Multiple insertion of unsaturated molecules into the Zr-N bonds of [η5:σ-Me2A(C9H6) (C2B10H10)]Zr(NMe2)2 (A = C, Si)

Article abstract of DOI:10.1021/om0304255

The compounds [η⁵:σ-Me₂A(C₉H₆) (C₂B₁₀H₁₀)] Zr(NMe₂)₂ (A = C, Si) reacted with CS₂, PhCN, CH₂=CHCN, ⁿBuNCS, and PhNCO to give the mono-, di-, and triinsertion products, depending upon the substrates. These unsaturated substances inserted exclusively into the Zr-N bonds, and the Zr-C(cage) bond remains intact in all reactions. It is believed that the preference of Zr-N over Zr-C(cage) insertion is governed by steric factors. The metal amide compounds also initiated the polymerization of CH₂=CHCN to produce poly(acrylonitrile) and catalyzed the trimerization of PhNCO. On the other hand, they reacted with methyl methacrylate to afford [{η⁵:σ-Me₂A (C₉H₆)(C₂B₁₀H₁₀)} Zr(OCH₃)(μ-OCH₃)]₂ and CH₂=C(Me)CONMe₂. All insertion products were fully characterized by various spectroscopic data, elemental analyses, and X-ray diffraction studies.

Full text of DOI:10.1021/om0304255

4522
Organometallics 2003, 22, 4522-4531
Mu ltip le In ser tion of Un sa tu r a ted Molecu les in to th e
Zr -N Bon d s of [η5:σ-Me2A(C9H6)(C2B10H10)]Zr (NMe2)2
(A ) C, Si)
Haiping Wang, Hung-Wing Li, and Zuowei Xie*
Department of Chemistry, The Chinese University of Hong Kong, Shatin,
New Territories, Hong Kong, China
Received J une 3, 2003
The compounds [η5:σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)2 (A ) C, Si) reacted with CS2, PhCN,
CH2dCHCN, nBuNCS, and PhNCO to give the mono-, di-, and triinsertion products,
depending upon the substrates. These unsaturated substances inserted exclusively into the
Zr-N bonds, and the Zr-C(cage) bond remains intact in all reactions. It is believed that
the preference of Zr-N over Zr-C(cage) insertion is governed by steric factors. The metal
amide compounds also initiated the polymerization of CH2dCHCN to produce poly-
(acrylonitrile) and catalyzed the trimerization of PhNCO. On the other hand, they reacted
with methyl methacrylate to afford [{η5:σ-Me2A(C9H6)(C2B10H10)}Zr(OCH3)(µ-OCH3)]2 and
CH2dC(Me)CONMe2. All insertion products were fully characterized by various spectroscopic
data, elemental analyses, and X-ray diffraction studies.
In tr od u ction
Ti-N bond in [Me2Si(η5-C5H4)(NBut)]TiCl2 also shows
reaction toward CO2.6 Although the insertion of small
molecules such as CO2, isocyanides, isocyanates, and
CH2dCHCN into the Zr-C,7 Zr-N,8 and Zr-Si9 bonds
has been documented, studies on the relative activity
of Zr-N/Zr-C bonds are very rare.5,10
Since the report of a new generation of group 4
metallocene precatalysts containing bridged cyclopen-
tadienyl ligands, there has been increasing interest in
the development of the chemistry of such ansa-metal-
locene systems.1 Replacement of one cyclopentadienyl
ring by an amido group reduces the overall valence
electrons and the steric congestion at an electrophilic
d0 metal center, leading to so-called constrained-
geometry ligands.2 Researchers at Dow Chemical3 and
Exxon4 have utilized these types of ligand systems to
develop a new generation of constrained-geometry Zieg-
ler-Natta olefin polymerization precatalysts, [R′2Si(η5-
C5R4)(NR′′)]MX2 (M ) Ti, Zr, Hf; R ) alkyl; R′, R′′ )
alkyl, aryl; X ) alkyl, halide). It is believed that the [R′2-
Si(η5-C5R4)(NR′′)]M fragment remains intact during the
olefin polymerization: that is, the olefin inserts exclu-
sively into the M-C bond. Such a reactivity pattern may
be altered if the property of monomers is changed. For
example, both the Zr-Me and Zr-N bonds in [Me2Si-
(η5-C5Me4)(NBut)]ZrMe2 can react with excess CO2,
leading to the formation of carboxylation products.5 The
We have recently developed a new class of constrained-
geometry ligands bearing a carboanion functionality,
[Me2A(C5H4)(C2B10H10)]2- (A ) C,11 Si12), [Me2A(C9H6)-
(C2B10H10)]2- (A ) C,13 Si14), and [iPr2NB(C9H6)(C2B10-
H
10)]2- 15
. Group 4 metal amide/chloride compounds with
these ligand systems are active catalysts for ethylene
polymerization upon activation with methylalumox-
ane.16,17 Do these compounds react with small molecules
(6) Ciruelos, S.; Cuenca, T.; Go´mez, R.; Go´mez-Sal, P.; Manzanero,
A.; Royo, P. Organometallics 1996, 15, 5577.
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Reactivity, Applications; Togni, A., Halterman, R. L., Eds.; Wiley-
VCH: New York, 1998; Vol. 1, p 241. (b) Durfee, L. D.; Rothwell, I. P.
Chem. Rev. 1988, 88, 1059.
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Metal and Metalloid Amides; Ellis Horwood: Chichester, U.K., 1980;
Chapter 10. (b) Walsh, P. J .; Carney, M. J . Bergman, R. G. J . Am.
Chem. Soc. 1991, 113, 6343.
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A.; Norton, J . R.; Goodson, P. A. J . Am. Chem. Soc. 1995, 117, 986.
(11) (a) Xie, Z.; Chui, K.; Yang, Q.; Mak, T. C. W. Organometallics
1999, 18, 3947. (b) Chui, K.; Yang, Q.; Mak, T. C. W.; Xie, Z.
Organometallics 2000, 19, 1391.
(12) (a) Xie, Z.; Wang, S.; Zhou, Z.-Y.; Xue, F.; Mak, T. C. W.
Organometallics 1998, 17, 489. (b) Xie, Z.; Wang, S.; Zhou, Z.-Y.; Mak,
T. C. W. Organometallics 1998, 17, 1907. (c) Xie, Z.; Wang, S.; Zhou,
Z.-Y.; Mak, T. C. W. Organometallics 1999, 18, 1641.
(13) Wang, S.; Yang, Q.; Mak, T. C. W.; Xie, Z. Organometallics 2000,
19, 334.
* To whom correspondence should be addressed. Fax: (852)-
26035057. Tel: (852)26096269. E-mail: zxie@cuhk.edu.hk.
(1) For reviews, see: (a) Britovsek, G. J . P.; Gibson, V. C.; Wass, D.
F. Angew. Chem., Int. Ed. 1999, 38, 428. (b) Kaminsky, W.; Arndt, M.
Adv. Polym. Sci. 1997, 127, 144. (c) Bochmann, M. J . Chem. Soc.,
Dalton Trans. 1996, 255. (d) Kaminsky, W. Macromol. Chem. Phys.
1996, 197, 3907. (e) Brintzinger, H. H.; Fisher, D.; Mu¨lhaupt, R.;
Rieger, B.; Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34,
1143. (f) Mo¨hring, R. C.; Coville, N. J . J . Organomet. Chem. 1994, 479,
1. (g) Marks, T. J . Acc. Chem. Res. 1992, 25, 57.
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(b) J utzi, P.; Siemeling, U. J . Organomet. Chem. 1995, 500, 175. (c)
Okuda, J . Comments Inorg. Chem. 1994, 16, 185.
(3) Stevens, J . C.; Timmers, F. J .; Wilson, D. R.; Schmidt, G. F.;
Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Eur. Patent 416 815,
1990.
(14) (a) Xie, Z.; Wang, S.; Yang, Q.; Mak, T. C. W. Organometallics
1999, 18, 2420. (b) Wang, S.; Yang, Q.; Mak, T. C. W.; Xie, Z.
Organometallics 1999, 18, 4478. (c) Wang, S.; Yang, Q.; Mak, T. C.
W.; Xie, Z. Organometallics 1999, 18, 1578.
(4) (a) Canich, J . M. Eur. Patent 420 436, 1991. (b) Canich, J . M.;
Hlatky, G. G.; Turner, H. W. U.S. Patent 542 236, 1990.
(5) Kloppenburg, L.; Petersen, J . L. Organometallics 1996, 15, 7.
(15) Zi, G.; Li, H.-W.; Xie, Z. Organometallics 2002, 21, 1136.
(16) Wang, H.; Wang, Y.; Li, H.-W.; Xie, Z. Organometallics 2001,
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10.1021/om0304255 CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/01/2003

Insertion of Unsaturated Molecules into Zr-N Bonds
Organometallics, Vol. 22, No. 22, 2003 4523
(C9H6 + C6H5CH3), 6.11 (d, J ) 4.4 Hz, 2H), 5.83 (m, 2H), 5.36
(m, 2H) (vinyl), 2.90 (s, 6H), 2.66 (s, 6H) (N(CH3)2), 2.20 (s,
3H) (C6H5CH3) 2.02 (s, 3H), 1.85 (s, 3H) ((CH3)2C). 13C NMR
(pyridine-d5): δ 157.82, 156.43 (CdN), 139.64, 132.01, 127.84,
127.42, 127.22, 126.82, 124.93, 124.66, 123.36, 118.56, 107.99
(C9H6 + C6H5 + vinyl), 95.32 (C2B10H10), 37.90, 35.23 (N(CH3)2),
44.32, 31.23, 22.10 ((CH3)2C). 11B NMR (pyridine-d5): δ -5.5
(4), -8.8 (6). IR (KBr, cm-1): ν 3039 (w), 2952 (s), 2866 (m),
2778 (w), 2589 (vs), 2559 (vs), 2172 (m), 1635 (w), 1544 (vs),
1456 (s), 1259 (w), 1182 (m), 1149 (m), 1092 (m), 1047 (m),
798 (m), 741 (m), 698 (m), 622 (w), 537 (m), 514 (m). Anal.
Calcd for C31H48B10N4Zr: C, 55.07; H, 7.16; N, 8.29. Found:
C, 54.73; H, 7.28; N, 8.37.
bearing an activated CdC double bond or other multiple
bonds? Reactivity patterns of compounds involving both
group 4 metal M-N and M-C(cage) bonds, to our
knowledge, have not been investigated yet. The com-
plexes [η5:σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)2 (A ) C
(1a ), Si (1b)) offer a unique opportunity to observe the
direct competition between amido and carboranyl ligands
in the migration step and to study whether amido or
caboranyl ligand migration is preferred. We report in
this paper our investigation on the reactions of 1a ,b
with CS2, PhCN, CH2dCHCN, nBuNCS, PhNCO and
methyl methacrylate (MMA).
Rea ction of 3a w ith Excess CH2dCHCN. To a toluene
solution (30 mL) of 3a ‚(toluene) (20 mg, 0.03 mmol) was added
CH2dCHCN (320 mg, 6.0 mmol) at room temperature, and
the reaction mixture was stirred for 1 h, giving a large amount
of precipitate. The polymerization was terminated by addition
of acidic ethanol. The white precipitate was filtered off and
washed with ethanol and acetone. The resulting powder was
finally dried in a vacuum oven at 80 °C overnight (230 mg,
72%). 1H NMR (DMSO-d6): δ 5.95 (br) (vinyl), 3.10 (br)
(CH2CHCN), 2.85 (s) (NMe2), 2.05 (br) (CH2CHCN). Mn(NMR)
≈ 1.5 × 105.
Exp er im en ta l Section
Gen er a l P r oced u r es. All experiments were performed
under an atmosphere of dry nitrogen with the rigid exclusion
of air and moisture using standard Schlenk or cannula
techniques or in a glovebox. All organic solvents were freshly
distilled from sodium benzophenone ketyl immediately prior
to use. Compounds 1a ,b were prepared according to the
literature methods.16 All other chemicals were purchased from
Aldrich Chemical Co. and were freshly distilled prior to use.
Infrared spectra were obtained from KBr pellets prepared in
the glovebox on a Nicolet Magna 550 Fourier transform
spectrometer. 1H and 13C NMR spectra were recorded on a
Bruker DPX 300 spectrometer at 300.13 and 75.47 MHz,
respectively. 11B NMR spectra were recorded on a Varian Inova
400 spectrometer at 128.32 MHz. All chemical shifts are
reported in δ units with reference to internal or external TMS
(0.00 ppm) or with respect to the residual protons of the
deuterated solvents for proton and carbon chemical shifts and
to external BF3‚OEt2 (0.00 ppm) for boron chemical shifts.
Elemental analyses were performed by MEDAC Ltd, Brunel
University, Middlesex, U.K.
P r ep a r a t ion of [η5:σ-Me2C(C9H 6)(C2B10H 10)]Zr [NdC-
(P h )NMe2]2 (2a ). To a toluene (20 mL) solution of [η5:σ-Me2C-
(C9H6)(C2B10H10)]Zr(NMe2)2 (1a ; 240 mg, 0.5 mmol) was added
dropwise a toluene (10 mL) solution of PhCN (110 mg, 1.0
mmol) at -30 °C with stirring. The mixture was warmed to
room temperature and stirred for 5 h. After filtration, the
resulting clear orange solution was concentrated under vacuum
to about 8 mL. 2a was isolated as yellow crystals after this
P r ep a r a tion of [{η5:σ-Me2C(C9H6)(C2B10H10)}Zr (OCH3)-
(µ-OCH3)]2‚2C6H5CH3 (4a ‚2(tolu en e)). To a toluene (20 mL)
solution of 1a (240 mg, 0.5 mmol) was added dropwise a
toluene (10 mL) solution of methyl methacrylate (100 mg, 1.0
mmol) with stirring at room temperature, and the mixture was
stirred overnight. After removal of the precipitate, the clear
yellow solution was concentrated under vacuum to about 10
mL, to which was added a few drops of n-hexane. 4a ‚2C6H5-
CH3 was isolated as colorless crystals after this solution stood
at room temperature for 2 days (220 mg, 81%). 1H NMR
(pyridine-d5): δ 8.24 (d, J ) 8.4 Hz, 1H), 7.25 (m, 5H), 7.16
(m, 7H), 6.86 (d, J ) 3.3 Hz, 1H), 6.73 (d, J ) 8.4 Hz, 1H),
5.78 (d, J ) 3.3 Hz, 1H) (C9H6 + C6H5CH3), 4.22 (s, 3H), 3.44
(s, 3H) (OCH3), 2.20 (s, 6H) (C6H5CH3), 2.06 (s, 3H), 1.88 (s,
3H) ((CH3)2C). 13C NMR (pyridine-d5): δ 143.15, 131.31,
127.30, 126.41, 124.23, 123.31, 123.12, 121.51, 120.23, 106.32
(C9H6 + C6H5CH3), 96.34 (C2B10H10), 60.12, 59.45 (OCH3),
45.15, 31.67, 22.80 ((CH3)2C). 11B NMR (pyridine-d5): δ -4.2
(2), -6.1 (2), -9.6 (6). IR (KBr, cm-1): ν 3098 (w), 2986 (m),
2946 (s), 2921 (s), 2824 (m), 2589 (vs), 2558 (vs), 1603 (w), 1458
(s), 1383 (m), 1336 (w), 1191 (m), 1139 (vs), 1092 (m), 1052
(m), 997 (s), 846 (w), 806 (s), 741 (s), 697 (m), 524 (m). Anal.
Calcd for C39H64B20O4Zr2 (4a + toluene): C, 47.05; H, 6.48.
Found: C, 47.21; H, 6.69.
1
solution stood at -30 °C for 3 days (280 mg, 82%). H NMR
(pyridine-d5): δ 8.09 (d, J ) 8.1 Hz, 1H), 6.98 (dd, J ) 7.8 and
8.1 Hz, 1H), 6.89 (dd, J ) 8.1 and 7.8 Hz, 1H), 6.77 (d, J ) 3.3
Hz, 1H), 6.65 (d, J ) 8.1 Hz, 1H), 5.87 (d, J ) 3.3 Hz, 1H)
(C9H6), 7.41 (s, 2H), 7.33 (d, J ) 6.9 Hz, 4H), 7.19 (m, 4H)
(C6H5), 2.78 (s, 6H), 2.60 (s, 6H) (N(CH3)2), 1.96 (s, 3H), 1.74
(s, 3H) ((CH3)2C). 13C NMR (pyridine-d5): δ 157.51, 156.12 (Cd
N), 139.59, 131.98, 127.62, 127.52, 127.32, 127.10, 126.82,
126.75, 124.84, 124.44, 123.58, 123.30, 122.17, 121.80, 118.32,
117.30, 107.23 (C9H6 + C6H5), 103.62, 96.65 (C2B10H10), 37.84,
34.92, 33.05 (N(CH3)2), 44.14, 31.02, 22.15 ((CH3)2C).11B NMR
(pyridine-d5): δ -6.5 (4), -10.5 (6). IR (KBr, cm-1): ν 3052
(w), 3016 (w), 2989 (w), 2920 (m), 2597 (vs), 2551 (vs), 1594
(vs), 1539 (vs), 1480 (s), 1439 (s), 1376 (vs), 1262 (m), 1209
(m), 1182 (w), 1132 (w), 1084 (m), 1024 (m), 994 (w), 913 (m),
813 (s), 778 (m), 740 (m), 702 (m), 665 (m), 558 (m). Anal. Calcd
for C32H44B10N4Zr: C, 56.18; H, 6.48; N, 8.19. Found: C, 55.94;
H, 6.59; N, 8.31.
P r ep a r a tion of [{η5:σ-Me2Si(C9H6)(C2B10H10)}Zr (OCH3)-
(µ-OCH3)]2‚2THF (4b‚2THF ). This compound was prepared
as colorless crystals from 1b (247 mg, 0.5 mmol) and methyl
methacrylate (100 mg, 1.0 mmol) in toluene/THF using a
procedure identical with that reported for 4a : yield 201 mg
1
(75%). H NMR (pyridine-d5): δ 8.09 (d, J ) 8.1 Hz, 1H), 7.29
(m, 1H), 7.14 (m, 1H), 6.97 (d, J ) 3.3 Hz, 1H), 6.92 (d, J )
8.1 Hz, 1H), 5.98 (d, J ) 3.3 Hz, 1H) (C9H6), 4.26 (s, 3H)
(OCH3), 3.63 (m, 4H) (THF), 3.42 (s, 3H) (OCH3), 1.59 (m, 4H)
(THF), 0.85 (s, 3H), 0.69 (s, 3H) ((CH3)2Si). 13C NMR (pyridine-
d5): δ 137.35, 130.08, 128.73, 127.98, 125.08, 123.85, 121.18,
105.63, 104.45 (C9H6), 101.03, 83.86 (C2B10H10), 65.11 (THF),
57.02, 55.55 (OCH3), 29.32 (THF), -0.99, -1.29 ((CH3)2Si). 11
B
NMR (pyridine-d5): δ -1.8 (2), -4.0 (2), -7.2 (2), -9.4 (1),
-11.05 (2), -13.46 (1). IR (KBr, cm-1): ν 3020 (w), 2951 (m),
2915 (m), 2831 (m), 2571 (vs), 1602 (w), 1491 (w), 1446 (m),
1415 (w), 1258 (s), 1136 (vs), 1088 (s), 1048 (w), 995 (s), 892
(m), 806 (s), 732 (m), 685 (m), 521 (m). Anal. Calcd for
P r ep a r a t ion of [η5:σ-Me2C(C9H 6)(C2B10H 10)]Zr [NdC-
(C2H3)NMe2]2‚C6H5CH3 (3a ‚(tolu en e)). This compound was
prepared as yellow crystals from 1a (240 mg, 0.5 mmol) and
acrylonitrile (53 mg, 1.0 mmol) in toluene using a procedure
identical with that reported for 2a . Yield: 130 mg (39%). H
NMR (pyridine-d5): δ 8.15 (d, J ) 8.4 Hz, 1H), 7.26 (m, 3H),
7.16 (m, 5H), 7.00 (d, J ) 3.2 Hz, 1H), 6.90 (d, J ) 3.2 Hz, 1H)
1
C
34H64B20O5Si2Zr2 (4b + THF): C, 40.52; H, 6.40. Found: C,
40.21; H, 6.69.
P r ep a r a tion of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr (η2-S2C-
NMe2)2‚2C6H5CH3 (5a ‚2(tolu en e)). To a toluene (20 mL)
solution of 1a (240 mg, 0.5 mmol) was added dropwise a
(17) Zi, G.; Li, H.-W.; Xie, Z. Organometallics 2002, 21, 3850.

4524 Organometallics, Vol. 22, No. 22, 2003
Wang et al.
toluene (10 mL) solution of CS2 (90 mg, 1.2 mmol) at -30 °C
with stirring. The mixture was warmed to room temperature
and stirred overnight. After removal of the precipitate, the
clear yellow solution was concentrated under vacuum to about
10 mL, to which was added a few drops of n-hexane. 5a ‚
2(toluene) was isolated as bright yellow crystals after this
solution stood at room temperature for 5 days (360 mg, 88%).
1H NMR (pyridine-d5): δ 8.14 (d, J ) 8.7 Hz, 1H), 7.63 (d, J )
8.4 Hz, 1H), 7.49 (dd, J ) 6.9 and 8.7 Hz, 1H), 7.28 (m, 6H),
7.16 (m, 5H), 7.11 (d, J ) 3.3 Hz, 1H), 6.72 (d, J ) 3.3 Hz, 1H)
(C9H6 + C6H5CH3), 3.16 (s, 6H), 2.95 (s, 6H) (N(CH3)2), 2.20
(s, 6H) (C6H5CH3), 1.91 (s, 3H), 1.77 (s, 3H) ((CH3)2C). 13C NMR
(pyridine-d5): δ 201.61, 199.15 (NCS2), 137.35, 136.81, 135.80,
128.72, 127.98, 127.22, 126.21, 125.82, 125.07, 123.80, 122.12,
111.05 (C9H6 + C6H5CH3), 106.00, 104.49 (C2B10H10), 39.69,
39.38, 34.66, 32.60 (N(CH3)2), 43.92, 31.02, 20.63 ((CH3)2C),
22.00 (C6H5CH3). 11B NMR (pyridine-d5): δ -4.9 (3), -7.6 (2),
-10.1 (5). IR (KBr, cm-1): ν 3032 (w), 2928 (m), 2862 (m), 2593
(vs), 2550 (vs), 1637 (w), 1519 (vs), 1457 (m), 1387 (vs), 1250
(m), 1207 (w), 1144 (s), 1048 (m), 987 (m), 813 (m), 737 (s),
696 (m), 574 (w). Anal. Calcd for C27H42B10N2S4Zr (5a +
toluene): C, 44.90; H, 5.86; N, 3.88. Found: C, 44.71; H, 5.77;
N, 4.02.
P r ep a r a tion of [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr (η2-S2-
CNMe2)2 (5b). This compound was prepared as bright yellow
crystals from 1b (247 mg, 0.5 mmol) and CS2 (90 mg, 1.2 mmol)
in toluene using a procedure identical with that reported for
5a : yield 261 mg (81%). 1H NMR (pyridine-d5): δ 7.97 (d, J )
8.4 Hz, 1H), 7.72 (d, J ) 8.4 Hz, 1H), 7.40 (dd, J ) 8.4 and 7.2
Hz, 1H), 7.26 (dd, J ) 8.4 and 7.2 Hz, 1H), 7.13 (d, J ) 3.3
Hz, 1H), 7.09 (d, J ) 3.3 Hz, 1H) (C9H6), 3.16 (s, 6H), 2.93 (s,
6H) (N(CH3)2), 0.74 (s, 3H), 0.61 (s, 3H) ((CH3)2Si). 13C NMR
(pyridine-d5): δ 202.68, 200.34 (NCS2), 139.18, 130.55, 129.81,
128.98, 128.84, 128.33, 127.85, 126.91, 109.92 (C9H6), 84.96
(C2B10H10), 41.45, 41.13, 32.85, 23.99 (N(CH3)2), 0.24, 0.00
((CH3)2Si). 11B NMR (pyridine-d5): δ 0.3 (2), -4.1 (4), -9.5 (4).
IR (KBr, cm-1): ν 3020 (w), 2955 (m), 2923 (m), 2858 (w), 2570
(vs), 1517 (vs), 1450 (m), 1388 (vs), 1254 (s), 1146 (s), 1091 (s),
1046 (m), 990 (m), 892 (w), 831 (s), 803 (m), 739 (m), 685 (m),
576 (w), 551 (w). Anal. Calcd for C19H34B10N2S4SiZr: C, 35.31;
H, 5.30; N, 4.34. Found: C, 35.43; H, 5.36; N, 4.57.
3H), 7.35 (m, 3H), 7.23 (m, 2H), 7.13 (m, 2H), 7.01 (m, 2H),
6.77 (d, J ) 3.0 Hz, 1H), 6.43 (d, J ) 3.0 Hz, 1H) (C9H6
+
C6H5), 2.36 (s, 12H) (N(CH3)2), 0.71 (s, 3H), 0.48 (s, 3H) ((CH3)2-
Si). 13C NMR (pyridine-d5): δ 165.55, 163.17 (NCO), 146.08,
133.38, 131.02, 128.97, 128.72, 128.04, 125.35, 125.13, 124.77,
124.54, 124.47, 123.80, 121.98, 111.67, 108,37, 105.05 (C9H6
+ C6H5), 89.20, 81.00 (C2B10H10), 36.41, 36.32, 31.02, 28.51
(N(CH3)2), -1.66, -1.56 ((CH3)2Si). 11B NMR (pyridine-d5): δ
-1.1 (3), -5.6 (2), -8.7 (1), -10.8 (4). IR (KBr, cm-1): ν 3057
(w), 3025 (w), 2957 (m), 2923 (m), 2876 (w), 2573 (vs), 1634
(w), 1565 (vs), 1491 (vs), 1445 (vs), 1407 (vs), 1305 (w), 1250
(m), 1212 (m), 1158 (w), 1089 (m), 1032 (w), 929 (w), 833 (m),
804 (s), 749 (m), 697 (m), 645 (m). Anal. Calcd for C31H44B10N4O2-
SiZr: C, 50.85; H, 6.06; N, 7.65. Found: C, 50.68; H, 6.07; N,
7.51.
P r ep a r a tion of [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr [η2-OC-
(NMe2)NP h ][η2-OC(NMe2)N(P h )Cd(NP h )O]‚THF (7b‚THF).
To a THF (20 mL) solution of 6b (184 mg, 0.25 mmol) was
added dropwise a THF (10 mL) solution of PhNCO (30 mg,
0.25 mmol) at room temperature with stirring. The mixture
was refluxed for 3 h. After removal of the precipitate, the clear
yellow solution was concentrated under vacuum to about 10
mL, to which was added a few drops of toluene. 7b‚THF was
isolated as colorless crystals after this solution stood at room
temperature for 5 days (160 mg, 69%). 1H NMR (pyridine-d5):
δ 7.90 (m, 2H), 7.63 (m, 2H), 7.47-7.37 (m, 8H), 7.33-7.10
(m, 6H), 6.54 (d, J ) 3.0 Hz, 1H), 6.37 (d, J ) 3.0 Hz, 1H),
5.89 (d, J ) 7.8 Hz, 1H) (C9H6 + C6H5), 3.64 (m, 4H), 1.59 (m,
4H) (THF), 2.58 (s, 9H), 1.88 (s, 3H) (N(CH3)2), 0.77 (s, 3H),
0.56 (s, 3H) ((CH3)2Si). 13C NMR (pyridine-d5): δ 164.70,
160.76, 152.51 (NCO), 146.86, 140.42, 132.38, 132.04, 129.23,
128.88, 128.70, 128.60, 128.12, 128.00, 127.09, 126.51, 125.96,
125.39, 124.84, 124.63, 124.19, 123.75, 121.25, 111.91 (C9H6
+ C6H5), 104.56, 81.41 (C2B10H10), 67.14, 25.11 (OC4H8), 36.28,
36.54, 31.02, 28.51 (N(CH3)2), -1.57, -1.70 ((CH3)2Si). 11B
NMR (pyridine-d5): δ -1.9 (2), -6.1 (3), -10.4 (5). IR (KBr,
cm-1): ν 3055 (w), 3019 (w), 2964 (m), 2932 (m), 2872 (m), 2575
(vs), 2540 (vs), 1704 (s), 1636 (vs), 1579 (vs), 1489 (vs), 1438
(vs), 1410 (vs), 1293 (m), 1243 (s), 1209 (m), 1157 (w), 1088
(m), 1062 (m), 1004 (m), 916 (m), 837 (m), 807 (s), 754 (s), 702
(s), 646 (m). Anal. Calcd for C42H57B10N5O4SiZr: C, 54.63; H,
6.22; N, 7.59. Found: C, 54.75; H, 6.11; N, 7.68.
P r ep a r a tion of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr [η2-OC-
(NMe2)NP h ]2 (6a ). To a toluene (20 mL) solution of 1a (240
mg, 0.5 mmol) was added dropwise a toluene (10 mL) solution
of PhNCO (120 mg, 1.0 mmol) at 0 °C with stirring. The
mixture was warmed to room temperature and stirred over-
night. Removal of the solvent gave a yellow solid. Recrystal-
lization from CH2Cl2 at room temperature afforded 6a as pale
yellow crystals (318 mg, 89%).1H NMR (pyridine-d5): δ 8.05
(d, J ) 8.4 Hz, 1H), 7.69 (d, J ) 8.4 Hz, 1H), 7.43 (m, 2H),
7.34 (m, 2H), 7.25 (m, 2H), 7.15 (m, 2H), 7.10 (m, 2H), 7.00
(m, 2H), 6.47 (d, J ) 3.3 Hz, 1H), 6.32 (d, J ) 3.3 Hz, 1H)
(C9H6 + C6H5), 2.36 (s, 6H), 2.20 (s, 6H) (N(CH3)2), 1.88 (s,
3H), 1.62 (s, 3H) ((CH3)2C). 13C NMR (pyridine-d5): δ 166.00,
163.60 (NCO), 146.29, 137.35, 136.42, 128.96, 128.72, 128.08,
127.98, 126.85, 126.16, 125.51, 125.15, 124.36, 124.17, 123.31,
122.95, 121.84, 117.85 (C9H6 + C6H5), 102.23, 100.69 (C2B10H10),
36.48, 36.34, 34.52, 32.64 (N(CH3)2), 44.19, 31.03, 20.63
((CH3)2C). 11B NMR (pyridine-d5): δ -5.0 (3), -7.8 (2), -10.7
(5). IR (KBr, cm-1): ν 3057 (w), 3024 (w), 2952 (m), 2930 (m),
2873 (w), 2589 (vs), 2558 (vs), 1634 (w), 1565 (vs), 1490 (vs),
1446 (vs), 1407 (vs), 1306 (w), 1240 (m), 1208 (m), 1027 (m),
932 (w), 796 (m), 750 (m), 700 (m), 646 (m), 511 (w). Anal.
Calcd for C32H44B10N4O2Zr: C, 53.67; H, 6.19; N, 7.83. Found:
C, 53.88; H, 6.23; N, 7.93.
Rea ction of 7b w ith Excess P h NCO. 7b‚THF (50 mg,
0.06 mmol) was dissolved in a mixture of THF and toluene
(20 mL, 1:1), to which was added PhNCO (360 mg, 3.0 mmol).
The mixture was refluxed for 10 h. The resultant brown
solution was concentrated under vacuum to about 8 mL and
cooled to -20 °C, giving colorless crystals (220 mg, 61%). This
1
product was identified as (PhNCO)3 by H, 13C NMR, MS and
unit cell measurement.18
P r ep a r a tion of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr (NMe2)-
[η2-SC(NMe2)NBu n ] (8a ). To a toluene (20 mL) solution of
1a (240 mg, 0.5 mmol) was added dropwise a toluene (10 mL)
solution of n-BuNCS (60 mg, 0.5 mmol) at 0 °C with stirring,
and the mixture was stirred at room temperature overnight.
The clear orange solution was concentrated under vacuum to
about 10 mL, to which was added a few drops of n-hexane. 8a
was isolated as yellow crystals after this solution stood at room
temperature for 1 week (180 mg, 61%). 1H NMR (pyridine-
d5): δ 8.10 (d, J ) 8.4 Hz, 1H), 7.56 (d, J ) 7.8 Hz, 1H), 7.14
(m, 2H), 6.78 (d, J ) 3.6 Hz, 1H), 6.42 (d, J ) 3.6 Hz, 1H)
(C9H6), 3.29 (m, 2H) (NCH2), 2.94 (s, 6H), 2.76 (s, 6H)
(N(CH3)2), 1.87 (s, 3H), 1.72 (s, 3H) ((CH3)2C), 1.25 (m, 4H)
((CH2)2), 0.92 (t, J ) 6.9 Hz, 3H) (CH2CH3). 13C NMR (pyridine-
d5): δ 175.60 (NCS), 135.76, 128.72, 127.98, 126.55, 125.14,
124.53, 121.71, 118.00, 104.62 (C9H6), 95.42 (C2B10H10), 50.72
(NCH2), 40.18, 32.36, 32.08 (N(CH3)2), 44.40, 28.52, 20.11
((CH3)2C), 35.33, 31.02, 13.55 ((CH2)2CH3). 11B NMR (pyridine-
P r ep a r a tion of [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr [η2-OC-
(NMe2)NP h ]2 (6b). This compound was prepared as colorless
crystals from 1b (247 mg, 0.5 mmol) and PhNCO (120 mg, 1.0
mmol) in toluene using a procedure identical with that
reported for 6a : yield 300 mg (82%). 1H NMR (pyridine-d5):
δ 7.88 (d, J ) 8.7 Hz, 1H), 7.80 (d, J ) 8.7 Hz, 1H), 7.43 (m,
(18) Zhou, X.; Zhang, L.; Zhu, M.; Cai, R.; Weng, L.; Huang, Z.; Wu,
Q. Organometallics 2001, 20, 5700.

Insertion of Unsaturated Molecules into Zr-N Bonds
Organometallics, Vol. 22, No. 22, 2003 4525
Ta ble 1. Cr ysta l Da ta a n d Su m m a r y of Da ta Collection a n d Refin em en t for 2a , 3a , 4a ,b, a n d 5a ,b
2a
3a ‚C6H5CH3
4a ‚2C6H5CH3
4b‚2THF
5a ‚2C6H5CH3
5b
formula
cryst size (mm)
fw
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
32H44B10N4Zr
C31H48B10N4Zr
C46H72B20O4Zr2
C
38H72B20O6Si2Zr2
C
34H50B10N2S4Zr
C19H34B10N2S4SiZr
0.52 × 0.27 × 0.21 0.36 × 0.30 × 0.13 0.22 × 0.20 × 0.16 0.40 × 0.20 × 0.10 0.45 × 0.18 × 0.15 0.40 × 0.32 × 0.18
684.03
triclinic
P1h
676.05
triclinic
P1h
1087.68
monoclinic
P21/n
11.011(2)
12.093(1)
20.825(4)
90
91.27(1)
90
2772.3(8)
2
1079.78
monoclinic
P21/n
11.154(2)
12.477(3)
20.636(4)
90
91.12(3)
90
2871(1)
2
814.32
monoclinic
P21/n
11.556(1)
12.393(1)
29.481(3)
90
102.29(1)
90
4125.3(7)
4
646.13
monoclinic
P21/n
10.738(1)
16.778(1)
18.912(1)
90
94.11(1)
90
3398.4(4)
4
9.019(1)
12.899(1)
16.468(1)
72.58(1)
79.59(1)
82.20(1)
1790.9(2)
2
10.780(2)
11.251(3)
16.684(3)
92.23(1)
91.93(1)
116.22(2)
1811.0(7)
2
Z
D
calcd, Mg/m3
1.268
1.240
1.303
1.249
1.311
1.263
radiation (λ), Å
2θ range, deg
µ, mm-1
Mo KR (0.710 73)
2.6-56.0
0.336
708
4.2-50.0
0.331
704
4.0-50.0
0.417
1120
3.8-50.0
0.444
1112
3.6-52.0
0.497
1688
4.2-51.0
0.618
1320
F(000)
no. of obsd rflns
no. of params refnd 425
8483
4268
386
2929
318
3289
318
5604
425
5281
335
goodness of fit
R1
wR2
0.961
0.044
0.087
1.066
0.089
0.237
1.095
0.074
0.163
1.073
0.088
0.238
1.100
0.067
0.177
1.091
0.066
0.174
Ta ble 2. Cr ysta l Da ta a n d Su m m a r y of Da ta Collection a n d Refin em en t for 6a ,b, 7b, 8a ,b a n d 9a
6a
6b
7b‚THF
8a
8b
9a
formula
cryst size (mm)
fw
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
32H44B10N4O2Zr
C31H44B10N4O2SiZr C42H57B10N5O4SiZr C23H43B10N3SZr
C22H43B10N3SSiZr C28H52B10N4S2Zr
0.45 × 0.22 × 0.12 0.50 × 0.50 × 0.21 0.40 × 0.36 × 0.14 0.75 × 0.35 × 0.34 0.38 × 0.25 × 0.20 0.24 × 0.12 × 0.10
716.03
monoclinic
P21/n
11.333(2)
17.457(4)
18.333(4)
90
92.14(3)
90
3624(1)
4
732.11
monoclinic
P21/n
11.455(3)
17.546(4)
18.394(4)
90
92.71(1)
90
3692(1)
4
923.34
triclinic
P1h
592.98
monoclinic
P21/c
12.738(1)
16.624(1)
15.883(1)
90
113.16(1)
90
3092.3(5)
4
609.06
monoclinic
P21/n
8.213(2)
21.496(4)
17.806(4)
90
93.21(3)
90
3139(1)
4
708.18
triclinic
P1h
12.708(3)
14.300(3)
14.366(3)
70.15(3)
78.06(3)
79.28(3)
2383.3(8)
2
11.747(1)
11.956(1)
16.297(1)
98.57(1)
97.99(1)
107.33(1)
2119.3(3)
2
Z
D
calcd, Mg/m3
1.312
1.317
1.288
1.274
1.289
1.110
radiation (λ), Å
2θ range, deg
µ, mm-1
Mo KR (0.710 73)
3.2-50.0
0.339
1480
3.2-56.0
0.365
1512
3.0-51.0
0.302
962
3.4-56.0
0.442
1232
3.0-50.0
0.474
1264
4.0-50.0
0.381
740
F(000)
no. of obsd rflns
no. of params refnd 452
5372
8944
443
6923
569
7433
354
4529
358
6612
402
goodness of fit
R1
wR2
1.071
0.073
0.178
0.965
0.038
0.086
1.033
0.077
0.206
1.041
0.035
0.102
1.123
0.066
0.152
0.975
0.081
0.205
Ta ble 3. Su m m a r y of Key Str u ctu r a l Da ta
av Zr-C(C5 ring)
Zr-C(cage)
av Zr-N
(Å)
av Zr-O
(Å)
av Zr-S
(Å)
C(C5 ring)-A-C(cage)
Cent-Zr-C(cage)
compd
(Å)
(Å)
(deg)
(deg)a
1a b
1bb
2a
3a
4a
2.521(8)
2.541(5)
2.544(2)
2.549(8)
2.539(1)
2.326(7)
2.348(5)
2.359(2)
2.365(7)
2.407(10)
2.016(8)
2.019(4)
1.972(2)
1.974(7)
109.4(6)
104.8(2)
110.4(2)
110.7(6)
109.7(9)
101.6
109.9
100.4
100.4
98.8
1.880(6)
2.159(6)c
1.874(2)
2.178(2)c
4b
2.552(3)
2.448(3)
103.7(1)
106.3
5a
5b
6a
6b
7b
8a
2.539(2)
2.558(5)
2.541(4)
2.554(3)
2.563(5)
2.532(2)
2.388(3)
2.456(5)
2.378(4)
2.414(2)
2.422(5)
2.410(2)
2.638(1)
2.645(1)
109.7(2)
103.7(2)
109.5(3)
104.3(1)
104.3(2)
110.1(2)
99.4
106.2
98.5
105.6
105.7
100.1
2.242(3)
2.227(2)
2.180(4)
1.997(2)
2.268(2)d
1.975(5)
2.270(5)d
2.268(8)d
2.165(3)
2.161(2)
2.151(3)
2.621(1)
2.606(2)
2.578(3)
8b
2.571(6)
2.438(5)
2.398(9)
105.8(3)
107.3
98.3
9a
2.559(10)
110.5(8)
a
b
d
Cent ) centroid of the five-membered ring of the indenyl group. See ref 16. c Zr-O(µ) distance. Zr-N(imido) distance.
d5): δ -5.3 (2), -7.0 (2), -11.4 (6). IR (KBr, cm-1): ν 3023
(w), 2954 (s), 2922 (m), 2879 (s), 2596 (vs), 2552 (vs), 1545 (vs),
1457 (s), 1427 (m), 1349 (s), 1255 (w), 1212 (w), 1152 (m), 1122
(m), 1053 (m), 917 (m), 797 (m), 741 (m), 657 (w), 547 (m).
Anal. Calcd for C23H43B10N3SZr: C, 46.58; H, 7.31; N, 7.09.
Found: C, 46.81; H, 7.33; N, 6.93.
P r ep a r a tion of [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr (NMe2)-
[η2-SC(NMe2)NBu n ] (8b). This compound was prepared as
yellow crystals from 1b (247 mg, 0.5 mmol) and n-BuNCS (60
mg, 0.5 mmol) using a procedure identical with that reported
for 8a . Yield: 230 mg (75%). 1H NMR (pyridine-d5): δ 7.92 (d,
J ) 7.8 Hz, 1H), 7.68 (d, J ) 7.8 Hz, 1H), 7.23 (m, 1H), 7.20

4526 Organometallics, Vol. 22, No. 22, 2003
Wang et al.
Sch em e 1
(m, 1H), 6.92 (d, J ) 3.3 Hz, 1H), 6.79 (d, J ) 3.3 Hz, 1H)
(C9H6), 3.30 (m, 2H) (NCH2), 3.00 (s, 6H), 2.78 (s, 6H)
(N(CH3)2), 1.24 (m, 4H) ((CH2)2), 0.91 (t, J ) 6.3 Hz, 3H)
(CH2CH3), 0.73 (s, 3H), 0.58 (s, 3H) ((CH3)2Si). 13C NMR
(pyridine-d5): δ 174.91 (NCS), 131.39, 129.11, 127.99, 125.55,
125.49, 124.69, 123.79, 110.08, 104.28 (C9H6), 100.14, 82.56
(C2B10H10), 50.96 (NCH2), 39.95, 32.03, 20.11 (N(CH3)2), 31.04,
22.18, 13.50 ((CH2)2CH3), -0.91, -1.76 ((CH3)2Si). 11B NMR
(pyridine-d5): δ -1.6 (2), -5.0 (2), -10.1 (6). IR (KBr, cm-1):
ν 3034 (w), 2955 (s), 2900 (s), 2779 (m), 2572 (vs), 1538 (vs),
1453 (m), 1422 (m), 1345 (s), 1299 (w), 1255 (s), 1149 (s), 1119
(s), 1090 (s), 1057 (m), 972 (w), 911 (s), 833 (s), 806 (s), 745
(m), 680 (m), 545 (m). Anal. Calcd for C22H43B10N3SSiZr: C,
43.38; H, 7.12; N, 6.90. Found: C, 43.30; H, 6.90; N, 7.06.
P r ep a r a tion of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr [η2-SC-
(NMe2)NBu n ]2 (9a ). Compound 8a (300 mg, 0.5 mmol) was
dissolved in a mixture of THF and toluene (20 mL, 1:1), to
which was added n-BuNCS (60 mg, 0.5 mmol) in THF (10 mL).
The reaction mixture was then refluxed for 10 h. The resulting
clear orange solution was concentrated under vacuum to about
10 mL, to which was added a few drops of n-hexane. 9a was
isolated as pale yellow crystals after this solution stood at room
temperature for 3 days (270 mg, 76%). 1H NMR (pyridine-d5):
δ 8.22 (d, J ) 8.7 Hz, 1H), 7.69 (d, J ) 8.4 Hz, 1H), 7.44 (dd,
J ) 6.6 and 8.4 Hz, 1H), 7.31 (m, 1H), 7.13 (d, J ) 3.3 Hz,
1H), 6.13 (d, J ) 3.3 Hz, 1H) (C9H6), 4.44 (m, 2H), 3.49 (m,
2H) (NCH2), 3.04 (s, 6H), 2.78 (s, 6H) (N(CH3)2), 1.88 (s, 3H),
1.73 (s, 3H) ((CH3)2C), 1.48 (m, 4H), 1.31-1.23 (m, 4H) ((CH2)2),
0.91-0.80 (m, 6H) (CH2CH3). 13C NMR (pyridine-d5): δ 176.62,
171.65 (NCS), 133.31, 128.71, 127.97, 126,23, 125.06, 123.60,
123.30, 119.51, 117.65 (C9H6), 104.73, 97.33 (C2B10H10), 51.78,
51.32 (NCH2), 40.13, 40.05, 39.77, 39.49 (N(CH3)2), 43.62,
22.14, 20.28 ((CH3)2C), 34.66, 32.80, 31.65, 31.01 ((CH2)2),
13.54, 13.34 (CH2CH3). 11B NMR (pyridine-d5): δ -5.6 (2), -7.2
(2), -10.9 (6). IR (KBr, cm-1): ν 3039 (w), 2955 (s), 2928 (s),
2870 (m), 2807 (w), 2592 (vs), 2549 (vs), 1545 (vs), 1455 (m),
1344 (s), 1244 (w), 1212 (w), 1119 (vs), 1052 (m), 1023 (w),
805 (m), 738 (s), 658 (w), 557 (w). Anal. Calcd for C28H52B10N4S2-
Zr: C, 47.48; H, 7.40; N, 7.91. Found: C, 47.36; H, 7.60; N,
7.77.
X-r a y Str u ctu r e Deter m in a tion . All single crystals were
immersed in Paratone-N oil and sealed under N2 in thin-walled
glass capillaries. Data were collected at 293 K on an MSC/
Rigaku RAXIS-IIC imaging plate using Mo KR radiation from
a Rigaku rotating-anode X-ray generator operating at 50 kV
and 90 mA or 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 calculations on F2 using the
SHELXTL program package (PC version).20 Most of the
carborane hydrogen atoms were located from difference Four-
ier syntheses. All other hydrogen atoms were geometrically
fixed using the riding model. Crystal data and details of data
collection and structure refinement are given in Tables 1 and
2, respectively. Key structural parameters are listed in Table
3. Further details are included in the Supporting Information.
Resu lts
Rea ction w ith P h CN. [η5:σ-Me2C(C9H6)(C2B10H10)]-
Zr(NMe2)2 (1a ) reacted readily with 2 equiv of PhCN to
(19) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction of Area Detector Data; University of Go¨ttingen, Go¨ttingen,
Germany, 1996.
(20) SHELXTL V 5.03 Program Package; Siemens Analytical X-ray
Instruments, Inc., Madison, WI, 1995.

Insertion of Unsaturated Molecules into Zr-N Bonds
Organometallics, Vol. 22, No. 22, 2003 4527
F igu r e 2. Molecular structure of [η5:σ-Me2C(C9H6)-
(C2B10H10)]Zr[NdC(C2H3)NMe2]2 (3a ; thermal ellipsoids
drawn at the 35% probability level).
F igu r e 1. Molecular structure of [η5:σ-Me2C(C9H6)-
(C2B10H10)]Zr[NdC(Ph)NMe2]2 (2a; thermal ellipsoids drawn
at the 35% probability level).
give the diinsertion product [η5:σ-Me2C(C9H6)(C2B10H10)]-
Zr[NdC(Ph)NMe2]2 (2a ) (Scheme 1). 2a did not react
further with excess PhCN. Both mono- and diinsertion
products were detected by NMR when 1 equiv of PhCN
was added to 1a . Attempts to isolate pure monoinsertion
product from the reaction mixture were unsuccessful.
imply that the first 2 equiv of acrylonitrile molecules
insert into the Zr-N bond via the CN triple bond to form
the intermediate 3a , and 1 equiv of CH2dCHCN then
inserts into the newly formed Zr-N(imido) bond through
its CdC double bond to generate the active species
containing the Zr-C σ bond, which initiates the chain
propagation.
The molecular structure of 3a has been confirmed by
single-crystal X-ray analyses, shown in Figure 2. The
asymmetric unit contains one toluene of solvation. The
coordination geometry of the Zr atom in 3a is very close
to that in 2a (Table 3). Similarly, both partial N(pπ)fZr-
(dπ) interactions and some degree of p-π bonding in the
NdC-NMe2 moieties are observed in 3a .
R ea ct ion w it h CH 2dC(Me)COOMe. The CdC
double bond in MMA is also activated. It might be
anticipated that 1a ,b could initiate the polymerization
of MMA. In fact, reaction of 1a ,b with excess MMA did
not produce any polymeric materials. On the other hand,
stoichiometric reactions gave the zirconium methoxide
compounds [{η5:σ-Me2A(C9H6)(C2B10H10)}Zr(OCH3)(µ-
OCH3)]2 (A ) C (4a ), Si (4b)) in about 80% isolated yield
(Scheme 1). In the reaction mixture, CH2dC(Me)-
CONMe2 was also detected by 1H NMR and GC-MS
spectroscopy. On the basis of these experimental results,
a possible reaction pathway is proposed in Scheme 2.
Coordination of MMA and migration of NMe2 give the
insertion product B. Elimination of CH2dC(Me)CONMe2
generates the exchange product C. Repeat of the above
reactions yields the monomer D, which dimerizes to
afford the final product 4a . The oxophilicity of Zr(IV) is
probably the driving force for the reactions.
The molecular structures of 4a ,b are confirmed by
X-ray crystallographic analyses, which indicate that
these compounds are isostructural and isomorphous.
They are centrosymmetric dimers and show either two
toluene (for 4a ) or two THF molecules of solvation (for
4b). Figure 3 shows their representative structure. Each
Zr atom is η5-bound to the five-membered ring of the
indenyl group and σ-bound to a cage carbon atom and
one terminal methoxy and two doubly bridging methoxy
groups, thus affording a distorted-square-pyramidal
The X-ray structural analysis of 2a confirms that the
CtN triple bond of PhCN inserts into the Zr-N bond
or the NMe2 group migrates to the carbon position of
the CN unit, leading to the formation of 2a . The Zr atom
is η5-bound to the five-membered ring of the indenyl
group and σ-bound to a cage carbon atom and two
nitrogen atoms in a distorted-tetrahedral geometry,
shown in Figure 1. The structural parameters of the [η5:
σ-Me2C(C9H6)(C2B10H10)]Zr fragment are very close to
those observed in its parent compound 1a (Table 3).16
The average Zr-N distance of 1.972(2) Å is slightly
shorter than that of 2.016(8) Å observed in 1a .16 The
relatively short Zr-N(1,3) distances and the large Zr-
N(1,3)-C angles (160.7(2) and 164.0(2)°) indicate partial
N(pπ)fZr(dπ) interactions between the imido nitrogen
and zirconium atoms. In addition, the C-NMe2 dis-
tances (1.358(3) and 1.353(4) Å) are between the N-C
single- and double-bond distances, which suggests some
degree of p-π bonding in the NdCNMe2 moieties. This
bonding feature is consistent with the fact that the sums
of the C-N-C bond angles around the NMe2 groups
are near 360°.
Rea ction w ith CH2dCHCN. It was reported that
M(NMe2)4 (M ) Ti, Zr, Hf) can initiate the polymeriza-
tion of CH2dCHCN in the absence of any cocatalysts.8a
Although both (Me2N)3M[NdC(NMe2)CdCH2] and (Me2-
N)3M[NdCdCHCH2NMe2] were suggested to be the
first insertion products, neither of these compounds
were characterized.21 Under similar reaction conditions,
1a reacted with 2 equiv of CH2dCHCN to generate the
diinsertion product [η5:σ-Me2C(C9H6)(C2B10H10)]Zr[Nd
C(C2H3)NMe2]2 (3a ). It reacted further with excess
CH2dCHCN, producing polyacrylonitrile. These results
(21) J enkins, A. D.; Lappert, M. F.; Srivastava, R. C. Eur. Polym.
J . 1971, 7, 289.

4528 Organometallics, Vol. 22, No. 22, 2003
Wang et al.
Sch em e 2
F igu r e 3. Molecular structure of [{η5:σ-Me2Si(C9H6)-
(C2B10H10)}Zr(OCH3)(µ-OCH3)]2 (4b ; thermal ellipsoids
drawn at the 35% probability level).
geometry. As indicated in Table 3, both the average Zr-
C(C5 ring) and Zr-C(cage) distances are slightly longer
than those in their parent compounds 1a ,b, due to the
increased steric hindrance. As expected, the Zr-O(ter-
minal) distances are significantly shorter than the Zr-
O(bridging) ones. The short Zr-O(terminal) distances
and very large Zr-O-C angles (170.3(7) and 171.9(3)°)
indicate partial O(pπ)fZr(dπ) interactions between Zr-
(IV) and the terminal MeO group.22
Rea ction w ith CS2. Reactions of 1a ,b with CS2 were
fast, and no monoinsertion products were isolated in
equimolar reactions. Only the diinsertion products [η5:
σ-Me2A(C9H6)(C2B10H10)]Zr(η2-S2CNMe2)2 (A ) C (5a ),
Si (5b)) were obtained in high yield. Both 1a and 1b
also reacted with CO2, as indicated by NMR. Attempts
to isolate pure insertion products, however, failed.
Compounds 5a ,b are isostructural, and their molec-
ular structures are shown in Figure 4. The crystal lattice
of 5a contains two independent toluene molecules of
solvation, whereas that for 5b is unsolvated. It is clear
that CS2 inserts into the Zr-N bond to form the η2-S2-
CNMe2 moiety. The small differences in the C-S
distances (0.010 and 0.027 Å in 5a , 0.022 and 0.041 Å
in 5b) suggest that the negative charge is delocalized
over the S-C-S fragment. Some degree of p-π bonding
in the SdCNMe2 moieties is also observed in the present
compounds.
Rea ction w ith P h NCO. Only the diinsertion prod-
ucts [η5:σ-Me2A(C9H6)(C2B10H10)]Zr[η2-OC(NMe2)NPh]2
(A ) C (6a ), Si (6b)) were isolated from either 1:1 or
1:2 molar ratio reactions. The CdO double bond of the
PhNdCdO molecule inserts into the Zr-N bond to form
the η2-OC(NMe2)NPh moiety with some electronic de-
localization over the O-C-N unit. The third equivalent
of the PhNdCdO molecule can further insert into the
newly formed Zr-N bond to generate the triinsertion
product [η5:σ-Me2Si(C9H6)(C2B10H10)]Zr[η2-OC(NMe2)-
F igu r e 4. Molecular structure of [η5:σ-Me2C(C9H6)-
(C2B10H10)]Zr(η2-S2CNMe2)2 (5a ; thermal ellipsoids drawn
at the 35% probability level).
NPh][η2-OC(NMe2)N(Ph)C(dNPh)O] (7b) (Scheme 1). A
tetrainsertion product was not detected by NMR from
the reaction of 7b with 1 equiv of PhNdCdO; instead,
the trimer (PhNCO)3 was isolated and identified. In fact,
either 7b or 1b can catalyze the trimerization of PhNd
CdO. These results suggest that the fourth equivalent
of isocyanate is superior in reacting with the coordinated
η2-OC(NMe2)N(Ph)C(dNPh)O moiety, leading to the
formation of trimer, probably because of steric reasons.
The proposed catalytic cycle is shown in Scheme 3.
Polymerization of isocyanates catalyzed by (η5-Me-
C5H4)2YNPri (THF)23 and (η5-C5H5)TiCl2(NMe2)24 were
2
reported. The presence of a carboranyl unit in 1b might
be responsible for the differences in their reactivities.
Single-crystal X-ray analyses reveal that compounds
6a ,b are isostructural and isomorphous. Figure 5 shows
a representative structure. The geometry of the [η5:σ-
Me2A(C9H6)(C2B10H10)]Zr fragment is almost identical
with that observed in this family of compounds. The
structural parameters of the η2-OC(NMe2)NPh moieties
indicate some electronic delocalization over the O-C-N
unit.
(23) Mao, L.; Shen, Q,; Xue, M.; Sun, J . Organometallics 1997, 16,
3711.
(24) Patten, T. E.; Novak, B. M. Macromolecules 1993, 26, 436.
(22) McGeary, M. J .; Coan, P. S.; Folting, K.; Streib, W. E.; Caulton,
K. G. Inorg. Chem. 1989, 28, 3283.

Insertion of Unsaturated Molecules into Zr-N Bonds
Organometallics, Vol. 22, No. 22, 2003 4529
F igu r e 5. Molecular structure of [η5:σ-Me2Si(C9H6)-
(C2B10H10)]Zr[η2-OC(NMe2)NPh]2 (6b; thermal ellipsoids
drawn at the 35% probability level).
F igu r e 6. Molecular structure of [η5:σ-Me2Si(C9H6)-
(C2B10H10)]Zr[η2-OC(NMe2)NPh][η2-OC(NMe2)N(Ph)C(d
NPh)O] (7b; thermal ellipsoids drawn at the 35% prob-
ability level).
Sch em e 3
F igu r e 7. Molecular structure of [η5:σ-Me2C(C9H6)-
(C2B10H10)]Zr(NMe2)[η2-SC(NMe2)NBun] (8a ; thermal el-
lipsoids drawn at the 35% probability level).
comparable to those found in 5a ,b. Some degree of p-π
bonding in the N-C-S moiety is observed in the present
compounds.
The molecular structure of 9a is shown in Figure 8.
Its structural parameters are similar to those of its
parent compound 8a . Some degree of p-π bonding in
both N-C-S moieties is also observed.
The molecular structure of 7b is shown in Figure 6.
Its crystal lattice contains a molecule of THF. The
structural parameters indicate that there is some
electronic delocalization over the O(2)-C(27)-N(1),
O(1)-C(37)-N(3), and O(3)-C(4)-N(5) units. Space-
filling drawings of 7b show that the central Zr atom is
fully protected by the surrounding ligands and no
coordination sites are available for the coordination of
the fourth equivalent of isocyanate, which could explain
why no further insertion was observed.
Discu ssion
The above experimental results show that the unsat-
urated molecules insert exclusively into the Zr-N bonds
of 1a ,b and the Zr-C(cage) bond remains intact. The
proposed reaction pathway is that coordination of the
unsaturated molecule followed by nucleophilic attack
initiates the insertion, into either the Zr-N (route a)
or the Zr-C(cage) (route b) bond, which is most probably
governed by steric factors,10b,25 shown in Scheme 4. To
help understand the experimental results, the space-
filling drawings of 1a are generated using X-ray data16
and shown in parts a and b of Figure 9, respectively.
Rea ction w ith n Bu NCS. Reactions of 1a ,b with 1
n
equiv of BuNCS gave the monoinsertion products [η5:
σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)[η2-SC(NMe2)NBun]
(A ) C (8a ), Si (8b)). 8a reacted further with the second
equivalent of nBuNCS, affording the diinsertion deriva-
tive [η5:σ-Me2C(C9H6)(C2B10H10)]Zr[η2-SC(NMe2)NBun]2
(9a ). 9a did not react further with nBuNCS, which is
different from the case for 6a .
Compounds 8a ,b are isostructural, but not isomor-
phous. Figure 7 shows a representative molecular
structure. The Zr-N(amido) distance is much longer
than the Zr-N(imido) distance by ca. 0.27 Å in 8a and
0.29 Å in 8b, respectively. The Zr-S distances are
(25) Gambarotta, S.; Strologo, S.; Floriani, C.; Chiesi-Villa, A.;
Guastini, C. Inorg. Chem. 1985, 24, 654.

4530 Organometallics, Vol. 22, No. 22, 2003
Wang et al.
Sch em e 4
makes the insertion into the Zr-N bond as the only
possible pathway (route a in Scheme 4). The general
lack of mobility of the linked carboranyl moiety may also
prevent such a trans attack.
F igu r e 8. Molecular structure of [η5:σ-Me2C(C9H6)-
(C2B10H10)]Zr[η2-SC(NMe2)NBun]2 (9a ; thermal ellipsoids
drawn at the 35% probability level).
After the insertion of the first molecule, although the
coordination environment of the Zr atom becomes more
crowded, the largest open site available for the coordi-
nation of an unsaturated molecule is still the triangular
area generated by the amido and imido nitrogen atoms
(N1 and N2) and the five-membered ring, as illustrated
by the space-filling drawings of 8a (Figures 10). An
attack trans to the carboranyl ligand is again preferred
for the second equivalent of unsaturated molecule.
Whether or not the third equivalent of unsaturated
molecule is inserted into the newly formed Zr-N bond
These figures clearly show that two NMe2 groups and
the five-membered ring form the largest open area
around the central Zr atom for the coordination of an
unsaturated molecule. Thus, the unsaturated substrate
can only coordinate to the Zr metal in a position that is
trans to the carboranyl group, which probably prevents
the migration of the cage (route b in Scheme 4) and
F igu r e 9. Space-filling drawings of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr(NMe2)2 (1a ):16 (a) axial view along the Zr-C(cage)
bond; (b) equatorial view.

Insertion of Unsaturated Molecules into Zr-N Bonds
Organometallics, Vol. 22, No. 22, 2003 4531
F igu r e 10. Space-filling drawings of [η5:σ-Me2C(C9H6)(C2B10H10)]Zr(NMe2)[η2-SC(NMe2)NBun] (8a ): (a) axial view along
the Zr-C(cage) bond; (b) equatorial view.
is dependent upon the availability of the open coordina-
tion site of the central Zr atom.
of the Zr atom. Possible reaction pathways for these
reactions were proposed.
New zirconium compounds were fully characterized
by various spectroscopic data, elemental analyses, and
single-crystal X-ray diffraction studies. The following
common structural features were observed in the inser-
tion products by comparison with their parent com-
pounds 1a ,b: (1) slightly longer Zr-C(C5 ring) and Zr-
C(cage) distances, (2) slightly smaller Cent-Zr-C(cage)
angles and similar C(C5 ring)-A-C(cage) angles (A )
C, Si), and (3) some degree of p-π bonding in the Xd
CNMe2 (X ) N, S) moieties.
Steric effects are also reflected in the structural
variations associated with the bond distances and angles
around the Zr center (Table 3). In general, the more
crowded coordination environment around the Zr center
leads to the longer Zr-C(C5 ring) and Zr-C(cage)
distances and smaller Cent-Zr-C(cage) angles. How-
ever, the C(C5 ring)-A-C(cage) (A ) C, Si) angles
remain almost unchanged, indicating that the geometry
of the linked indenyl-carboranyl ligands is not affected
by the inserted groups.
Con clu sion s
Ack n ow led gm en t. 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 4267/00P) and the National
Science Foundation of China through the Outstanding
Young Investigator Award Fund (Project No. 20129002).
Reactions of [η5:σ-Me2A(C9H6)(C2B10H10)]Zr(NMe2)2 (A
) C (1a ), Si (1b)) with various unsaturated molecules
were investigated. Small molecules such as CS2, PhCN,
CH2dCHCN, nBuNCS, and PhNCO inserted exclusively
into the Zr-N bonds to give mono-, di-, and triinsertion
products, depending upon the substrates. The Zr-
C(cage) bond remains intact in all reactions. It is
suggested that the preference of Zr-N over Zr-C(cage)
insertion is governed by steric factors.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal-
lographic data and data collection details, atomic coordinates,
bond distances and angles, anisotropic thermal parameters,
and hydrogen atom coordinates and figures giving atom-
numbering schemes for compounds 2a , 3a , 4a ,b, 5a ,b, 6a ,b,
7b, 8a ,b, and 9a . This material is available free of charge via
the Internet at http://pubs.acs.org.
Compounds 1a,b initiated the polymerization of CH2d
CHCN to produce poly(acrylonitrile) and catalyzed the
trimerization of PhNCO. 1a ,b reacted with methyl
methacrylate to afford metal methoxide and CH2d
C(Me)CONMe2, probably due to the high oxophilicity
OM0304255