane
Organometallics, Vol. 27, No. 6, 2008 1159
preparation of organometallic amide complexes.1i,19 It is very
interesting to note that both complexes 2 and 3 are very stable
in toluene even at refluxing temperature, although they contain
both basic M-NMe2 and acidic cage C-H or indenyl CH2.
However, treatment of 4 with Ti(NMe2)4 in polar solvent DME
(dimethoxyethane) or directly dissolving 3a in DME resulted
in the isolation of [σ:η5-(C9H6)C2B9H10]Ti(NMe2)(DME) (5a)
in 26% yield. In a similar manner, directly dissolving 3b in
pyridine (Py) led to the isolation of [σ:η5-(C9H6)C2B9-
H10]Zr(NMe2)(Py)2 (5b′) in 86% yield (Scheme 3), whereas 3c
is stable in pyridine. On the other hand, complex 3b is stable
in DME and THF at room temperature, but decomposes under
refluxing conditions.
Directly dissolving 2b in polar solvents did not offer the
expected product [η5:σ-(C9H6)C2B10H10]Zr(NMe2)2; instead,
[σ:η5-(C9H6)C2B9H10]Zr(NMe2)(L)n (L ) DME, n ) 1 (5b);
L ) Py, n ) 2 (5b′); L ) THF, n ) 2 (5b′′)) were isolated
respectively from DME, pyridine, and THF solution at room
temperature (Scheme 4). Considering the stability of 3b in DME
or THF at room temperature, the formation of 5 from 2b should
not be via 3b. Therefore, a possible reaction pathway is proposed
in Scheme 4. Intramolecular amine elimination of 2b affords
the intermediate [η5:σ-(C9H6)C2B10H10]Zr(NMe2)2 (A), followed
by nucleophilic attack of amine generated in situ on the cage
boron atom to give the final product and release HB(NMe2)2.13c–j
A doublet at 29 ppm observed in the proton-coupled 11B NMR
spectrum of the reaction mixture supported the formation of
HB(NMe2)2.13a,b
Figure 1. Molecular structure of [η5-(C9H7)C2B9H10]Zr(NMe2)2-
(HNMe2) (3b) (thermal ellipsoids drawn at the 30% probability
level).
CH2 at 2.77 ppm,14 a broad singlet of cage CH at 3.20 ppm, a
singlet of the olefinic proton at 5.62 ppm,14 and the multiplets
of aromatic protons in the range 7.0–8.3 ppm. In addition to
the indenyl carbon resonances, four signals assignable to the
coordinated dimethyl amine and dimethyl amido carbons at 39.2,
41.7, 47.7, and 49.6 ppm were observed in the 13C NMR
spectrum of 3b, which was significantly different from that of
2b. The 11B NMR of 3b exhibited a 1:1:4:2:1 pattern. Similar
spectroscopic features were also observed in the NMR spectra
of 3a. Due to the very poor solubility of 3c in benzene-d6 and
CD2Cl2, its NMR spectra had to be recorded in pyridine-d5.
The compositions of 3a,b,c were confirmed by elemental
analyses.
Single-crystal X-ray analyses revealed that 3b,c are isostruc-
tural and adopt monomeric three-legged piano stool geometry
containing an η5-dicarbollyl ligand with two amido and one
amine ligand in the basal positions, a structure that is similar
to (η5-C2B9H11)Zr(NEt2)2(HNEt2),15 [η5-(Me2NCH2)C2B9H10]-
Zr(NMe2)2(HNMe2),16 and [η5-(Bn2NCH2CH2)C2B9H10]Zr-
(NMe2)2(HNMe2) (Bn ) C6H5CH2).17 The representative struc-
ture of 3b is shown in Figure 1. For easy comparison, key
structural parameters are compiled in Table 1. The short
Zr-N(1)/N(2) distances of 2.027(3)/2.032(3) Å and the planar
geometry around the N(1) and N(2) atoms indicate that both
nitrogen atoms with sp2 hybridization are engaged in
N(pπ)fZr(dπ) interactions.18 As expected, the Zr-N(3) distance
of 2.345(3) Å is much longer than the Zr-N(amido) distances
and the N(3) adopts a pyramidal geometry. The average
Zr-cage atom distance is 2.530(4) Å. These structural data are
very close to those found in (η5-C2B9H11)Zr(NEt2)2(HNEt2),15
[η5-(Me2NCH2)C2B9H10]Zr(NMe2)2(HNMe2),16 and [η5-(Bn2-
NCH2CH2)C2B9H10]Zr(NMe2)2(HNMe2).17
The 1H NMR spectra of 5 in pyridine-d5 displayed two
doublets at ∼6.1 and ∼6.4 ppm with J ≈ 4.5 Hz corresponding
to the olefinic protons and a singlet at ∼3.2 ppm assignable to
N(CH3)2 with an integral ratio of 1:1:6, in addition to the
aromatic, cage, and coordinated solvent peaks. Their 13C NMR
spectra showed a characteristic Ti-C(indenyl) resonance at 92.6
ppm or Zr-C(indenyl) resonance at ∼85 ppm as well as
dimethyl amido signals in the range 42–46 ppm, besides the
aromatic and coordinated solvent carbon signals. A 2:2:2:3
pattern was observed in the 11B NMR spectra.
Single-crystal X-ray analyses confirmed the molecular struc-
tures of 5a, 5b, and 5b′′. The representative structures of 5a
and 5b′′ are shown in Figures 2 and 3. The central metal atom
is η5-bound to the dicarbollyl, η1-bound to the indenyl, σ-bound
to the dimethyl amino group, and coordinated by one DME or
two THF molecules, respectively. The C(11)-C(19)/C(18)-C(19)
distances of 1.461(4)/1.345(5) Å in 5a, 1.465(9)/1.36(1) Å in
5b, and 1.442(9)/1.325(9) Å in 5b′′ indicate a single and a
double bond, respectively. The Ti(1)-C(11) distance of 2.425(3)
Å is significantly longer than the typical Ti-C σ-bond distances,
for example, 2.128(5) Å in (η5-C5Me5)Ti(Me)2[ONMe(But)],20
2.132(4) Å in [σ:η1:σ-(2-O-3,5-But2-C6H2)(C5H3N){3,5-(CF3)2-
C6H2}]Ti(CH2Ph)2,21 2.165(4) Å in [η5:η1-(C9H6)(CH2CH2-
Amine elimination reactions between metal amides and
ligands bearing acidic protons are a useful method for the
(19) (a) For example, see: Li, H.; Li, L.; Marks, T. J. Angew. Chem.,
Int. Ed. 2004, 43, 4937. (b) Neale, N. R.; Tilley, T. D. J. Am. Chem. Soc.
2005, 127, 14745. (c) Braunschweig, H.; Breitling, F. M.; Radacki, K.;
Seeler, F. J. Organomet. Chem. 2005, 690, 5000. (d) Wood, M. C.; Leitch,
D. C.; Yeung, C. S.; Kozak, J. A.; Schafer, L. L. Angew. Chem., Int. Ed.
2007, 46, 354. (e) Pärssinen, A.; Luhtanen, T.; Klinga, M.; Pakkanen, T.;
Leskelä, M.; Repo, T. Organometallics 2007, 26, 3690. (f) Cuenca, T. In
ComprehensiVe Organometallic Chemistry III; Crabtree, R. H., Mingos,
D. M. P., Eds.; Elsevier: Oxford, 2007; Vol. 4, Chapter 4.05, p 323. (g)
Chan, E. Y-X., Rodriguez-Delgado, A. In ComprehensiVe Organometallic
Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier: Oxford,
2007; Vol. 4, Chapter 4.08, p 759.
(14) Since the dihedral angle is close to 90°, the 3JH-H coupling constant
is too small to be observed, see: ref 10, and: Karplus, M J. Chem. Phys.
1959, 30, 11.
(15) Bowen, D. E.; Jordan, R. F.; Rogers, R. D. Organometallics 1995,
14, 3630.
(16) Lee, J.-D.; Lee, Y.-J.; Son, K.-C.; Cheong, M.; Ko, J.; Kang, S. O.
Organometallics 2007, 26, 3374.
(17) Lee, Y.-J.; Lee, J.-D.; Jeong, H.-J.; Son, K.-C.; Ko, J.; Cheong,
M.; Kang, S. O. Organometallics 2005, 24, 3008.
(18) (a) Wang, H.; Li, H.-W.; Xie, Z. Organometallics 2003, 22, 4522.
(b) McGeary, M. J.; Coan, P. S.; Folting, K.; Streib, W. E.; Caulton, K. G.
Inorg. Chem. 1989, 28, 3283.
(20) Dove, A. P.; Xie, X.; Waymouth, R. M. Chem. Commun 2005,
2152.
(21) Chan, M. C. W.; Kui, S. C. F.; Cole, J. M.; McIntyre, G. J.; Matsui,
S.; Zhu, N.; Tam, K.-H. Chem.-Eur. J 2006, 12, 2607.

1160 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 3b, 3c, 5a, 5b, 5b′′, and 6
3b
3c
5a
5ba
5b′′
6
(M)
(Zr)
(Hf)
(Ti)
(Zr)
(Zr)
(Hf)
av M-cage atom
av M-N(amido)
M-N(amine)
2.530(4)
2.030(3)
2.345(3)
2.56(1)
2.077(9)
2.361(8)
2.350(4)
1.891(3)
2.469(8)
2.010(6)
2.464(8)
2.003(5)
2.565(8)
2.005(5)
M-C(11)
2.425(3)
62.6(1)
80.9(2)
2.477(6)
65.7(3)
78.7(4)
2.487(6)
65.7(3)
78.8(3)
M-C(11)-C(1)
M-C(1)-C(11)
89.3(2)
91.5(5)
107.9(4)
a See ref 11.
Scheme 3
Scheme 4
Figure 3. Molecular structure of [σ:η5-(C9H6)C2B9H10]-
Zr(NMe2)(THF)2 (5b′′) (thermal ellipsoids drawn at the 30%
probability level).
C2B9H10)(CH2)2(η1-NBn2)]Ti(NMe2)2.17 The Zr-N(1) distances
of 2.003(5) Å in 5b′′ and 2.010(6) Å in 5b are close to those
reported in the literature, 2.005(7) Å in (µ-O)[Zr(NMe2)(O-
Ar)2]2 (Ar ) 2,6-But2-4-Me-3,5-N2C4),25 2.029(4) Å in [η5:σ-
Me2Si(C9H6)C2B10H10]Zr(NEt2)2,2c 2.026(2)
Å
in [η5:σ-
OMe)]TiMeCl2,22 1.97(2) and 2.232(9) Å in [η5:σ-Me2C-
(C5H4)(C2B10H10)]Ti(CH2Ph)(NMe2),23 2.160(2) Å in (η5-
Pri2NB(C9H6)C2B10H10]Zr(NMe2)2,6b and 2.030(3) Å in 3b. The
Zr-C(11) distance of 2.491(6) Å in 5b′′ and 2.477(6) Å in 5b
are much longer than the Zr-C σ-bond distances of 2.272(3)
Å in [σ:η1:σ-(2-O-3,5-But2-C6H2)(C5H3N){3,5-(CF3)2-C6H2}]-
Zr(CH2Ph)2,21 2.312(6) Å in [(η5-C5H4)SiMe2(η5-2-Me-C13H7)]-
Zr(CH2Ph)2,26 2.290(2) Å in (CBC)Zr(CH2TMS)2 (CBC )
{1,4,811-tetraazabicyclo[6.6.2]hexadecane}2-),27 2.242(6) Å in
[η1:σ:η5-{MeN(CH2)CH2CH2}C2B9H10]Zr(CH2TMS)(THF),28
and Zr-C(cage) distance of 2.345(2) Å in [η5:σ-Pri2NB(C9H6)
C2B10H10Zr(NMe2)2.6b To the best of our knowledge, the
measured M-C(indenyl) distances in 5 represent the longest
group 4 metal–carbon σ-bond length reported thus far.
C2B9H11)(η5-C5Me5)TiMe, and 2.294(3)
Å
in (η5-
C2B9H11)Ti(C5Me4CH2).24 The Ti-N(1) distance of 1.891(3) Å
is well comparable to those reported in the literature, 1.900(2)
Å in (η5-C2B9H11)Ti(NMe2)2(HNMe2),6b 1.862(3) Å in [σ:η1:
η5-(OCH2)(Me2NCH2)C2B9H9]Ti(NMe2),12c 1.868(3) Å in [σ:η1:
η5-(OCH2)(Et2NCH2)C2B9H9]Ti(NEt2),12c 1.892(3) Å in [η5:σ-
Pri2NP(C9H6)C2B10H10]Ti(NMe2)2,7b and 1.900(4) Å in [(η5-
Reaction of Amide Complexes 3. As described previously,
attempts to prepare the constrained-geometry Hf complex by
directly dissolving 3c in polar solvents failed. On the other hand,
a C-O bond cleavage product, [{η5-(C9H7)C2B9H10}Hf(NMe2)(µ:
η1-OCH2CH2OCH3)]2 (6), was isolated in 12% yield at room
temperature from a DME solution of 3c. A possible reaction
(22) Buil, M. L.; Esteruelas, M. A.; López, A. M.; Mateo, A. C.; Oñate,
E. Organometallics 2007, 26, 554.
(23) Wang, H.; Wang, Y.; Chan, H.-S.; Xie, Z. Inorg. Chem. 2006, 45,
5675.
(24) Bei, X., Jr.; Young, V. G.; Jordan, R. F. Organometallics 2001,
20, 355.
(25) Lee, A. V.; Schafer, L. L. Organometallics 2006, 25, 5249.
(26) Sebastián, A.; Royo, P.; Gómez-Sal, P.; Ranírez de Arellano, C.
Eur. J. Inorg. Chem. 2004, 3814.
(27) O’Connor, P.; Berg, D. J.; Twamley, B. Organometallics 2005,
24, 28.
Figure 2. Molecular structure of [σ:η5-(C9H6)C2B9H10]-
Ti(NMe2)(DME) (5a) (thermal ellipsoids drawn at the 30% prob-
ability level).
(28) Cheung, M.-S.; Chan, H.-S.; Xie, Z. Organometallics 2005, 24,
5217.

Group 4 Metal Complexes from 1-Indenyl-1,2-carborane
Organometallics, Vol. 27, No. 6, 2008 1161
Scheme 5
Scheme 6
η5:-(Pri2C6H3NdCH)C2B9H10]Hf(NMe2)2(NHMe2),13d 2.004(12)
Å in [η5:σ-Pri2NP(C9H6)(C2B10H10)]Hf(NMe2)2,7b and 1.991(1)
Å in [σ:σ-Pri2NP(O)(C9H6)(C2B10H10)]Hf(NEt2)2(THF).31 The
Hf(1)-O(1)/Hf(1)-O(1A) distances of 2.162(4)/2.101(4) Å in
6 are longer than 2.075(1) Å in [σ:σ-Pri2NP(O)(C9H6)-
(C2B10H10)]Hf(NEt2)2(THF),31 1.999(3) Å in (η5-C5Me5){σ:η2-
[OC-C(Ph)NC(NMe2)NPh]}Hf(NMe2),30 and 2.021(3) Å in (η5-
C5Me5)[σ:η1-(O-C6H2-2,4-Me2-6-C3H4ON)]HfCl2.32
In view of the wide applications of guanidine derivatives as
electronically and sterically flexible ligands in organometallic
chemistry,19g,33 we would like to incorporate guanidines into
metallacarboranes to study the effects of metal/charge combina-
tions on the reactivity of group 4 metal complexes. Treatment
of 3 with 1 or 2 equiv of guanidines always gave a mixture of
inseparable products. In the presence of 3 or more equiv of
guanidines PriNdC(NR2)-NHPri (NR2 ) NMe2 (7), NEt2 (7′),
N(CH2)4 (7′′)), ionic complexes [{η2-(PriN)2C(NR2)}3M][(C9H7)-
C2B9H11] (M ) Ti, NR2 ) N(CH2)4 (8a′′); M ) Zr, NR2 )
NMe2 (8b), NEt2 (8b′), N(CH2)4 (8b′′); M ) Hf, NR2 ) NEt2
(8c′), N(CH2)4 (8c′′)) were isolated in 57%-91% yields
(Scheme 6). It is clear that the high acidity of guanidines (pKa
≈ 13.6)33a drives the protonation reactions to completion.
Figure 4. Molecular structure of [{η5-(C9H7)C2B9H10}Hf(NMe2)(µ:
η1-OCH2CH2OCH3)]2 (6) (thermal ellipsoids drawn at the 30%
probability level).
pathway is shown in Scheme 5. Replacement of Me2NH by
DME, followed by σ-bond metathesis and dimerization, gives
6.29
1
The H NMR spectrum of 6 showed two doublets at 8.17
and 7.15 ppm with J ) 7.5 Hz, two triplets at 7.33 and 7.26
ppm with J ) 7.5 Hz, and two singlets at 6.41 and 3.24 ppm
assignable to the indenyl group, in addition to a singlet at 3.25
ppm attributable to the N(CH3)2 and resonances at 3.49, 3.17,
and 3.06 ppm corresponding to OCH2CH2OCH3. Its 11B NMR
displayed a 2:2:2:2:2:2:2:2:2 pattern, which is significantly
different from the parent complex 3c.
An X-ray analysis revealed that 6 is a dimer and showed
two THF of solvation. Each Hf atom is σ-bound to a dimethyl-
amino group and two doubly bridging O atoms, η5-bound to a
dicarbollyl ligand and coordinated to an O atom in a typical
four-legged piano stool geometry (Figure 4). The Hf(1)-cage
atom distance of 2.565(8) Å in 6 is close to 2.56(1) Å in 3c
and 2.63(1) Å in [η1:η5:-(Pri2C6H3NdCH)C2B9H10]Hf(NMe2)2-
(NHMe2).13d The Hf(1)-N(1) distance of 2.005(5) Å in 6 is
comparable with 2.077(9) Å in 3c, 2.067(4) Å in (η5-C5Me5){σ:
η2-[OC-C(Ph)NC(NMe2)NPh]}Hf(NMe2),30 2.059(7) Å in [η1:
1
The H NMR spectra of 8 exhibited a broad singlet in the
range -1.0 to -1.3 ppm corresponding to the bridging BHB
proton in addition to the resonances of the indenyl and
guanidinate protons. The characteristic guanidinate carbon (N3C)
resonance at ∼170 ppm was observed in their 13C NMR spectra.
Their 11B NMR spectra displayed a 1:1:1:1:1:1:1:1:1 pattern,
which is similar to that of 4.
(31) Wang, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25, 2569.
(32) Coles, S. R.; Clarkson, G. J.; Gott, A. L.; Munslow, I. J.;
Spitzmesser, S. K.; Scott, P. Organometallics 2006, 25, 6019.
(33) (a) Bailey, P. H.; Pace, S. Coord. Chem. ReV. 2001, 214, 91. (b)
Jones, C.; Junk, P. C.; Platts, J. A.; Stasch, A. J. Am. Chem. Soc. 2006,
128, 2206. (c) Ong, T.-G.; Yap, G. P. A.; Richeson, D. R. J. Am. Chem.
Soc. 2003, 125, 8100. (d) Holland, A. W.; Bergman, R. G. J. Am. Chem.
Soc. 2002, 124, 9010. (e) Duncan, A. P.; Mullins, S. M.; Arnold, J.;
Bergman, R. G. Organometallics 2001, 20, 1808. (f) Ong, T.-G.; Yap,
G. P. A.; Richeson, D. S. Organometallics 2002, 21, 2839. (g) Carmalt,
C. J.; Newport, A. C.; O’Neill, S. A.; Parkin, I. P.; White, A. J. P.; Williams,
D. J. Inorg. Chem. 2005, 44, 615. (h) Mullins, S. M.; Duncan, A. P.;
Bergman, R. G.; Arnold, J. Inorg. Chem. 2001, 40, 6952. (i) Tin, M. K. T.;
Yap, G. P. A.; Richeson, D. S. Inorg. Chem. 1998, 37, 6728. (j) Brazeau,
A. L.; Wang, Z.; Rowley, C. N.; Barry, S. T. Inorg. Chem. 2006, 45, 2276.
(k) Baunemann, A.; Winter, M.; Csapek, K.; Gemel, C.; Fischer, R. A.
Eur. J. Inorg. Chem. 2006, 4665. (l) Ong, T.-G.; Yap, G. P. A.; Richeson,
D. R. Chem. Commun. 2003, 2612. (m) Tin, M. K. T.; Thirupathi, N.; Yap,
G. P. A.; Richeson, D. S. Dalton Trans. 1999, 2947. (n) Zhang, W.-X.;
Nishiura, M.; Hou, Z. Synlett 2006, 8, 1213.
(29) For the C-O bond activation by group 4 metal complexes, see:
refs 12c, 28, and: (a) Prinz, H.; Bott, S. G.; Atwood, J. L. J. Am. Chem.
Soc. 1986, 108, 2113. (b) Borkowsky, S. L.; Jordan, R. F.; Hinch, G. D.
Organometallics 1991, 10, 1268. (c) Alvanipour, A.; Atwood, J. L.; Bott,
S. G.; Junk, P. C.; Kynast, U. H.; Prinz, H. Dalton Trans 1998, 1223. (d)
Brandley, C. A.; Veiros, L. F.; Pun, D.; Lobkovsky, E.; Keresztes, I.; Chirik,
P. J. J. Am. Chem. Soc. 2006, 128, 16600. (e) Brandley, C. A.; Veiros,
L. F.; Chirik, P. J. Organometallics 2007, 26, 3191.
(30) Gott, A. L.; Coles, S. R.; Clarke, A. J.; Clarkson, G. J.; Scott, P.
Organometallics 2007, 26, 136.

1162 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
Scheme 7
Figure 5. Molecular structure of the cation in [{η2-(PriN)2-
C(NMe2)}3Zr][(C9H7)C2B9H11] (8b) (thermal ellipsoids drawn at
the 30% probability level).
Single-crystal X-ray diffraction studies confirmed that 8 are
ionic complexes, consisting of well-separated cations [{η2-
(PriN)2C(NR2)}3M]+ and monoanions [(C9H7)C2B9H11]-. Dif-
ferent from [η5-(Et)C5Me4]2ZrMe(C2B9H12),34 no Zr-H-B
bonding interaction is observed in complexes 8. In the cation,
the metal is η2-bound to three guanidinates with an average
Zr-N distance of ∼2.2 Å. Figure 5 shows the representative
structure of the cation in 8b.
Although the controlled syntheses of mono- and diguanidinate
complexes from the reactions of 3 with 1 or 2 equiv of
guanidines were unsuccessful, they were achieved by stepwise
insertion of carbodiimide into the M-N bonds in 3. Treatment
of 3b with 1 or 2 equiv of diisopropylcarbodiimide in THF at
room temperature afforded, after recrystallization from toluene,
monoguanidinate complex [η5-(C9H7)C2B9H10]Zr(NMe2)[η2-
(PriN)2C(NMe2)] · 0.5C7H8 (9 · 0.5C7H8) or diguanidinate com-
plex [η5-(C9H7)C2B9H10]Zr[η2-(PriN)2C(NMe2)]2 (10) in 6% or
90% isolated yields, respectively. It is noted that the former
reaction also generated 10, leading to the rather low isolated
yield of 9. Reaction of 9 with an equimolar amount of
diisopropylcarbodiimide afforded 10. Both complexes reacted
further with guanidine 7 in refluxing THF to produce complex
8b (Scheme 7).
as shown in Figure 6. The average Zr-cage atom distance of
2.532(4) Å in 9 is almost the same as that of 2.530(4) Å in 3b.
For easy comparison, key structural parameters are compiled
in Tables 1 and 2.
It was communicated earlier that heating 10 in toluene caused
an unexpected C-N bond cleavage process to produce 11a.11
Under the same reaction conditions, 11a was isolated in 28%
yield from a refluxing toluene solution of 9. A possible reaction
pathway is illustrated in Scheme 8. Intramolecular amine
elimination of 9 gives the intermediate D/D′, which undergoes
C-N bond cleavage upon heating to generate carbodiimide and
metallacarborane amide E. Interaction between D/D′ and in situ
generated carbodiimide affords F. 1,5-Sigmatropic rearrange-
ment35 over the indenyl ring followed by an intramolecular
proton shift gives the final product 11a.36
Reaction of Amide Complex 5b. Complex 5b reacted with
2 equiv of guanidines PriNH-C(NR2)dNPri in refluxing toluene
In addition to the resonances of indenyl and cage protons,
1
the H NMR spectrum of 9 exhibited a singlet at 3.03 ppm
assignable to Zr-N(CH3)2, two multiplets at 3.83 and 2.51 ppm,
and two broad peaks at 1.13 and 0.79 ppm attributable to
guanidinate, whereas a multiplet at 3.84 ppm and two peaks at
2.57 and 1.21 ppm corresponding to guanidinates were observed
in the 1H NMR spectrum of 10. The characteristic guanidinate
carbon (CN3) resonances at 173.1 and 172.0 were also observed
in the 13C NMR spectra of 9 and 10, respectively. Their 11B
NMR showed 1:1:1:4:1:1 and 1:1:4:2:1 patterns, which are
different from those of 3b and 8.
The solid-state structure of 9 was confirmed by a single-
crystal X-ray diffraction study. The Zr atom in 9 is coordinated
by one N atom, an η2-guanidinate, and an η5-dicarbollyl ligand,
Figure 6. Molecular structure of [η5-(C9H7)C2B9H10]Zr(NMe2)[η2-
(PriN)2C(NMe2)] (9) (thermal ellipsoids drawn at the 30% prob-
ability level).
(34) Hlatky, G. G.; Turner, H. W.; Eckman, R. R. J. Am. Chem. Soc.
1989, 111, 2728.

Group 4 Metal Complexes from 1-Indenyl-1,2-carborane
Organometallics, Vol. 27, No. 6, 2008 1163
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 9, 10, 11a, 11b, 11c, 13a, 13c, and 14
9
10ab
11aa
11bab
11ca
13aa
13ca
14
av Zr-cage atom
av Zr-N(guanidinate)
Zr-N(amido)
2.532(4)
2.213(3)
2.018(3)
2.61(2)
2.210(8)
2.481(5)
2.196(3)
2.494(2)
2.18(1)
2.492(5)
2.195(3)
2.552(6)
2.186(4)
2.082(4)
2.554(4)
2.189(3)
2.081(2)
2.603(6)
2.006(4)
Zr-N(imine)
2.223(3)
2.499(4)c
2.24(1)
2.242(3)
2.488(4)c
Zr-C(indenyl)
2.51(1)c
2.716(5)c
2.603(5)d
66.3(3)
81.3(3)
61.8(2)
2.700(3)c
2.618(3)d
65.9(2)
81.4(2)
61.6(1)
Zr-C(11)-C(1)
65.8(2)
78.4(2)
61.1(1)
65.3(5)
78.6(6)
61.4(4)
65.8(2)
78.4(2)
61.1(1)
Zr-C(1)-C(11)
85.1(2)
60.3(1)
108.5(5)
60.3(3)
88.1(3)
N-Zr-N(guanidinate)
a See ref 11. b Average values of two crystallographically independent molecules in the unit cell. c Zr-C(11). d Zr-C(19).
Scheme 8
Scheme 9
reaction temperature may play a role in the formation of the
final products.
To understand the above reaction pathway, reaction of 5b
withcarbodiimideswasattempted,astheinsertionofR′NdCdNR′
into the M-N bond gives the M-guanidinates.37 Treatment of
5b with 1 equiv of R′NdCdNR′ (R′ ) Pri, Cy) in THF at room
temperature gave the Zr-N insertion products [σ:η5-
(C9H6)C2B9H10]Zr[η2-(R′N)2C(NMe2)](THF) (R′ ) Pri (12a),
Cy (12c)) in 71–74% isolated yields. Complexes 12a,c reacted
further with another equivalent of R′NdCdNR′ to generate
the Zr-C insertion species [σ:η5-{3-[C(dNR′)NR′]-1-C9H6}-
C2B9H10]Zr[η2-(R′N)2C(NMe2)] (R′ ) Pri (13a), Cy (13c)) in
quantitative yields.11 They were cleanly converted to [η1:σ:η5-
{2-[CdNR′(NHR′)]C9H5}C2B9H10]Zr[η2-(R’N)2C(NMe2)] (R′
) Pri (11a), Cy (11c)) upon refluxing in toluene. A possible
reaction mechanism was discussed in the preliminary com-
munication.11 In sharp contrast, reaction of 5b with an equimolar
amount of diphenylketene in THF at room temperature afforded,
after recrystallization from THF, [σ:η5-{[3-C(dCPh2)-O]-
C9H6}C2B9H10]Zr(NMe2)(THF)2 (14) in 64% isolated yield.
These transformations are outlined in Scheme 10. The formation
to give unprecedented zirconacarboranes [η1:σ:η5-{[2-{Cd
NPri(NHPri)}]C9H5}C2B9H10]Zr[η2-(PriN)2C(NR2)] (R ) Me
(11a), Et (11b)) in 30–47% yields.11 These complexes were
also isolated from equimolar reactions in a much lower yield.
On the other hand, interaction of 5b with 3 equiv of guanidines
in refluxing THF afforded 8b-8b′′ in 33–60% isolated yields
(Scheme 9). These results suggested that the solvents and
(35) For 1,5-sigmatropic rearrangement in indene derivatives, see: (a)
Stradiotto, M.; McGlinchey, M. J. Coord. Chem. ReV. 2001, 219–221, 311.
(b) Christopher, J. N.; Jordan, R. F.; Peterson, J. L., Jr.; Young, V. G.
Organometallics 1997, 16, 3044. (c) Dolbier, W. R., Jr.; McCullagh, L.;
Rolison, D.; Anapolle, K. E. J. Am. Chem. Soc. 1975, 97, 934. (d) Stradiotto,
M.; Hazendonk, P.; Bain, A. D.; Brook, M. A.; McGlinchey, M. J.
Organometallics 2000, 19, 590.
(36) A similar reaction pathway was proposed for the conversion of 10
to 11a, see ref 11.

1164 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
Scheme 10
Figure 7. Molecular structure of [σ:η5-{[3-C(dCPh2)-O]-
C9H6}C2B9H10]Zr(NMe2)(THF)2 (14) (thermal ellipsoids drawn at
the 30% probability level).
The molecular structure of 14 was confirmed by single-crystal
X-ray analyses and is shown in Figure 7. The Zr atom is
σ-bound to the N and O atoms, η5-bound to the dicarbollyl,
and coordinated to two THF molecules. The Zr-N(1) distance
of 2.006(4) Å is close to that observed in 3b, 5b, 5b′′, and 9.
The Zr-O distance of 2.034(3) Å is very comparable to 1.996(4)
Å in (CBC)Zr(O-2,6-C6H3Me2)2 (CBC ) {1,4,811-tetraazabi-
cyclo[6.6.2]hexadecane}2-),27 1.957(6) Å in (µ-O)[Zr(NMe2)(O-
Ar)2]2 (Ar ) 2,6-But2-4-Me-3,5-N2C4),25 and 1.952(2) Å in
[σ:η1 :σ-(2-O-3,5-But 2 -C6 H2 )(C5 H3 N){3,5-(CF3 )2 -
C6H2}]Zr(CH2Ph)2.21 The C(20)-C(21) distance of 1.353(7) Å
and the planar geometry around them indicate the double-bond
character.
Conclusion
of 14 may involve the coordination of ketene to the Zr atom,
followed by the nucleophilic attack of the indenyl on ketene
(Scheme 10). Complex 14 is stable in THF and does not react
further with another equivalent of ketene presumably due to
steric reasons. It is not clear at this stage why 5b shows a
different chemoselectivity toward ketene and carbodiimide.
Insertion of the CdO unit in R2CdCdO into the M-C38 and
M-N39 bonds has been documented, but the preference in
reactivity is not clearly addressed yet.
Several group 4 metal amides derived from 1-indenyl-1,2-
carborane (1) and [Me3NH][7-C9H7-7,8-C2B9H11] (4) were
synthesized and structurally characterized. Interconversions
among [η5-(C2B10H11)C9H6]M(NMe2)3 (2), [η5-(C9H7)C2B9H10]-
M(NMe2)2(HNMe2) (3), and [σ:η5-(C9H6)C2B9H10]M(NMe2)-
(L)n (5) were studied, which showed that the nature of solvents
and metals played a very important role in these transformations.
Stepwise insertion of diisopropylcarbodiimide into the Zr-N
bond in 3b gave the monoguanidinate complex [η5-(C9H7)-
C2B9H10]Zr(NMe2)[η2-(PriN)2C(NMe2)] (9) and diguanidinate
complex [η5-(C9H7)C2B9H10]Zr[η2-(PriN)2C(NMe2)]2 (10), re-
spectively. They were not obtained from the reaction of 3b with
the corresponding guanidine, which only afforded triguanidinate
complexes [{η2-(PriN)2C(NR2)}3M][(C9H7)C2B9H11] (8) (M )
Ti, Zr, Hf; NR2 ) NMe2, NEt2, N(CH2)4). Heating 9 or 10 in
toluene gave the same C-N bond cleavage product [η1:σ:η5-
{[2-CdNPri(NHPri)]C9H5}C2B9H10]Zr[η2-(PriN)2CNMe2] (11a).
A possible mechanism for the formation of 11a was proposed,
which was supported by experimental results. This work showed
that guanidinate ligands are not always inert. Under certain
circumstances, guanidinates can undergo C-N bond cleavage to
generate amides and carbodiimides.
1
The H NMR spectrum of 14 displayed two characteristic
doublets at 6.19 and 5.03 ppm with J ) 1.8 Hz assignable to
the olefinic and the benzylic CH, a singlet at 2.57 ppm for the
N(CH3)2 group, a singlet at 3.77 ppm attributable to the cage
CH, several multiplets in the range 7.0 to 7.9 ppm corresponding
to the aromatic protons, and THF resonances at 1.59 and 3.63
ppm, respectively. Its 11B NMR exhibited a 1:1:4:2:1 pattern.
(37) Selected examples, see: (a) Chandra, G.; Jenkins, A. D.; Lappert,
M. F.; Srivastava, R. C. J. Chem. Soc. A 1970, 2550. (b) Thomas, E. W.;
Nishizawa, E. E.; Zimmermann, D. C.; Williams, D. J. J. Med. Chem. 1989,
32, 228. (c) Montilla, F.; Pastor, A.; Galindo, A. J. Organomet. Chem. 2004,
689, 993. (d) Ong, T.-G.; O’Brien, J. S.; Korobkov, I.; Richeson, D. S.
Organometallics 2006, 25, 4728. (e) Montilla, F.; del Río, D.; Pastor, A.;
Galindo, A. Organometallics 2006, 25, 4996.
(38) Selected examples, see: (a) Beckhaus, R.; Wagner, T.; Zimmermann,
C.; Herdtweck, E. J. Organomet. Chem. 1993, 460, 181. (b) Moloy, K. G.;
Fangan, P. J.; Manriquez, J. M.; Marks, T. J. J. Am. Chem. Soc. 1986, 108,
56. (c) Gambarotta, S.; Strologo, S.; Floriani, C.; Chiesi-Villa, A.; Guastini,
C. Inorg. Chem. 1984, 24, 654. (d) Himbert, G.; Henn, L.; Hoge, R. J.
Organomet. Chem. 1980, 184, 317.
Experimental Section
General Procedures. All experiments were performed under an
atmosphere of dry nitrogen 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
(39) Selected examples, see ref 12c and: (a) Liu, R.; Zhang, C.; Zhu,
Z.; Luo, J.; Zhou, X.; Weng, L. Chem.-Eur. J. 2006, 12, 6940. (b) Ando,
F.; Kohmura, Y.; Koketsu, J. Bull. Chem. Soc. Jpn. 1987, 69, 1564.

Group 4 Metal Complexes from 1-Indenyl-1,2-carborane
Organometallics, Vol. 27, No. 6, 2008 1165
benzophenone ketyl immediately prior to use. Diphenylketene,40
PriNH-C(NMe2)dNPri (7),41 PriNH-C(NEt2)dNPri (7′),42 PriNH-
C[N(CH2)4]dNPri (7′′),42 and 1-indenyl-1,2-carborane (1)10 were
prepared according to literature methods. M(NMe2)4 (M ) Ti, Zr,
Hf) and other chemicals were purchased from Aldrich 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 transform spectrometer. 1H NMR spectra
were recorded on a Bruker DPX 300 spectrometer at 300.0 MHz.
13C NMR spectra were recorded on a Bruker DPX 300 spectrometer
at 75.5 MHz or a Varian Inova 400 spectrometer at 100.7 MHz.
11B NMR spectra were recorded on a Varian Inova 400 spectrom-
eter at 128.0 MHz. All chemical shifts were reported in δ units
with reference to the residual protons and carbons of the deuterated
solvents for proton and carbon chemical shifts and to external
BF3 · OEt2 (0.00 ppm) for boron chemical shifts. Elemental analyses
were performed by MEDAC Ltd., U.K., or Shanghai Institute of
Organic Chemistry, CAS, China.
Preparation of [η5-(C9H7)C2B9H10]Ti(NMe2)2(HNMe2) (3a). Com-
pound 4 (154 mg, 0.5 mmol) was added to a toluene solution (10
mL) of Ti(NMe2)4 (112 mg, 0.5 mmol) at room temperature, and
the mixture was stirred for 12 h. After filtration, the deep red filtrate
was concentrated to ca. 3 mL. Complex 3a was obtained as a red
crystalline solid after this solution stood at room temperature for 2
days (133 mg, 62%). 1H NMR (benzene-d6): δ 8.25 (d,J ) 7.5 Hz,
1H), 7.07 (m, 3H) (aromatic), 5.60 (s, 1H) (olefinic), 3.90 (s, 1H)
(cage CH), 2.79 (s, 2H) (CH2), 2.87 (s, 6H) (N(CH3)2), 2.33 (s,
6H) (N(CH3)2), 2.09 (d, J ) 6.0 Hz, 3H) (HN(CH3)2), 1.86 (d, J )
6.0 Hz, 3H) (HN(CH3)2). 13C{1H} NMR (benzene-d6): δ 144.8,
143.6, 143.5, 127.0, 126.2, 125.3, 124.0, 123.9 (aromatic and
olefinic), 51.4 (N(CH3)2), 47.0 (N(CH3)2), 44.2 (HN(CH3)2), 43.5
(HN(CH3)2), 37.3 (CH2), the cage carbons were not observed.
11B{1H} NMR (benzene-d6): δ 6.8 (1B), -1.4 (1B), -2.9 (1B),
-4.2 (3B), -10.7 (1B), -13.3 (1B), -17.3 (1B). IR (KBr, cm-1):
VB-H 2528 (vs). Anal. Calcd for C17H36B9N3Ti (3a): C, 47.74; H,
8.48; N, 9.83. Found: C, 47.84; H, 8.17; N, 9.74.
Preparation of [η5-(C9H7)C2B9H10]Zr(NMe2)2(HNMe2) (3b). Com-
pound 4 (154 mg, 0.5 mmol) was added to a toluene solution (10
mL) of Zr(NMe2)4 (134 mg, 0.5 mmol) at room temperature, and
the mixture was stirred for 5 min until a clear solution was formed.
After filtration, the filtrate was concentrated to ca. 3 mL. Complex
3b was obtained as yellow crystals after the solution stood at room
temperature for 12 h (226 mg, 96%). 1H NMR (benzene-d6): δ
8.23 (d,J ) 7.8 Hz, 1H), 7.07 (m, 3H) (aromatic), 5.62 (s, 1H)
(olefinic), 3.20 (s, 1H) (cage CH), 2.77 (s, 2H) (CH2), 2.55 (s, 6H)
(N(CH3)2), 2.06 (s, 6H) (N(CH3)2), 1.99 (d, J ) 6.0 Hz, 3H)
(HN(CH3)2), 1.73 (d, J ) 6.0 Hz, 3H) (HN(CH3)2). 13C{1H} NMR
(benzene-d6): δ 145.2, 142.1, 140.4, 127.7, 126.3, 125.9, 124.4,
123.6 (aromatic and olefinic), 49.6 (N(CH3)2), 47.7 (N(CH3)2), 41.7
(HN(CH3)2), 39.2 (HN(CH3)2), 37.9 (CH2), the cage carbons were
not observed. 11B{1H} NMR (benzene-d6): δ -1.3 (1B), -2.7 (1B),
-6.5 (4B), -13.8 (2B), -19.7 (1B). IR (KBr, cm-1): VB-H 2542
(vs). Anal. Calcd for C17H36B9N3Zr (3b): C, 43.35; H, 7.70; N,
8.92. Found: C, 43.80; H, 7.61; N, 8.54.
Preparation of [η5-(C2B10H11)C9H6]Zr(NMe2)3 (2b). A toluene
solution (3 mL) of Zr(NMe2)4 (133 mg, 0.5 mmol) was added to a
toluene solution (3 mL) of 1 (129 mg, 0.5 mmol), and the mixture
was stirred at room temperature for 5 min. After removal of the
solvent, the residue was dried under vacuum at room temperature
for 12 h to give 2b as a yellow oil (240 mg, 100%). 1H NMR
(benzene-d6): δ 7.89 (m, 1H), 7.30 (m, 1H), 6.86 (m, 2H) (aromatic),
6.47 (d,J ) 3.6 Hz, 1H), 5.99 (d,J ) 3.6 Hz, 1H) (olefinic), 3.29
(s, 1H) (cage H), 2.58 (s, 18H) (CH3). 13C{1H} NMR (benzene-
d6): δ 126.3, 125.6, 124.3, 123.3, 123.0, 122.2, 120.5, 105.4, 97.8
(indenyl), 76.0, 66.7 (cage C), 43.7 (CH3). 11B{1H} NMR (benzene-
d6): δ -1.7 (1B), -4.0 (1B), -9.3 (4B), -12.6 (4B). IR (KBr,
cm-1): VB-H 2578 (vs). Anal. Calcd for C17H35B10N3Zr (2b): C,
42.47; H, 7.34; N, 8.74. Found: C, 42.96; H, 7.46; N, 8.45.
Preparation of [η5-(C2B10H11)C9H6]Hf(NMe2)3 (2c). This
complex was prepared as a pale yellow oil from Hf(NMe2)4 (177
mg, 0.5 mmol) and 1 (129 mg, 0.5 mmol) in toluene (6 mL) at
-30 °C, using the identical procedures reported for 2b: yield 284
1
Alternate Method. Complex 2b (240 mg, 0.5 mmol) was added
to a toluene solution (5 mL) of NHMe2 (50 mg, 1.1 mmol) at -30
°C. The Schlenk flask was closed and stirred at room temperature
for 12 h. Removal of the volatile chemicals afforded a pale yellow
solid identified as 3b (231 mg, 98%).
mg (100%). H NMR (benzene-d6): δ 7.89 (d, J ) 8.1 Hz, 1H),
7.29 (dd, J ) 6.9 Hz, 2.4 Hz, 1H), 6.85 (m, 2H) (aromatic), 6.42
(d, J ) 3.9 Hz, 1H), 5.96 (d, J ) 3.9 Hz, 1H) (olefinic), 3.33 (s,
1H) (cage H), 2.65 (s, 18H) (CH3). 13C{1H} NMR (benzene-d6): δ
126.4, 125.4, 124.6, 123.5, 123.3, 122.5, 120.6, 105.1, 97.7
(indenyl), 75.6, 66.5 (cage C), 43.4 (CH3). 11B{1H} NMR (benzene-
d6): δ -1.7 (1B), -3.9 (1B), -9.3 (4B), -12.6 (4B). IR (KBr,
cm-1): VB-H 2580 (vs). Anal. Calcd for C17H35B10HfN3 (2c): C,
35.94; H, 6.21; N, 7.40. Found: C, 36.43; H, 6.46; N, 7.01.
Preparation of [Me3NH][7-C9H7-7,8-C2B9H11] (4). An aqueous
solution of trimethylamine (45%, 10 mL) was added to a methanol
solution (30 mL) of 1 (1.29 g, 5.0 mmol) at room temperature, and
the pale yellow solution was heated to reflux for 8 h. After removal
of the volatile chemicals, the residue was dried in vacuum at room
temperature for 6 h to afford 4 as a pale orange solid (1.53 g, 99%).
1H NMR (acetone-d6): δ 7.55 (d, J ) 7.5 Hz, 1H), 7.34 (d, J )
7.5 Hz, 1H), 7.27 (t, J ) 7.5 Hz, 1H), 7.11 (t, J ) 7.5 Hz, 1H)
(aromatic), 6.00 (t, J ) 1.8 Hz, 1H) (olefinic), 3.17 (d, J ) 1.8 Hz,
2H) (CH2), 3.15 (s, 9H) (N(CH3)3), 1.95 (s, 1H) (cage CH), -2.15
(bs, 1H) (BHB). 13C{1H} NMR (acetone-d6): δ 149.3, 148.1, 144.7,
126.4, 125.9, 124.7, 124.0, 121.6 (indenyl), 46.0 (N(CH3)3), 37.5
(CH2), the cage carbons were not observed. 11B{1H} NMR
(acetone-d6): δ -9.5 (1B), -10.4 (1B), -13.5 (1B), -16.6 (1B),
-17.3 (1B), -19.9 (1B), -21.9 (1B), -33.2 (1B), -37.0 (1B). IR
(KBr, cm-1): VB-H 2525 (vs). Anal. Calcd for C14H28B9N (4): C,
54.65; H, 9.17; N, 4.55. Found: C, 54.33; H, 9.13; N, 4.48.
Preparation of [η5-(C9H7)C2B9H10]Hf(NMe2)2(HNMe2) (3c).
This complex was prepared as pale yellow crystals from Hf(NMe2)4
(177 mg, 0.5 mmol) and 4 (154 mg, 0.5 mmol) in toluene (10 mL)
using the identical procedures reported for 3b: yield 274 mg (98%).
1H NMR (pyridine-d5): δ 8.00 (m, 1H), 7.28 (m, 1H), 7.12 (m,
2H) (aromatic), 6.19 (s, 1H) (olefinic), 3.29 (s, 1H) (cage CH),
3.16 (s, 1H) (HN(CH3)2), 3.09 (s, 2H) (CH2), 2.95 (s, 12H)
(N(CH3)2), 2.37 (s, 6H) (HN(CH3)2). 13C{1H} NMR (pyridine-d5):
δ 144.5, 142.9, 141.0, 128.7, 128.0, 125.8, 125.0, 124.1 (aromatic
and olefinic), 43.7 (N(CH3)2), 38.4 (HN(CH3)2), 36.5 (CH2), the
cage carbons were not observed. 11B{1H} NMR (pyridine-d5): δ
1.2 (2B), -5.9 (2B), -10.3 (2B), -16.0 (2B), -26.8 (1B). IR (KBr,
cm-1): VB-H 2548 (vs). Anal. Calcd for C17H36B9HfN3 (3c): C,
36.57; H, 6.50; N, 7.53. Found: C, 37.03; H, 6.61; N, 7.29.
Alternate Method. Complex 2c (284 mg, 0.5 mmol) was added
to a toluene solution (5 mL) of NHMe2 (50 mg, 1.1 mmol) at -30
°C. The Schlenk flask was closed and stirred at room temperature
for 6 h. Removal of the volatile chemicals afforded a pale yellow
solid identified as 3c (273 mg, 98%).
Preparation of [σ:η5-(C9H6)C2B9H10]Ti(NMe2)(DME) (5a). A
DME solution (5 mL) of 3a (214 mg, 0.5 mmol) was stirred at
room temperature for 6 h. After filtration, the resulting clear solution
was concentrated to 2 mL. Complex 5a was obtained as deep red
crystals after this solution stood at room temperature for 48 h (56
mg, 26%). 1H NMR (pyridine-d5): δ 7.40 (d, J ) 7.5 Hz, 1H),
6.87 (t, J ) 7.5 Hz, 1H), 6.66 (d, J ) 7.5 Hz, 1H) (aromatic), 6.45
(40) Taylor, E. C.; McKillop, A.; Hawks, G. H. Org. Synth. 1972, 52,
36.
(41) Coles, M. P.; Hitchcock, P. B. Eur. J. Inorg. Chem. 2004, 2662.
(42) Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25, 5515.

1166 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
(d, J ) 4.8 Hz, 1H) (olefinic), 6.40 (t, J ) 7.5 Hz, 1H) (aromatic),
6.13 (d, J ) 4.8 Hz, 1H) (olefinic), 3.47 (s, 4H) (DME), 3.25 (s,
6H) (DME), 3.29 (s, 6H) (N(CH3)2). 13C{1H} NMR (pyridine-d5):
δ 143.5, 140.4, 128.7, 128.0, 121.7, 120.7, 118.1, 115.9 (aromatic
and olefinic), 92.6 (Ti-C), 71.4 (DME), 57.9 (DME), 46.0
(N(CH3)2), the cage carbons were not observed. 11B{1H} NMR
(pyridine-d5): δ 12.0 (2B), -2.7 (2B), -4.1 (2B), -11.1 (3B). IR
(KBr, cm-1): VB-H 2516 (vs). Anal. Calcd for C15H27B9NOTi (5a
- 0.5DME): C, 47.10; H, 7.11; N, 3.66. Found: C, 47.17; H, 7.43;
N, 3.28.
(OCH2), 1.59 (m, 8H) (THF). 11B{1H} NMR (pyridine-d5): δ -8.6
(2B), -9.5 (2B), -12.5 (2B), -15.6 (2B), -16.4 (2B), -19.0 (2B),
-20.8 (2B), -32.2 (2B), -36.0 (2B). IR (KBr, cm-1): VB-H 2526
(vs). Anal. Calcd for C34H64B18Hf2N2O4.5 (6 + 0.5THF): C, 36.32;
H, 5.74; N, 2.49. Found: C, 36.44; H, 5.77; N, 2.56.
Preparation of [{η2-(PriN)2C-N(CH2)4}3Ti][(C9H7)C2B9-
H11] (8a′′). Compound 7′′ (394 mg, 2.0 mmol) was added to a THF
solution (10 mL) of 3a (214 mg, 0.5 mmol), and this mixture was
heated to reflux for 12 h. The resulting filtrate was concentrated to
3 mL after filtration. Complex 8a′′ was obtained as deep red crystals
after this solution stood at room temperature for 3 days (252 mg,
Preparation of [σ:η5-(C9H6)C2B9H10]Zr(NMe2)(DME) (5b).
Complex 2b (240 mg, 0.5 mmol) was dissolved in DME (2 mL) at
room temperature to give 5b as red crystals after the solution stood
at room temperature for 2 weeks (195 mg, 83%). 1H NMR
(pyridine-d5): δ 7.51 (d, J ) 7.8 Hz, 1H), 7.21 (d, J ) 7.8 Hz,
1H), 6.79 (t, J ) 7.8 Hz, 1H), 6.58 (t, J ) 7.8 Hz, 1H) (aromatic),
6.42 (d, J ) 4.5 Hz, 1H), 6.06 (d, J ) 4.5 Hz, 1H) (olefinic), 3.48
(s, 4H) (DME), 3.25 (s, 6H) (DME), 3.11 (s, 6H) (N(CH3)2), 3.07
(s, 1H) (cage CH). 13C{1H} NMR (pyridine-d5): δ 140.9, 139.1,
120.1, 119.6, 119.4 110.1 (aromatic and olefinic), 85.5 (cage C),
84.9 (Zr-C), 71.4 (DME), 58.3 (cage C), 57.9 (DME), 42.7
(N(CH3)2). 11B{1H} NMR (pyridine-d5): δ 4.0 (2B), -4.5 (2B),
-6.2 (2B), -14.4 (3B). IR (KBr, cm-1): VB-H 2513 (vs). These
data are identical with those reported in the literature.11
1
57%). H NMR (pyridine-d5): δ 8.19 (d, J ) 7.5 Hz, 1H), 7.34
(m, 2H), 7.16 (d, J ) 7.5 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic),
3.74 (m, 6H) (NCHMe2), 3.40 (m, 12H) (NCH2CH2), 3.16 (s, 2H)
(CH2), 2.76 (s, 1H) (cage CH), 1.87 (m, 6H) (NCH2CH2), 1.66 (m,
6H) (NCH2CH2), 1.31 (d, J ) 6.3 Hz, 18H) (CH3), 1.09 (d, J )
6.3 Hz, 18H) (CH3), -1.19 (br, 1H) (BHB). 13C{1H} NMR
(pyridine-d5): δ 170.7 (CN3), 147.4, 143.9, 125.8, 125.6, 123.9,
121.1 (aromatic and olefinic), 49.5, 49.0 (NCHMe2), 48.2, 46.5
(NCH2CH2), 36.8 (CH2), 25.0 (CH(CH3)2), 24.7, 23.6 (NCH2CH2),
23.2 (CH(CH3)2), the cage carbons were not observed. 11B{1H}
NMR (pyridine-d5): δ -8.3 (1B), -9.3 (1B), -12.5 (1B), -15.4
(2B), -18.8 (1B), -20.7 (1B), -32.0 (1B), -35.8 (1B). IR (KBr,
cm-1): VB-H 2520 (vs). Anal. Calcd for C44H84B9N9Ti (8a′′): C,
59.76; H, 9.57; N, 14.25. Found: C, 58.99; H, 9.39; N, 13.61.
Preparation of [σ:η5-(C9H6)C2B9H10]Zr(NMe2)(Py)2 (5b′). A
pyridine solution (5 mL) of 3b (236 mg, 0.5 mmol) was stirred at
room temperature for 6 h. The resulting deep red solution was
concentrated to ca. 2 mL, to which was added n-hexane (5 mL).
The red precipitate was collected by filtration and dried in vacuum
Preparation of [{η2-(PriN)2C(NMe2)}3Zr][(C9H7)C2B9H11]
(8b). This complex was prepared as pale yellow crystals from 3b
(236 mg, 0.5 mmol) and 7 (342 mg, 2.0 mmol) in THF (10 mL)
using the identical procedures reported for 8a′′: yield 335 mg (79%).
1H NMR (pyridine-d5): δ 8.18 (d, J ) 7.2 Hz, 1H), 7.34 (m, 2H),
7.17 (d, J ) 7.2 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic), 3.60
(m, 6H) (NCHMe2), 3.17 (s, 2H) (CH2), 2.75 (s, 1H) (cage CH),
2.72 (s, 18H) (N(CH3)2), 1.24 (d, J ) 6.6 Hz, 18H) (CH3), 1.04 (d,
J ) 6.3 Hz, 18H) (CH3), -1.27 (br, 1H) (BHB). 13C{1H} NMR
(pyridine-d5): δ 173.5 (CN3), 148.7, 147.4, 143.9, 125.8, 125.6,
123.9, 121.1 (aromatic and olefinic), 47.0 (NCHMe2), 39.1
(N(CH3)2), 36.8 (CH2), 25.2, 24.3 (CH3), the cage carbons were
not observed. 11B{1H} NMR (pyridine-d5): δ -8.5 (1B), -9.3 (1B),
-12.5 (1B), -15.5 (1B), -16.1, (1B), -18.9 (1B), -20.8 (1B),
-32.1 (1B), -35.9 (1B). IR (KBr, cm-1): VB-H 2520 (vs). Anal.
Calcd for C38H78B9N9Zr (8b): C, 53.72; H, 9.25; N, 14.84. Found:
C, 54.24; H, 9.29; N, 14.56.
1
for 1 h to afford 5b′ as a red powder (232 mg, 86%). H NMR
(pyridine-d5): δ 8.71 (m, 4H), 7.56 (m, 2H), 7.19 (m, 4H) (pyridine),
7.51 (d, J ) 7.2 Hz, 1H), 7.23 (d, J ) 7.2 Hz, 1H), 6.80 (t, J ) 7.2
Hz, 1H), 6.58 (t, J ) 7.2 Hz, 1H) (aromatic), 6.42 (d, J ) 4.2 Hz,
1H), 6.07 (d, J ) 4.2 Hz, 1H) (olefinic), 3.11 (s, 6H) (N(CH3)2).
13C{1H} NMR (pyridine-d5): δ 149.6, 135.3, 123.3 (pyridine),
140.8, 139.1, 128.7, 128.0, 120.1, 119.6, 119.4 110.1 (aromatic and
olefinic), 85.5 (cage C), 84.8 (Zr-C), 58.3 (cage C), 42.6 (N(CH3)2).
11B{1H} NMR (pyridine-d5): δ 4.0 (2B), -4.5 (2B), -6.0 (2B),
-14.3 (3B). IR (KBr, cm-1): VB-H 2528 (vs). Anal. Calcd for
C23H32B9N3Zr (5b′): C, 51.25; H, 5.98; N, 7.80. Found: C, 51.66;
H, 6.53; N, 7.73.
Preparation of [σ:η5-(C9H6)C2B9H10]Zr(NMe2)(THF)2 ·
THF (5b′′ · THF). This complex was prepared as orange-red
crystals from 2b (240 mg, 0.5 mmol) and THF (2 mL) using the
identical procedures reported for 5b: yield 107 mg (36%). 1H NMR
(pyridine-d5): δ 7.50 (d, J ) 7.5 Hz, 1H), 7.20 (d, J ) 7.5 Hz,
1H), 6.79 (t, J ) 7.5 Hz, 1H), 6.58 (t, J ) 7.5 Hz, 1H) (aromatic),
6.41 (d, J ) 4.5 Hz, 1H), 6.06 (d, J ) 4.5 Hz, 1H) (olefinic), 3.64
(m, 8H) (THF), 3.10 (s, 6H) (N(CH3)2), 1.60 (m, 8H) (THF).
13C{1H} NMR (pyridine-d5): δ 140.9, 139.1, 128.7, 125.8, 120.1,
119.6, 119.5, 110.1 (aromatic and olefinic), 85.6 (cage C), 84.9
(Zr-C), 67.2 (THF), 58.3 (cage C), 42.6 (N(CH3)2), 25.1 (THF).
11B{1H} NMR (pyridine-d5): δ 4.3 (2B), -4.3 (2B), -6.0 (2B),
-14.1 (3B). IR (KBr, cm-1): VB-H 2526 (vs). Anal. Calcd for
C19H34B9NO1.5Zr (5b′′ - 0.5THF): C, 46.67; H, 7.01; N, 2.86.
Found: C, 46.19; H, 6.99; N, 2.49.
Alternate Method. This complex was also prepared from 5b
(235 mg, 0.5 mmol) and 7 (257 mg, 1.5 mmol), or 9 (276 mg, 0.5
mmol) and 7 (172 mg, 1.0 mmol), or 10 (339 mg, 0.5 mmol) and
7 (86 mg, 0.5 mmol) in refluxing THF (10 mL). Complex 8b was
collected as pale yellow crystals after workup in 33% (140 mg), or
57% (242 mg), or 73% (310 mg) yield, respectively.
Preparation of [{η2-(PriN)2C(NEt2)}3Zr][(C9H7)C2B9H11]
(8b′). This complex was prepared as pale yellow crystals from 3b
(236 mg, 0.5 mmol) and 7′ (398 mg, 2.0 mmol) in THF (10 mL)
using the identical procedures reported for 8a′′: yield 387 mg (83%).
1H NMR (pyridine-d5): δ 8.20 (d, J ) 7.2 Hz, 1H), 7.34 (m, 2H),
7.15 (d, J ) 7.2 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic), 3.53
(m, 6H) (NCHMe2), 3.16 (s, 2H) (CH2), 3.15 (q, J ) 6.9 Hz, 6H)
(CH2CH3), 2.94 (q, J ) 6.9 Hz, 6H) (CH2CH3), 2.74 (s, 1H) (cage
CH), 1.29 (d, J ) 6.0 Hz, 18H) (CH3), 1.08 (d, J ) 6.3 Hz, 18H)
(CH3), 1.01 (t, J ) 6.9 Hz, 18H) (CH2CH3), -1.09 (br, 1H) (BHB).
13C{1H} NMR (pyridine-d5): δ 175.2 (CN3), 147.4, 143.9, 125.8,
125.6, 123.9, 121.1 (aromatic and olefinic), 47.6, 47.4 (NCHMe2),
41.7, 39.2 (CH2CH3), 36.8 (CH2), 25.0, 24.2 (CH(CH3)2), 13.0
(CH2CH3), the cage carbons were not observed. 11B{1H} NMR
(pyridine-d5): δ -8.5 (1B), -9.4 (1B), -12.7 (1B), -15.6 (1B),
-16.1, (1B), -18.9 (1B), -20.9 (1B), -32.1 (1B), -35.8 (1B).
IR (KBr, cm-1): VB-H 2522 (vs). Anal. Calcd for C44H90B9N9Zr
(8b′): C, 56.60; H, 9.71; N, 13.50. Found: C, 56.75; H, 9.29; N,
13.24.
Alternate Method. A suspension of 5b (235 mg, 0.5 mmol) in
THF (5 mL) was heated to reflux for 4 h. Removal of the volatile
chemicals afforded an orange solid identified as 5b′′ (262 mg, 99%).
Preparation of [{η5-(C9H7)C2B9H10}Hf(NMe2)(µ:η1-OCH2-
CH2OCH3)]2 · 2THF (6 · 2THF). A DME solution (10 mL) of 3c
(279 mg, 0.5 mmol) stood at room temperature for 5 days to give
6 · 2THF as orange crystals (37 mg, 12%). 1H NMR (pyridine-d5):
δ 8.17 (d, J ) 7.5 Hz, 2H), 7.33 (t, J ) 7.5 Hz, 2H), 7.26 (t, J )
7.5 Hz, 2H), 7.15 (d, J ) 7.5 Hz, 2H) (aromatic), 6.41 (s, 2H)
(olefinic), 3.63 (m, 8H) (THF), 3.49 (s, 6H) (OCH3), 3.25 (s, 12H)
(N(CH3)2), 3.24 (s, 4H) (CH2), 3.17 (m, 4H) (OCH2), 3.06 (m, 4H)

Group 4 Metal Complexes from 1-Indenyl-1,2-carborane
Organometallics, Vol. 27, No. 6, 2008 1167
Table 3. Crystal Data and Summary of Data Collection and Refinement for 3b, 3c, 5a, 5b′′ · THF and 6 · 2THF
3b
3c
5a
5b” · THF
6 · 2THF
formula
cryst size (mm)
fw
cryst syst
space group
a, Å
C17H36B9N3Zr
0.50 × 0.40 × 0.20
471.00
monoclinic
P21/n
15.196(3)
9.917(2)
16.573(3)
90
107.43(3)
90
2382.9(8)
4
1.313
Mo KR (0.71073)
3.2 to 50.0
0.471
C17H36B9HfN3
0.50 × 0.40 × 0.30
558.27
monoclinic
P21/c
15.551(3)
10.170(2)
19.253(4)
90
122.79(3)
90
2559.9(9)
4
1.449
Mo KR (0.71073)
4.7 to 50.0
4.084
C17H32B9NO2Ti
0.40 × 0.40 × 0.30
427.63
monoclinic
P21/c
9.786(1)
13.942(1)
17.754(1)
90
105.44(1)
90
2335.0(3)
4
1.216
Mo KR (0.71073)
3.8 to 54.0
0.380
C25H46B9NO3Zr
0.30 × 0.20 × 0.10
597.14
C40H76B18Hf2N2O6
0.40 × 0.30 × 0.20
1232.59
monoclinic
P21/n
9.448(1)
14.743(2)
18.820(2)
90
97.71(1)
90
2597.7(5)
2
triclinic
j
P1
9.487(2)
13.100(3)
13.729(3)
94.24(3)
105.41(3)
108.92(3)
1531.7(5)
2
b, Å
c, Å
R, deg
ꢀ, deg
γ, deg
V, Å3
Z
Dcalcd, Mg/m3
radiation (λ), Å
2θ range, deg
µ, mm-1
F(000)
1.295
1.576
Mo KR (0.71073)
4.2 to 50.0
0.387
Mo KR (0.71073)
3.5 to 52.0
4.039
976
1104
896
624
1224
no. of obsd reflns
no. of params refnd
goodness of fit
R1
3767
272
1.067
0.046
4382
271
1.120
0.083
5088
271
0.939
0.060
5395
352
1.068
0.065
5124
307
1.100
0.033
wR2
0.130
0.208
0.149
0.166
0.072
Table 4. Crystal Data and Summary of Data Collection and Refinement for 8b, 8b′′, 8c′′, 9 · 0.5C7H8, and 14 · THF
8b
8b′′
8c′′
9 · 0.5C7H8
14 · THF
formula
cryst size (mm)
fw
cryst syst
space group
a, Å
C38H78B9N9Zr
0.30 × 0.20 × 0.20
849.60
orthorhombic
Pnna
17.773(2)
22.528(3)
12.737(1)
90
90
90
5100(1)
4
1.107
C44H84B9N9Zr
0.30 × 0.20 × 0.10
927.71
orthorhombic
Pnna
17.786(1)
22.652(2)
13.190(1)
90
90
90
5313.8(7)
4
1.160
C44H84B9HfN9
0.30 × 0.20 × 0.10
1014.98
orthorhombic
Pnna
17.749(1)
22.514(2)
13.119(1)
90
90
90
5242.2(7)
4
1.286
C
25.5H47B9N4Zr
C39H56B9NO4Zr
0.30 × 0.20 × 0.10
791.36
0.50 × 0.40 × 0.30
598.18
triclinic
triclinic
j
j
P1
P1
10.156(2)
10.811(2)
16.456(2)
78.11(1)
73.68(1)
69.56(1)
1613.1(4)
2
9.627(1)
11.510(1)
18.669(2)
86.48(1)
86.61(1)
81.02(1)
2036.8(3)
2
b, Å
c, Å
R, deg
ꢀ, deg
γ, deg
V, Å3
Z
Dcalcd, Mg/m3
radiation (λ), Å
2θ range, deg
µ, mm-1
F(000)
1.232
1.290
Mo KR (0.71073)
3.6 to 50.0
0.250
Mo KR (0.71073)
3.6 to 55.7
0.246
Mo KR (0.71073)
3.6 to 55.7
2.029
Mo KR (0.71073)
2.6 to 50.0
0.363
Mo KR (0.71073)
2.2 to 50.0
0.311
1816
1984
2112
626
828
no. of obsd reflns
no. of params refnd
goodness of fit
R1
4500
287
1.088
0.062
6314
318
0.997
0.066
6245
318
1.042
0.041
5646
370
1.043
0.046
7154
487
1.017
0.062
wR2
0.172
0.201
0.117
0.116
0.137
Alternate Method. This complex was also prepared from 5b
(235 mg, 0.5 mmol) and 7′ (300 mg, 1.5 mmol) in refluxing THF.
Complex 8b′ was collected as pale yellow crystals (205 mg, 44%).
Preparation of [{η2-(PriN)2C-N(CH2)4}3Zr][(C9H7)C2B9-
H11] (8b′′). This complex was prepared as pale yellow crystals from
3b (236 mg, 0.5 mmol) and 7′′ (394 mg, 2.0 mmol) in THF (10
mL) using the identical procedures reported for 8a′′: yield 417 mg
Alternate Method. This complex was also prepared from 5b
(235 mg, 0.5 mmol) and 7′′ (297 mg, 1.5 mmol) in refluxing THF.
Complex 8b′′ was collected as pale yellow crystals (278 mg, 60%).
Preparation of [{η2-(PriN)2C(NEt2)}3Hf][(C9H7)C2B9H11]
(8c′). This complex was prepared as pale yellow crystals from 3c
(279 mg, 0.5 mmol) and 7′ (398 mg, 2.0 mmol) in THF (10 mL)
using the identical procedures reported for 8a′′: yield 444 mg (87%).
1H NMR (pyridine-d5): δ 8.21 (d, J ) 7.2 Hz, 1H), 7.34 (m, 2H),
7.15 (d, J ) 7.2 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic), 3.73
(m, 6H) (NCHMe2), 3.19 (q, J ) 6.9 Hz, 6H) (CH2CH3), 3.16 (s,
2H) (CH2), 2.96 (q, J ) 6.9 Hz, 6H) (CH2CH3), 2.77 (s, 1H) (cage
CH), 1.26 (d, J ) 5.4 Hz, 18H) (CH3), 1.06 (d, J ) 6.3 Hz, 18H)
(CH3), 1.01 (t, J ) 6.9 Hz, 18H) (CH2CH3), -1.10 (br, 1H) (BHB).
13C{1H} NMR (pyridine-d5): δ 174.3 (CN3), 147.4, 143.9, 125.8,
125.7, 123.9, 121.1 (aromatic and olefinic), 49.2, 49.1 (NCHMe2),
41.6, 39.2 (CH2CH3), 36.8 (CH2), 25.0, 24.1 (CH(CH3)2), 13.1
(CH2CH3), the cage carbons were not observed. 11B{1H} NMR
(pyridine-d5): δ -8.3 (1B), -9.2 (1B), -12.4 (1B), -15.3 (2B),
-18.7 (1B), -20.6 (1B), -32.0 (1B), -35.6 (1B). IR (KBr, cm-1):
1
(90%). H NMR (pyridine-d5): δ 8.19 (d, J ) 7.2 Hz, 1H), 7.35
(m, 2H), 7.16 (d, J ) 7.2 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic),
3.65 (m, 6H) (NCHMe2), 3.36 (m, 6H) (NCH2), 3.17 (s, 2H) (CH2),
3.10 (m, 6H) (NCH2), 2.74 (s, 1H) (cage CH), 1.88 (br, 6H)
(NCH2CH2), 1.63 (br, 6H) (NCH2CH2), 1.28 (d, J ) 6.3 Hz, 18H)
(CH3), 1.04 (d, J ) 6.0 Hz, 18H) (CH3), -1.24 (br, 1H) (BHB).
13C{1H} NMR (pyridine-d5): δ 169.5 (CN3), 147.4, 143.9, 125.8,
125.6, 123.9, 121.1 (aromatic and olefinic), 49.4 (NCHMe2), 46.8
(NCH2CH2), 46.5 (NCHMe2), 39.0 (NCH2CH2), 36.8 (CH2), 25.3
(NCH2CH2), 25.1 (CH(CH3)2), 25.0 (NCH2CH2), 23.7 (CH(CH3)2),
the cage carbons were not observed. 11B{1H} NMR (pyridine-d5):
δ -8.4 (1B), -9.4 (1B), -12.5 (1B), -15.6 (2B), -19.0 (1B),
-20.9 (1B), -32.1 (1B), -35.9 (1B). IR (KBr, cm-1): VB-H 2522
(vs). Anal. Calcd for C44H84B9N9Zr (8b′′): C, 56.97; H, 9.13; N,
13.59. Found: C, 56.58; H, 9.26; N, 13.26.
V
B-H 2522 (vs). Anal. Calcd for C44H90B9HfN9 (8c′): C, 51.76; H,
8.88; N, 12.35. Found: C, 51.88; H, 8.99; N, 12.45.

1168 Organometallics, Vol. 27, No. 6, 2008
Shen et al.
Preparation of [{η2-(PriN)2C-N(CH2)4}3Hf][(C9H7)C2B9H11]
(8c′′). This complex was prepared as pale yellow crystals from 3c
(279 mg, 0.5 mmol) and 7′′ (394 mg, 2.0 mmol) in THF (10 mL)
using the identical procedures reported for 8a′′: yield 462 mg (91%).
1H NMR (pyridine-d5): δ 8.19 (d, J ) 7.2 Hz, 1H), 7.34 (m, 2H),
7.16 (d, J ) 7.2 Hz, 1H) (aromatic), 6.43 (s, 1H) (olefinic), 3.79
(m, 6H) (NCHMe2), 3.41 (m, 6H) (NCH2), 3.15 (s, 2H) (CH2),
3.12 (m, 6H) (NCH2), 2.76 (s, 1H) (cage CH), 1.87 (m, 6H)
(NCH2CH2), 1.62 (m, 6H) (NCH2CH2), 1.27 (d, J ) 6.3 Hz, 18H)
(CH3), 1.05 (d, J ) 5.7 Hz, 18H) (CH3), -1.19 (br, 1H) (BHB).
13C{1H} NMR (pyridine-d5): δ 168.8 (CN3), 147.4, 143.9, 125.8,
125.6, 123.9, 121.1 (aromatic and olefinic), 49.4 (NCHMe2), 46.5
(NCH2CH2), 46.3 (NCHMe2), 39.0 (NCH2CH2), 36.8 (CH2), 25.4
(NCH2CH2), 25.1 (CH(CH3)2), 24.0 (NCH2CH2), 23.8 (CH(CH3)2),
the cage carbons were not observed. 11B{1H} NMR (pyridine-d5):
δ -8.5 (1B), -9.2 (1B), -12.4 (1B), -15.5 (2B), -18.8 (1B),
-20.8 (1B), -32.0 (1B), -35.8 (1B). IR (KBr, cm-1): VB-H 2522
(vs). Anal. Calcd for C44H84B9HfN9 (8c′′): C, 52.07; H, 8.34; N,
12.42. Found: C, 51.85; H, 8.47; N, 12.43.
1H NMR (pyridine-d5): δ 8.45 (d, J ) 7.5 Hz, 1H), 7.78 (d, J )
7.5 Hz, 1H), 7.24 (m, 2H) (aromatic), 6.85 (s, 1H) (olefinic), 4.63
(m, 1H) (NCHMe2), 4.37 (m, 1H) (NCHMe2), 4.19 (m, 1H)
(NCHMe2), 3.10 (m, 1H) (NCHMe2), 2.69 (s, 6H) (N(CH3)2), 1.87
(br, 3H) (CH3), 1.42 (br, 3H) (CH3), 1.35 (d, J ) 6.0 Hz, 3H) (CH3),
1.29 (d, J ) 6.6 Hz, 3H) (CH3), 1.18 (d, J ) 6.6 Hz, 3H) (CH3),
1.06 (d, J ) 6.3 Hz, 3H) (CH3), 0.30 (br, 3H) (CH3), 0.16 (br, 3H)
(CH3). 13C{1H} NMR (pyridine-d5): δ 173.8 (CN3), 165.7 (CN2),
143.2, 138.1, 128.7, 128.0, 125.1, 121.9, 121.3, 116.3 (aromatic
and olefinic), 86.1 (Zr-C and cage C), 59.3 (cage C), 49.6, 48.9,
46.6 (N-CH), 39.6 (N(CH3)2), 39.1 (N-CH), 24.3, 23.7, 23.4, 23.0,
22.5, 22.1, 21.8, 20.6 (CH3). 11B{1H} NMR (pyridine-d5): δ 6.2
(1B), 3.1 (1B), -2.7 (1B), -5.2 (1B), -6.5 (1B), -12.9 (3B),
-16.3 (1B). IR (KBr, cm-1): VB-H 2523 (vs). These data are
identical with those reported in the literature.11
Preparation of [σ:η5-{[3-C(dCPh2)-O]C9H6}C2B9H10]Zr-
(NMe2)(THF)2 · THF (14 · THF). Complex 5b (236 mg, 0.5 mmol)
was slowly added to a THF solution (5 mL) of diphenylketene (97
mg, 0.5 mmol), and the mixture was stirred at room temperature
for 2 h. After filtration, the clear filtrate was concentrated to 2 mL.
Complex 14 · THF was obtained as yellowish-green crystals after
this solution stood at room temperature for 24 h (253 mg, 64%).
1H NMR (pyridine-d5): δ 7.87 (d, J ) 7.8 Hz, 1H), 7.50 (m, 4H),
7.34 (m, 2H), 7.14 (m, 4H), 7.03 (m, 3H) (aromatic), 6.19 (d, J )
1.8 Hz, 1H) (olefinic), 5.03 (d, J ) 1.8 Hz, 1H) (benzylic CH),
3.77 (s, 1H) (cage CH), 3.63 (m, 12H) (THF), 2.57 (s, 6H)
(N(CH3)2), 1.59 (m, 12H) (THF). 13C{1H} NMR (pyridine-d5): δ
150.6, 146.5, 143.8, 141.8, 141.6, 131.7, 131.2, 129.8, 128.6, 128.0,
127.4, 126.4, 126.2, 125.4, 125.1, 124.5, 122.3, 116.8 (aromatic
and olefinic), 67.1 (THF), 52.6 (benzylic CH), 36.8 (N(CH3)2), 25.1
(THF), the cage carbon atoms were not observed. 11B{1H} NMR
(pyridine-d5): δ 1.2 (1B), -3.5 (1B), -6.1 (4B), -15.0 (2B), -18.7
(1B). IR (KBr, cm-1): VB-H 2543 (vs). Anal. Calcd for
C31H40B9NO2Zr (14 - THF): C, 57.53; H, 6.23; N, 2.16. Found:
C, 57.52; H, 6.64; N, 1.92.
X-ray Structure Determination. All single crystals were im-
mersed in Paraton-N oil and sealed under nitrogen 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.43 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 on F2 using the SHELXTL program
package.44All hydrogen atoms except for those of the disordered anions
in 8b, 8b′′, and 8c′′ were geometrically fixed using the riding model.
Complexes 5b′′, 6, 9, and 14 showed the solvation of one THF, two
THF, half toluene, and one THF molecule, respectively. The anion
[7-C9H7-7,8-C2B9H11]- in 8b, 8b′′, and 8c′′ was positionally disordered
with 0.5:0.5 occupancies. Crystal data and details of data collection
and structure refinements are given in Tables 3 and 4. Further details
are included in the Supporting Information.
Preparation of [η5-(C9H7)C2B9H10]Zr(NMe2)[η2-(PriN)2-
C(NMe2)] · 0.5C7H8 (9 · 0.5C7H8). Diisopropylcarbodiimide (63 mg,
0.5 mmol) was slowly added to a THF solution (10 mL) of 3b
(236 mg, 0.5mmol) at room temperature, and the mixture was stirred
at room temperature for 1 h. Removal of the solvent and
recrystallization from toluene afforded 9 · 0.5C7H8 as yellow crystals
1
(18 mg, 6%). H NMR (pyridine-d5): δ 8.20 (d, J ) 7.2 Hz, 1H),
7.34 (d, J ) 7.2 Hz, 1H), 7.24 (m, 2H) (aromatic), 7.19 (m, 2.5H)
(toluene), 6.35 (s, 1H) (olefinic), 3.83 (m, 2H) (NCHMe2), 3.13 (s,
2H) (CH2), 3.03 (s, 6H) (Zr-N(CH3)2), 2.51 (s, 6H) (C-N(CH3)2),
2.20 (s, 1.5H) (toluene), 1.13 (br, 6H), 0.79 (br, 6H) (NCH(CH3)2).
13C{1H} NMR (pyridine-d5): δ 173.1 (CN3), 144.4, 143.9, 128.7,
128.0, 125.8, 125.1, 123.9 121.1 (aromatic, olefinic and toluene),
47.9 (Zr-N(CH3)2), 47.0 (NCHMe2), 39.4 (C-N(CH3)2), 36.4
(CH2), 24.1, 23.1 (NCH(CH3)2), 21.9 (toluene CH3), the cage
carbons were not observed. 11B{1H} NMR (pyridine-d5): δ 3.5 (1B),
-3.6 (1B), -6.0 (1B), -11.4 (4B), -16.0 (1B), -26.6 (1B). IR
(KBr, cm-1): VB-H 2541 (vs). Anal. Calcd for C25.5H47B9N4Zr (9
+ 0.5C7H8): C, 51.20; H, 7.92; N, 9.37. Found: C, 51.08; H, 8.17;
N, 9.02.
Preparation of [η5-(C9H7)C2B9H10]Zr[η2-(PriN)2C(NMe2)]2
(10). Diisopropylcarbodiimide (126 mg, 1.0 mmol) was added to a
THF solution (10 mL) of 3b (236 mg, 0.5 mmol), and the mixture
was stirred for 2 h at room temperature. The resulting solution was
concentrated to ca. 2 mL, to which was added n-hexane (10 mL).
Complex 10 was collected as a yellow solid after this solution stood
1
at room temperature for 2 h (305 mg, 90%). H NMR (pyridine-
d5): δ 8.41 (d, J ) 7.2 Hz, 1H), 7.37 (d, J ) 7.2 Hz, 1H), 7.23 (t,
J ) 7.2 Hz, 1H), 7.15 (t, J ) 7.2 Hz, 1H) (aromatic), 6.33 (s, 1H)
(olefinic), 3.84 (m, 4H) (Me2CHN), 3.47 (s, 1H) (cage CH), 3.20
(s, 2H) (CH2), 2.57 (s, 12H) (N(CH3)2), 1.21 (br, 24H)
(NCH(CH3)2). 13C{1H} NMR (pyridine-d5): δ 172.0 (CN3), 144.4,
144.1, 125.2, 124.8, 123.8 123.6 (aromatic and olefinic), 48.3
(NCHMe2), 39.4 (N(CH3)2), 36.4 (CH2), 23.3, 22.9 (NCH(CH3)2),
the cage carbons were not observed. 11B{1H} NMR (pyridine-d5):
δ 1.4 (1B), -6.1 (1B), -8.7 (4B), -16.3 (2B), -29.3 (1B). IR
(KBr, cm-1): VB-H 2540 (vs). These data are identical with those
reported in the literature.11
Acknowledgment. This work was supported by grants
from NSFC/RGC Joint Research Scheme (N_CUHK446/06),
and a Strategic Investments Scheme administrated by The
Chinese University of Hong Kong.
Supporting Information Available: Crystallographic data in
CIF format for 3b, 3c, 5a, 5b′′ · THF, 6 · 2THF, 8b, 8b′′, 8c′′,
9 · 0.5C7H8, and 14 · THF. This material is available free of charge
via the Internet at http://pubs.acs.org.
Preparationof[η1:σ:η5-{[2-CdNPri(NHPri)]C9H5}C2B9H10]Zr[η2-
(PriN)2C(NMe2)] (11a). A toluene suspension of 9 (276 mg, 0.5
mmol) was heated to reflux for 12 h. After filtration of the hot
solution, the resulting clear red filtrate was concentrated to ca. 3
mL, from which 11a was collected as red crystals (89 mg, 28%).
OM701108V
(44) Sheldrick, G. M. SHELXTL 5.10 for Windows NT: Structure
Determination Software Programs; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 1997.
(43) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction of Area Detector Data; University of Göttingen: Germany,1996.