Synthesis, structure, and reactivity of [σ:η1: η5-(OCH2)(Me2NCH2)C 2B9H9]Ti(NR2) (R = Me, Et)

Article abstract of DOI:10.1021/om070128q

Interaction of [Me₃NH][7,8-CH₂OCH₂-7,8- C₂B₉H₁₀] with M(NR₂)₄ gave the simple amine elimination products [η⁵-(CH ₂OCH₂)C₂B₉H₉]M(NMe ₂)₂(NHMe₂) (M = Zr (2a), Hf (2b)) or the unexpected C-O bond cleavage products [σ:η¹: η⁵-(OCH₂)(Me₂NCH₂)C ₂B₉H₉]Ti(NR₂) (R = Me (3a), Et (3b)). The higher oxophilicity of the Ti center provides the driving force for the latter reactions. It is suggested that the C-O bond cleavage is prior to the amine elimination in the formation of 3a,b. This serves as a convenient and practical method for the preparation of constrained-geometry half-sandwich metallacarboranes with two different functional sidearms. Complex 3a can undergo a clean amine exchange reaction to produce new constrained-geometry titanacarborane amides. Reactions of 3a with unsaturated molecules CyN= C=NCy, S=C=S, Xyl-N=C, PhC=N, BuⁿN=C=S, Ph₂C=C=O, and PhN=C=0 gave monoinsertion products. They, except for [σ:η¹: η⁵-(OCH₂)(Me₂NCH₂)C ₂B₉H₉]Ti[η³-CyNC(NMe ₂)NCy] (7), do not react with amines. In sharp contrast, 7 can react readily with Me₂NH to regenerate 3a and release guanidine, which leads to the discovery of new catalytic guanylation of amines. All new complexes were fully characterized by various spectroscopic techniques and elemental analyses. Most of them were further confirmed by single-crystal X-ray analyses.

Full text of DOI:10.1021/om070128q

2694
Organometallics 2007, 26, 2694-2704
Synthesis, Structure, and Reactivity of
[σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(NR2) (R ) Me, Et)
Hao Shen,† Hoi-Shan Chan,† and Zuowei Xie*,†,‡
Department of Chemistry, The Chinese UniVersity of Hong Kong, Shatin, New Territories, Hong Kong,
People’s Republic of China, and State Key Laboratory of Elemento-Organic Chemistry, Nankai UniVersity,
Tianjin, People’s Republic of China
ReceiVed February 8, 2007
Interaction of [Me3NH][7,8-CH2OCH2-7,8-C2B9H10] with M(NR2)4 gave the simple amine elimination
products [η5-(CH2OCH2)C2B9H9]M(NMe2)2(NHMe2) (M ) Zr (2a), Hf (2b)) or the unexpected C-O
bond cleavage products [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(NR2) (R ) Me (3a), Et (3b)). The higher
oxophilicity of the Ti center provides the driving force for the latter reactions. It is suggested that the
C-O bond cleavage is prior to the amine elimination in the formation of 3a,b. This serves as a convenient
and practical method for the preparation of constrained-geometry half-sandwich metallacarboranes with
two different functional sidearms. Complex 3a can undergo a clean amine exchange reaction to produce
new constrained-geometry titanacarborane amides. Reactions of 3a with unsaturated molecules CyNd
CdNCy, SdCdS, Xyl-NdC, PhCtN, BunNdCdS, Ph2CdCdO, and PhNdCdO gave monoinsertion
products. They, except for [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-CyNC(NMe2)NCy] (7), do not react
with amines. In sharp contrast, 7 can react readily with Me2NH to regenerate 3a and release guanidine,
which leads to the discovery of new catalytic guanylation of amines. All new complexes were fully
characterized by various spectroscopic techniques and elemental analyses. Most of them were further
confirmed by single-crystal X-ray analyses.
η5 π-ligand instead of the Cp unit in the hope that incorporation
of the dicarbollide fragment into the above constrained-geometry
ligand framework would provide the opportunities for studying
the effects of metal/charge combinations and metal unsaturation
on the reactivity of group 4 metal complexes.4 Several examples
of group 4 metallacarboranes bearing tethered Lewis base
functionalities have been prepared.5-7 Their neutral alkyl
derivatives can undergo C-H/C-O bond activation,5c and the
chloride/amide species are active catalysts for ethylene poly-
merization in the presence of cocatalyst MAO (methyl
aluminaoxane).5d,6a,7c
Introduction
Constrained-geometry ligands (Cp-D) containing both mono-
cyclopentadienyl (Cp) and σ-heteroatom (D) components have
attracted considerable attention.1 Group 3 and 4 metal complexes
derived from these ligands are very active catalysts for polym-
erization/copolymerization of R-olefins1,2 and catalytic addition
of amines and alkynes to carbodiimides.3 As an extension of
the structural variations in Cp-D constrained-geometry ligands,
the dicarbollide ion (C2B9H112-) is rationally employed as an
* Corresponding author. Fax: (852)26035057. Tel: (852)26096269.
E-mail: zxie@cuhk.edu.hk.
We have very recently found an unexpected reaction of [Me3-
NH][7,8-CH2OCH2-7,8-C2B9H10] with Ti(NMe2)4, which leads
to the isolation of a new constrained-geometry half-sandwich
titanacarborane amide [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti-
(NMe2) incorporating two different sidearms; one is strongly
bonded to the Ti center by taking the advantage of its high
oxophilicity, whereas the other is hemilabile in nature. Prelimi-
nary results show that this complex is a very efficient catalyst
† The Chinese University of Hong Kong.
‡ Nankai University.
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10.1021/om070128q CCC: $37.00 © 2007 American Chemical Society
Publication on Web 04/04/2007

Constrained-Geometry Half-Sandwich Metallacarboranes
Organometallics, Vol. 26, No. 10, 2007 2695
for the guanylation of amines.8 To understand the reaction
pathways and the formation of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti(NMe2) and to study the reactivity pattern of this type
of complexes toward unsaturated molecules, we have investi-
gated in detail the reaction of [Me3NH][7,8-CH2OCH2-7,8-
C2B9H10] with M(NR2)4 (M ) Ti, Zr, Hf; R ) Me, Et) and the
reactivity of the resultant constrained-geometry titanacarborane
amides toward amines, RNdCdNR, SdCdS, Xyl-NdC,
PhCtN, BunNdCdS, Ph2CdCdO, PhNdCdO, and esters.
The full account of this work is reported in this article.
Scheme 1
Results and Discussion
Reaction of 1 with M(NR2)4. µ-1,2-CH2OCH2-1,2-C2B10H10
was prepared according to a literature method9 and was
converted to [Me3NH][µ-7,8-CH2OCH2-7,8-C2B9H10] (1) in
95% yield in KOH/EtOH solution followed by treatment with
Me3NHCl. Compound 1 reacted readily with 1 equiv of
M(NMe2)4 (M ) Zr, Hf) in toluene at room temperature to give
the amine elimination10 products [η5-(CH2OCH2)C2B9H9]M-
(NMe2)2(NHMe2) (M ) Zr (2a), Hf (2b)) in almost quantitive
yields (Scheme 1). They are stable in refluxing toluene and do
not react further with another equivalent of 1.
The 1H NMR spectra of 2a,b are very similar. They showed
2
in pyridine-d5 two doublets at ∼4.1 and ∼3.6 ppm with J )
7.5 Hz assignable to the axial and equatorial protons of the
methylene units, a singlet at ∼3.1 ppm corresponding to the
two dimethylamido groups, and a singlet at ∼2.3 ppm attribut-
able to the coordinated dimethylamine. Their 13C NMR spectra
were consistent with the 1H NMR results. The 11B NMR spectra
of both 2a and 2b in pyridine-d5 exhibited a 1:1:2:2:2:1 pattern.
The compositions of 2a,b were further confirmed by elemental
analyses.
1
In the H NMR spectrum (pyridine-d5) of 3a, four doublets
Under the same reaction conditions, however, treatment of 1
with Ti(NR2)4 (R ) Me or Et) afforded a mixture of products,
which were slowly converted to a major species upon heating
at 80 °C and finally to another major product as the temperature
was increased to 110 °C according to the NMR experiments. A
suspension of 1 and Ti(NR2)4 (R ) Me or Et) in toluene was
then heated to reflux for 6 h to generate unexpected C-O bond
cleavage complexes [σ:η1:η5-(OCH2)(R2NCH2)C2B9H9]Ti(NR2)
(R ) Me (3a), Et (3b)) in very good isolated yields. This is a
convenient and practical method for the preparation of con-
strained-geometry half-sandwich metallacarboranes with two
different functional sidearms, which are introduced in a single
reaction. Many attempts to isolate the intermediate formed at
80 °C as indicated in NMR experiments failed due to its
instability. We then employed an unsaturated molecule to trap
this intermediate. Treatment of 1 with 1 equiv of Ti(NEt2)4 at
80 °C for 6 h (monitored by 11B NMR), followed by addition
of excess CS2, gave, after recrystallization from THF, the
insertion product [σ-(OCH2)(Et2NHCH2)C2B9H10]Ti(η3-S2-
CNEt2)3 (4) in 36% yield (Scheme 1).
2
at 5.50, 5.47 ppm with J ) 11.1 Hz and 3.61, 3.10 ppm with
2J ) 14.4 Hz assignable to the two sidearm CH2 units, one
singlet at 3.17 ppm corresponding to the dimethylamido protons,
and two singlets at 2.31 and 2.28 ppm attributable to the sidearm
N(CH3)2 group were observed. Its 13C NMR spectrum showed
two CH2 signals at 77.2 and 65.5 ppm and three N(CH3)2
resonances at 50.8, 50.3, and 44.1 ppm, respectively. Inequiva-
lent methyls of the sidearm amido group in the NMR spectra
clearly indicate that the tethered amine is coordinated to the Ti
metal center even in pyridine solution. The 11B NMR of 3a
exhibited a 1:1:1:1:1:1:1:1:1 pattern in the range 13 to -18 ppm.
Similar characteristics were also observed in the NMR spectra
of 3b. The 1H NMR spectrum of 4 exhibited, in addition to the
resonances of ethyl protons, a broad singlet at -2.05 ppm
corresponding to the bridging BHB proton and four doublets at
2
2
5.46, 4.86 ppm with J ) 12.0 Hz and 3.78, 3.52 ppm with J
) 14.1 Hz assignable to the two sidearm CH2 groups. A
characteristic S2CN carbon resonance at 202.8 ppm was
observed in the 13C NMR spectrum.11 Its 11B NMR displayed
a 4:3:1:1 pattern, which is significantly different from that of
3b.
Single-crystal X-ray diffraction studies confirmed that both
3a,b adopt a three-legged piano stool structure containing an
η5-dicarbollyl ligand, one amido unit, and tethered amine and
alkoxide ligands in the basal positions, as shown in Figures 1
and 2, respectively. It is very clear that a C-O bond is broken
and a new C-N bond is formed during the reaction. For easy
comparison, key structural parameters are compiled in Table
1. The average Ti-cage atom, Ti-N(sidearm), and Ti-
(8) Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25, 5515.
(9) Heying, T. L.; Ager, J. W.; Clark, S. L.; Alexander, R. P.; Papetti,
S.; Reid, J. A.; Trotz, S. I. Inorg. Chem. 1963, 2, 1097.
(10) Amine elimination reaction is a good method to prepare group 4
metal amides. For examples, see: (a) Hughes, A. K.; Meetsma, A.; Teuben,
J. H. Organometallics 1993, 12, 1936. (b) Diamond, G. M.; Rodewald, S.;
Jordan, R. F. Organometallics 1995, 14, 5. (c) Bowen, D. E.; Jordan, R.
F.; Rogers, R. D. Organometallics 1995, 14, 3630. (d) Carpenetti, D. W.;
Kloppenburg, L.; Kupec, J. T.; Petersen, J. L. Organometallics 1996, 15,
1572. (e) Wang, H.; Wang, Y.; Li, H.-W.; Xie, Z. Organometallics 2001,
20, 5110. (f) Zi, G.; Li, H.-W.; Xie, Z. Organometallics 2002, 21, 3850.
(g) Kwong, W.-C.; Chan, H.-S.; Tang, Y.; Xie, Z. Organometallics 2004,
23, 4301. (h) Wang, H.; Chan, H.-S.; Xie, Z. Organometallics 2006, 25,
2569.
(11) Wang, H.; Li, H.-W.; Xie, Z. Organometallics 2003, 22, 4522.

2696 Organometallics, Vol. 26, No. 10, 2007
Shen et al.
Full characterization of 4 helps us to understand the possible
reaction pathway for the formation of 3b, as shown in Scheme
1. Coordination of the oxygen atom in 1 to the Ti atom followed
by nucleophilic attack of the amide leads to the cleavage of the
C-O bond and the formation of a new N-C bond. Proton
exchange between Me3NH+ and the newly formed amine results
in the formation of an intermediate A. Insertion of CS2 into the
Ti-N bonds in A generates the product 4. On the other hand,
intramolecular amine elimination of A affords 3b, which is
promoted by heat. The higher oxophilicity of the Ti atom over
the Zr and Hf resulted from the size effect,13 facilitates the
breaking of the C-O bond, and leads to different pathways in
the reactions of M(NMe2)4 with 1.
Reaction of 3a with Amines. Amine exchange reaction is a
useful method for the preparation of metal amides. Complex
3a reacted readily with 1 equiv of 4-methoxyaniline or 2 equiv
of 2-amino-3-picoline in toluene at room temperature to give
[σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[NH(C6H4-4-OMe)] (5)
or [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[σ:η1-(2-NH-3-CH3-
C5H3N)][η1-C5H3N-2-NH2-3-CH3] (6) in 61% and 46% yields,
Figure 1. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti(NMe2) (3a).
1
respectively (Scheme 2). The H NMR spectra indicated the
absence of the Me2N amido groups in both 5 and 6 and
supported a molar ratio of one aniline moiety per cage in 5 and
two picoline units per cage in 6. The 11B NMR spectrum of 5
exhibited a 1:1:1:1:1:1:1:1:1 pattern, whereas a 1:1:1:2:1:1:2
pattern was observed for 6.
An X-ray analysis revealed that 6 adopts a distorted-
octahedral geometry by an η5-dicarbollyl ligand, one oxygen
and one nitrogen from the sidearms, and three nitrogens from
the two picoline units, and showed one and a half toluene of
solvation in the unit cell (Figure 4). The Ti-Narm and Ti-Oarm
distances of 2.398(3) and 1.931(2) Å in 6 are significantly longer
than those observed in its parent complex 3a (Table 1), probably
due to very crowded environments around the Ti atom in 6.
The Ti-N(4) distance of 2.026(3) Å is much shorter than the
Ti-N(5) distance of 2.212(3) Å, suggesting there is no charge
delocalization over the N(4)-C(31)-N(5) unit.
Reaction of 3a with Unsaturated Molecules. Reaction of
3a with 1 equiv of DCC (dicyclohexylcarbodiimide) in toluene
gave, after simple workup, the monoinsertion product [σ:η1:
η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-CyNC(NMe2)NCy] (7) in
82% isolated yield (quantitative NMR yield). A characteristic
CN3 resonance at 174.9 ppm was observed in the 13C NMR
spectrum of 7. The proton chemical shift of the Me2N amido
group was shifted from 3.17 ppm in 3a to 2.80 ppm in 7. Its
11B NMR displayed a 1:5:2:1 pattern, which is very different
from that of 3a.
Single-crystal X-ray analyses confirmed that DCC inserted
exclusively into the Ti-N σ-bond to form a guanidine unit, as
shown in Figure 5. The C(15)-N(2)/N(3)/N(4) distances of
1.341(3)/1.373(3)/1.362(3) Å are similar, indicating the partial
delocalization of electrons over N(2), N(3), N(4), and C(15)
atoms. This argument is supported by the planarity of N(3),
with the sum of angles of 359.9(2)°.
Treatment of 7 with Me2NH regenerated 3a with the
formation of CyNdC(NMe2)NHCy as indicated by NMR
analyses. This result suggests that 3a can catalyze hydroami-
nation of carbodiimides. This finding leads to a successful
development of a new atom-economical catalytic process for
the guanylation of amines with a very broad substrate scope of
primary, secondary, heterocyclic, aliphatic, and aromatic amines.8
The proposed catalytic cycle involves the insertion of carbo-
Figure 2. Molecular structure of [σ:η1:η5-(OCH2)(Et2NCH2)-
C2B9H9]Ti(NEt2) (3b).
N(amide) distances of 2.365(4), 2.205(3), and 1.862(3) Å in
3a and 2.376(4), 2.246(3), and 1.868(3) Å in 3b are comparable
to the corresponding values of 2.432(5), 2.240(3), and 1.895-
(4) Å in [η1:η5-(Me2NCH2)2C2B9H9]Ti(NMe2)2,6b 2.395(3),
2.196(2), and 1.886(3) Å in [η1:η5-(Pri2C6H3NdCH)C2B9H10]-
Ti(NMe2)2,5d 2.389(10), 2.128(4), and 1.911(4) Å in [η1:η5-
(Me2C6H3NdCH)C2B9H10]Ti(NMe2)2,5d 2.396(5), 2.202(3), and
1.895(4) Å in [η1:η5-(Me2N)CH(NMe2)C2B9H10]Ti(NMe2)2,5d
and 2.413(5), 2.315(3), and 1.900(4) Å in [η1:η5-(Bz2NCH2-
CH2)C2B9H10]Ti(NMe2)2.6c The Ti-O distances of 1.833(2) Å
in 3a and 1.845(2) Å in 3b are shorter than that of 1.879(7) Å
in (η5-C5Me5)Ti[σ:η5-(OCHMe)C2B9H10]12 and 1.869(2) Å in
(η5-C5Me5)[σ:η5-(OCHMe)C2B9H10]Ti(CH3CN).12
The molecular structure of 4 was also confirmed by single-
crystal X-ray analyses. It is a zwitterionic salt, in which the Ti
atom is η3-bound to each S2C-NEt2 group and σ-bound to the
O atom of the sidearm (Figure 3). As shown in Table 1, the
Ti-O distance of 1.833(2) Å in 4 is very close to the
corresponding values in 3a,b. The average Ti-S distance of
2.532(1) Å is much shorter than that of 2.642(1) Å in [η5:σ-
Me2C(C9H6)C2B10H10]Zr(η3-S2C-NMe2)2,11 probably owing to
steric reasons.
(12) Bei, X.; Kreuder, C.; Swenson, D. C.; Jordan, R. F. Organometallics
1998, 17, 1085.
(13) (a) Chandra, G.; Lappert, M. F. J. Chem. Soc. A 1968, 1940. (b)
Diamond, G. M.; Jordan, R. F. Organometallics 1996, 15, 4030.

Constrained-Geometry Half-Sandwich Metallacarboranes
Organometallics, Vol. 26, No. 10, 2007 2697
Table 1. Selected Bond Lengths (Å) and Angles (deg)
3a
3b
4
6
7
11ba
12
13
14
15
av Ti-cage atom
Ti-Oarm
2.365(4)
1.833(2)
2.205(3)
1.862(3)
2.376(4)
1.845(2)
2.246(3)
1.868(3)
2.422(4)
1.931(2)
2.398(3)
2.315(3)
2.026(3)
2.212(3)
2.418(3)
1.901(2)
2.322(2)
2.179(2)
2.028(2)
2.393(4)
1.882(2)
2.353(3)
2.062(3)
2.377(4)
1.850(2)
2.259(3)
2.288(2)
2.409(4)
1.873(2)
2.311(3)
2.089(3)
2.402(4)
1.860(2)
2.327(2)
2.383(3)
2.059(1)
2.358(2)
1.833(2)
Ti-Narm
Ti-N
Ti-O
1.896(2)
2.041(2)
2.056(2)
1.852(2)
2.040(2)
1.775(2)
Ti-S
2.532(1)b
2.492(1)
107.6(3)
103.4(3)
106.1(2)
93.1(2)
Ccage-C-Narm
Ccage-C-Oarm
Ti-Oarm-C
Ti-Narm-C
106.6(2)
103.1(2)
105.6(2)
94.3(2)
107.0(2)
102.6(3)
106.9(2)
92.9(2)
106.9(3)
103.2(3)
107.0(2)
93.7(2)
107.1(2)
103.1(2)
107.3(1)
96.0(1)
105.9(2)
102.7(2)
107.8(2)
94.9(2)
105.8(2)
101.7(2)
108.3(2)
94.2(2)
106.1(2)
103.3(2)
108.2(2)
94.9(2)
107.0(2)
103.2(2)
103.9(1)
94.8(1)
b
a Average values of two independent molecules in the unit cell. Average value of six Ti-S bonds.
Figure 3. Molecular structure of [σ-(OCH2)(Et2NHCH2)C2B9H10]-
Ti(η3-S2CNEt2)3 (4).
Figure 4. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[σ:η1-(2-NH-3-CH3-C5H3N)][η1-C5H3N-2-NH2-3-
CH3] (6) (the solvated toluene molecules are not shown).
Scheme 2
diimide into the Ti-amide bond followed by the protonation
of the resultant intermediate with amines. These interesting
results prompt us to explore the reactivity pattern of 3a (as
shown in Scheme 3) in search of new catalytic hydroaminations
of unsaturated organic molecules.
Figure 5. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[η3-CyNC(NMe2)NCy] (7).
Interaction of 3a with 1.5 equiv of CS2 in toluene at room
temperature afforded [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(η3-
S2CNMe2) (8) in 94% isolated yield. Complex 8 is insoluble in
toluene, in which 3a is soluble, which facilitates the separation.
unique 13C resonance of the S2CN unit at 201.3 ppm, which is
very close to that of 202.8 ppm in 4, 201.6 and 199.2 ppm in
[η5:σ-Me2C(C9H6)C2B10H10]Zr(η3-S2CNMe2)2,11 was also ob-
served. The 11B NMR displayed a 1:1:1:1:1:2:1:1 pattern. The
composition of 8 was further confirmed by elemental anlyses.
Reaction of 3a with 1 equiv of 2,6-xylylisonitrile in refluxing
toluene generated [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η2-
1
The H NMR spectrum in pyridine-d5 showed an upfield shift
for S2CN(CH3)2 protons and significant downfield shifts for all
sidearm protons in comparison with its parent complex 3a. A

2698 Organometallics, Vol. 26, No. 10, 2007
Shen et al.
Scheme 3
C(NMe2)dN(C6H3-2,6-Me2)] (9) in 72% isolated yield. In
addition to the sidearm and xylyl protons, two singlets at 3.38
and 2.64 ppm assignable to the NdCN(CH3)2 methyl protons
(versus one singlet of amido protons at 3.17 ppm in 3a) were
observed in the 1H NMR spectrum of 9, indicating the restricted
rotation around the C-NMe2 single bond on the NMR time
scale. This phenomenon is also observed in other metal-η2-
iminocarbamoyl complexes.14 A characteristic signal of NCd
N at 197.6 ppm was found in the 13C NMR spectrum of 9. Its
11B NMR exhibited a 1:2:2:2:2 pattern. The composition was
further confirmed by elemental analyses.
Treatment of 3a with 1 equiv of benzonitrile in refluxing
toluene afforded [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[Nd
C(NMe2)Ph] (10) in 92% isolated yield. In the 1H NMR
spectrum, the insertion of PhCN into the Ti-NMe2 bond was
found to result in a downfield shift of all sidearm protons and
an upfield shift of amido protons compared to those of 3a. The
13C chemical shift of the CN2 unique carbon was observed at
156.3 ppm, which is very close to that of 157.5 and 156.1 ppm
observed in [η5:σ-Me2C(C9H6)C2B10H10]Zr[NdC(Ph)NMe2]2.11
The 11B NMR showed a 1:1:1:1:1:1:1:1:1 pattern. Many
attempts to grow single crystals failed.
An equimolar reaction of 3 with n-butyl isothiocyanate in
refluxing toluene gave [σ:η1:η5-(OCH2)(R2NCH2)C2B9H9]Ti-
[η3-SC(NR2)NBun] (R ) Me (11a), R ) Et (11b)) in 76-82%
isolated yields. The 1H NMR spectra of 11a,b showed an upfield
shift for the amido protons of the NC(NR2)S unit and a
downfield shift for sidearm protons in comparison with those
of 3a,b. Unique 13C resonances at 174.7 ppm in 11a and 171.2
ppm in 11b were observed. The 11B NMR spectra exhibited a
1:1:1:1:1:1:1:2 pattern for both 11a and 11b.
dent molecules in the unit cell. The representative one is shown
in Figure 6. The C(21)-N(2)/N(3) distances of 1.329(5)/1.349-
(4) Å and planarity of N(3) with a sum of angles of 359.5(3)°
suggest the electron delocalization over the NC(NEt2)S frag-
ment.
Insertion of the CdC or CdO bond of a ketene into the Ti-O
or M-N bond has been documented.15 It is interesting to know
how a ketene reacts with 3a, as it contains both Ti-O and Ti-N
bonds. Reaction of 3a with 1 equiv of diphenylketene in
refluxing toluene produced [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]-
Ti[σ:η1-OC(NMe2)dCPh2] (12) in 84% isolated yield. Complex
12 showed no reactivity toward ketene. It was fully characterized
by various spectroscopic techniques and elemental analyses.
Single-crystal X-ray analyses revealed that the Ti center in
12 is coordinated by two N and two O atoms and an
η5-dicarbollyl ligand in a four-legged piano stool geometry, as
shown in Figure 7. This result confirms the insertion of the Cd
O bond into the Ti-N bond and inertness of the Ti-O bond
toward the CdC bond of the ketene, probably due to steric
reasons. Steric factors may also dominate the migration of the
NMe2 unit, leading to the trans arrangement of two amido
groups. The C(15)-C(18) distance of 1.338(4) Å suggests a
double bond. The Ti-O(2) distance of 1.896(2) Å is comparable
to the Ti-O(1) distance of 1.850(2) Å. The Ti-N(1) distance
of 2.259(3) Å is close to the Ti-N(2) distance of 2.288(2) Å.
It has been reported that PhNCO can insert into either a Ti-N
or Ti-O bond.16 Reaction of 3a with PhNCO afforded
exclusively [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-OC(NMe2)-
NPh] (13) in 84% isolated yield. The Ti-O bond in 3a remains
intact. As shown in Figure 8, the arrangment of the two N and
The molecular structure of 11b was further confirmed by
single-crystal X-ray analyses, revealing there are two indepen-
(15) For examples, see: (a) Vuitel, L.; Jacot-Guillarmod, A. Synthesis
1972, 11, 608. (b) Blandy, C.; Gervais, D. Inorg. Chim. Acta 1981, 47,
197. (c) Ando, F.; Kohmura, Y.; Koketsu, J. Bull. Chem. Soc. Jpn. 1987,
69, 1564. (d) Liu, R.; Zhang, C.; Zhu, Z.; Luo, J.; Zhou, X.; Weng, L.
Chem.-Eur. J. 2006, 12, 6940.
(16) For examples, see: (a) Wang, H.; Chan, H.-S.; Okuda, J.; Xie, Z.
Organometallics 2005, 24, 3118. (b) Patten, T. E.; Novak, B. M.
Macromolecules 1993, 26, 436. (c) Ghosh, R.; Nethaji, M.; Samuelson, A.
G. J. Organomet. Chem. 2005, 690, 1282.
(14) (a) Amor, F.; Sa´nchez-Nieves, J.; Royo, P.; Jacobsen, H.; Blacque,
O.; Berke, H.; Lanfranchi, M.; Pellinghelli, M. A.; Tiripicchio, A. Eur. J.
Inorg. Chem. 2002, 11, 2810. (b) Martins, A. M.; Ascenso, J. R.; de
Azevedo, C. G.; Dias, A. R.; Duarte, M. T.; da Silva, J. F.; Veiros, L. F.;
Rodrigues, S. S. Organometallics 2003, 22, 4218. (c) Wang, H.; Wang,
Y.; Chan, H.-S.; Xie, Z. Inorg. Chem. 2006, 45, 5675.

Constrained-Geometry Half-Sandwich Metallacarboranes
Organometallics, Vol. 26, No. 10, 2007 2699
Figure 6. Molecular structure of [σ:η1:η5-(OCH2)(Et2NCH2)-
C2B9H9]Ti[η3-SC(NEt2)NBun] (11b).
Figure 9. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[σ:η1-OCH(Ph)N(Ph)C(NMe2)dO] (14).
Scheme 4
Figure 7. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[σ:η1-OC(NMe2)dCPh2] (12).
reacted readily with benzaldehyde, leading to the isolation of
[σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[σ:η1-OCH(Ph)N(Ph)C-
(NMe2)dO] (14) in 72% yield. Complex 14 was fully charac-
terized by various spectroscopic techniques and elemental
analyses. Single-crystal X-ray analyses confirmed that PhCHd
O inserted into the Ti-N bond in 13 to form a six-membered
metallacycle as shown in Figure 9. The significant differences
in the Ti-O(2)/O(3) and C-O distances suggest that O(2) is
an oxide and O(3) is an oxo.
Stoichoimetric reactions of 3b with methyl esters such as
methyl methacrylate (MMA), methyl propiolate, or dimethyl
acetylenedicarboxylate afforded the same dimeric complex [{σ:
η1:η5-(µ-OCH2)(Et2NCH2)C2B9H9}Ti(OMe)]2 (15) in ca. 80%
isolated yield. It is suggested that high oxophilicity of the Ti
atom is the driving force of these reactions. The formation of
HCtCCONEt2 was confirmed by NMR and GC-MS analyses.
Accordingly, a possible reaction pathway is proposed and shown
in Scheme 4.
Figure 8. Molecular structure of [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[η3-OC(NMe2)NPh] (13).
two O atoms is similar to that observed in 12. Two amido
fragments are in trans positions to avoid steric repulsion.
Different from other group 4 metal amide complexes,11,16 13
showed no reactivity toward PhNCO. On the other hand, 13

2700 Organometallics, Vol. 26, No. 10, 2007
Shen et al.
toward various amines. In sharp contrast, 7 can react readily
with Me2NH to regenerate 3a and release guanidine, which leads
to the discovery of a new catalytic guanylation of amines.8
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. All organic solvents were freshly distilled from sodium
benzophenone ketyl immediately prior to use. µ-1,2-CH2OCH2-
9
1,2-C2B10H10 and diphenylketene18 were prepared according to
literature methods. All 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
1
on a Perkin-Elmer 1600 Fourier transform spectrometer. H and
13C NMR spectra were recorded on a Bruker DPX 300 spectrometer
at 300.0 and 75.5 MHz, respectively. 11B NMR spectra were
recorded on a Varian Inova 400 spectrometer 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.
Figure 10. Molecular structure of [{σ:η1:η5-(µ-OCH2)(Et2NCH2)-
C2B9H9}Ti(OMe)]2 (15) (the solvated toluene molecule is not
shown).
A unique singlet at 4.39 ppm of OCH3 protons was observed
1
in the H NMR spectrum of 15, in addition to the sidearm
protons. The 11B NMR spectrum exhibited nine peaks. An X-ray
analysis revealed that 15 is a centrosymmetric dimer and showed
one toluene of solvation. Each Ti atom is σ-bound to a terminal
methoxyl group and two doubly bridging sidearm O atoms, η5-
bound to a dicarbollyl ligand and η1-bound to the N atom of
the sidearm in a typical four-legged piano stool geometry (Figure
10). The significantly short Ti-O(2) distance of 1.775(2) Å
and a large C(17)-O(2)-Ti angle of 152.6(2)° indicate the
presence of O(pπ)fTi(dπ) interactions.11,17
Preparation of [Me3NH][µ-7,8-CH2OCH2-7,8-C2B9H10] (1).
Compound µ-1,2-CH2OCH2-1,2-C2B10H10 (1.86 g, 10.0 mmol) was
dissolved in ethanol (50 mL), to which was added KOH (2.80 g,
50.0 mmol). The mixture was heated to reflux overnight. After
removal of the solvent, the residue was dissolved in water (20 mL).
Addition of Me3NHCl (5.70 g, 60.0 mmol) afforded a white
precipitate. Compound 1 was collected by suction filtration, washed
with water, and dried under vacuum (2.23 g, 95%). 1H NMR
(acetone-d6): δ 3.89 (d, J ) 7.8 Hz, 2H) (CHH), 3.61 (d, J ) 7.8
Hz, 2H) (CHH), 3.22 (s, 9H) (CH3), -2.65 (brs, 1H) (BHB). 13C-
{1H} NMR (acetone-d6): δ 73.9 (CH2), 46.4 (CH3), the cage carbon
atoms were not observed. 11B{1H} NMR (acetone-d6): δ -11.4
(2B), -14.1 (2B), -18.4 (3B), -30.6 (1B), -35.1 (1B). IR (KBr,
cm-1): ν 2527 (vs) (B-H). Anal. Calcd for C7H24B9NO (1): C,
35.69; H, 10.27; N, 5.95. Found: C, 35.27; H, 10.09; N, 5.70.
Preparation of [η5-(CH2OCH2)C2B9H9]Zr(NMe2)2(NHMe2)
(2a). To a toluene (10 mL) solution of Zr(NMe2)4 (133 mg, 0.5
mmol) was added 1 (118 mg, 0.5 mmol), and the mixture was stirred
at room temperature for 12 h. Removal of the solvent afforded 2a
The above results clearly show that a range of unsaturated
molecules can insert exclusively into the Ti-N bond in 3 to
form the corresponding insertion products (Scheme 3). Unfor-
tunately, all these products (8-13) with the exception of 7 do
not show any reactivity toward amines under various reaction
conditions, even refluxing toluene.
Conclusion
Reaction of M(NMe2)4 with [Me3NH][7,8-CH2OCH2-7,8-
C2B9H10] generated simple amine elimination products [η5-(CH2-
OCH2)C2B9H9]M(NMe2)2(NHMe2) (2) for M ) Zr and Hf or
unexpected C-O bond cleavage complexes [σ:η1:η5-(OCH2)(R2-
NCH2)C2B9H9]Ti(NR2) (R ) Me (3a), Et (3b)). The latter is a
convenient and practical method for the preparation of con-
strained-geometry half-sandwich metallacarboranes with two
different functional sidearms. It is believed that the C-O bond
is broken prior to the formation of the Ti-η5-dicarbollyl bond
after the full characterization of [σ-(OCH2)(Et2NHCH2)-
C2B9H10]Ti(η3-S2CNEt2)3 (4). The higher oxophilicity of the
Ti center provides the driving force for this reaction.
Amine exchange reaction of 3a with amines (R′R′′NH)
afforded new constrained-geometry titanacarborane amides
[σ:η1:η5-(OCH2)(R2NCH2)C2B9H9]Ti(NR′R′′). A variety of
unsaturated molecules such as carbodiimides, carbon disulfide,
isonitrile, nitrile, isothiocyanate, ketene, and isocyanate can
insert exclusively into the Ti-amide bond in 3 to give
monoinsertion products. The Ti-O bond remains intact. These
insertion products, except for [σ:η1:η5-(OCH2)(Me2NCH2)-
C2B9H9]Ti[η3-CyNC(NMe2)NCy] (7), show no reactivities
1
as a pale yellow pure solid (195 mg, 98%). H NMR (pyridine-
d5): δ 4.09 (d, J ) 7.5 Hz, 2H) (CHH), 3.62 (d, J ) 7.5 Hz, 2H)
(CHH), 3.06 (s, 12H) (N(CH3)2); 2.34 (s, 6H) (HN(CH3)2). 1H NMR
(benzene-d6): δ 3.95 (d, J ) 8.4 Hz, 2H) (CHH), 3.51 (d, J ) 8.4
Hz, 2H) (CHH), 2.71 (s, 12H) (N(CH3)2); 2.00 (d, J ) 6.0 Hz,
6H) (HN(CH3)2). 13C{1H} NMR (pyridine-d5): δ 74.3 (CH2), 44.3
(N(CH3)2), 38.6 (HN(CH3)2), the cage carbon atoms were not
observed. 13C{1H} NMR (benzene-d6): δ 77.4 (CH2), 44.2 (N(CH3)2),
40.6 (HN(CH3)2), the cage carbon atoms were not observed. 11B-
{1H} NMR (pyridine-d5): δ 1.2 (1B), -8.9 (1B), -11.9 (2B),
-14.3 (2B), -16.2 (2B), -33.4 (1B). 11B{1H} NMR (benzene-
d6): δ 0.9 (1B), -5.5 (5B), -18.3 (2B), -20.1 (1B). IR (KBr,
cm-1): ν 2535 (vs) (B-H). Anal. Calcd for C8H25B9N2OZr (2a -
HNMe2): C, 27.16; H, 7.12; N, 7.92. Found: C, 26.93; H, 6.98;
N, 7.56.
Preparation of [η5-(CH2OCH2)C2B9H9]Hf(NMe2)2(NHMe2)
(2b). This complex was prepared as a pale yellow solid from Hf-
(NMe2)4 (177 mg, 0.5 mmol) and 1 (118 mg, 0.5 mmol) in toluene
(10 mL) using the identical procedures reported for 2a (235 mg,
97%). 1H NMR (pyridine-d5): δ 4.10 (d, J ) 7.8 Hz, 2H) (CHH),
3.57 (d, J ) 7.8 Hz, 2H) (CHH), 3.08 (s, 12H) (N(CH3)2); 2.36 (s,
(17) McGeary, M. J.; Coan, P. S.; Folting, K.; Streib, W. E.; Caulton,
K. G. Inorg. Chem. 1989, 28, 3283.
(18) Taylor, E. C.; McKillop, A.; Hawks, G. H. Org. Synth. 1972, 52,
36.

Constrained-Geometry Half-Sandwich Metallacarboranes
Organometallics, Vol. 26, No. 10, 2007 2701
1
6H) (HN(CH3)2). H NMR (benzene-d6): δ 3.97 (d, J ) 8.4 Hz,
-15.2 (1B), -18.6 (1B). 11B{1H} NMR (benzene-d6): δ 11.0 (1B),
2.4 (1B), 1.0 (1B), -2.2 (1B), -3.5 (1B), -9.9 (2B), -15.2 (1B),
-17.3 (1B). IR (KBr, cm-1): ν 2531 (vs) (B-H). Anal. Calcd for
C12H33B9N2OTi (3b): C, 39.32; H, 9.07; N, 7.64. Found: C, 39.80;
H, 9.12; N, 7.50.
2H) (CHH), 3.56 (d, J ) 8.4 Hz, 2H) (CHH), 2.76 (s, 12H)
(N(CH3)2); 2.03 (d, J ) 6.0 Hz, 6H) (HN(CH3)2). 13C{1H} NMR
(pyridine-d5): δ 74.1 (CH2), 43.9 (N(CH3)2), 38.1 (HN(CH3)2), the
cage carbon atoms were not observed. 13C{1H} NMR (benzene-
d6): δ 77.2 (CH2), 44.0 (N(CH3)2), 40.6 (HN(CH3)2), the cage
carbon atoms were not observed. 11B{1H} NMR (pyridine-d5): δ
1.5 (1B), -11.4 (1B), -13.1 (2B), -14.4 (2B), -16.7 (2B), -35.3
(1B). 11B{1H} NMR (benzene-d6): δ 0.5 (1B), -4.0 (1B), -5.8
(4B), -18.3 (2B), -20.7 (1B). IR (KBr, cm-1): ν 2547 (vs) (B-
H). Anal. Calcd for C8H25B9HfN2O (2b - HNMe2): C, 21.78; H,
5.71; N, 6.35. Found: C, 22.14; H, 6.02; N, 6.27.
Preparation of [σ-(OCH2)(Et2NHCH2)C2B9H10]Ti(η3-S2CNEt2)3
(4). To a toluene (10 mL) solution of Ti(NEt2)4 (168 mg, 0.5 mmol)
was added 1 (118 mg, 0.5 mmol), and the suspension was heated
to 70-80 °C for 6 h. After the reaction mixture was cooled to
ambient temperature, CS2 (152 mg, 2.0 mmol) was added. The
mixture was then stirred at room temperature for 12 h. The yellow
precipitate was collected by filtration. Recrystallization from THF
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(NMe2)
(3a). To a toluene (40 mL) solution of Ti(NMe2)4 (1.12 g, 5.0 mmol)
was added 1 (1.18 g, 5.0 mmol), and the suspension was heated to
reflux for 6 h until a clear red solution was obtained. After filtration,
the clear filtrate was concentrated to ca. 5 mL. Complex 3a was
isolated as orange crystals after this solution stood at room
temperature for 12 h (1.42 g, 91%). 1H NMR (pyridine-d5): δ 5.50
(d, J ) 11.1 Hz, 1H) (OCHH), 5.47 (d, J ) 11.1 Hz, 1H) (OCHH),
3.61 (d, J ) 14.4 Hz, 1H) (NCHH), 3.17 (s, 6H) (N(CH3)2), 3.10
(d, J ) 14.4 Hz, 1H) (NCHH), 2.31 (s, 3H) (N(CH3)2), 2.28 (s,
1
afforded 4 as yellow crystals (133 mg, 36%). H NMR (pyridine-
d5): δ 5.46 (d, J ) 12.0 Hz, 1H) (OCHH), 4.86 (d, J ) 12.0 Hz,
1H) (OCHH), 4.36 (q, J ) 6.9 Hz, 2H) (CH2CH3), 3.78 (d, J )
14.1 Hz, 1H) (NCHH), 3.69 (m, 12H) (CH2CH3), 3.52 (d, J ) 14.1
Hz, 1H) (NCHH), 3.33 (q, J ) 6.9 Hz, 2H) (CH2CH3), 1.35 (m,
6H) (CH2CH3), 1.10 (m, 18H) (CH2CH3), -2.05 (brs, 1H) (BHB).
13C{1H} NMR (pyridine-d5): δ 202.8 (S2CN), 81.0 (OCH2), 66.5
(NCH2), 58.5 (CH2CH3), 56.1 (CH2CH3), 44.4 (CH2CH3), 11.8
(CH2CH3), 10.9 (CH2CH3), 8.2 (CH2CH3), the cage carbon atoms
were not observed. 11B{1H} NMR (pyridine-d5): δ -9.6 (4B),
-21.1 (3B), -32.3 (1B), -35.7 (1B). IR (KBr, cm-1): ν 2521
(vs) (B-H). Anal. Calcd for C23H55B9N4OS6Ti (4): C, 37.27; H,
7.48; N, 7.56. Found: C, 37.68; H, 7.47; N, 7.28.
1
3H) (N(CH3)2). H NMR (benzene-d6): δ 5.32 (d, J ) 12.0 Hz,
1H) (OCHH), 5.02 (d, J ) 12.0 Hz, 1H) (OCHH), 3.23 (s, 6H)
(N(CH3)2), 2.95 (d, J ) 14.4 Hz, 1H) (NCHH), 2.71 (d, J ) 14.4
Hz, 1H) (NCHH), 1.70 (s, 3H) (N(CH3)2), 1.53 (s, 3H) (N(CH3)2).
1H NMR (CDCl3): δ 5.66 (d, J ) 11.4 Hz, 1H) (OCHH), 5.45 (d,
J ) 11.4 Hz, 1H) (OCHH), 3.97 (d, J ) 14.4 Hz, 1H) (NCHH),
3.76 (s, 6H) (N(CH3)2), 3.61 (d, J ) 14.4 Hz, 1H) (NCHH), 2.77
(s, 3H) (N(CH3)2), 2.62 (s, 3H) (N(CH3)2). 13C{1H} NMR (pyridine-
d5): δ 77.2 (OCH2), 65.5 (NCH2), 50.8 (N(CH3)2), 50.3 (N(CH3)2),
44.1 (N(CH3)2), the cage carbon atoms were not observed. 13C-
{1H} NMR (benzene-d6): δ 77.9 (OCH2), 66.4 (NCH2), 54.0
(N(CH3)2), 51.0 (N(CH3)2), 44.2 (N(CH3)2), the cage carbon atoms
were not observed. 13C{1H} NMR (CDCl3): δ 77.9 (OCH2), 67.1
(NCH2), 55.2 (N(CH3)2), 52.2 (N(CH3)2), 44.9 (N(CH3)2), the cage
carbon atoms were not observed. 11B{1H} NMR (pyridine-d5): δ
12.9 (1B), 1.0 (1B), -0.8 (1B), -3.4 (1B), -4.9 (1B), -9.7 (1B),
-11.5 (1B), -13.9 (1B), -17.8 (1B). 11B{1H} NMR (benzene-
d6): δ 11.1 (1B), 2.4 (1B), 0.6 (1B), -1.9 (1B), -3.9 (1B), -10.2
(2B), -15.3 (1B), -17.6 (1B). 11B{1H} NMR (CDCl3): δ 9.8 (1B),
1.5 (1B), 0.1 (1B), -3.1 (1B), -5.2 (1B), -10.7 (2B), -15.6 (1B),
-18.7 (1B). IR (KBr, cm-1): ν 2571 (vs) (B-H). Anal. Calcd for
C8H25B9N2OTi (3a): C, 30.95; H, 8.12; N, 9.02. Found: C, 30.75;
H, 8.10; N, 8.80.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[NH-
(C6H4-4-OMe)] (5). To a toluene (10 mL) solution of 3a (311 mg,
1.0 mmol) was added 4-methoxyaniline (123 mg, 1.0 mmol) at
-30 °C, and the mixture was then stirred at room temperature for
12 h. The solution was concentrated to ca. 3 mL. Complex 5 was
isolated as a deep brown solid after this solution stood at room
1
temperature for 24 h (237 mg, 61%). H NMR (pyridine-d5): δ
12.23 (brs, 1H) (NH), 6.76 (d, J ) 9.0 Hz, 2H), 6.71 (d, J ) 9.0
Hz, 2H) (aromatic CH), 5.80 (d, J ) 11.1 Hz, 1H) (OCHH), 5.70
(d, J ) 11.1 Hz, 1H) (OCHH), 3.89 (d, J ) 14.7 Hz, 1H) (NCHH),
3.54 (s, 3H) (OCH3), 3.39 (d, J ) 14.7 Hz, 1H) (NCHH), 2.49 (s,
3H) (NCH3), 2.38 (s, 3H) (NCH3). 13C{1H} NMR (pyridine-d5):
δ 153.4, 147.2, 116.5, 114.2 (aromatic C), 78.4 (OCH2), 65.9
(NCH2), 54.6 (OCH3), 52.4 (NCH3), 52.2 (NCH3), the cage carbon
atoms were not observed. 11B{1H} NMR (pyridine-d5): δ 13.5 (1B),
2.0 (1B), 0.2 (1B), -2.9 (1B), -4.6 (1B), -8.9 (1B), -11.2 (1B),
-13.9 (1B), -17.1 (1B). IR (KBr, cm-1): V 2541 (vs) (B-H).
Anal. Calcd for C13H27B9N2O2Ti (5): C, 40.19; H, 7.00; N, 7.21.
Found: C, 40.24; H, 6.60; N, 7.25.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[σ:η1-
(2-NH-3-CH3-C5H3N)][η1-C5H3N-2-NH2-3-CH3]‚1.5C7H8 (6‚
1.5C7H8). This complex was prepared as red crystals from 3a (311
mg, 1.0 mmol) and 2-amino-3-picoline (216 mg, 2.0 mmol) in
toluene (10 mL) using the identical procedures reported for 5,
followed by recrystallization from toluene/THF (285 mg, 46%).
1H NMR (pyridine-d5): δ 9.74 (brs, 1H) (NH), 8.19 (d, J ) 5.1
Hz, 1H), 7.81 (d, J ) 5.1 Hz, 1H), 7.23 (d, J ) 7.2 Hz, 1H)
(aromatic CH), 7.3 - 7.1 (m, 7.5H) (aromatic CH), 7.02 (d, J )
Preparation of [σ:η1:η5-(OCH2)(Et2NCH2)C2B9H9]Ti(NEt2)
(3b). This complex was prepared as orange crystals from Ti(NEt2)4
(1.68 g, 5.0 mmol) and 1 (1.18 g, 5.0 mmol) in toluene (40 mL)
1
using the identical procedures reported for 3a (1.39 g, 76%). H
NMR (pyridine-d5): δ 5.89 (d, J ) 11.7 Hz, 1H) (OCHH), 5.53
(d, J ) 11.7 Hz, 1H) (OCHH), 4.32 (m, 2H) (CH2CH3), 4.04 (m,
2H) (CH2CH3), 3.96 (d, J ) 14.7 Hz, 1H) (NCHH), 3.72 (d, J )
14.4 Hz, 1H) (NCHH), 2.92 (m, 4H) (CH2CH3), 1.14 (t, J ) 7.2
1
Hz, 6H) (CH2CH3), 0.89 (m, 6H) (CH2CH3). H NMR (benzene-
3
3
7.2 Hz, 1H), 6.59 (dd, J1 ) 5.1 Hz, J2 ) 7.2 Hz, 1H) (aromatic
d6): δ 5.34 (d, J ) 11.7 Hz, 1H) (OCHH), 5.12 (d, J ) 11.7 Hz,
1H) (OCHH), 4.10 (m, 2H) (CH2CH3), 3.82 (m, 2H) (CH2CH3),
3.09 (d, J ) 15.0 Hz, 1H) (NCHH), 3.03 (d, J ) 15.0 Hz, 1H)
(NCHH), 2.54 (m, 2H) (CH2CH3), 2.05 (m, 2H) (CH2CH3), 1.01
(t, J ) 7.2 Hz, 6H) (CH2CH3), 0.39 (t, J ) 7.2 Hz, 3H) (CH2CH3),
0.26 (t, J ) 7.2 Hz, 3H) (CH2CH3). 13C{1H} NMR (pyridine-d5):
δ 77.7 (OCH2), 61.8 (NCH2), 53.1 (CH2CH3), 49.0 (CH2CH3), 45.5
(CH2CH3), 13.6 (CH2CH3), 9.6 (CH2CH3), 7.7 (CH2CH3), the cage
carbon atoms were not observed. 13C{1H} NMR (benzene-d6): δ
78.1 (OCH2), 62.7 (NCH2), 53.7 (CH2CH3), 49.3 (CH2CH3), 45.8
(CH2CH3), 15.5 (CH2CH3), 9.9 (CH2CH3), 7.8 (CH2CH3), the cage
carbon atoms were not observed. 11B{1H} NMR (pyridine-d5): δ
9.9 (1B), 0.9 (1B), 0.0 (1B), -3.4 (1B), -5.1 (1B), -11.0 (2B),
3
3
CH), 6.42 (brs, 2H) (NH2), 6.22 (dd, J1 ) 5.1 Hz, J2 ) 7.2 Hz,
1H) (aromatic CH), 5.71 (d, J ) 11.4 Hz, 1H) (OCHH), 5.63 (d,
J ) 11.4 Hz, 1H) (OCHH), 3.92 (d, J ) 14.7 Hz, 1H) (NCHH),
3.45 (d, J ) 14.7 Hz, 1H) (NCHH), 2.39 (s, 3H) (NCH3), 2.20 (s,
4.5H) (toluene), 2.15 (s, 3H) (NCH3), 2.13 (s, 3H) (ArCH3) , 1.98
(s, 3H) (ArCH3). 13C{1H} NMR (pyridine-d5): δ 167.3, 158.4,
145.4, 138.7, 138.6, 136.9, 116.0, 114.3, 112.8, 110.5 (aromatic
C), 137.6, 128.7, 128.0, 125.1 (toluene), 77.4 (OCH2), 65.8 (NCH2),
53.1 (NCH3), 51.2 (NCH3), 20.6 (toluene), 16.7 (ArCH3), 14.4
(ArCH3), the cage carbon atoms were not observed. 11B{1H} NMR
(pyridine-d5): δ 16.2 (1B), 3.9 (1B), 0.8 (1B), -3.8 (2B), -7.5
(1B), -11.1 (1B), -16.0 (2B). IR (KBr, cm-1): ν 2542 (vs) (B-

2702 Organometallics, Vol. 26, No. 10, 2007
Table 2. Crystal Data and Summary of Data Collection and Refinement for 3a, 3b, 4, 6‚1.5C7H8, and 7
Shen et al.
3a
3b
4
6·1.5C7H8
7
formula
cryst size, mm
fw
C8H25B9N2OTi
0.40 × 0.30 × 0.20
310.49
C12H33B9N2OTi
0.50 × 0.40 × 0.20
366.59
C23H55B9N4OS6Ti
0.50 × 0.40 × 0.30
741.26
C28.5H46B9N5OTi
0.50 × 0.40 × 0.20
619.89
C21H47B9N4OTi
0.50 × 0.40 × 0.20
516.82
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
monoclinic
Cc
13.647(3)
7.167(2)
18.496(4)
90
110.72(1)
90
1692.0(6)
4
monoclinic
P21/c
14.926(3)
8.031(2)
17.685(4)
90
105.44(3)
90
2043.4(7)
4
monoclinic
P21/c
16.458(3)
14.762(3)
17.517(3)
90
111.77(1)
90
3952.2(13)
4
triclinic
P1h
triclinic
P1h
9.062(2)
12.408(3)
16.109(3)
80.89(3)
86.30(3)
70.29(3)
1683.5(6)
2
9.799(2)
11.521(2)
14.453(3)
100.07(3)
105.59(3)
104.93(3)
1465.4(5)
2
Z
D
calcd, Mg/m3
1.219
1.192
1.246
1.223
1.171
radiation (γ), Å
2θ range, deg
µ, mm-1
Mo KR (0.71073)
4.7 to 56.7
0.496
Mo KR (0.71073)
4.8 to 50.0
0.421
Mo KR (0.71073)
2.9 to 56.7
0.559
Mo KR (0.71073)
4.0 to 50.0
0.286
Mo KR (0.71073)
3.0 to 50.8
0.314
F(000)
648
776
1568
654
552
no. of obsd reflns
no. of params refnd
goodness of fit
R1
3414
190
0.934
0.042
3604
226
1.050
0.053
9819
405
1.008
0.045
5931
406
1.017
0.061
4727
325
1.067
0.047
wR2
0.106
0.145
0.113
0.160
0.144
Table 3. Crystal Data and Summary of Data Collection and Refinement for 11b, 12-14, and 15‚C7H8
11b
12
13
14
15‚C7H8
formula
cryst size, mm
fw
C17H42B9N3OSTi
0.40 × 0.30 × 0.20
481.79
C22H35B9N2O2Ti
0.30 × 0.20 × 0.10
504.71
C15H30B9N3O2Ti
0.30 × 0.20 × 0.10
429.61
C22H36B9N3O3Ti
0.30 × 0.20 × 0.10
535.73
C25H60B18N2O4Ti2
0.30 × 0.20 × 0.10
743.13
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
triclinic
P1h
monoclinic
P21/n
13.986(1)
12.447(1)
16.066(2)
90
110.29(1)
90
2623.2(5)
4
monoclinic
P21/n
11.325(2)
11.754(2)
18.389(4)
90
104.76(3)
90
2367.1(8)
4
monoclinic
P21/n
11.920(1)
15.011(2)
15.748(2)
90
100.65(1)
90
2769.2(5)
4
monoclinic
P21/n
10.431(1)
15.730(2)
12.825(1)
90
105.79(1)
90
2025.0(3)
2
10.108(2)
16.169(3)
17.220(3)
99.89(3)
95.60(3)
92.94(3)
2752.7(9)
4
Z
D
calcd, Mg/m3
1.163
1.278
1.206
1.285
1.219
radiation (γ), Å
2θ range, deg
µ, mm-1
Mo KR (0.71073)
2.4 to 50.0
0.402
Mo KR (0.71073)
3.3 to 50.0
0.350
Mo KR (0.71073)
4.2 to 50.0
0.378
Mo KR (0.71073)
3.5 to 56.6
0.340
Mo KR (0.71073)
4.2 to 56.7
0.428
F(000)
1024
1056
896
1120
780
no. of obsd reflns
no. of params refnd
goodness of fit
R1
7923
577
1.178
0.060
4622
325
1.012
0.050
3555
271
1.117
0.053
6873
343
0.991
0.057
5021
244
1.059
0.044
wR2
0.164
0.112
0.153
0.141
0.118
H). Anal. Calcd for C25H42B9N5OTi (6 + toluene): C, 52.33; H,
7.38; N, 12.20. Found: C, 51.96; H, 7.37; N, 12.01.
(OCH2), 66.0 (NCH2), 54.7 (CH3), 52.6 (CH3), 41.2 (CH3), 34.9,
33.7, 32.4, 27.2, 26.2, 25.5, 24.7 (Cy), the cage carbon atoms were
not observed. 11B{1H} NMR (pyridine-d5): δ 12.3 (1B), -2.1 (5B),
-9.6 (2B), -16.8 (1B). 11B{1H} NMR (CDCl3): δ 12.0 (1B), 1.8
(1B), -0.5 (1B), -3.7 (2B), -9.2 (1B), -11.9 (1B), -14.7 (1B),
-17.6 (1B). IR (KBr, cm-1): ν 2549 (vs) (B-H). Anal. Calcd for
C21H47B9N4OTi (7): C, 48.81; H, 9.17; N, 10.84. Found: C, 48.99;
H, 9.09; N, 10.96.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-
CyNC(NMe2)NCy] (7). To a toluene (10 mL) solution of 3a (311
mg, 1.0 mmol) was added dicyclohexylcarbodiimide (206 mg, 1.0
mmol); the mixture was stirred at room temperature for 12 h and
then heated to reflux for 30 min. The hot solution was filtered, and
the clear filtrate was concentrated to ca. 3 mL. Complex 7 was
isolated as orange crystals after this solution stood at room
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(η3-
S2CNMe2) (8). To a toluene (10 mL) solution of 3a (311 mg, 1.0
mmol) was added carbon disulfide (114 mg, 1.5 mmol), and the
mixture was stirred at room temperature for 12 h. Complex 8 was
1
temperature for 12 h (424 mg, 82%). H NMR (pyridine-d5): δ
5.86 (d, J ) 12.0 Hz, 1H) (OCHH), 5.71 (d, J ) 12.0 Hz, 1H)
(OCHH), 4.03 (d, J ) 14.4 Hz, 1H) (NCHH), 3.44 (d, J ) 14.4
Hz, 1H) (NCHH), 3.32 (m, 2H) (NCH), 2.80 (s, 6H) (N(CH3)2),
2.61 (s, 3H) (CH3), 2.35 (s, 3H) (CH3), 1.1-1.9 (m, 20H) (Cy). 1H
NMR (CDCl3): δ 5.59 (d, J ) 12.0 Hz, 1H) (OCHH), 5.54 (d, J
) 12.0 Hz, 1H) (OCHH), 3.80 (d, J ) 14.4 Hz, 1H) (NCHH),
3.40 (d, J ) 14.4 Hz, 1H) (NCHH), 3.47 (m, 2H) (NCH), 2.92 (s,
6H) (N(CH3)2), 2.67 (s, 3H) (N(CH3)2), 2.40 (s, 3H) (N(CH3)2),
1.0-2.0 (m, 20H) (Cy). 13C{1H} NMR (pyridine-d5): δ 174.9
(N3C), 78.1 (OCH2), 65.2 (NCH2), 54.0 (CH3), 52.0 (CH3), 40.3
(CH3), 39.2, 34.6, 32.0, 26.8, 24.9, 14.8 (Cy), the cage carbon atoms
were not observed. 13C{1H} NMR (CDCl3): δ 175.4 (N3C), 78.5
1
collected as a yellow solid by filtration (363 mg, 94%). H NMR
(pyridine-d5): δ 5.95 (d, J ) 12.0 Hz, 1H) (OCHH), 5.77 (d, J )
12.0 Hz, 1H) (OCHH), 4.10 (d, J ) 14.7 Hz, 1H) (NCHH), 3.55
(d, J ) 14.7 Hz, 1H) (NCHH), 3.10 (s, 6H) (N(CH3)2), 2.63 (s,
3H) (CH3), 2.50 (s, 3H) (CH3). 13C{1H} NMR (pyridine-d5): δ
201.3 (S2CN), 80.0 (OCH2), 66.6 (NCH2), 54.6 (CH3), 52.2 (CH3),
39.5 (CH3), the cage carbon atoms were not observed. 11B{1H}
NMR (pyridine-d5): δ 17.9 (1B), 4.9 (1B), 2.0 (1B), -1.9 (1B),
-2.8 (1B), -5.8 (2B), -10.4 (1B), -14.7 (1B). IR (KBr, cm-1):

Constrained-Geometry Half-Sandwich Metallacarboranes
Organometallics, Vol. 26, No. 10, 2007 2703
ν 2527 (vs) (B-H). Anal. Calcd for C9H25B9N2OS2Ti (8): C, 27.96;
(CH2CH2CH3), 1.04 (t, J ) 7.2 Hz, 3H) (NCH2CH3), 0.87 (t, J )
7.2 Hz, 3H) (NCH2CH3), 0.78 (t, J ) 7.2 Hz, 3H) ((CH2)3CH3).
13C{1H} NMR (pyridine-d5): δ 171.2 (N2CS), 79.5 (OCH2), 60.9
(NCH2), 53.7 (NCH2CH3), 48.8 (NCH2CH3), 45.6 (CH2Prn), 31.4
(NCH2CH2Et),19.7(CH2CH2CH3),13.7(NCH2CH3),13.4(NCH2CH3),
12.3 ((CH2)3CH3), 10.9 (NCH2CH3), the cage carbon atoms were
not observed. 11B{1H} NMR (pyridine-d5): δ 13.7 (1B), 4.2 (1B),
1.0 (1B), -2.8 (2B), -8.2 (1B), -10.1 (1B), -16.0 (2B). IR (KBr,
cm-1): ν 2544 (vs) (B-H). Anal. Calcd for C17H42B9N3OSTi
(11b): C, 42.38; H, 8.79; N, 8.72. Found: C, 42.46; H, 8.78; N,
8.79.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[σ:η1-
OC(NMe2)dCPh2] (12). This complex was prepared as orange
crystals from 3a (311 mg, 1.0 mmol) and diphenylketene (194 mg,
1.0 mmol) in toluene (10 mL) using the identical procedures
reported for 7, followed by recrystallization from DME (424 mg,
84%). 1H NMR (pyridine-d5): δ 7.52 (m, 2H), 7.30 (m, 4H), 7.22
(m, 2H), 7.07 (m, 2H) (aromatic H), 6.01 (d, J ) 11.7 Hz, 1H)
(OCHH), 5.92 (d, J ) 11.7 Hz, 1H) (OCHH), 3.97 (d, J ) 14.4
Hz, 1H) (NCHH), 3.47 (d, J ) 14.4 Hz, 1H) (NCHH), 2.90 (s,
3H) (NCH3), 2.83 (s, 3H) (NCH3), 2.63 (s, 6H) (NCH3). 13C{1H}
NMR (pyridine-d5): δ 163.3 (NCO), 142.9, 142.5, 140.2, 130.2,
129.9, 129.0, 128.7, 128.1, 128.0, 127.8, 126.4, 124.5, 124.1
(aromatic and olefinic C), 80.2 (OCH2), 63.7 (NCH2), 54.0 (NCH3),
50.8 (NCH3), 40.2 (NCH3), the cage carbon atoms were not
observed. 11B{1H} NMR (pyridine-d5): δ 16.3 (1B), 3.6 (1B), 1.3
(1B), -1.3 (1B), -3.0 (1B), -7.2 (1B), -10.3 (1B), -13.5(1B),
-15.9 (1B). IR (KBr, cm-1): ν 2552 (vs) (B-H). Anal. Calcd for
C22H35B9N2O2Ti (12): C, 52.36; H, 6.99; N, 5.55. Found: C, 52.49;
H, 6.77; N, 5.37.
H, 6.52; N, 7.25. Found: C, 27.62; H, 6.59; N, 7.24.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η2-
C(NMe2)N(C6H3-2,6-Me2)] (9). This complex was prepared as a
yellow solid from 3a (311 mg, 1.0 mmol) and 2,6-xylyl isonitrile
(131 mg, 1.0 mmol) in toluene (10 mL) using the identical
1
procedures reported for 7 (318 mg, 72%). H NMR (pyridine-d5):
δ 7.25 (t, J ) 7.2 Hz, 1H), 7.15 (d, J ) 7.2 Hz, 2H) (C6H3), 5.97
(d, J ) 11.7 Hz, 1H) (OCHH), 5.47 (d, J ) 11.7 Hz, 1H) (OCHH),
4.36 (d, J ) 14.7 Hz, 1H) (NCHH), 3.57 (d, J ) 14.7 Hz, 1H)
(NCHH), 3.38 (s, 3H) (NCH3), 2.64 (s, 3H) (NCH3), 2.38 (s, 3H)
(NCH3), 2.24 (s, 3H) (NCH3), 2.23 (s, 3H) (ArCH3), 2.20 (s, 3H)
(ArCH3). 13C{1H} NMR (pyridine-d5): δ 197.6 (NCN), 145.4,
130.7, 128.7, 128.0, 125.8, 125.0 (aromatic C), 77.4 (OCH2), 66.3
(NCH2), 53.7 (NCH3), 49.7 (NCH3), 43.6 (NCH3), 36.3 (NCH3),
17.8 (ArCH3), 14.8 (ArCH3), the cage carbon atoms were not
observed. 11B{1H} NMR (pyridine-d5): δ 7.3 (1B), -0.56 (2B),
-3.5 (2B), -10.0 (2B), -17.6 (2B). IR (KBr, cm-1): ν 2553 (vs)
(B-H), 1636 (s) (CdN). Anal. Calcd for C17H34B9N3OTi (9): C,
46.23; H, 7.76; N, 9.51. Found: C, 46.00; H, 7.70; N, 9.79.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[NdC-
(NMe2)Ph] (10). This complex was prepared as an orange solid
from 3a (311 mg, 1.0 mmol) and benzonitrile (103 mg, 1.0 mmol)
in toluene (10 mL) using the identical procedures reported for 7
(380 mg, 92%). 1H NMR (pyridine-d5): δ 7.27 (m, 3H), 7.05 (m,
2H) (aromatic H), 5.72 (d, J ) 11.4 Hz, 1H) (OCHH), 5.62 (d, J
) 11.4 Hz, 1H) (OCHH), 3.91 (d, J ) 14.4 Hz, 1H) (NCHH),
3.37 (d, J ) 14.4 Hz, 1H) (NCHH), 2.98 (s, 6H) (NCH3), 2.58 (s,
3H) (NCH3), 2.23 (s, 3H) (NCH3). 13C{1H} NMR (pyridine-d5):
δ 156.3 (N2C), 136.7, 128.5, 127.9, 126.6 (aromatic C), 77.9
(OCH2), 65.1 (NCH2), 52.0 (NCH3), 51.8 (NCH3), 38.1 (NCH3),
the cage carbon atoms were not observed. 11B{1H} NMR (pyridine-
d5): δ 9.2 (1B), -0.7 (1B), -3.0 (1B), -4.2 (1B), -5.5 (1B), -9.2
(1B), -12.7 (1B), -14.7(1B), -19.8 (1B). IR (KBr, cm-1): ν 2548
(vs) (B-H), 1550 (s) (CdN). Anal. Calcd for C15H30B9N3OTi
(10): C, 43.56; H, 7.31; N, 10.16. Found: C, 44.05; H, 7.46; N,
9.70.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-OC-
(NMe2)NPh] (13). This complex was prepared as orange crystals
from 3a (311 mg, 1.0 mmol) and phenyl isocyanate (119 mg, 1.0
mmol) in toluene (10 mL) using the identical procedures reported
1
for 7 (361 mg, 84%). H NMR (pyridine-d5): δ 7.89 (d, J ) 7.8
Hz, 1H), 7.31 (m, 2H), 7.01 (t, J ) 7.8 Hz, 1H), 6.94 (t, J ) 7.8
Hz, 1H) (aromatic H), 5.96 (d, J ) 12.0 Hz, 1H) (OCHH), 5.74
(d, J ) 12.0 Hz, 1H) (OCHH), 4.12 (d, J ) 14.4 Hz, 1H) (NCHH),
3.60 (d, J ) 14.4 Hz, 1H) (NCHH), 2.92 (s, 6H) (NCH3), 2.62 (s,
3H) (NCH3), 2.52 (s, 3H) (NCH3). 13C{1H} NMR (pyridine-d5):
δ 197.6 (OCN2), 145.4, 130.7, 128.7, 128.0, 125.8, 125.0 (aromatic
C), 77.4 (OCH2), 66.3 (NCH2), 53.7 (NCH3), 49.7 (NCH3), 43.6
(NCH3), 36.3 (NCH3), the cage carbon atoms were not observed.
11B{1H} NMR (pyridine-d5): δ 18.0 (1B), 5.4 (1B), 3.1 (1B), -2.7
(3B), -6.8 (1B), -10.2 (1B), -15.6 (1B). IR (KBr, cm-1): ν 2538
(vs) (B-H). Anal. Calcd for C15H30B9N3O2Ti (13): C, 41.94; H,
7.04; N, 9.78. Found: C, 42.01; H, 7.33; N, 9.68.
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[η3-SC-
(NMe2)NBun] (11a). This complex was prepared as a yellow solid
from 3a (311 mg, 1.0 mmol) and n-butyl isothiocyanate (115 mg,
1.0 mmol) in toluene (10 mL) using the identical procedures
1
reported for 7 (324 mg, 76%). H NMR (pyridine-d5): δ 5.86 (d,
J ) 12.0 Hz, 1H) (OCHH), 5.73 (d, J ) 12.0 Hz, 1H) (OCHH),
4.10 (m, 1H) (NCHHPrn), 3.99 (d, J ) 14.7 Hz, 1H) (NCHH),
3.86 (m, 1H) (NCHHPrn), 3.47 (d, J ) 14.7 Hz, 1H) (NCHH),
2.96 (s, 6H) (NCH3), 2.58 (s, 3H) (NCH3), 2.40 (s, 3H) (NCH3),
1.41 (m, 2H) (NCH2CH2Et), 1.13 (m, 2H) (CH2CH3), 0.75 (t, J )
7.5 Hz, 3H) (CH2CH3). 13C{1H} NMR (pyridine-d5): δ 174.7
(N2CS), 79.3 (OCH2), 65.1 (NCH2), 53.5 (NCH3), 53.1 (NCH3),
45.4 (NCH2Prn), 39.5 (NCH3), 30.4 (NCH2CH2Et), 20.0 (CH2CH3),
13.3 (CH2CH3), the cage carbon atoms were not observed. 11B-
{1H} NMR (pyridine-d5): δ 15.0 (1B), 3.6 (1B), 0.7 (1B), -2.4
(1B), -4.0 (1B), -6.9 (1B), -11.3 (1B), -16.2 (2B). IR (KBr,
cm-1): ν 2548 (vs) (B-H). Anal. Calcd for C13H34B9N3OSTi
(11a): C, 36.68; H, 8.05; N, 9.87. Found: C, 36.59; H, 8.12; N,
9.99.
Preparation of [σ:η1:η5-(OCH2)(Et2NCH2)C2B9H9]Ti[η3-SC-
(NEt2)NBun] (11b). This complex was prepared as yellow crystals
from 3b (367 mg, 1.0 mmol) and n-butyl isothiocyanate (115 mg,
1.0 mmol) in toluene (10 mL) using the identical procedures
reported for 7, followed by recrystallization from DME (395 mg,
82%). 1H NMR (pyridine-d5): δ 5.94 (d, J ) 12.0 Hz, 1H) (OCHH),
5.79 (d, J ) 12.0 Hz, 1H) (OCHH), 4.03 (m, 1H) (NCHHPrn),
3.89 (d, J ) 14.7 Hz, 1H) (NCHH), 3.74 (m, 1H) (NCHHPrn),
3.70 (d, J ) 14.7 Hz, 1H) (NCHH), 3.48 (m, 4H) (NCH2CH3),
2.76 (m, 2H) (NCH2CH3), 2.53 (m, 2H) (NCH2CH3), 1.36 (m, 2H)
(NCH2CH2Et), 1.19 (t, J ) 7.2 Hz, 6H) (NCH2CH3), 1.12 (m, 2H)
Preparation of [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti[σ:η1-
OCH(Ph)N(Ph)C(NMe2)dO] (14). This complex was prepared
as yellow crystals from 13 (215 mg, 0.5 mmol) and benzaldehyde
(53 mg, 0.5 mmol) in toluene (10 mL) using the identical procedures
1
reported for 7 (193 mg, 72%). H NMR (pyridine-d5): δ 8.79 (s,
1H) (NCH(Ph)O), 7.89 (m, 2H), 7.53 (m, 2H), 7.43 (m, 2H), 7.31
(m, 2H), 7.01 (t, J ) 7.5 Hz, 1H), 6.94 (t, J ) 7.5 Hz, 1H) (aromatic
H), 5.96 (d, J ) 12.3 Hz, 1H) (OCHH), 5.74 (d, J ) 12.3 Hz, 1H)
(OCHH), 4.12 (d, J ) 14.7 Hz, 1H) (NCHH), 3.59 (d, J ) 14.7
Hz, 1H) (NCHH), 2.92 (s, 6H) (NCH3), 2.62 (s, 3H) (NCH3), 2.53
(s, 3H) (NCH3). 13C{1H} NMR (pyridine-d5): δ 191.8 (OdCN2),
136.4, 133.9, 129.1, 128.7, 128.3, 128.0, 127.8, 125.1, 122.2, 121.7,
120.0, 119.9 (aromatic C), 80.6 (NCH(Ph)O), 79.0 (OCH2), 65.1
(NCH2), 54.9 (NCH3), 50.6 (NCH3), 35.8 (NCH3), the cage carbon
atoms were not observed. 11B{1H} NMR (pyridine-d5): δ 17.5 (1B),
5.0 (1B), 2.7 (1B), -3.0 (3B), -7.1 (1B), -10.4 (1B), -16.0 (1B).
IR (KBr, cm-1): ν 2539 (vs) (B-H), 1573 (s) (CdO). Anal. Calcd
for C22H36B9N3O3Ti (14): C, 49.33; H, 6.77; N, 7.84. Found: C,
49.62; H, 6.82; N, 7.38.

2704 Organometallics, Vol. 26, No. 10, 2007
Shen et al.
Preparation of [{σ:η1:η5-(µ-OCH2)(Et2NCH2)C2B9H9}Ti-
(OMe)]2‚C7H8 (15‚C7H8). This complex was prepared as pale
yellow crystals from 3b (367 mg, 1.0 mmol) and methyl propiolate
(84 mg, 1.0 mmol) in toluene (10 mL) using the identical procedures
reported for 7, followed by recrystallization from THF/toluene (308
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.19
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.20 All hydrogen atoms were geo-
metrically fixed using the riding model. Crystal data and details of
data collection and structure refinements are given in Tables 2 and
3, respectively. Further details are included in the Supporting
Information.
1
mg, 83%). H NMR (pyridine-d5): δ 7.26 (t, J ) 7.2 Hz, 2H)
(toluene H), 7.16 (m, 3H) (toluene H), 5.87 (d, J ) 11.7 Hz, 2H)
(OCHH), 5.80 (d, J ) 11.7 Hz, 2H) (OCHH), 4.39 (s, 6H) (OCH3),
3.71 (d, J ) 15.0 Hz, 2H) (NCHH), 3.63 (d, J ) 15.0 Hz, 2H)
(NCHH), 3.43 (m, 2H) (NCH2CH3), 3.08 (m, 2H) (NCH2CH3), 2.56
(m, 4H) (NCH2CH3), 2.20 (s, 3H) (toluene CH3), 0.84 (t, J ) 7.2
Hz, 6H) (NCH2CH3), 0.77 (t, J ) 7.2 Hz, 6H) (NCH2CH3). 13C-
{1H} NMR (pyridine-d5): δ 137.7, 128.7, 128.0, 125.1 (toluene
C), 79.3 (OCH2), 65.3 (NCH2), 60.8 (OCH3), 50.5 (NCH2CH3),
47.6 (NCH2CH3), 20.6 (toluene CH3), 10.7 (NCH2CH3), 5.1
(NCH2CH3), the cage carbon atoms were not observed. 11B{1H}
NMR (pyridine-d5): δ 14.3 (1B), 2.1 (1B), 0.3 (1B), -2.0 (1B),
-3.8 (1B), -8.1 (1B), -10.6 (1B), -13.4 (1B), -16.8 (1B). IR
(KBr, cm-1): ν 2549 (vs) (B-H). Anal. Calcd for C25H60B18N2O4-
Ti2 (15 + C7H8): C, 40.41; H, 8.14; N, 3.77. Found: C, 40.57; H,
8.62; N, 3.51.
Acknowledgment. The work described in this paper was
supported by grants from the Research Grants Council of the
Hong Kong Special Administration Region (Project No. CUHK
403805) and State Key Laboratory of Elemento-Organic Chem-
istry, Nankai University (Project No. 0314).
Supporting Information Available: Crystallographic data in
CIF format for 3a, 3b, 4, 6‚1.5C7H8, 7, 11b, 12, 13, 14, and 15‚
C7H8. This material is available free of charge via the Internet at
http://pubs.acs.org.
Alternate Method. Complex 15 was also prepared in 79% yield
from the reaction of 3b (367 mg, 1.0 mmol) with MMA (100 mg,
1.0 mmol) in toluene (10 mL), or 73% yield from the reaction of
3b (367 mg, 1.0 mmol) with dimethyl acetylenedicarboxylate (142
mg, 1.0 mmol) in toluene (10 mL) using the identical procedures
described above.
OM070128Q
(19) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction of Area Detector Data; University of Go¨ttingen: Go¨ttingen,
Germany, 1996.
(20) Sheldrick, G. M. SHELXTL 5.10 for Windows NT: Structure
Determination Software Programs; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 1997.
X-ray Structure Determination. All single crystals were
immersed in Paraton-N oil and sealed under nitrogen in thin-walled