Synthesis, structure, and reactivity of Group 4 metallacycles incorporating a Me2C-linked cyclopentadienyl-carboranyl ligand

Article abstract of DOI:10.1039/b716929a

Group 4 metallacycles [η⁵:σ-Me₂C(C ₅H₄)(C₂B₁₀H₁₀)] Ti[η²-N(Me)CH₂CH₂N(Me)] (1a), [η⁵:σ-Me₂C(C₅H₄)(C ₂B₁₀H₁₀)]Zr[η²-N(Me)CH ₂CH₂N(Me)](HNMe₂) (1b) and [η⁵: σ-Me₂C(C₅H₄)(C₂B ₁₀H₁₀)]M[η²-N(Me)CH₂CH ₂CH₂N(Me)] (M = Ti (2a), Zr (2b), Hf (2c)) were synthesized by reaction of [η⁵:σ-Me₂C(C ₅H₄)(C₂B₁₀H₁₀)]M(NMe ₂)₂ (M = Ti, Zr, Hf) with MeNH(CH₂) _nNHMe (n = 2, 3). These metal complexes reacted with unsaturated molecules such as 2,6-Me₂C₆H₃NC, PhNCO and PhCN to give exclusively M-N bond insertion products. The M-C_cage bond remained intact. Such a preference of M-N over M-C_cage insertion is suggested to most likely be governed by steric factors, and the mobility of the migratory groups plays no obvious role in the reactions. This work also shows that the insertion of unsaturated molecules into the metallacycles is a useful and effective method for the construction of very large ring systems.

Full text of DOI:10.1039/b716929a

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis, structure, and reactivity of Group 4 metallacycles incorporating a
Me2C-linked cyclopentadienyl-carboranyl ligand†‡
Mei-Mei Sit, Hoi-Shan Chan and Zuowei Xie*
Received 1st November 2007, Accepted 2nd January 2008
First published as an Advance Article on the web 8th February 2008
DOI: 10.1039/b716929a
5
2
Group 4 metallacycles [g :r-Me2C(C5H4)(C2B10H10)]Ti[g -N(Me)CH2CH2N(Me)] (1a),
5
2
[g :r-Me2C(C5H4)(C2B10H10)]Zr[g -N(Me)CH2CH2N(Me)](HNMe2) (1b) and
5
2
[g :r-Me2C(C5H4)(C2B10H10)]M[g -N(Me)CH2CH2CH2N(Me)] (M = Ti (2a), Zr (2b), Hf (2c)) were
5
synthesized by reaction of [g :r-Me2C(C5H4)(C2B10H10)]M(NMe2)2 (M = Ti, Zr, Hf) with
MeNH(CH2)nNHMe (n = 2, 3). These metal complexes reacted with unsaturated molecules such as
2,6-Me2C6H3NC, PhNCO and PhCN to give exclusively M–N bond insertion products. The M–Ccage
bond remained intact. Such a preference of M–N over M–Ccage insertion is suggested to most likely be
governed by steric factors, and the mobility of the migratory groups plays no obvious role in the
reactions. This work also shows that the insertion of unsaturated molecules into the metallacycles is a
useful and effective method for the construction of very large ring systems.
Introduction
Results and discussion
5
Synthesis of [g5:r-Me2C(C5H4)(C2B10H10)]-
M[g2-N(Me)(CH2)nN(Me)]
Reactivity studies on [g :r-A(C9H6)(C2B10H10)]Zr(NMe2)2 (A =
Me2C,1 Me2Si,1 iPr2NP2) and [g :r-Me2C(C5H4)(C2B10H10)]-
5
Ti(NMe2)X (X = Cl, alkyl) complexes3 indicate that the un-
saturated molecules insert into the M–N bond only in the
absence of M–Calkyl bonds and the M–Ccage bond remains intact,
i.e. the relative reactivity follows the trend: M–Calkyl > M–N
>> M–Ccage.3 Since the M–Ccage and M–Calkyl bond distances are
almost identical, the preference of M–N over M–Ccage insertion
is suggested to most likely be governed by steric factors.1–4 On
Salt metathesis and amine elimination are two useful meth-
ods for the preparation of metal amides.7 Reactions of
5
LiN(Me)CH2CH2N(Me)Li with 0.5 equiv. of {[g :r-Me2C(C9H6)-
8
5
(C2B10H10)]Zr(l–Cl)1.5Cl}2{Li(THF)2} or
1 equiv. of [g :r-
Me2C(C5H4)(C2B10H10)]ZrCl29 in THF did not afford isolable pure
products. On the other hand, treatment of [g :r-Me2C(C5H4)-
(C2B10H10)]M(NMe2)2 with 5 or 1.1 equiv. of MeNHCH2CH2-
5
8
5
the other hand, [g :r-Me2C(C5H4)(C2B10H10)]2Zr is reported to
NHMe in toluene gave the corresponding titanium or zir-
catalyze the polymerization of methyl methacrylate in the absence
of any cocatalyst through the action of the nucleophilic cage
5
2
conium amide complexes [g :r-Me2C(C5H4)(C2B10H10)]Ti[g -
5
N(Me)CH2CH2N(Me)] (1a) in 68% yield, or [g :r-Me2C(C5H4)-
(C2B10H10)]Zr[g -N(Me)CH2CH2N(Me)](HNMe2) (1b) in 73%
5
5
atom.5 Complexes [g :r-Me2C(C5H4)(C2B10H10)]M(g -C5Me5)Cl
(M = Ti, Zr) are active catalysts for ethylene polymerization in
the presence of modified methylalumoxane. Possible involvement
of the activation of the M–Ccage r bond is suggested.6 With this in
mind, a question subsequently arises as to whether the mobility
of the carborane cage plays a role in the migratory insertions
aforementioned as the cage is tethered to the cyclopentadienyl unit
in comparison to the terminal amido groups. One possible way
to address this issue is to link the two terminal amido groups
via several methylene moieties, lowering their mobility and then
to investigate the reactivity patterns of the resultant metallacycles
toward unsaturated molecules. We report in this article the synthe-
2
yield, respectively (Scheme 1). The formation of volatile Me2NH
and the chelate effect of the bidentate diamido ligand provide
the driving forces for the above reactions. Both complexes were
fully characterized by 1H, 13C and 11B NMR as well as elemental
analyses. Complex 1b contained a coordinated Me2NH molecule
probably due to the relatively larger size of the Zr atom.
5
2
sis, structure, and reactivity of [g :r-Me2C(C5H4)(C2B10H10)]M[g -
N(Me)(CH2)nN(Me)] (M = Ti, Zr, Hf; n = 2, 3).
Department of Chemistry, The Chinese University of Hong Kong, Shatin,
NT, Hong Kong, China. E-mail: zxie@cuhk.edu.hk; Fax: +852 2603-5057
† Dedicated to Professor Ken Wade on the occasion of his 75th birthday.
‡ CCDC reference numbers 665266–665274. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b716929a
Scheme 1
1454 | Dalton Trans., 2008, 1454–1464
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
5
In a very similar manner, complexes [g :r-Me2C(C5H4)-
2
(C2B10H10)]M[g -N(Me)CH2CH2CH2N(Me)] (M = Ti (2a), Zr
(2b) and Hf (2c)) were prepared in 64–82% isolated yields
5
from the reactions of [g :r-Me2C(C5H4)(C2B10H10)]M(NMe2)2
with MeNH(CH2)3NHMe in toluene (Scheme 2). They showed
similar spectroscopic features and no coordination of Me2NH,
presumably owing to the formation of sterically more demanding
six-membered metallacycles.
Scheme 2
5
2
Fig.
2
Molecular structure of [g :r-Me2C(C5H4)(C2B10H10)]Ti[g -
The molecular structures of 1a and 2a were confirmed by
single-crystal X-ray analyses, and are shown in Fig. 1 and 2,
respectively. Key structural data are compiled in Table 1 for
N(Me)CH2CH2CH2N(Me)] (2a).
5
comparison. The Ti atom in both complexes is g -bound to the
five-membered ring of the cyclopentadienyl group, r-bound to
a carborane cage atom, and two nitrogen atoms in a distorted-
˚
tetrahedral geometry. The average Ti–Cring distances of 2.336(8) A
˚
˚
in 1a and 2.367(3) A in 2a, the Ti–Ccage distances of 2.173(8) A
˚
in 1a and 2.199(3) A in 2a, the average Ti–N distances of
1.869(6) A in 1a and 1.882(2) A in 2a are very comparable to each
other. These measured values are close to those of 2.369(3) A,
˚
˚
˚
5
˚
˚
2.209(2) A, and 1.894(2) A observed in their parent complex [g :r-
Me2C(C5H4)(C2B10H10)]Ti(NMe2)2,8 and other titanium amides.7
The Cring–C–Ccage angles of 109.6(7)◦ in 1a and 108.4(3)◦ in
2a, the Cent–Ti–Ccage angles of 105.9◦ in 1a and 105.3◦ in
2a are very similar to the corresponding values of 108.5(2)◦
and 105.0◦ found in [g :r-Me2C(C5H4)(C2B10H10)]Ti(NMe2)2.8
5
The N–Ti–N angle of 96.2(4)◦ in 1a is, however, significantly
smaller than that of 105.6(1)◦ in 2a and 106.1(2)◦ in [g :r-
5
Me2C(C5H4)(C2B10H10)]Ti(NMe2)2.8 These data suggest that the
5
coordination geometry around the Ti atom in 2a and [g :r-
Me2C(C5H4)(C2B10H10)]Ti(NMe2)2 is almost identical, and no ring
strain is incorporated after linking two nitrogen atoms by three
methylene units.
5
2
Fig.
1
Molecular structure of [g :r-Me2C(C5H4)(C2B10H10)]Ti[g -
N(Me)CH2CH2N(Me)] (1a).
◦
˚
Table 1 Selected bond distances (A) and angles ( )
Complex (M) 1a (Ti) 2a (Ti) 3a (Ti)
2.367(3) 2.367(6)
3b (Zr)
2.502(4)
2.394
2.394(3)
4b (Zr)
2.516(6)
2.371
2.371(5)
2.217(5)
5b (Zr)
2.542(4)
6b (Zr)
2.530(6)
2.461
2.461(5)
7b (Zr)
2.515(3)
2.428
2.425(3)
8b (Zr)b
av. M–Cring
av. M–Centa
av. M–Ccage
av. M–Namide
av. M–Namine
av. M–Nimine
av. M–Nimide
av. M–Nnitrile
2.336(8)
2.497(11)
2.203
2.341(9)
2.024
2.173(8)
1.869(6)
2.207
2.199(3)
1.882(2)
2.285
2.285(5)
2.439
2.439(3)
2.090(3)
2.403(3)
2.408(3)
2.265(3)
2.075(4), 2.279(4)
2.443(5)
2.112(5)
2.236(3)
2.212(2)
1.958(9)
2.320(5)
Cent–M–Ccage 105.9
105.3
108.4(3)
105.6(1)
103.2
109.1(4)
118.0(2)
100.6
110.9(2)
118.6(1)
98.1
109.2(5)
93.7(2)
96.3
110.4(3)
96.8
109.9(4)
100.1
110.9(2)
116.9(1)
99.7
110.5(8)
105.8(3)
Cring–C–Ccage
N–M–N
109.6(7)
96.2(4)
a Cent: the centroid of the cyclopentadienyl ring. b Average values of the two crystallographically independent molecules in the unit cell.
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 1454–1464 | 1455
©

View Article Online
Reactivity
Reaction of 1a,b or 2b,c with
2 equiv. of XyNC (2,6-
Me2C6H3NC) in toluene at room temperature gave the diinser-
5
2
2
=
tion products [g :r-Me2C(C5H4)(C2B10H10)]M[g :g -XyN( C)-
=
N(Me)(CH2)nN(Me)(C )NXy] (3a, M = Ti, n = 2; 3b, M =
Zr, n = 2; 7b, M = Zr, n = 3; 7c, M = Hf, n = 3) in 58–70%
isolated yields. Only diinsertion products were isolated in the
presence of 1 or more equiv. of XyNC (Schemes 3–5). The results
showed that XyNC molecules inserted exclusively into the M–N
bond giving ring expansion products, and the M–Ccage bond
remained intact regardless of the ring size of the metallacycles.
They were characterized by various spectroscopic techniques and
=
elemental analyses. The unique N–C N resonance at ∼205 ppm
was observed in the 13C NMR spectra of the insertion products.
Single-crystal X-ray analyses confirmed the molecular structures
of 3a,b and 7b, and showed half a molecule of benzene of
solvation for both 3a,b. Complexes 3a,b are isostructural and
isomorphous. Fig. 3 and 4 show the representative structures of 3a
and 7b, respectively. In these structures, the central metal atom is
5
coordinated by an g -cyclopentadienyl ligand, a cage carbon atom
2
and two g -iminocarbamoyl ligands in a five-legged piano stool
geometry. As indicated in Table 1, the key structural parameters
5
2
2
Fig. 4 Molecular structure of [g :r-Me2C(C5H4)(C2B10H10)]Zr[g :g -
=
=
XyN CN(Me)(CH2)3N(Me)C NXy] (7b).
in 3b and 7b are very similar, and are agreeably comparable with
7
2
˚
˚
the literature data. The average Zr–C(sp ) distances [2.162(3) A
2
˚
˚
in 3b and 2.190(3) A in 7b] and Zr–N(sp ) distances [2.236(3) A
in 3b and 2.212(2) A in 7b] are close to the corresponding values
˚
˚
of 2.259(4) A and 2.221(3) A in Zr(NMeCyc)2[C(NAr)NMeCyc]2
(Cyc = cyclohexyl, Ar = 2,6-dimethylphenyl),10a 2.209(8) A and
˚
5
10b
˚
=
2.143(6)
A in (g -C9H6)Zr[C(NMe2) N(2,6-Me2C6H3)]2Cl.
2
2
˚
˚
The average Ti–C(sp ) (2.033(6) A) and Ti–N(sp ) (2.111(5) A)
distances are close to the corresponding values of 2.061(5)
Scheme 3
5
2
˚
and 1.955(4)
A
in [g :r-Me2C(C5H4)(C2B10H10)]Ti(Cl)[g -
3
˚
˚
=
C(NMe2) N(C6H3Me2-2,6)], 2.032(5) A and 1.982(4) A in
(g -C9H6)Ti[C(NMe2) N(2,6-Me2Ph)]Cl2.
Treatment of 1b with 1 or 2 equiv. of PhNCO in DME
5
10b
=
(dimethoxyethane) at room temperature afforded a diinser-
5
2
2
tion product {[g :r-Me2C(C5H4)(C2B10H10)]Zr[l-g :g -OCN(Ph)-
N(Me)CH2CH2(Me)N(Ph)NCO]}2 (4b) in 69% isolated yield
=
(Scheme 4). A characteristic N–C O resonance at 156.1 ppm
was observed in the 13C NMR spectrum of 4b. Unlike [g :r-
5
Me2A(C9H6)(C2B10H10)]Zr[g -N(Ph)C(NMe2)O]2 (A = Me2C,1
2
Me2Si,1 iPr2NP2), 4b did not show any activity toward Ph-
NCO. The reasons are presumably owing to the steric effects
imposed by the very crowded coordination environments around
the Zr atom in 4b, which may also lead to the formation of
the dinuclear complex bearing an 18-membered metallacyclic
ring. Such a dimeric structure was confirmed by a single-crystal
5
diffraction study. Each Zr atom is g -bound to a cyclopentadienyl
ring, g -bound to each of two OC(NMeR)NPh moieties and r-
2
bound to a cage carbon atom in a five-legged piano stool geometry
˚
(Fig. 5). The average Zr–Cring distance of 2.516(6) A and Zr–
˚
Ccage distance of 2.371(5) A are very close to the corresponding
values found in 3b. The average Zr–N/O distance of 2.217(5)/
5
2
2
˚
˚
˚
2.196(4) A compare well with the 2.242(3)A/2.165(3) A ob-
Fig.
3
=
Molecular structure of [g :r-Me2C(C5H4)(C2B10H10)]Ti[g :g -
5
2
1
=
XyN CN(Me)(CH2)2N(Me)C NXy] (3a).
served in [g :r-Me2C(C9H6)(C2B10H10)]Zr[g -N(Ph)C(NMe2)O]2
1456 | Dalton Trans., 2008, 1454–1464
This journal is The Royal Society of Chemistry 2008
©

View Article Online
Scheme 4
5
2
2
Fig. 5 Molecular structure of {[g :r-Me2C(C5H4)(C2B10H10)]Zr[l-g :g -OCN(Ph)N(Me)CH2CH2(Me)N(Ph)NCO]}2 (4b).
5
2
and 2.186(4)/2.161(3) in [g :r-iPr2NP(C9H6)(C2B10H10)]Zr[g -
expansion reaction led to the formation of a 20-membered
metallacyclic ring. Its 13C NMR spectrum exhibited a unique
2
2
=
OCN(Ph)][g -OC(NMe2)N(Ph)C (NPh)O].
Reaction of 2b with 2 equiv. of PhCN in DME at room
=
N C–N resonance at 163.4 ppm. As shown in Fig. 6, each
Zr atom is coordinated by an g -cyclopentadienyl ring, a cage
5
5
temperature generated a diinsertion dimeric complex {[g :r-
=
Me2C(C5H4)(C2B10H10)]Zr[l-N C(Ph)N(Me)(CH2)3N(Me)(Ph)-
carbon atom and two nitrogen atoms in a four-legged piano
˚
=
C N]}2 (8b) in 64% isolated yield (Scheme 5). Such a ring
stool geometry. The average Zr–N distance of 1.958(9) A is
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 1454–1464 | 1457
©

View Article Online
5
=
=
Fig. 6 Molecular structure of {[g :r-Me2C(C5H4)(C2B10H10)]Zr[l-N C(Ph)N(Me)(CH2)3N(Me)(Ph)C N]}2 (8b), showing one of the two crystallo-
graphically independent molecules in the unit cell.
=
NHC(CH3) CHC≡N]}2 (6b) in 42% isolated yield (Scheme 4).
The NMR data were not obtainable due to the insolubility of
6b in organic solvents. Its composition and molecular structure
were unambiguously confirmed by elemental analyses and single-
crystal X-ray analyses. As shown in Fig. 7, each Zr atom is coor-
5
dinated to an g -cyclopentadienyl ring, a cage carbon atom and
four nitrogen atoms in a five-legged piano stool geometry. A much
˚
shorter Zr–N(1) distance of 2.075(4) A over the Zr–N(2) distance
˚
of 2.443(5) A and the planar geometry of N(1) suggest that N(1)
is the amido nitrogen and N(2) is the amino nitrogen. The Zr–
˚
N(3)/N(4) distances of 2.279(4)/2.320(5) A, C(28)–N(4)/C(27)
˚
distances of 1.149(7)/1.387(8) A and C(25)–N(3)/C(27) distances
˚
of 1.316(7)/1.392(7) A as well as the planarity of the N(4)–
C(28)–C(27A)–C(25A)–N(3A) fragment indicated some electron
delocalization over such a unit. These structural data imply that
the N(3) atom is best described as an amido nitrogen formed via
a 1,3-proton shift. Scheme 6 shows a possible reaction pathway
for the formation of 6b. Acid–base reaction between 1b and
CH3CN gives the intermediate A which contains Zr–Calkyl, Zr–
Ccage and Zr–N bonds. The second equivalent of CH3CN inserts
into the Zr–Calkyl bond to afford the monoinsertion species B/Bꢀ,
which dimerizes to form the final product 6b. This result suggests
that the reactivity follows the order: Zr–Calkyl > Zr–N >>
Zr–Ccage
Complex 1b reacted with TMS–N C N–TMS in toluene
at room temperature to afford desilylation product
.
= =
a
5
2
{[g :r-Me2C(C5H4 )(C2B10H10 )]Zr[g -N(Me)(CH2 )2NH(Me)][l-
= =
TMSN C N]}2 (5b) in 53% isolated yield (Scheme 4). This com-
plex was fully characterized by various spectroscopic techniques.
A unique N C N resonance at 125.1 ppm was observed in its 13C
= =
NMR spectrum. As shown in Fig. 8, the coordination environment
Scheme 5
of the Zr atom in 5b is very similar to that observed in 6b.
The C(26)–N(4)/N(3) distances of 1.167(4)/1.286(4) A and the
˚
˚
= =
linearity of the N(3)–C(26)–N(4) unit suggest that the N C N
moiety remains in the product, which is consistent with the NMR
close to the corresponding value of 1.972(2) A observed in
5
1
=
[g :r-Me2C(C9H6)(C2B10H10)]Zr[N C(Ph)NMe2]2.
On the other hand, interaction of 1b with 2 equiv. of CH3CN
˚
results. The Zr–N(1)/N(2) distances of 2.403(3)/2.090(3) A and
the planarity of N(1) indicate that N(1) is the amido nitrogen and
N(2) is the amino nitrogen.
in DME at room temperature gave an unexpected product
{[g :r-Me2C(C5H4 )(C2B10H10 )]Zr[g -N(Me)(CH2 )2NH(Me)][l-
5
2
1458 | Dalton Trans., 2008, 1454–1464
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
5
2
=
Fig. 7 Molecular structure of {[g :r-Me2C(C5H4)(C2B10H10)]Zr[g -N(Me)(CH2)2NH(Me)][l-NHC(CH3) CHC≡N]}2 (6b).
Scheme 6
= =
It is noteworthy that 2b did not react with TMS–N C N–TMS
even in refluxing toluene, indicating that the coordinated Me2NH
Scheme 7
in 1b played a role in the desilylation process. Scheme 7 shows a
proposed mechanism for the formation of 5b.
show that unsaturated molecules insert exclusively into the M–
N bonds to give the ring expansion products, and the M–Ccage
bond remains intact. These results suggest that the inertness of
the M–Ccage bond toward unsaturated molecules is best ascribed
Conclusion
Group 4 metallacycles can be conveniently prepared via amine ex-
change reaction of [g :r-Me2C(C5H4)(C2B10H10)]M(NMe2)2 with
diamines HN(Me)(CH2)nN(Me)H (n = 2, 3) in toluene. The
formation of volatile Me2NH and the chelate effect of the diamido
ligands are the driving forces of the reactions. Reactivity studies
to the steric effect of the cage, and the mobility of the migratory
groups may not play a role in the insertion reactions. This work
also shows that insertion of unsaturated molecules into the M–N
bonds in metallacycles is a useful and effective method for the
construction of large ring systems.
5
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 1454–1464 | 1459
©

View Article Online
5
2
=
=
N]}2 (5b).
Fig. 8 Molecular structure of {[g :r-Me2C(C5H4)(C2B10H10)]Zr[g -N(Me)(CH2)2NH(Me)][l-TMSN
C
not observed. 11B NMR (128 MHz, C6D6): d −3.2 (2B), −6.2 (2B),
−9.7 (4B), −12.3 (2B). IR (KBr, cm−1): m 2576 (vs) (B–H). Anal.
calcd for C14H30B10N2Ti: C, 43.97; H, 7.91; N, 7.33. Found: C,
43.88; H, 8.34; N, 7.10%.
Experimental
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 heated to reflux over sodium ben-
zophenone for several days and freshly distilled prior to use.
Preparation of [g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2-N(Me)-
CH2CH2N(Me)](HNMe2) (1b). To
a
toluene (15 mL)
5
solution of [g :r-Me2C(C5H4)(C2B10H10)]Zr(NMe2)2 (214 mg,
0.5 mmol) was added dropwise a toluene (8 mL) solution of
MeNHCH2CH2NHMe (49 mg, 0.6 mmol) at −30 ◦C with stirring.
The mixture was warmed to room temperature and stirred for
20 min. After filtration, the resulting orange-red solution was
concentrated under vacuum to about 5 mL, to which was added
5 mL of n-hexane. Complex 1b was isolated as an orange solid
after this solution had stood at −30 ◦C for 2 d (173 mg, 73%). 1H
NMR (300 MHz, C6D6): d 5.98 (d, J = 1.8 Hz, 1H), 5.59 (brs,
1H), 5.44 (brs, 1H), 5.34 (brs, 1H) (C5H4), 2.88 (s, 6H) (N(CH3)),
2.67 (m, 4H) (NCH2), 1.73 (d, J = 6.0 Hz, 6H) (NH(CH3)2),
1.44 (s, 3H), 1.42 (s, 3H) (C(CH3)2). 13C NMR (75 MHz, C6D6):
d 146.2, 113.4, 110.4, 107.5 (C5H4), 56.4, 52.4 (NCH2), 46.9,
42.8 (N(CH3)), 41.7 (C(CH3)2), 37.9, 32.2 (C(CH3)2), 33.4
(NH(CH3)2), the cage carbons were not observed. 11B NMR
(128 MHz, C6D6): d −2.1 (1B), −3.1 (1B), −4.6 (1B), −5.2 (1B),
−9.0 (3B), −11.1 (3B). IR (KBr, cm−1): m 2552 (vs) (B–H). Anal.
calcd for C14H30B10N2Zr [1b–Me2NH]: C, 39.50; H, 7.10; N, 6.58.
Found: C, 39.76; H, 7.62; N, 6.68%.
5
[g :r-Me2C(C5H4)(C2B10H10)]M(NMe2)2 (M = Ti, Zr, Hf) were
prepared according to the literature method.8 All chemicals were
purchased from either Aldrich or Acros Chemical Co. and used
as received unless otherwise noted. IR spectra were obtained from
KBr pellets prepared in the glovebox on a Perkin-Elmer 1600
Fourier transform spectrometer. H and 13C NMR spectra were
1
recorded on a Bruker DPX 300 spectrometer at 300 and 75 MHz,
respectively. 11B NMR spectra were recorded on a Varian Inova
400 spectrometer at 128 MHz. All chemical shifts were reported
in d units with reference to the residual solvent resonances of
the deuterated solvents for proton and carbon chemical shifts,
and to external BF3·OEt2 (d = 0.00 ppm) for boron chemical
shifts. Elemental analyses were performed by Shanghai Institute
of Organic Chemistry, The Chinese Academy of Sciences, China.
Syntheses
Prepartion of [g5:r-Me2C(C5H4)(C2B10H10)]Ti[g2-N(Me)CH2-
CH2N(Me)] (1a). To a toluene (15 mL) solution of [g :r-
Me2C(C5H4)(C2B10H10)]Ti(NMe2)2 (191 mg, 0.5 mmol) was added
dropwise a toluene (8 mL) solution of MeNHCH2CH2NHMe
(220 mg, 2.5 mmol) at 0 ◦C with stirring. The mixture was
5
Preparation of [g5:r-Me2C(C5H4)(C2B10H10)]Ti[g2-N(Me)-
CH2CH2CH2N(Me)] (2a). To a toluene (15 mL) solution of
5
[g :r-Me2C(C5H4)(C2B10H10)]Ti(NMe2)2 (191 mg, 0.5 mmol) was
◦
warmed to room temperature and then heated at 60 C for 2 d.
added dropwise a toluene (8 mL) solution of MeNH(CH2)3NHMe
(153 mg, 1.5 mmol) at 0 ◦C with stirring. The mixture was warmed
to room temperature and heated at 90 ◦C for 2 d. After filtration,
the resulting red solution was concentrated under vacuum to
about 8 mL. Complex 2a was isolated as orange-red crystals after
this solution had stood at room temperature for 3 d (124 mg,
After filtration, the resulting red solution was concentrated under
vacuum to about 5 mL. Complex 1a was isolated as red crystals
after this solution had stood at room temperature for 1 d (129 mg,
1
68%). H NMR (300 MHz, C6D6): d 5.55 (brs, 2H), 5.43 (brs,
2H) (C5H4), 3.49 (d, J = 9.0 Hz, 2H), 3.25 (d, J = 9.0 Hz, 2H)
(NCH2), 2.62 (s, 6H) (N(CH3)), 1.44 (s, 6H) (C(CH3)2). 13C NMR
(75 MHz, C6D6): d 135.4, 112.2, 109.2 (C5H4), 57.6 (NCH2), 50.4
(N(CH3)), 42.4 (C(CH3)2), 31.9 (C(CH3)2), the cage carbons were
1
64%). H NMR (300 MHz, C6D6): d 5.47 (m, 4H) (C5H4), 3.12
(m, 2H), 2.86 (m, 2H) (NCH2), 2.69 (s, 6H) (N(CH3)), 1.59 (m,
2H) (CH2CH2CH2), 1.43 (s, 6H) (C(CH3)2). 13C NMR (75 MHz,
1460 | Dalton Trans., 2008, 1454–1464
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
C6D6): d 149.5, 112.4, 110.0 (C5H4), 62.6 (NCH2), 48.7 (N(CH3)),
42.0 (C(CH3)2), 31.9 (C(CH3)2), 31.2 (CH2CH2CH2), the cage
carbons were not observed. 11B NMR (128 MHz, C6D6): d −2.6
(2B), −5.6 (2B), −8.9 (4B), −11.7 (2B). IR (KBr, cm−1): m 2598
(vs), 2565 (vs), 2540 (vs) (B–H). Anal. calcd for C15H32B10N2Ti:
C, 45.45; H, 8.14; N, 7.07. Found: C, 44.92; H, 7.95; N, 7.26%.
33.2 (C(CH3)2), 21.3, 20.5 (C6H3(CH3)2), the cage carbons were
not observed. 11B NMR (128 MHz, pyridine-d5): d −3.9 (2B),
−5.9 (2B), −9.2 (3B), −10.3 (2B), −13.4 (1B). IR (KBr, cm−1):
m 2598 (vs), 2538 (vs) (B–H). Anal. calcd for C32H48B10N4Ti: C,
59.61; H, 7.50; N, 8.69. Found: C, 59.88; H, 7.65; N, 8.40%.
Preparation
of
[g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2:g2-
Preparation of [g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2-N(Me)-
CH2CH2CH2N(Me)] (2b). To a toluene (15 mL) solution of
[g :r-Me2C(C5H4)(C2B10H10)]Zr(NMe2)2 (214 mg, 0.5 mmol) was
=
=
XyN CN(Me)(CH2)2N(Me)C NXy]
(3b). This
complex
was prepared as colorless crystals from 1b (235 mg, 0.5 mmol)
and XyNC (131 mg, 1.0 mmol) in toluene using an identical
procedure to that reported for 3a: yield 247 mg (68%). Crystals
suitable for X-ray analyses were grown from a benzene–THF
solution at room temperature. 1H NMR (300 MHz, pyridine-d5):
d 7.08 (m, 6H) (C6H3), 6.05 (m, 4H) (C5H4), 3.87 (dd, J = 8.4
and 7.2 Hz, 2H), 3.36 (m, 2H) (NCH2), 2.51 (s, 6H) (NCH3),
2.29 (s, 6H), 1.91 (s, 6H) (C6H3(CH3)2), 1.71 (s, 6H) (C(CH3)2).
13C NMR (75 MHz, pyridine-d5): d 207.4 (C=N), 146.8, 146.7,
130.9, 130.7, 128.9, 127.5, 127.3, 124.0, 121.4 (aryl C), 105.5,
102.4 (C5H4), 54.7 (NCH2), 42.0 (C(CH3)2), 35.1 (NCH3), 32.6
(C(CH3)2), 19.6, 18.8 (C6H3(CH3)2), the cage carbons were not
observed. 11B NMR (128 MHz, pyridine-d5): d −3.3 (2B), −5.3
(2B), −9.1 (5B), −13.3 (1B). IR (KBr, cm−1): m 2554 (vs) (B–H).
Anal. calcd for C32H48B10N4Zr: C, 55.86; H, 7.03; N, 8.14. Found:
C, 55.40; H, 7.39; N, 7.86%.
5
added dropwise a toluene (8 mL) solution of MeNH(CH2)3NHMe
(56 mg, 0.55 mmol) at 0 ◦C with stirring. The mixture was warmed
to room temperature and stirred overnight. After filtration, the
resulting yellow solution was concentrated under vacuum to
about 8 mL. Complex 2b was isolated as yellow crystals after this
solution had stood at room temperature for 2 d (179 mg, 82%). 1H
NMR (300 MHz, C6D6): d 5.66 (d, J = 2.7 Hz, 2H), 5.61 (d, J =
2.7 Hz, 2H) (C5H4), 2.90 (m, 4H) (NCH2), 2.66 (s, 6H) (N(CH3)),
1.97 (m, 2H), (CH2CH2CH2), 1.40 (s, 6H) (C(CH3)2). 13C NMR
(75 MHz, C6D6): d 146.4, 113.0, 109.3 (C5H4), 57.3 (NCH2), 46.0
(N(CH3)), 42.5 (C(CH3)2), 32.6 (C(CH3)2), 27.4 (CH2CH2CH2),
the cage carbons were not observed. 11B NMR (128 MHz, C6D6):
d −2.3 (2B), −5.1 (2B), −8.6 (2B), −9.2 (2B), −11.9 (2B). IR
(KBr, cm−1): m 2562 (vs) (B–H). Anal. calcd for C15H32B10N2Zr: C,
40.97; H, 7.33; N, 6.37. Found: C, 40.99; H, 7.74; N, 6.13%.
Preparation of [g5:r-Me2C(C5H4)(C2B10H10)]Hf[g2-N(Me)-
CH2CH2CH2N(Me)] (2c). This complex was prepared as yellow
crystals from [g :r-Me2C(C5H4)(C2B10H10)]Hf(NMe2)2 (258 mg,
Preparation of {[g5:r-Me2C(C5H4)(C2B10H10)]Zr[l-g2:g2-OCN-
(Ph)N(Me)CH2CH2(Me)N(Ph)NCO]}2 (4b). To a DME (30 mL)
solution of 1b (235 mg, 0.5 mmol) was added dropwise a DME
(10 mL) solution of PhNCO (112 mg, 1.0 mmol) at −30 ◦C with
stirring. The mixture was warmed to room temperature and stirred
for 10 min. After filtration, the resulting pale yellow solution was
concentrated under vacuum to about 30 mL. Complex 4b was
isolated as colorless crystals after this solution had stood at room
temperature for 2 d (228 mg, 69%). 1H NMR (300 MHz, pyridine-
d5): d 9.13 (brs, 2H), 7.98 (d, J = 7.8 Hz, 6H), 7.64 (dd, J = 7.8 and
6.9 Hz, 8H), 7.03 (dd, J = 7.8 and 6.9 Hz, 4H) (C6H5), 6.62–6.17
(m, 8H) (C5H4), 3.57 (brs, 8H) (NCH2), 3.06 (s, 12H) (N(CH3)),
1.44 (s, 12H) (C(CH3)2). 13C NMR (75 MHz, pyridine-d5): d 156.1
5
0.5 mmol) and MeNH(CH2)3NHMe (56 mg, 0.55 mmol) in
toluene using an identical procedure to that reported for 2b:
1
yield 214 mg (82%). H NMR (300 MHz, C6D6): d 5.59 (d, J =
2.1 Hz, 2H), 5.57 (d, J = 2.1 Hz, 2H) (C5H4), 3.01 (m, 4H)
(NCH2), 2.75 (s, 6H) (N(CH3)), 1.78 (m, 2H) (CH2CH2CH2),
1.38 (s, 6H) (C(CH3)2). 13C NMR (75 MHz, C6D6): d 145.8, 112.0,
108.7 (C5H4), 57.8 (NCH2), 45.1 (N(CH3)), 42.0 (C(CH3)2),
32.5 (C(CH3)2), 28.2 (CH2CH2CH2), the cage carbons were not
observed. 11B NMR (128 MHz, C6D6): d −1.4 (1B), −2.1 (1B),
−4.9 (2B), −8.9 (4B), −12.0 (2B). IR (KBr, cm−1): m 2566 (vs)
(B–H). Anal. calcd for C15H32B10N2Hf: C, 34.18; H, 6.12; N, 5.32.
Found: C, 34.11; H, 6.57; N, 4.78%.
=
(N–C O), 140.9, 132.0, 129.1, 128.7, 128.3, 128.0, 121.9, 120.1
(aryl C + C5H4), 57.9 (NCH2), 46.9 (NCH3), 40.7 (C(CH3)2),
34.9, 29.9 (C(CH3)2), the cage carbons were not observed. 11B
NMR (128 MHz, pyridine-d5): d −3.7 (6B), −9.0 (4B), −11.2
(4B), −13.3 (6B). IR (KBr, cm−1): m 2549 (vs) (B–H). Anal. calcd
for C56H80B20N8O2Zr2: C, 50.65; H, 6.07; N, 8.44. Found: C, 50.42;
H, 6.40; N, 8.24%.
Preparation
of
[g5:r-Me2C(C5H4)(C2B10H10)]Ti[g2:g2-
=
=
XyN CN(Me)(CH2)2N(Me)C NXy] (3a). To
a
toluene
(15 mL) solution of 1a (190 mg, 0.5 mmol) was added dropwise
a toluene (8 mL) solution of XyNC (2,6-Me2C6H3NC) (131 mg,
◦
1.0 mmol) at −30 C with stirring. The mixture was warmed to
room temperature and stirred overnight. After filtration, the white
solid was collected and redissolved in THF (20 mL). The resulting
pale-yellow solution was concentrated to about 8 mL. Complex
3a was isolated as yellow crystals after this solution had stood
at room temperature for 2 d (225 mg, 66%). Crystals suitable
for X-ray analyses were grown from a benzene–THF solution at
Preparation of {[g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2-N(Me)-
= =
(CH2)2NH(Me)][l-TMSN C N]}2 (5b). To a toluene (15 mL)
solution of 1b (235 mg, 0.5 mmol) was added dropwise a toluene
= =
(8 mL) solution of TMSN C NTMS (170 mg, 1.0 mmol) at
−30 ◦C with stirring, and the mixture was warmed to room
temperature and stirred overnight. After filtration, the resulting
clear orange solution was concentrated under vacuum to about
10 mL. Complex 5b was isolated as yellow crystals after this
solution had stood at room temperature for 5 d (142 mg, 53%).
1H NMR (300 MHz, pyridine-d5): d 6.65 (d, J = 2.7 Hz, 1H),
6.46 (d, J = 2.7 Hz, 1H), 5.88 (d, J = 2.7 Hz, 1H), 5.18 (d, J =
2.7 Hz, 1H) (C5H4), 3.61 (m, 2H), 3.18 (m, 2H) (CH3NCH2),
1
room temperature. H NMR (300 MHz, pyridine-d5): d 7.09 (m,
6H) (C6H3), 5.85 (d, J = 2.4 Hz, 2H), 5.83 (d, J = 2.4 Hz, 2H)
(C5H4), 3.81 (dd, J = 8.4 and 7.2 Hz, 2H), 3.38 (m, 2H) (NCH2),
2.53 (s, 6H) (N(CH3)), 2.27 (s, 6H), 1.94 (s, 6H) (C6H3(CH3)2),
1.72 (s, 6H) (C(CH3)2). 13C NMR (75 MHz, pyridine-d5): d 203.9
=
(C N), 148.2, 147.5, 133.0, 132.6, 129.0, 128.4, 125.4 (aryl C),
105.4, 103.0 (C5H4), 53.7 (NCH2), 42.3 (C(CH3)2), 36.8 (NCH3),
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 1454–1464 | 1461
©

View Article Online
3.40 (s, 6H) (N(CH3)), 2.64 (m, 4H) (CH3NHCH2), 2.33 (d, J =
5.7 Hz, 6H) (NHCH3), 1.59 (s, 6H), 1.45 (s, 6H) (C(CH3)2),
0.44 (s, 18H) (Si(CH3)3). 13C NMR (75 MHz, pyridine-d5): d
C, 56.45; H, 7.18; N, 7.98. Found: C, 56.71; H, 6.96;
N, 7.62%.
Preparation
of
[g5:r-Me2C(C5H4)(C2B10H10)]Hf[g2:g2-
= =
144.1 (C5H4), 125.1 (N C N), 117.6, 113.0, 112.1, 110.0 (C5H4),
=
=
XyN CN(Me)(CH2)3N(Me)C NXy]
(7c). This
complex
103.8, 102.4 (cage C), 59.6 (CH3NCH2), 51.9 (CH3NHCH2), 50.6
(N(CH3)), 39.5 (NH(CH3)), 40.7 (C(CH3)2), 27.6, 26.3 (C(CH3)2),
2.0 (Si(CH3)3). 11B NMR (128 MHz, pyridine-d5): d −3.4 (6B),
−6.3 (6B), −9.2 (8B). IR (KBr, cm−1): m 2556 (vs) (B–H). Anal.
calcd for C32H68B20N6Si2Zr2 (5b–C4H12N2): C, 38.75; H, 6.91; N,
8.47. Found: C, 39.18; H, 6.94; N, 7.95%.
was prepared as colorless crystals from 2c (257 mg, 0.5 mmol)
and XyNC (131 mg, 1.0 mmol) in toluene solution using an
identical procedure to that reported for 3a: yield 231 mg (58%).
1H NMR (300 MHz, pyridine-d5): d 7.04 (m, 6H) (C6H3), 6.21
(brs, 2H), 5.96 (brs, 2H) (C5H4), 3.76 (brs, 2H), 3.18 (brs, 2H)
(NCH2), 2.45 (s, 6H) (NCH3), 2.15 (m, 2H) (CH2CH2CH2), 2.03
(s, 6H), 1.58 (s, 6H) (C6H3(CH3)2), 1.68 (s, 6H) (C(CH3)2). The
13C NMR was not obtainable due to very poor solubility. 11B
NMR (128 MHz, pyridine-d5): d −3.0 (2B), −5.2 (2B), −8.9 (4B),
−10.2 (2B). IR (KBr, cm−1): m 2598 (vs), 2544 (vs) (B–H). Anal.
calcd for C33H50B10N4Hf: C, 50.21; H, 6.38; N, 7.10. Found: C,
50.55; H, 6.32; N, 6.59%.
Preparation of {[g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2-N(Me)-
=
(CH2)2NH(Me)][l-NHC(CH3) CHC≡N]}2 (6b). This complex
was prepared as yellow crystals from 1b (235 mg, 0.5 mmol) and
CH3CN (62 mg, 1.5 mmol) in DME using an identical procedure
to that reported for 4b: yield 106 mg (42%). NMR data were
not obtainable since the crystals were not soluble in any organic
solvents. IR (KBr, cm−1): m 3788 (w), 3719 (w), 3272 (w), 2903 (m),
2550 (vs) (B–H), 2328 (w), 2166 (s), 1625 (w), 1521 (s), 1048 (m),
1005 (m), 803 (m). Anal. calcd for C36H72B20N8Zr2: C, 42.57; H,
7.15; N, 11.03. Found: C, 42.95; H, 7.32; N, 10.61%.
5
=
Preparation of {[g :r-Me2C(C5H4)(C2B10H10)]Zr[l-N C(Ph)-
=
N(Me)(CH2)3N(Me)(Ph)C N]}2 (8b). This complex was pre-
pared as pale-yellow crystals from 2b (220 mg, 0.5 mmol) and
PhCN (104 mg, 1.0 mmol) in DME using an identical procedure
to that reported for 4b: yield 206 mg (64%). Crystals suitable
for X-ray analyses were grown from a THF solution at room
temperature. 1H NMR (300 MHz, pyridine-d5): d 7.42 (m, 12H),
6.82 (brs, 8H) (C6H5), 6.16 (brs, 4H), 4.92 (brs, 4H) (C5H4),
2.98 (m, 8H) (NCH2), 2.77 (s, 12H) (NCH3), 1.98 (m, 2H)
(CH2CH2CH2), 1.56 (s, 12H) (C(CH3)2). 13C NMR (75 MHz,
Preparation
of
[g5:r-Me2C(C5H4)(C2B10H10)]Zr[g2:g2-
=
=
XyN CN(Me)(CH2)3N(Me)C NXy]
(7b). This
complex
was prepared as colorless crystals from 2b (220 mg, 0.5 mmol) and
XyNC (131 mg, 1.0 mmol) in toluene solution using an identical
procedure to that reported for 3a: yield 222 mg (63%). 1H NMR
(300 MHz, pyridine-d5): d 7.08 (m, 6H) (C6H3), 6.25 (brs, 2H),
6.01 (brs, 2H) (C5H4), 3.80 (m, 2H), 3.20 (m, 2H) (NCH2), 2.47
(s, 6H) (N(CH3)), 2.24 (s, 6H), 2.18 (m, 2H) (CH2CH2CH2), 1.99
(s, 6H) (C6H3(CH3)2), 1.68 (s, 6H) (C(CH3)2). The 13C NMR was
not obtainable due to very poor solubility. 11B NMR (128 MHz,
pyridine-d5): d −3.2 (2B), −5.4 (2B), −9.0 (6B). IR (KBr, cm−1): m
2593 (vs), 2547 (vs) (B–H). Anal. calcd for C33H50B10N4Zr:
=
pyridine-d5): d 163.4 (N–C N), 144.5, 140.6, 140.4, 127.9, 126.4,
110.1, 109.2, 108.8, 106.5 (aryl C + C5H4), 103.2, 100.6 (cage C),
71.4 (NCH2), 57.9 (N(CH3)), 41.6 (C(CH3)2), 32.5 (C(CH3)2), 26.6
(CH2CH2CH2). 11B NMR (128 MHz, pyridine-d5): d −3.2 (6B),
−5.5 (6B), −9.2 (8B). IR (KBr, cm−1): m 2558 (vs) (B–H). Anal.
calcd for C61H90B20N8O0.75Zr2 [8b + 0.75THF]: C, 54.43; H, 6.74;
N, 8.32. Found: C, 54.75; H, 6.62; N, 8.14%.
Table 2 Crystal data and summary of data collection and refinement for 1a, 2a, 3a·0.5C6H6 and 3b·0.5C6H6
1a
2a
3a·0.5C6H6
3b·0.5C6H6
Formula
Crystal size/mm
Mr
C14H30B10N2Ti
0.50 × 0.50 × 0.40
382.4
C15H32B10N2Ti
0.40 × 0.30 × 0.20
396.4
C35H51B10N4Ti
0.40 × 0.30 × 0.20
683.8
C35H51B10N4Zr
0.40 × 0.30 × 0.20
727.1
Crystal system
Space group
Trigonal
R3m
25.806(4)
25.806(4)
9.888(2)
90
90
120
5702.7(16)
9
1.002
Trigonal
R3m
26.045(1)
26.045(1)
9.844(1)
90
90
120
5782.8(7)
9
1.025
Monoclinic
P21/n
10.500(2)
17.092(3)
21.352(4)
90
98.56(3)
90
3789.5(13)
4
Monoclinic
P21/n
10.472(1)
17.389(2)
21.659(3)
90
98.68(3)
90
3898.8(9)
4
˚
a/A
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
3
˚
V/A
Z
Dc/Mg m−3
1.199
0.71073
50.0
1.239
0.71073
56.6
˚
Radiation (k(Mo-Ka))/A
0.71073
50.0
0.339
0.71073
56.0
0.336
◦
2hmax
/
l/mm−1
0.257
0.313
F(000)
1800
3637
1271
133
1872
13291
2843
139
0.973
0.045
1444
7069
6681
451
0.968
0.072
1516
26972
9663
451
1.014
0.045
Measured reflections
Observed reflections [I > 2r (I)]
Parameters
Goodness of fit on F2
R(int)
0.956
0.058
Final R indices [I > 2r (I)]
R1 = 0.054, wR2 = 0.131 R1 = 0.043, wR2 = 0.105 R1 = 0.071, wR2 = 0.174 R1 = 0.049, wR2 = 0.119
1462 | Dalton Trans., 2008, 1454–1464
This journal is The Royal Society of Chemistry 2008
©

View Article Online
Table 3 Crystal data and summary of data collection and refinement for 4b, 5b, 6b, 7b and 8b·0.75THF
4b
5b
6b
7b
8b·0.75THF
Formula
Crystal size/mm
Mr
C56H80B20N8O4Zr2
0.50 × 0.30 × 0.10
1327.9
Triclinic
¯
P1
10.896(2)
17.104(2)
20.437(3)
73.67(1)
80.77(1)
74.87(1)
3512.7(8)
2
C36H80B20N8Si2Zr2
0.30 × 0.20 × 0.20
1079.9
Monoclinic
P21/n
15.741(2)
10.721(1)
16.257(2)
90
101.21(1)
90
2691.0(5)
2
1.333
C36H72B20N8Zr2
0.40 × 0.30 × 0.20
1015.7
Monoclinic
P21/c
14.933(2)
9.927(1)
17.170(2)
90
93.55(1)
90
2540.3(4)
2
C33H50B10N4Zr
0.50 × 0.40 × 0.30
702.1
Monoclinic
P21/n
10.696(2)
17.369(3)
21.358(2)
90
96.45(1)
90
3942.7(10)
4
1.183
C61H90B20N8O0.75Zr2
0.40 × 0.20 × 0.20
1346.1
Monoclinic
P21/c
19.677(2)
24.137(3)
34.482(4)
90
98.69(1)
90
16189(3)
8
1.105
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
◦
a/
b/
◦
◦
c /
3
˚
V/A
Z
Dc/Mg m−3
1.255
0.71073
50.0
1.328
0.71073
50.0
˚
Radiation (k(Mo-Ka))/A
0.71073
56.0
0.469
0.71073
50.0
0.307
0.71073
50.0
0.297
◦
2hmax
/
l/mm−1
0.345
0.448
F(000)
Measured reflections
1368
19247
1120
17992
1048
13447
1464
20935
5584
86960
Observed reflections [I > 2r (I)] 12298
6500
307
1.003
0.051
4479
310
1.045
0.045
6939
433
1.070
0.036
28466
1721
0.817
0.167
Parameters
811
0.841
0.0640
Goodness of fit on F2
R(int)
Final R indices [I > 2r (I)]
R1 = 0.062, wR2 = 0.126 R1 = 0.048, wR2 = 0.117 R1 = 0.054, wR2 = 0.136 R1 = 0.036, wR2 = 0.093 R1 = 0.086, wR2 = 0.211
X-Ray structure determination
3 H. Wang, Y. Wang, H.-S. Chan and Z. Xie, Inorg. Chem., 2006, 45,
5675.
4 Z. Xie, Acc. Chem. Res., 2003, 36, 1.
All single crystals were immersed in Paraton-N oil and sealed
under N2 in thin-walled glass capillaries. Data were collected at
293 K on a Brucker SMART 1000 CCD diffractometer using Mo-
Ka radiation. An empirical absorption correction was applied
using the SADABS program.11 All structures were solved by
direct methods and subsequent Fourier difference techniques
and refined anisotropically for all non-hydrogen atoms by full-
matrix least squares calculations on F2 using the SHELXTL
program package.12 All hydrogen atoms except for the disordered
solvent molecules were geometrically fixed using the riding model.
Molecular structures of 3a,b showed half benzene of solvation.
There were two crystallographyically independent molecules in
the unit cell of 8b and three highly disordered THF molecules
with a site occupancy of 0.5, resulting in a relatively high R
value. The THF molecules were refined by means of a ‘similarity
restraint’. Crystal data and details of data collection and structure
refinements were given in Tables 2 and 3.
5 E. Hong, Y. Kim and Y. Do, Organometallics, 1998, 17, 2933.
6 Y. Han, E. Hong, Y. Kim, M. H. Lee, J. Kim, J.-W. Hwang and Y. Do,
J. Organomet. Chem., 2003, 679, 48.
7 (a) Z. Xie, Coord. Chem. Rev., 2006, 250, 259; (b) M.-S. Cheung,
H.-S. Chan and Z. Xie, Organometallics, 2005, 24, 3037; (c) M.-S.
Cheung, H.-S. Chan and Z. Xie, Organometallics, 2005, 24, 5217;
(d) M.-S. Cheung, H.-S. Chan and Z. Xie, Organometallics, 2005,
24, 4207; (e) M.-S. Cheung, H.-S. Chan, S. Bi, Z. Lin and Z. Xie,
Organometallics, 2005, 24, 4333; (f) Y.-J. Lee, J.-D. Lee, H.-J. Jeong,
K.-C. Son, J. Ko, M. Cheong and S. O. Kang, Organometallics, 2005,
24, 3008; (g) Y.-J. Lee, J.-D. Lee, J. Ko, S.-H. Kim and S. O. Kang, Chem.
Commun., 2003, 1364; (h) J. Wang, K. Vyakaranam, J. A. Maguire, W.
Quintana, F. Teixidor, C. Vin˜as and N. S. Hosmane, J. Organomet.
Chem., 2003, 680, 173; (i) Y. Wang, H. Wang, H.-W. Li and Z. Xie,
Organometallics, 2002, 21, 3311; (j) D.-H. Kim, J. H. Won, S.-J. Kim,
J. Ko, S.-H. Kim, S. Cho and S. O. Kang, Organometallics, 2001, 20,
4298; (k) Y. Zhu, K. Vyakaranam, J. A. Maguire, W. Quintana, F.
Texidor, C. Vin˜as and N. S. Hosmane, Inorg. Chem. Commun., 2001, 4,
486; (l) A. K. Hughes, A. Meetsma and J. H. Teuben, Organometallics,
1993, 12, 1936; (m) D. W. Carpenetti, L. Kloppenburg, J. T. Kupec and
J. L. Petersen, Organometallics, 1996, 15, 1572; (n) G. M. Diamond,
S. Rodewald and R. F. Jordan, Organometallics, 1995, 14, 5; (o) G.
Chandra and M. F. Lappert, J. Chem. Soc. A, 1968, 1940; (p) J. Wang,
C. Zheng, J. A. Maguire and N. S. Hosmane, Organometallics, 2003,
22, 4839; (q) T. Cuenca, in Comprehensive Organometallic Chemistry
III, ed. R. H. Crabtree and D. M. P. Mingos, Elsevier, Oxford, 2007,
vol. 4, ch. 4.05, p. 323; (r) E. Y.-X. Chan and A. Rodriguez-Delgado,
in Comprehensive Organometallic Chemistry III, ed. R. H. Crabtree
and D. M. P. Mingos, Elsevier, Oxford, 2007, vol. 4, ch. 4.08, p. 759;
(s) A. E. Guiducci, C. L. Boyd and P. Mountford, Organometallics,
2006, 25, 1167; (t) J. Zhang, R. Cai, Z. Chen and X. Zhou, Inorg.
CCDC reference numbers 665266–665274 for 1a, 2a, 3a, 3b, 4b,
5b, 6b, 7b and 8b, respectively.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b716929a
Acknowledgements
This work was supported by grants form the National Natural
Science Foundation of China and the Research Grants Council
(RGC) of Hong Kong Joint Research Scheme (Project No.
N_CUHK446/06) and RGC of Hong Kong SAR (Project No.
403805).
´
Chem., 2007, 46, 321; (u) J. Ca´mpora, I. Matas, P. Palma, E. Alvarez,
C. Graiff and A. Tiripicchio, Organometallics, 2007, 26, 3840; (v) B. D.
Ward, G. Orde, E. Clot, A. R. Cowley, L. H. Grade and P. Mountford,
Organometallics, 2005, 24, 2368; (w) F. Amor, J. Sa´nchez-Nieves, P.
Royo, H. Jacobsen, O. Blacque, H. Berke, M. Lanfranchi, M. A.
Pellinghelli and A. Tiripicchio, Eur. J. Inorg. Chem., 2002, 2810; (x) N.
Thirupathi, G. P. A. Yap and D. S. Richeson, Organometallics, 1999, 19,
2573; (y) C. K. Broder, A. E. Goeta, J. A. K. Howard, A. K. Hughes,
A. L. Johnson, J. M. Malget and K. Wade, J. Chem. Soc., Dalton Trans.,
2000, 3526.
References
1 H. Wang, H.-W. Li and Z. Xie, Organometallics, 2003, 22, 4522.
2 H. Wang, H.-S. Chan, J. Okuda and Z. Xie, Organometallics, 2005, 24,
3118.
8 H. Wang, Y. Wang, H.-W. Li and Z. Xie, Organometallics, 2001, 20,
5110.
This journal is
The Royal Society of Chemistry 2008
Dalton Trans., 2008, 1454–1464 | 1463
©

View Article Online
5
9 [g :r-Me2C(C5H4)(C2B10H10)]ZrCl2 was prepared in situ by treatment
Duarte, J. F. da Silva, L. F. Veiros and S. S. Rodrigues, Organometallics,
2003, 22, 4218.
5
of [g :r-Me2C(C5H4)(C2B10H10)]Zr(NMe2)2 with excess Me3SiCl in
toluene using the literature method, see: H. Wang, H.-W. Li, X. Huang,
Z. Lin and Z. Xie, Angew. Chem., Int. Ed., 2003, 42, 4347.
10 (a) F. Benetollo, G. Carta, G. Cavinato, L. Crociani, G. Paolucci, G.
Rossetto, F. Veronese and P. Zanella, Organometallics, 2003, 22, 3985;
(b) A. M. Martins, J. R. Ascenso, C. G. de Azevedo, A. R. Dias, M. T.
11 G. M. Sheldrick, SADABS, Program for Empirical Absorption Correc-
tion of Area Detector Data, University of Go¨ttingen, Germany, 1996.
12 G. M. Sheldrick, SHELXTL, 5.10 for Windows NT: Structure Deter-
mination Software Programs, Brucker Analytical X-ray Systems, Inc.,
Madison, WI, 1997.
1464 | Dalton Trans., 2008, 1454–1464
This journal is
The Royal Society of Chemistry 2008
©