Alkyl complexes of group 4 metals containing a tridentate-linked amido-cyclopentadienyl ligand: Synthesis, structure, and reactivity including ethylene polymerization catalysis

Article abstract of DOI:10.1021/om980722n

A series of group 4 metal complexes M(η⁵:η¹: η¹-C₅Me₄SiMe₂NCH ₂CH₂X)R₂ (M = Ti; R = Me, CH₂Ph; M = Zr, Hf; R = Me, Et, ⁿPr, ⁿBu, CH₂Ph, CH ₂SiMe₃, Ph) containing the tridentate-linked amido - tetramethylcyclopentadienyl ligand C₅Me₄SiMe ₂NCH₂CH₂X (X = OMe, NMe₂) were synthesized by alkylation of the dichloro complexes M(η⁵: η¹:η¹-C₅Me₄-SiMe ₂NCH₂CH₂X)Cl₂. The complexes were characterized by ¹H and ¹³C NMR spectroscopy, mass spectrometry, and elemental analysis. Nuclear Overhauser effect measurements of the dimethyl complexes show that, in solution, the side chains of the zirconium derivatives coordinate intramolecularly, in contrast to the titanium complexes. The crystal structures of the zirconium alkyls Zr(η⁵: η¹η¹-C₅Me₄SiMe ₂NCH₂CH₂OMe)R₂ (R = Me, Ph) were determined by X-ray diffraction studies. Both complexes adopt a trigonal-bipyramidal structure, with the five-membered ring and the methoxy group in the apical positions. Insertion of carbon monoxide into the hafnium dimethyl and di(n-butyl) complexes led to the η²-acyl derivatives Hf(η⁵:η¹:η¹-C₅Me ₄SiMe₂NCH₂CH₂OMe)(η²- COR)R (R = Me, ⁿBu). Chloro mono(ethyl) complexes underwent insertion of fert-butyl isonitrile to give η²-iminoacyl derivatives M(η⁵:η¹-C₅Me₄SiMe ₂NCH₂CH₂X){η²-C(=N ^tBu)Et}Cl. The X-ray diffraction structure of the titanium complex Ti(η⁵:η¹-C₅Me₄SMe ₂NCH₂CH₂OMe){η²C(=N ^tBu)Et}Cl showed a square-pyramidal configuration with the imino nitrogen trans to the amido nitrogen. The zirconium dimethyl complexes Zr(η⁵:η¹:η¹-C₅Me ₄SiMe₂NCH₂CH₂X)Me₂ reacted with B(C₆F₅)₃ to form the contact ion pairs [Zr(η⁵:η¹:η¹-C ₅Me₄SiMe₂NCH₂CH₂X)Me] ⁺[MeB(C₆F₅)₃]^-. Reaction between the titanium dibenzyl Ti(η⁵:η¹-C ₅Me₄SiMe₂NCH₂CH₂X) (CH₂Ph)₂ and B(C₆F⁵)₃ resulted in the clean formation of the solvent-separated ion pair [Ti(η⁵:η¹:η¹-C₅Me ₄SiMe₂-NCH₂CH₂X)(CH ₂Ph)]⁺[(PhCH₂)B(C₆F ₅)₃]^-. When activated with methylaluminoxane, the complexes Ti(η⁵:η¹-C₅Me ₄SiMe₂NCH₂CH₂OMe)Cl₂ and M(η⁵:η¹:η¹-C₅Me ₄SiMe₂NCH₂CH_2- OMe)R₂ (M = Zr, Hf; R = Me, ⁿBu) are active in the polymerization of ethylene.

Full text of DOI:10.1021/om980722n

5836
Organometallics 1998, 17, 5836-5849
Alk yl Com p lexes of Gr ou p 4 Meta ls Con ta in in g a
Tr id en ta te-Lin k ed Am id o-Cyclop en ta d ien yl Liga n d :
Syn th esis, Str u ctu r e, a n d Rea ctivity In clu d in g Eth ylen e
P olym er iza tion Ca ta lysis
Francisco Amor, Angelika Butt, Karen E. du Plooy, Thomas P. Spaniol, and
J un Okuda*
Institut fu¨r Anorganische Chemie und Analytische Chemie, J ohannes Gutenberg-Universita¨t,
J .-J .-Becher-Weg 24, D-55099 Mainz, Germany
Received August 25, 1998
A series of group 4 metal complexes M(η5:η1:η1-C5Me4SiMe2NCH2CH2X)R2 (M ) Ti; R )
Me, CH2Ph; M ) Zr, Hf; R ) Me, Et, nPr, nBu, CH2Ph, CH2SiMe3, Ph) containing the
tridentate-linked amido-tetramethylcyclopentadienyl ligand C5Me4SiMe2NCH2CH2X (X )
OMe, NMe2) were synthesized by alkylation of the dichloro complexes M(η5:η1:η1-C5Me4-
1
SiMe2NCH2CH2X)Cl2. The complexes were characterized by H and 13C NMR spectroscopy,
mass spectrometry, and elemental analysis. Nuclear Overhauser effect measurements of
the dimethyl complexes show that, in solution, the side chains of the zirconium derivatives
coordinate intramolecularly, in contrast to the titanium complexes. The crystal structures
of the zirconium alkyls Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)R2 (R ) Me, Ph) were
determined by X-ray diffraction studies. Both complexes adopt a trigonal-bipyramidal
structure, with the five-membered ring and the methoxy group in the apical positions.
Insertion of carbon monoxide into the hafnium dimethyl and di(n-butyl) complexes led to
the η2-acyl derivatives Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(η2-COR)R (R ) Me, nBu).
Chloro mono(ethyl) complexes underwent insertion of tert-butyl isonitrile to give η2-iminoacyl
derivatives M(η5:η1-C5Me4SiMe2NCH2CH2X){η2-C(dNtBu)Et}Cl. The X-ray diffraction struc-
ture of the titanium complex Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe){η2-C(dNtBu)Et}Cl showed
a square-pyramidal configuration with the imino nitrogen trans to the amido nitrogen. The
zirconium dimethyl complexes Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2X)Me2 reacted with B(C6F5)3
to form the contact ion pairs [Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2X)Me]+[MeB(C6F5)3]-. Reaction
between the titanium dibenzyl Ti(η5:η1-C5Me4SiMe2NCH2CH2X)(CH2Ph)2 and B(C6F5)3
resulted in the clean formation of the solvent-separated ion pair [Ti(η5:η1:η1-C5Me4SiMe2-
NCH2CH2X)(CH2Ph)]+[(PhCH2)B(C6F5)3]-. When activated with methylaluminoxane, the
complexes Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe)Cl2 and M(η5:η1:η1-C5Me4SiMe2NCH2CH2-
n
OMe)R2 (M ) Zr, Hf; R ) Me, Bu) are active in the polymerization of ethylene.
In tr od u ction
tous metallocene derivatives M(C5R′5)2LmXn and the
half-sandwich complexes M(C5R′5)LmXn. These linked
amido-cyclopentadienyl transition-metal complexes can
also be regarded as hybrids of metallocenes and the
Complexes of early transition metals and lanthanides
containing a linked amido-cyclopentadienyl ligand
C5R′4ZNR′′ (Z ) SiMe2, SiMe2CH2, CH2CH2, CH2CH2-
CH2)1-5 occupy a position halfway between the ubiqui-
(3) (a) Canich, J . M.; Hlatky, G. G.; Turner, H. W. PCT Appl. WO
92-00333, 1992. Canich, J . M. (Exxon Chemical Co.) Eur. Patent Appl.
EP 420 436-A1, 1991. (b) Stevens, J . C.; Timmers, F. J .; Wilson, D. R.;
Schmidt, G. F.; Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S.
(Dow Chemical Co.) Eur. Patent Appl. EP 416 815-A2, 1991.
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1993, 12, 1936. (b) Sinnema, P.-J .; van der Veen, L.; Spek, A. L.;
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Sinnema, P.-J .; Liekelema, K.; Staal, O. K. B.; Hessen, B.; Teuben, J .
H. J . Mol. Catal. 1998, 128, 143.
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(b) Kloppenburg, L.; Peterson, J . L. Organometallics 1996, 15, 7. (c)
Carpenetti, D. W.; Kloppenburg, L.; Kupec, J . T.; Petersen, J . L.
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Organometallics 1997, 16, 3548. (e) Ciruelos, S.; Cuenca, T.; Gomez-
Sal, P.; Manzanero, A.; Royo, P. Organometallics 1995, 14, 177. (f)
Ciruelos, S.; Cuenca, T.; Gomez-Sal, P.; Gomez, R.; Manzanero, A.;
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W. P.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem. Soc. 1994, 116,
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J . Organometallics 1995, 14, 3129. (d) Okuda, J .; du Plooy, K. E.;
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du Plooy, K. E.; Spaniol, T. P.; Okuda, J . Organometallics 1997, 16,
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558, 139. (j) Eberle, T.; Spaniol, T. P.; Okuda, J . Eur. J . Inorg. Chem.
1998, 237. (k) Okuda, J .; Eberle, T. Half-Sandwich Complexes as
Metallocene Analogues. In Metallocenes; Togni, A., Halterman, R. L.,
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10.1021/om980722n CCC: $15.00 © 1998 American Chemical Society
Publication on Web 12/03/1998

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5837
electronically even more unsaturated and sterically
more open bis(amido) chelate complexes.6
Resu lts a n d Discu ssion
Syn th esis of Dia lk yl Com p lexes. The dichloroti-
tanium complexes Ti(η5:η1-C5Me4SiMe2NCH2CH2X)Cl2
(1a ,d ) can be alkylated with Grignard reagents MgRCl
or dialkylmagnesium MgR2 to give the dialkyl deriva-
tives Ti(η5:η1-C5Me4SiMe2NCH2CH2X)R2, R ) Me (2a ,d )
and CH2Ph (6a ,d ), in reproducibly good yields as pen-
tane-soluble, pale yellow and red crystals, respectively
(eq 1). Although detectable in most instances, other
Whereas the active species in group 4 metallocene-
catalyzed R-olefin polymerization has been established
as the 14-electron alkyl cation [M(C5R′5)2R]+,7 the active
species of group 4 metal catalysts containing a linked
amido-cyclopentadienyl ligand, presently being com-
mercialized to produce novel copolymers of ethylene
with R-olefin and styrene,3 is presumed to be the 12-
electron alkyl cation [Ti(η5:η1-C5R′4ZNR′′)R]+.4c,8 Iso-
electronic to this are scandium hydride and alkyls of
the type [Sc(η5:η1-C5Me4SiMe2NtBu)X] (X ) H, nPr, nBu)
that were demonstrated by Bercaw et al. to effect the
living polymerization of R-olefins.1a,b In contrast to
this, 10-electron cations [Ti(C5R′5)R2]+ or 9-electron
cations [Ti(C5R′5)R]+ are generated when half-sandwich
alkyl complexes Ti(C5R′5)R3 are activated with cocata-
lysts.9 Although the former is capable of polymerizing
R-olefins9a-c and the latter is active in the syndiospecific
polymerization of styrene,9d,e such extremely electron-
deficient species often defy structural characteriza-
tion.
We recently introduced a potentially tridentate varia-
tion of the linked amido-cyclopentadienyl ligand, C5R′4-
SiMe2NCH2CH2X, which was designed to mimic the
bis(cyclopentadienyl) ligand set in the d0-metallocene
fragment.2c,d The additional two-electron donor function
X ) OMe and NMe2 was hypothesized to act as a
semilabile ligand that would stabilize highly electro-
philic metal centers temporarily and allow an unsatur-
ated substrate molecule to approach the metal more
readily.10 We report here the synthesis and character-
ization of an extensive series of group 4 metal dialkyl
complexes containing such tridentate-linked amido-
cyclopentadienyl ligands. The insertion chemistry of
unsaturated molecules such as tert-butyl isonitrile and
ethylene was explored, and attempts at the generation
of alkyl cations supported by these tridentate-linked
amido-cyclopentadienyl ligands are presented here.
Preliminary results have been published earlier.2c,h
(1)
dialkyl complexes could not be isolated in pure state.
When more than 1 equiv of an alkylating reagent
containing â-hydrogens was employed, rapid reduction
even at -78 °C ensued, resulting in the formation of
intractable dark products.
The red dibenzyl complexes 6a and 6d proved to be
particularly robust. This is probably due to the presence
of agostic bonding of one of the benzyl groups in the solid
state, as was found in the crystallographically charac-
terized Ti(η5:η1-C5Me4SiMe2NCH2Ph)(CH2Ph)2 and
2g
related mono(cyclopentadienyl)titanium benzyl com-
plexes.11 No unusual features were observed in the H
1
NMR spectra of 6a and 6d : the methylene protons of
the benzyl groups were recorded as AB spin systems at
2
around δ 2.0 (6a : δ 2.08, 2.19 with J HH ) 10.6 Hz; 6d :
2
δ 2.05, 2.18 with J HH ) 10.9 Hz).
It appears that the additional donor group X on the
amido substituent has no direct influence on the stabil-
ity of the titanium dialkyl complexes. NOESY spectra
(C6D6, 25 °C, tmix ) 2.0 s) of the dimethyl complexes 2a
and 2d indicated no interaction between the methyl
groups on titanium and the additional donor; thus
intramolecular coordination of the side chain at the
tetravalent titanium center is at most fluxional. Since
only small chemical shift differences for the OMe and
NMe2 groups were recorded in the temperature range
-80 to +80 °C, we assume that the equilibrium between
the bidentate and tridentate form of the ligands lies on
the side of the open form where the third donor is not
intramolecularly coordinated.12
(6) (a) Schrock, R. R.; Schattenmann, F.; Aizenberg, M.; Davis, W.
M. J . Chem. Soc., Chem. Commun. 1998, 199. (b) Warren, T. H.;
Schrock, R. R.; Davis, W. M. Organometallics 1998, 17, 308. (c)
Baumann, R. H.; Davis, W. M.; Schrock, R. R. J . Am. Chem. Soc. 1997,
119, 3830. (d) Horton, A. D.; de With, J . Organometallics 1997, 16,
5424. (e) Scollard, J . D.; McConville, D. H.; Payne, N. C.; Vittal, J . J .
Macromolecules 1996, 29, 5241. (f) Scollard, J . D.; McConville, D. H.
J . Am. Chem. Soc. 1996, 118, 10008. (g) Aoyagi, K.; Gantzel, P. K.;
Kalai, K.; Tilley, T. D. Organometallics 1996, 15, 923. (h) Cloke, F. G.
N.; Hitchcock, P. B.; Love, J . B. J . Chem. Soc., Dalton. Trans. 1995,
25.
(7) (a) Brintzinger, H.-H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143. (b)
J ordan, R. F. Adv. Organomet. Chem. 1991, 32, 3235.
The double alkylation of the four dichloro complexes
of zirconium and hafnium 1b,c,e,f using the appropriate
alkylating reagent was general and straightforward.
Even alkyl complexes containing â-hydrogens such as
ethyl, n-propyl, and n-butyl were formed in good to
(8) (a) Chen, Y. X.; Stern, C. L.; Yang, S.; Marks, T. J . J . Am. Chem.
Soc. 1996, 118, 12451. (b) J ia, L.; Yang, X.; Stern, C. L.; Marks, T. J .
Organometallics 1997, 16, 842. (c) Chen, Y. X.; Stern, C. L.; Marks T.
J . J . Am. Chem. Soc. 1997, 119, 2582. (d) Chen, Y. X.; Marks, T. J .
Organometallics 1997, 16, 3649. (e) Chen, Y. X.; Metz, M. V.; Li, L.;
Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1998, 120, 6287.
(9) (a) Gillis, D. J .; Tudoret, M.-J .; Baird, M. C. J . Am. Chem. Soc.
1994, 116, 6435. (b) Gillis, D. J .; Quyoum, R.; Tudoret, M.-J .; Wang,
Q.; J eremic, D.; Roszak, A. W.; Baird, M. C. Organometallics 1996,
15, 3600. (c) Nomura, K.; Naga, N.; Miki, M.; Ynagi, K.; Imai, A.
Organometallics 1998, 17, 2152. (d) Zambelli, A.; Pellecchia, C.;
Pappalardo, D.; Oliva, L. J . Am. Chem. Soc. 1995, 117, 6593. (e) For
a review on the syndiospecific styrene polymerization, see: Po, R.;
Cardi, N. Prog. Polym. Sci. 1996, 21, 47.
(11) (a) Mena, M.; Pellinghelli, M.; Royo, P.; Serrano, R.; Tiripicchio,
A. J . Chem. Soc., Chem. Commun. 1986, 1118. (b) Chen, Y. X.; Fu, P.
F.; Stern, C. L.; Marks, T. J . Organometallics 1997, 16, 842. (c) Gielens,
E. E. C. G.; Tiesnitsch, J . Y.; Hessen, B.; Teuben, J . H. Organometallics
1998, 17, 1652.
(12) Even in the more Lewis-acidic 12-electron complexes of the type
Ti(C5R′4ZNR′′2)Cl2 the tethered donor group is engaged in a fluxional
bonding: Flores, J . C.; Chien, J . C. W.; Rausch, M. D. Organometallics
1994, 13, 4140. J utzi, P.; Kleimeier, J . J . Organomet. Chem. 1995, 486,
287. Herrmann, W. A.; Morawietz, M. J . A.; Priermeier, T.; Mashima,
K. J . Organomet. Chem. 1995, 486, 291. van der Zeijden, A. H.;
Matheis, C.; Fro¨hlich, R. Organometallics 1997, 16, 2651. For a brief
review, see: J utzi, P. Eur. J . Inorg. Chem. 1998, 663.
(10) (a) For a brief review on functionalized cyclopentadienyl ligands,
see: Okuda, J . Comments Inorg. Chem. 1994, 16, 185. (b) For related
ligand systems, see: Mu, Y.; Piers, W. E.; MacQuarrie, D. C.;
Zaworotko, M. J .; Young, V. G., J r. Organometallics 1996, 15, 2720.
Spence, R. E. v. H.; Peirs, W. E. Organometallics 1995, 14, 4617.

5838 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
excellent yields, resulting in the isolation in most cases
of unexpectedly thermally stable, pentane-soluble, color-
less crystals (eq 2). NMR spectra consistently showed
(2)
the presence of a mirror plane bisecting the molecule.
Thus for all complexes, enantiotopic pairs of methyl
signals were recorded as singlets for the C5Me4, SiMe2,
and NMe2 groups in the temperature range -80 to +80
°C. The amido substituent CH2CH2X gives rise to an
AA′XX′ spin system with tripletlike features. The
chemical shifts for the methyl groups of X did not
change significantly with changing temperature. For
instance, for the zirconium diphenyl 8b, expected to be
sterically fairly strained, the 1H NMR spectroscopic shift
in C6D6 varied merely from δ 2.15 at 25 °C to δ 2.24 at
80 °C. NOESY spectra clearly showed that the ad-
ditional coordination of X in the dimethyl complexes 2b
and 2e is fairly rigid on the NMR time scale. In contrast
to the titanium analogues 2a and 2d , there were NOE
cross-peaks between the resonance for ZrMe2 and those
for OMe and NMe2 in 2b and 2e. We assume that for
the series of zirconium and hafnium dialkyl complexes
the tridentate coordination mode is the dominant one
on the NMR time scale.
F igu r e 1. ORTEP diagram of the molecular structure of
the complex Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Me2 (2b).
Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for the sake of clarity.
occupy the apical positions. The two methyl groups and
the doubly bonded amido nitrogen atom (Zr-N distance
2.099(3) Å, sum of angles at N 360°) occupy the equato-
rial sites. All three ligands are turned away from the
C5Me4 ligand. The Zr-O bond length of 2.375(2) Å lies
within the range of distances usually observed for a
bond between tetravalent zirconium and an ether oxy-
gen atom.13 The five-membered chelate ring is slightly
puckered, with the methyl group of the methoxy func-
tion out of the mirror plane that bisects the molecule.
Somewhat surprising was the observation of this
structural type for the sterically more congested diphen-
yl derivative Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Ph2
(8b) (Figure 2 and Tables 1 and 3). Evidently, through
propeller-like torsion, the two phenyl groups are accom-
modated within the coordination sphere of the Zr-
(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe) fragment. Diphen-
yl complexes of group 4 metallocenes are well-known.14
Previously reported single-crystal X-ray structure analy-
ses of the dichloro complexes Hf(η5:η1:η1-C5Me4SiMe2-
NCH2CH2OMe)Cl2 (1c)2i and Zr(η5:η1:η1-C5Me4SiMe2-
NCH2CH2NMe2)Cl2 (1e)2c as well as of di(n-butyl) Hf(η5:
η1:η1-C5Me4SiMe2NCH2CH2OMe)nBu2 (5c)2h all revealed
an analogous configuration. Five-coordinate half-sand-
wich complexes of transition metals most commonly
adopt a square-pyramidal configuration;15 hence only a
limited number of trigonal bipyramidal structures have
been reported in the literature.16 The coordination of
The planar chiral dichloro complex Zr(η5:η1:η1-C5H3-
tBuSiMe2NCH2CH2NMe2)Cl2 (1g) was found to possess
a rigidly coordinated NMe2 group up to +80 °C, as
evidenced by the two well-separated signals of the NMe2
group in both the 1H and 13C NMR spectra. On the other
hand, the NMR spectrum of the analogous titanium
derivative, with only one peak for the two rapidly
interconverting NMe2 methyls, confirms that the tita-
nium complex is fluxional.2c When the less Lewis-acidic,
planar chiral dialkyl derivative Zr(η5:η1:η1-C5H3tBuSiMe2-
NCH2CH2NMe2)(CH2SiMe3)2 (7g) was studied by vari-
able-temperature 1H NMR spectroscopy, a decoalescence
of the NMe2 signals was observed at 7 °C. Above this
coalescence temperature nitrogen inversion renders the
two diastereotopic NMe2 groups equivalent. A value for
the activation barrier of ∆G‡ ) 13.1(1) kcal mol-1 was
obtained for the reversible dissociation/association of the
amino nitrogen (eq 3).
(13) (a) Erker, G.; Sarter, C.; Albrecht, M.; Dehnicke, S.; Kru¨ger,
C.; Raabe, E.; Schlund, R.; Benn, R.; Rufinska, A.; Mynott, R. J .
Organomet. Chem. 1990, 382, 89. (b) Holland, P.; Andersen, R. A.;
Bergman. Organometallics 1998, 17, 433. (c) Cardin, D. J .; Lappert,
M. F.; Raston, C. L. Chemistry of Organo-Zirconium and -Hafnium
Compounds; Wiley: New York, 1986.
(3)
(14) Erker, G. J . Organomet. Chem. 1977, 134, 189.
(15) Kubacek, P.; Hoffmann, R.; Havlas, Z. Organometallics 1982,
1, 180. Despite the large number of half-sandwich complexes of the
general type (C5R5)ML(4-n)Xn (see: Poli, R. Chem. Rev. 1991, 91, 509),
there are only a few cases with indirect evidence for trigonal bipyra-
midal configuration; for example: Abugideiri, F.; Gordon, J . C.; Poli,
R.; Owens-Waltermire, B. E.; Rheingold, A. L. Organometallics 1993,
12, 1575. For general references on five-coordination, see: Ward, T.
R.; Bu¨rgi, H.-B.; Gilardoni, F.; Weber, J . J . Am. Chem. Soc. 1997, 119,
11974. Holmes, R. R. Prog. Inorg. Chem. 1984, 32, 119.
An X-ray diffraction study verified the pseudo-trigo-
nal-bipyramidal configuration of the dimethyl derivative
2b (Figure 1, Tables 1 and 2). The η5-bonded five-
membered ring and the OMe group approximately

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5839
Ta ble 1. Exp er im en ta l Da ta for th e Cr ysta l Str u ctu r e Deter m in a tion of
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Me2 (2b), Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)P h 2 (8b), a n d
Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe){η2-C(NtBu )Et}Cl (12a )
2b
8b
12a
Crystal Data
empirical formula
fw
C
16H30NOSiZr
C26H35NOSiZr
496.86
C21H39ClN2OSiTi
446.98
371.72
cryst color
cryst size, mm
cryst system
space group
a, Å
colorless
0.3 × 0.3 × 0.3
monoclinic
P21/c (no. 14)
8.416(3)
14.667(2)
15.769(2)
102.61(2)
1899.5(8)
4
colorless
0.4 × 0.4 × 0.7
monoclinic
P21/n (no. 14)
8.800(2)
15.903(2)
18.273(2)
91.32(1)
2556.6(7)
4
yellow
0.6 × 0.3 × 0.3
monoclinic
P21 (no. 4)
8.180(9)
12.026(7)
13.004(5)
95.32(8)
1274(3)
2
b, Å
c, Å
â, deg
V, Å3
Z
F
calc., g cm-3
1.300
0.639
780
1.291
0.493
1040
1.165
0.500
480
µ(Mo KR), mm-1
F(000)
Data Collection
wavelength
T, K
Mo KR (0.710 70 Å)
293(2)
Mo KR (0.710 70 Å)
296(2)
Mo KR (0.710 70 Å)
296(2)
θ-range, deg
index ranges
3-28
3-27
3-26
h, 0 to 11;
k, 0 to 19;
l, -20 to 20
h, 0 to 11;
k, 0 to 20;
l, -23 to 23
h, 0 to 10;
k, 0 to 14;
l, -16 to 15
Solution and Refinement
no. of rflns measd
no. of indep rflns
no. of obsd rflns
ext coeff
4860
5890
2789
4564 [Rint ) 0.0190]
3246 [I > 2σ(I)]
5533 [Rint ) 0.0392]
3405 [I > 2σ(I)]
2606 [Rint ) 0.0423]
1972 [I > 2σ(I)]]
0.0058(5)
GOF
1.161
1.167
1.144
R
0.0368
0.0549
0.0611
wR2 [I > 2σ(I)]
0.0687
0.419 and -0.320
0.1117
0.372 and -0.364
0.1403
0.563 and -0.400
largest e-max, e-min, e‚Å-3
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Me2
(2b)
bond lengths
bond angles
Zr-N
2.099(3)
2.272(4)
2.266(5)
2.375(2)
2.450(3)
2.484(3)
2.524(3)
2.602(3)
2.616(3)
1.704(3)
1.869(3)
1.393(5)
1.429(5)
1.451(4)
1.461(6)
2.23
N-Zr-C(11)
120.6(2)
114.3(2)
108.5(2)
70.18(9)
77.7(1)
Zr-C(11)
Zr-C(12)
Zr-O
N-Zr-C(12)
C(12)-Zr-C(11)
N-Zr-O
Zr-C(1)
Zr-C(2)
Zr-C(5)
Zr-C(3)
Zr-C(4)
Si-N
Si-C(1)
O-C(9)
O-C(10)
N-C(8)
C(8)-C(9)
Cpcent-Zr
O-Zr-C(11)
O-Zr-C(12)
N-Si-C(6)
N-Si-C(7)
N-Si-C(1)
C(6)-Si-C(7)
C(9)-O-C(10)
C(9)-O-Zr
C(10)-O-Zr
C(8)-N-Si
C(8)-N-Zr
Si-N-Zr
81.7(1)
113.9(2)
114.9(2)
93.0(1)
105.2(3)
114.3(3)
114.8(2)
126.8(3)
127.8(2)
124.2(2)
107.9(1)
111.1(3)
110.8(4)
98.9
F igu r e 2. ORTEP diagram of the molecular structure of
the complex Zr(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Ph2 (8b).
Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for the sake of clarity.
N-C(8)-C(9)
O-C(9)-C(8)
Cpcent-Zr-N
the oxygen atom does not result in any distortion when
compared to bidentate chelates such as Zr(η5:η1-C5Me4-
SiMe2NtBu)Me2.5c
containing two higher alkyls, Hf(η5:η1:η1-C5Me4SiMe2-
NCH2CH2OMe)nBu2 (5c), decomposed in the solid state
only above 90 °C, giving 1-butene as the sole volatile
product detectable by GC MS. Complexes 3-5 are more
thermally sensitive in solution, however, although no
clear decomposition pathway has been identified so far
by NMR spectroscopy.17 Iodinolysis of 5c afforded in
quantitative yield 1-iodobutane along with the dark
yellow diiodo homologue of 1c, Hf(η5:η1:η1-C5Me4SiMe2-
The thermal stability of the dialkyl complexes quali-
tatively follows the general order Ti , Zr < Hf and Et
n
n
< Pr < Bu < CH2SiMe3 < Me < Ph < CH2Ph. The
zirconium diphenyl complex did not undergo any de-
composition reaction during prolonged heating (100 °C
for 1 week). A representative member of the series
(16) (a) Liu, A. H.; Murray, R. C.; Dewan, J . C.; Santarsiero, B. D.;
Schrock, R. R. J . Am. Chem. Soc. 1987, 109, 4282. (b) Nadasdi, T. T.;
Huang, Y.; Stephan, D. W. Inorg. Chem. 1993, 32, 347.
(17) McDermott, J . X.; Wilson, M. E.; Whitesides, G. M. J . Am.
Chem. Soc. 1976, 98, 6529.

5840 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)P h 2
(8b)
Sch em e 1
bond lengths
bond angles
Zr-N
2.095(5)
2.284(6)
2.288(6)
2.330(4)
2.450(5)
2.489(5)
2.534(5)
2.598(6)
2.607(6)
1.704(5)
1.874(6)
1.39(2)
N-Zr-C(21)
110.6(2)
119.1(2)
114.6(2)
71.4(2)
79.3(2)
79.1(2)
113.4(3)
115.3(3)
104.9(3)
92.7(2)
113.3(9)
115.3(8)
126.0(4)
128.8(4)
122.7(4)
107.9(2)
112.1(9)
108.8(9)
110(1)
Zr-C(21)
Zr-C(31)
Zr-O
N-Zr-C(31)
C(21)-Zr-C(31)
N-Zr-O
Zr-C(1)
Zr-C(2)
Zr-C(5)
Zr-C(4)
Zr-C(3)
Si-N
Si-C(1)
O-C(91)
O-C(92)
O-C(10)
N-C(8)
C(21)-Zr-O
C(31)-Zr-O
N-Si-C(6)
N-Si-C(7)
C(6)-Si-C(7)
N-Si-C(1)
C(91)-O-Zr
C(92)-O-Zr
C(10)-O-Zr
C(8)-N-Si
C(8)-N-Zr
Si-N-Zr
N-C(8)-C(92)
N-C(8)-C(91)
O-C(91)-C(8)
O-C(92)-C(8)
Cpcent-Zr-N
diastereomers are fluxional, the acyl group rotating
freely about the metal carbon bond via a monohapto-
bound acyl group.
When the titanium dimethyl complexes 2a and 2d
were reacted with tert-butyl isonitrile, mixtures of sev-
eral compounds were obtained from very sluggish reac-
tions. Originally when we attempted to isolate the
diethyl derivatives of titanium, we obtained evidence
for the formation of a chloro mono(ethyl) compound Ti-
(η5:η1-C5Me4SiMe2NCH2CH2X)(Et)Cl, although it could
not be isolated. Upon addition of tert-butyl isonitrile to
the reaction mixture of ethylmagnesium chloride and
the dichloro complexes 1a and 1d , we were able to iso-
late the chloro(tert-butylimino)propionyl complexes Ti-
(η5:η1-C5Me4SiMe2NCH2CH2X){η2-C(dNtBu)Et}Cl (12a,d)
as air-stable, yellow crystals in excellent yields (eq 4).
1.41(2)
1.414(7)
1.462(8)
1.47(2)
1.48(2)
2.23
C(8)-C(92)
C(8)-C(91)
Cpcent-Zr
110(1)
98.8
NCH2CH2OMe)I2 (11c). The robustness of dialkyl com-
plexes containing â-hydrogens is remarkable. When
Zr(η5:η1-C5Me4SiMe2NtBu)Cl2 was treated with 2 equiv
of an alkyllithium reagent, no clean reaction was
observed and no dialkyls isolated, indicating the critical
role of the third donor group. Few metallocene deriva-
tives that contain two alkyl groups with â-hydrogen
atoms have been mentioned in the literature.18 This is
even more scarce in half-sandwich complexes.19 Re-
cently, a series of group 4 diamido complexes containing
higher alkyls were reported,6a-c after Andersen had
recognized some time ago that amido ligands support
higher alkyls at d0 metal centers.20
In ser tion Rea ction s. Since insertion of carbon mon-
oxide into the alkyl bond of group 4 metallocene dialkyls
constitutes a well-studied important type of reaction,21
we briefly examined the reaction of carbon monoxide
with the hafnium dimethyl 2c and di(n-butyl) 5c. As
followed by 1H NMR spectroscopy, a slow reaction of the
dialkyl with carbon monoxide (1 bar) occurred over a
period of 12 h to give the mono(insertion) product Hf-
(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(COR)R (R ) Me
(9c); R ) nBu (10c)) (Scheme 1). The unsymmetrical η2-
acyl derivatives are easily identified by the low-field
shift of the acyl carbon in the 13C NMR spectrum. Thus
a signal at δ 342.3 and at δ 343.0 for the acetyl 9c and
valeroyl 10c, respectively, was found. Curiously only one
of the possible diastereomers (exo or endo isomer) was
found in each case, even at -80 °C. In contrast to the
zirconocene monoacyl complexes21 the exo and endo
(4)
The chirality at the metal was evident from the lack of
a mirror plane, rendering all enantiotopic groups in-
equivalent in the NMR spectra. Most strikingly, for 12a
1
the H NMR resonances for the four ring methyl groups
were spread over a range δ 1.32-2.63. The resonances
of the ethyl group appeared as a triplet at δ 1.00 for
the methyl and as a high-order ABX3 multiplet at 2.28
and 2.60.
A single-crystal X-ray diffraction study confirmed the
structure (Figure 3, Tables 1 and 4). The pseudo-square-
pyramidal configuration consists of cyclopentadienyl,
amido, chloro, and the dihapto-bonded (imino)propionyl
group. The methoxy group of the side chain does not
interact with the titanium center, similar to the struc-
ture of Ti(η5:η1-C5H4SiMe2NCH2CH2OMe)Cl2.2d The imi-
no nitrogen (Ti-N(2) 2.061(7) Å) is coordinated trans to
the doubly bonded amido nitrogen (Ti-N(1) 1.957(8) Å),
in agreement with the former being a weak σ-donor lig-
and. The geometry of the (imino)propionyl group (Ti-
C(11) 2.050(9), C(11)-N(2) 1.24(1) Å, Ti-C(11)-N(2)
72.9(5)°) is comparable to that reported in other tetra-
valent titanium complexes that contain a similar ligand
unit.22
(18) (a) J ordan, R. F.; Bradley, P. K.; Baenzinger, N. C.; LaPointe,
R. E. J . Am. Chem. Soc. 1990, 112, 1289. (b) Burger, B. J .; Thompson,
M. E.; Cotter, W. D.; Bercaw, J . E. J . Am. Chem. Soc. 1990, 112, 1566.
(c) Guo, Z.; Swenson, D. C.; J ordan, R. F. Organometallics 1994, 13,
1424. (d) Schock, L. E.; Marks, T. J . J . Am. Chem. Soc. 1988, 110,
7701. (e) Erker, G.; Schlund, R.; Kru¨ger, C. Organometallics 1989, 8,
2349. (f) Takahashi, T.; Nishihara, Y.; Ishida, T. Chem. Lett. 1995, 159.
(19) (a) Hessen, B.; van der Heijden, H. J . Am. Chem. Soc. 1996,
118, 11670. (b) Kondakov, D.; Negishi, E. J . Chem. Soc., Chem.
Commun. 1996, 963.
(20) (a) Andersen, R. A Inorg. Chem. 1979, 18, 2928. (b) Planalp, R.
P.; Andersen, R. A.; Zalkin, A. Organometallics 1983, 2, 16.
(21) (a) Erker, G. Acc. Chem. Res. 1984, 17, 103. (b) Tatsumi, K.;
Nakamura, A.; Hofmann, P.; Stauffert, P.; Hoffmann, R. J . Am. Chem.
Soc. 1985, 107, 4440.
Following an analogous procedure, it was possible to
prepare the heavier homologues of 12a and 12d M(η5:
(22) (a) Chamberlain, L.; Durfee, L. D.; Fanwick, P. E.; Kobriger,
L.; Latesky, S. L.; McMullen, A. K.; Rothwell, I. P. J . Am. Chem. Soc.
1987, 109, 390. (b) Bochmann, M.; Wilson, L. M.; Hursthouse, M. B.;
Short, R. L. Organometallics 1987, 6, 2556. (c) Campora, J .; Buchwald,
S. L.; Gutierrez-Puebla, D. E.; Monge, A. Organometallics 1995, 14,
2039. (d) Fandos, R.; Lanfranchi, M.; Otero, A.; Pellinghelli, M. A.;
Ruiz, M. J .; Teuben, J . H. Organometallics 1997, 16, 5283.

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5841
F igu r e 3. ORTEP diagram of the molecular structure of
the complex Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe){η2-C-
(dNtBu)Et}Cl (12a ). Thermal ellipsoids are drawn at the
50% probability level. Hydrogen atoms are omitted for the
sake of clarity.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Ti(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)-
{η2-C(dNtBu )Et}Cl (12a )
F igu r e 4. Variable-temperature 1H NMR spectra (400
MHz) of Zr(η5:η1-C5Me4SiMe2NCH2CH2NMe2){η2-C(dNtBu)-
Et}Cl (12e) in toluene-d8.
bond lengths
bond angles
Ti-N(1)
1.957(8)
2.061(7)
2.050(9)
2.377(3)
2.270(8)
2.341(8)
2.341(8)
2.442(7)
2.411(7)
1.696(8)
1.872(9)
1.24(1)
1.48(1)
1.52(1)
1.50(2)
1.41(2)
1.40(2)
1.467(12)
1.45(2)
2.03
N(1)-Ti-C(11)
99.4(3)
96.3(2)
35.2(3)
89.4(2)
72.9(5)
71.9(5)
135.9(9)
131.9(9)
112.4(9)
113.5(6)
117.6(5)
91.7(4)
104.9(7)
131.2(8)
123.1(7)
105.4(4)
115(1)
Sch em e 2
Ti-N(2)
N(1)-Ti-Cl
Ti-C(11)
Ti-Cl
C(11)-Ti-N(2)
N(2)-Ti-Cl
Ti-C(1)
Ti-C(11)-N(2)
C(11)-N(2)-Ti
C(11)-N(2)-C(14)
C(12)-C(11)-N(2)
C(11)-C(12)-C(13)
N(1)-Si-C(6)
N(1)-Si-C(7)
N(1)-Si-C(1)
C(6)-Si-C(7)
C(8)-N(1)-Si
C(8)-N(1)-Ti
Si-N(1)-Ti
Ti-C(2)
Ti-C(5)
Ti-C(3)
Ti-C(4)
Si-N(1)
Si-C(1)
N(2)-C(11)
N(2)-C(14)
C(11)-C(12)
C(12)-C(13)
O-C(9)
O-C(10)
N(1)-C(8)
C(8)-C(9)
Cpcent-Ti
N(1)-C(8)-C(9)
C(8)-C(9)-O
C(9)-O-C(10)
Cpcent-Ti-N
109(1)
111(1)
106
multiplets of the ethyl group undergo an upfield shift
of about 0.5 ppm upon cooling. On the basis of the
structure of the titanium complex 12a , we assume a
pseudo-octahedral structure for the zirconium and
hafnium complexes with the imino nitrogen arranged
trans to the amido-nitrogen atom and the NMe2 group
adopting the site trans to the C5Me4 ligand.
Alk yl Ca tion F or m a tion a n d Eth ylen e P olym er -
iza tion . Alkyl cations supported by the tridentate-
linked amido-cyclopentadienyl ligands were expected
to be more amenable to study than those containing the
original bidentate amido-cyclopentadienyl ligands. How-
ever, the generation, detection, and isolation of alkyl
cations, in most cases, were severely hampered by what
appeared to be high thermal sensitivity leading to rapid
decomposition and complicated fluxional behavior. Un-
fortunately the usual methods for the generation of
metallocene alkyl cations such as protonolytic and oxi-
dative cleavage failed.23 When the zirconium dimethyl
complexes 2b and 2e were treated with 1 equiv of
B(C6F5)3 in bromobenzene (eq 5), the formation of the
corresponding methyl cation [Zr(η5:η1-C5Me4SiMe2NCH2-
η1-C5Me4SiMe2NCH2CH2X){η2-C(dNtBu)Et}Cl (12b,c,e,f).
Again, even in cases where the isolation of the diethyl
proved to be difficult (3b), the chloro (imino)propionyl
derivatives were obtained as colorless, analytically pure
crystals in high yields. While the metal-centered chiral-
ity was obvious from the NMR spectra, the variable-
1
temperature H NMR spectra of the NMe2-functional-
ized derivatives M(η5:η1-C5Me4SiMe2NCH2CH2NMe2){η2-
C(dNtBu)Et}Cl (12e,f) revealed interesting fluxional
behavior. As seen in Figure 4, there is only one set of
methyl signals for the NMe2 group of 12e at higher
temperatures, indicating fast inversion at nitrogen
because the side chain is not rigidly coordinated. Upon
cooling to 0 °C, decoalescence occurs and the signal
splits into two. The activation barrier is estimated to
be ∆G‡ (301.15 K) ) 13.7(1) kcal mol-1. At -30 °C the
two resonances again disappear into the baseline, while
two C5Me4 signals are also broadened. This phenomenon
can be interpreted as the freezing-out of the rotation
about the zirconium-iminoacyl carbon (Scheme 2). In
agreement with this suggestion, the two eight-line

5842 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
F igu r e 5. 1H NMR spectrum (400 MHz, 25 °C) of [Ti(η5:η1:ηx-C5Me4SiMe2NCH2CH2NMe2)(CH2Ph)]+[PhCH2B(C6F5)3]- in
bromobenzene-d5.
CH2X)Me]+ with the familiar anion [MeB(C6F5)3]- 24
could be detected by NMR spectroscopy. The signals
[MeB(C6F5)3]- appears to be coordinating.25 We believe
that an equilibrium between the contact ion pair and
the solvent-separated ion pair exists.
When the titanium dibenzyl complexes 6a and 6d
were reacted with equimolar amounts of B(C6F5)3 in
bromobenzene at room temperature, clean formation of
the corresponding benzyl cations was observed. At-
tempts at isolating these compounds have failed so far,
although a dark red powder precipitates upon addition
of pentane. As Figure 5 shows for 6d , it is quite obvious
that the reaction according to Scheme 3 results in the
formation of [Ti(η5:η1-C5Me4SiMe2NCH2CH2NMe2)(CH2-
Ph)]+[PhCH2B(C6F5)3]-, stable for a period of several
hours. On the basis of the NMR spectroscopic evidence,
we believe it to be a solvent-separated ion pair rather
than a contact ion pair (B favored over A in Scheme 3).
The anion shows 19F NMR spectroscopic features that
are indicative of a free [PhCH2B(C6F5)3]- ion (∆δ(m-,
p-F) ) 2.8 ppm).25 The methylene protons of the benzyl
group bonded to the boron appear at δ 3.27 as a broad
singlet and all aromatic protons are recorded well below
δ 6.5, excluding the possibility of any strong interaction
of the aromatic ring with the cationic metal center.
The methylene protons of the benzyl group at the
cationic titanium center give rise to an AB spin pattern
(5)
were somewhat broad in the observed temperature
range 0-25 °C. The cation lacks a mirror plane with
two and four signals for the SiMe2 and C5Me4 methyl
groups, respectively. In addition, in 2e/B(C6F5)3 the
signals for the diastereotopic methyl groups of the NMe2
function are well separated at -25 °C, indicating a
slowed dissociation of the additional donor function.
The resonances for the zirconium methyl signals appear
at δ -0.21 (2b/B(C6F5)3) and -0.14 ppm (2e/B(C6F5)3)
in the 1H NMR spectrum and at δ 34.8 (2b/B(C6F5)3)
and 35.3 ppm (2e/B(C6F5)3) in the 13C NMR spectrum.
These values are comparable to those reported for [Zr-
(η5-C5Me5)Me2(toluene)]+[MeB(C6F5)3]- (δ -0.11 and
45.5, respectively)9a and [Zr(η5:η1-C5Me4SiMe2NtBu)Me-
(toluene)]+[B(C6F5)4]- (δ -0.45 and 32.2, respectively).8b
J udged from the values of ∆δ(m-, p-F), 3.7 and 5.9 ppm
for 2b/B(C6F5)3 and 2e/B(C6F5)3, respectively, the anion
2
at δ 2.51 and 2.27 ppm with J HH ) 11.4 Hz. The
coupling constant is similar to that observed in the
parent neutral dibenzyl 6d (10.6 Hz), indicating that
there is no agostic or dihapto bonding of the benzyl
group.23,26 The diastereotopic methyls of the NMe2 group
(23) Mono(ring) alkyl zirconium cations seem to be thermally less
robust: Crowther, D. J .; J ordan, R. F.; Baenziger, N. C.; Verma, A.
Organometallics 1990, 9, 2574.
(24) (a) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1991,
113, 3623. (b) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc.
1994, 116, 10015.
(25) Horton, A. D.; de With, J .; van der Linden, A. J .; van de Weg,
H. Organometallics 1996, 15, 2672.

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5843
Ta ble 5. P olym er iza tion of Eth ylen e w ith
Meth yla lu m in oxa n e-Activa ted
Sch em e 3
M(η5:η1:ηx-C5Me4SiMe2NCH2CH2OMe)R2 Com p lexesa
c
precat
temp (°C)
yield (g)
activityb
Tm
1a
1a
2b
2b
2c
2c
5b
5b
5c
5c
25
70
25
70
25
70
25
70
25
70
0.08d
1.55
0.08
3.80
0.06
0.66
0.20e
1.12
0.21
0.08
12
239
13
586
9
102
31
173
32
132.3
131.3
136.5
129.7
134.8
127.5
131.1
129.5
130.7
125.3
12
a
Ethylene pressure 3 bar, precatalyst 5.0 µmol, 2.5 mmol of
methylalumoxane, metal-to-aluminum ratio: 1:500, 200 mL of
b
toluene, 1.5 h reaction time. Activity: kg of polyethylene/mol of
metal‚h‚ethylene concentration. c The melting temperatures were
measured by DSC (DSC-7 Perkin-Elmer) from the second scan
d
with a heating ratio of 10 °C/min. Molecular weight (GPC, vs
polystyrene): Mn ) 13 000, Mw ) 4 660 000. e Molecular weight
(GPC, vs polystyrene): Mn ) 970 000, Mw ) 9 310 000.
Con clu sion
The linked amido-cyclopentadienyl ligand is an
ancillary ligand set that is comparable to the linked bis-
(cyclopentadienyl) ligand system in ansa-metallocenes.2k
Although donating two π-electrons less to a d0-metal
center, the pronounced donor property of the amido
group imparts resistance to reduction at the metal cen-
ter comparable to that of the metallocene unit. When
the formal electron count at the metal is identical with
that of the metallocene as a result of additional σ-donors
such as OMe and NMe2, as in the tridentate ligands
discussed above, one starts seeing differences as a result
of the relative “electron richness” of the complexes con-
taining the linked amido-cyclopentadienyl ligand. Most
prominently, â-hydrogen elimination of higher alkyl
groups clearly slows down in the dialkyl complexes, at
least for the less reducible metals Zr and Hf. This
feature is also prevalent in the group 4 metal bis(amido)
complexes recently studied.6a-c The metal-carbon bond
energy however does not change dramatically, as ob-
served in the ready insertion reaction of CO and tert-
butyl isonitrile. The additional donor furthermore en-
abled the observation of a benzyl titanium cation, the
presumed active species in the polymerization of R-ole-
fins, when titanium complexes with linked amido-
cyclopentadienyl ligands are used.3,8 Since the addi-
tional σ-donor is not bonded rigidly in the kinetic sense
and undergoes reversible dissociation and association,
polymerization of R-olefins is not completely suppressed.
Recent studies confirm the extremely high electrophi-
licity of the alkyl cation within the coordination sphere
of the linked amido-cyclopentadienyl system. It was
reported that the reaction of the dibenzyl Ti(η5:η1-C5-
Me4SiMe2NtBu)(CH2Ph)2 with B(C6F5)3 results in a
C-H activation product, [Ti{η5:η1:η1-(C5Me3CH2)SiMe2Nt-
Bu}]+[PhCH2B(C6F5)3]-, and that the dimethyl Ti(η5:
η1-C5Me4SiMe2NtBu)Me2 forms a dimeric cation [{Ti(η5:
η1-C5Me4SiMe2NtBu)Me}2(µ-Me)]+.8d In conclusion, we
have delineated a “metallocene-like” coordination sphere29
for group 4 metal centers based on the functionalized
give rise to one signal in the 1H NMR spectrum, whereas
in the 13C NMR spectrum two signals are recorded,
suggesting a fluxional coordination of the side chain.
As a matter of fact, the signal of the NMe2 group
decoalesces below -20 °C into two resonances. We
assume that at room temperature the side chain is
engaged in a fluxional (“weak”) bonding without halting
the nitrogen inversion. Rigid coordination of the NMe2
group would probably cause stronger inequivalency of
the methyl signals. Thus, the strongly electrophilic,
formally 12-electron cation appears to be sufficiently
stabilized by this mode of fluxional coordination.
Polymerization of ethylene and 1-hexene was ob-
served with the above cations, but with erratic results.
Therefore study of ethylene polymerization was con-
ducted with the dichloro titanium 1a and the zirconium
and hafnium dialkyl derivatives 2b , 5b , 2c, and 5c
containing the methoxy-functionalized ligand. Upon
activation with methylaluminoxane (metal-to-aluminum
ratio 1:500), ethylene is readily polymerized to give high
molecular weight polyethylene of melting temperatures
in the range 130-135 °C. The results are summarized
in Table 5. The polymerization generally proceeded
significantly faster at 70 °C. As often observed in
metallocene catalysis,7 the activity of zirconium cata-
lysts is higher than that of the titanium and hafnium
homologues at a given metal-to-aluminum ratio. Com-
pared to similar complexes containing the bidentate
ligand such as Ti(η5:η1-C5Me4SiMe2NtBu)Cl2 under iden-
tical conditions,2j it is evident that side chain modifica-
tion results in significantly lower activities (12 vs 950
kg polyethylene/(mol Ti h)).27 We tentatively ascribe this
to the occupation of one additional site at the metal site
that blocks the π-complex formation of the ethylene.28
(26) (a) Pellecchia, C.; Immirzi, A.; Grassi, A.; Zambelli, A. Orga-
nometallics 1993, 12, 4473. (b) Bochmann, M.; Lancaster, S. J .;
Hursthouse, M. B.; Malik, K. M. A. Organometallics 1994, 13, 2235.
(27) A similar scenario was reported during the syndiospecific
polymerization using the titanium catalyst [Ti(η5:ηx-C5Me4CH2CH2-
Ph)R]+: Flores, J . C.; Wood, J . S.; Chien, W.; Rausch, M. D. Organo-
metallics 1996, 15, 4944.
(28) (a) Wu, Z.; J ordan, R. F. J . Am. Chem. Soc. 1995, 117, 5867.
(b) Casey, C. P.; Hallenbeck, S. L.; Wright, J . M.; Landis, C. R. J . Am.
Chem. Soc. 1997, 119, 9690. (c) Galakhov, M. V.; Heinz, G.; Royo, P.
J . Chem. Soc., Chem. Commun. 1998, 17.

5844 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
1
in 75% yield: mp 35 °C; H NMR δ 0.42 (s, 6 H, SiCH3), 0.45
(s, 6 H, TiCH3), 1.89, 1.99 (s, 6 H, C5(CH3)4), 3.11 (s, 3 H,
OCH3), 3.38 (“t”, 2 H, CH2O), 4.33 (“t”, 2 H, NCH2); 13C NMR
linked amido-cyclopentadienyl ligands. Coordination
properties of such ligands at the even more electrophilic
d0-metal center of the heavier group 3 metals are
currently also a focus of our attention.30
1
1
δ 3.3 (q, J CH ) 119 Hz, SiCH3), 11.9, 15.1 (q, J CH ) 126 Hz,
1
1
C5(CH3)4), 49.7 (q, J CH ) 118 Hz, TiCH3), 50.6 (t, J CH ) 134
Hz, NCH2), 58.2 (q, 1J CH ) 139 Hz, OCH3), 75.3 (t, 1J CH ) 145
Hz, CH2O), 97.4 (s, ring C at Si), 128.0, 134.1 (s, C5(CH3)4); EI
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments were performed
under argon using standard Schlenk or glovebox techniques.
THF, pentane, and hexane were purified by distillation from
sodium/benzophenone ketyl. Toluene was distilled over sodium
sand. Li2[C5Me4SiMe2NCH2CH2X] (X ) OMe, NMe2),2i M(η5:
η1:η1-C5Me4SiMe2NCH2CH2OMe)Cl2 (M ) Zr (1b); Hf (1c)),2i
TiCl3(THF)2,31 Mg(CH2Ph)2(THF)2,32 LiEt,33 LinPr,33 and
B(C6F5)334 were synthesized according to published procedures.
PbCl2 (Fluka) was dried at 120 °C before use. MgMeCl (Ald-
rich), MgEtCl (Aldrich), LinBu (Aldrich), Mg(CH2SiMe3)Cl
(Aldrich), LiPh (Aldrich), and tBuNC (Fluka) were used as
received. Alkyllithium35 and Grignard36 solutions were titrated
prior to use. NMR spectra were recorded on a Bruker DRX
400 spectrometer (1H, 400 MHz; 13C, 101 MHz; 11B, 128 MHz;
19F, 376 MHz) in C6D6 at 298 K, unless otherwise stated.
Chemical shifts for 1H and 13C spectra were referenced inter-
nally using the residual solvent resonances and reported rela-
tive to tetramethylsilane. 11B spectra were referenced exter-
nally to BF3(Et2O), 19F spectra to CFCl3. Mass spectra were
recorded on a Finnigan 8230 spectrometer. Elemental analyses
were performed by the microanalytical laboratory of this
department or by the Analytische Laboratorien GmbH, Lind-
lar, Germany.
MS: m/z 330 (3, MH+), 314 (100, M+ - CH3), 298 (30, M+
-
OMe), 272 (41, MH2 - CH2CH2OMe), 256 (22, MH+ - CH2-
CH2OMe, - CH3), 241 (37, MH+ - CH2CH2OMe, - 2CH3).
Anal. Calcd for C16H31NOSiTi: C, 58.34; H, 9.49; N, 4.25.
Found: C, 56.55; H, 9.28; N, 4.42.
+
Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe)(CH2P h )2 (6a ). Hex-
ane (40 mL) was added to a solid mixture of 1a (0.39 g, 1.09
mmol) and the THF adduct of dibenzylmagnesium (0.42 g, 1.20
mmol) at -78 °C. The mixture was allowed to warm to room
temperature and stirred at room temperature overnight. All
volatiles were removed in vacuo, and the residue was extracted
with hexane (20 mL). After filtration through glass fiber, the
yellow solution was concentrated and cooled to -30 °C over-
night to give red crystals: yield 0.35 g (67%); 1H NMR δ 0.41
(s, 6 H, SiCH3), 1.74, 1.86 (s, 6 H, C5(CH3)4), 2.08, 2.19 (d, 2
2
H, J HH ) 10.6 Hz, TiCH2), 2.92 (“t”, 2 H, CH2O), 2.95 (s, 3 H,
OCH3), 3.82 (“t”, 2 H, NCH2), 6.88-7.17 (m, 10 H, C6H5); 13C-
{1H} NMR δ 3.4 (SiCH3), 11.4, 14.9 (C5(CH3)4), 52.1 (NCH2),
57.8 (OCH3), 74.4 (CH2O), 79.5 (TiCH2), 98.9 (ring C at Si),
121.9 (para C6H5), 126.8 (meta C6H5), 128.5 (ortho C6H5), 129.2,
135.4 (C5(CH3)4), 149.2 (ipso C6H5); EI MS m/z 482 (21, M+),
390 (17, M+ - C7H7), 299 (29, M+ - 2C7H7). Anal. Calcd for
Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe)Cl2 (1a ). THF (40
mL) was added at -78 °C to a solid mixture of Li2[C5Me4SiMe2-
NCH2CH2OMe] (1.00 g, 3.7 mmol) and TiCl3(THF)3 (1.39 g,
3.7 mmol). After warming to room temperature, solid PbCl2
(1.04 g, 3.7 mmol) was added, and the mixture was stirred for
30 min. All volatiles were removed in vacuo, and the residue
was extracted with pentane (3 × 15 mL). Filtration followed
by concentrating the filtrate and cooling to -30 °C afforded
C
28H39NOSiTi: C, 69.87; H, 8.11; N, 2.91. Found: C, 69.56;
H, 8.00; N, 2.81.
Rea ction of 6a w ith B(C6F 5)3. C6D5Br (0.5 mL) was added
to an equimolar mixture of 6a (20 mg, 41 µmol) and B(C6F5)3
(21 mg, 41 µmol) in an NMR tube at -78 °C. The color turned
dark red at room temperature: 1H NMR (C6D5Br) δ 0.12, 0.35
(s, 3 H, SiCH3), 1.45, 1.69, 1.77, 2.15 (s, 3 H, C5(CH3)4), 2.16
2
(s, 3 H, OCH3), 2.43, 2.90 (d, 1 H, J HH ) 6.8 Hz, TiCH2), 3.16
1
light-yellow-brown crystals: 67% yield; mp 98 °C; H NMR δ
(m, 1 H, CH2OMe), 3.31 (br s, 2 H, CH2B(C6F5)3), 3.36 (m, 1
H, CH2OMe), 3.45, 4.64 (m, 1 H, SiNCH2), 6.44 (br, 2 H, CH2-
C6H5), 6.86-7.15 (signals overlap. with solvent signals, 8 H,
CH2C6H5); 13C{1H} NMR (C6D5Br) δ 0.4, 2.8 (SiCH3), 11.1, 13.1,
13.8, 15.2 (C5(CH3)4), 32.0 (br, CH2B(C6F5)3), 49.1 (SiNCH2),
62.6 (CH2OMe), 74.5 (OCH3), 88.3 (TiCH2), 108.4 (ring C at
Si), 122.0, 122.6, 122.9, 127.2, 128.9, 130.7, 131.9, 134.9, 135.9,
136.4, 142.4 (ring C), 135.6, 137.8, 138.9, 147.5 (C6F5), 148.7
(ipso CH2C6H5) 149.8 (ipso C6F5); 11B NMR (C6D5Br) δ -12.1;
0.46 (s, 6 H, SiCH3), 2.00, 2.02 (s, 6 H, C5(CH3)4), 2.90 (s, 3 H,
OCH3), 3.08 (“t”, 2 H, CH2O), 4.34 (“t”, 2 H, NCH2); 13C{1H}
NMR δ 2.9 (SiCH3), 12.9, 16.2 (C5(CH3)4), 54.9 (NCH2), 57.9
(OCH3), 72.5 (CH2O), 104.6 (ring C at Si), 135.8, 141.0 (C5-
(CH3)4); EI MS m/z 369 (5, M+), 324 (100, M+ - CH2OMe),
295 (33, M+ - NHCH2CH2OMe), 178 (52, C5Me4SiMe2+), 45
(50, CH2OMe+). Anal. Calcd for C14H25Cl2NOSiTi: C, 45.42;
H, 6.81; N, 3.78. Found: C, 45.10; H, 6.71; N, 3.77.
Ti(η5:η1-C5Me4SiMe2NCH 2CH 2OMe)Me2 (2a ). Methyl-
magnesium chloride (1.0 mL of a 1.6 M solution in THF) was
added to a suspension of 1a (0.30 g, 0.84 mmol) in hexane (30
mL) at 0 °C. After the mixture was stirred for 3 h at room
temperature, all volatiles were removed in vacuo. Extraction
of the residue with pentane (20 mL) was followed by filtration
through glass fiber, and the volume of the filtrate was reduced.
Crystallization from pentane at -30 °C gave yellow needles
3
19F NMR (C6D5Br) δ -130.2 (d, J FF ) 22.9 Hz, ortho C6F5),
3
3
-163.4 (t, J FF ) 20.6 Hz, para C6F5), -166.3 (t, J FF ) 20.6
Hz, meta C6F5).
Ti(η5:η1-C5Me4SiMe2NCH2CH2OMe){C(dNtBu)Et}Cl (12a).
Ethylmagnesium chloride (1.30 mL of a 1.7 M solution in THF)
was added to a mixture of 1a (0.82 g, 2.21 mmol) and tert-
butyl isonitrile (0.25 mL, 2.21 mmol) in hexane (30 mL) at -78
°C. The mixture was allowed to warm to room temperature
over a period of 5 h under stirring. All volatiles were removed
in vacuo, and the residue was extracted with pentane (15 mL).
Filtration was followed by concentrating the filtrate and
cooling the concentrated pentane solution to -78 °C to afford
(29) For other chelating, dianionic ligand systems, see: bis(alkox-
ide): van der Linden, A.; Schaverien, C. J .; Meijboom, N.; Ganter, C.;
Orpen, A. G. J . Am. Chem. Soc. 1995, 117, 3008. Fokken, S.; Spaniol,
T. P.; Kang, H.-C.; Massa, W. Organometallics 1996, 15, 5069.
Tetraaza-macrocycle: Martin, A.; Uhrhammer, R.; Gardner, T. G.;
J ordan, R. F. Organometallics 1998, 17, 382. Calix[4]arenes: Caselli,
A.; Giannini. L.; Solari, E.; Floriani, C.; Re, N.; Chiesi-Villa, A.; Rizzoli,
C. Organometallics 1997, 16, 5457. Schiff bases: Woodman, P.;
Hitchcock. P. B.; Scott, P. J . Chem. Soc., Chem. Commun. 1996, 2735.
(30) (a) Hultzsch, K. C.; Spaniol, T. P.; Okuda, J . Organometallics
1997, 16, 4845. (b) Hultzsch, K. C.; Spaniol, T. P.; Okuda, J . Organo-
metallics 1998, 17, 485. (c) Hultzsch, K. C.; Spaniol, T. P.; Okuda, J .
Angew. Chem., Int. Ed. Engl., in press.
1
yellow needles: yield 0.70 g (71%); H NMR δ 0.59, 0.70 (s, 3
3
H, SiCH3), 1.00 (t, 3 H, J HH ) 7 Hz, CH2CH3), 1.32 (s, 3 H,
C5(CH3)4), 1.34 (s, 9 H, C(CH3)3), 1.95, 2.10 (s, 3 H, C5(CH3)4),
2.28, 2.60 (m, 1 H, CH2CH3), 2.63 (s, 3 H, C5(CH3)4), 3.05 (s, 3
H, OCH3), 3.28 (“t”, 2 H, CH2O), 3.48, 3.60 (m, 1 H, NCH2);
13C{1H} NMR δ 3.3, 4.8 (SiCH3), 11.7 (CH2CH3), 11.8, 12.2,
15.5, 16.3 (C5(CH3)4), 28.3 (CH2CH3), 30.2 (C(CH3)3), 52.6
(NCH2), 58.0 (OCH3), 63.3 (C(CH3)3), 73.9 (CH2O), 104.2 (ring
C at Si), 125.8, 127.5, 128.7, 133.8 (C5(CH3)4), 238.8 (CN); EI
MS m/z 446 (4, M+), 417 (1, M+ - Et), 411 (23, M+ - Cl), 382
(31) Manzer, L. E. Inorg. Synth. 1982, 21, 135.
(32) Schrock, R. R. J . Organomet. Chem. 1976, 122, 209.
(33) Appelquist, D. E.; O’Brien, D. F. J . Am. Chem. Soc. 1963, 85,
743.
(34) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1964, 2, 245.
(35) Suffert, J . J . Org. Chem. 1989, 54, 509.
(3, M+ - C2H5 - Cl), 363 (2, M+ - CNCMe3), 334 (95, M+
CNCMe3, - C2H5), 327 (3, M+ - CNCMe3, - Cl), 298 (14, M+
-
(36) Watson, S. C.; Eastham, J . F. J . Organomet. Chem. 1967, 9, 165.

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5845
- CNCMe3, - C2H5, - Cl). Anal. Calcd for C21H39N2ClOSiTi:
C, 56.46; H, 8.73; N, 6.27. Found: C, 56.63; H, 8.72; N, 6.44.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Me2 (2b). Follow-
ing a procedure similar to that described for the preparation
of 2a , 1b (0.41 g, 1.0 mmol) was reacted with methylmagne-
sium chloride (1.05 mL of a 1.9 M solution in THF) to afford
colorless crystals: yield 0.23 g (61%); H NMR δ -0.35 (s, 6
H, ZrCH3), 0.41 (s, 6 H, SiCH3), 2.06, 2.08 (s, 6 H, C5(CH3)4),
3.08 (“t”, 2 H, NCH2), 3.35 (s, 3 H, OCH3), 3.44 (“t”, 2 H, CH2O);
(C5(CH3)4), 46.6 (NCH2), 58.1 (ZrCH2), 62.4 (OCH3), 78.9
(CH2O), 97.9 (ring C at Si), 121.3 (para C6H5), 125.5, 126.8
(C5(CH3)4), 127.8 (meta C6H5), 128.3 (ortho C6H5), 150.6 (ipso
C6H5); EI MS m/z 433 (100, M+ - C7H7), 342 (36, M+ - 2C7H7).
Anal. Calcd for C28H39NOSiZr: C, 64.00; H, 7.43; N, 2.76.
Found: C, 63.78; H, 7.31; N, 2.60.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(CH2SiMe3)2 (7b).
The preparation of this compound is analogous to the prepara-
tion of 2a . The reaction between 1b (0.50 g, 1.21 mmol) and
trimethylsilylmethylmagnesium chloride (2.42 mL of a 1.0 M
solution in Et2O) gave colorless crystals: yield 0.54 g (87%);
1
13C NMR δ 3.2 (q, 1J CH ) 120 Hz, SiCH3), 11.7, 14.3 (q, 1J CH
)
126 Hz, C5(CH3)4), 31.8 (q, 1J CH ) 113 Hz, ZrCH3), 45.8 (t, 1J CH
) 134 Hz, NCH2), 61.0 (q, 1J CH ) 144 Hz, OCH3), 79.0 (t, 1J CH
) 144 Hz, CH2O), 96.1 (s, ring C at Si), 124.1, 126.2 (s, C5-
(CH3)4); EI MS m/z 372 (9%, M+), 356 (11%, M+ - CH3), 340
(8%, M+ - OCH3). Anal. Calcd for C16H31NOSiZr: C, 51.56;
H, 8.38; N, 3.76. Found: C, 51.29; H, 8.14; N, 3.62.
2
1H NMR δ -0.73, 0.13 (d, 2 H, J HH ) 11 Hz, ZrCH2), 0.15 (s,
18 H, Si(CH3)3), 0.40 (s, 6 H, Si(CH3)2), 2.03, 2.09 (s, 6 H, C5-
(CH3)4), 3.11 (“t”, 2 H, NCH2), 3.45 (“t”, 2 H, CH2O), 3.45 (s, 3
H, OCH3); 13C{1H} NMR δ 2.8 (Si(CH3)2), 4.6 (Si(CH3)3), 12.9,
14.9 (C5(CH3)4), 42.5 (ZrCH2), 45.9 (NCH2), 62.8 (OCH3), 78.8
(CH2O), 98.0 (ring C at Si), 124.8, 125.9 (C5(CH3)4); EI MS m/z
Rea ction of 2b w ith B(C6F 5)3. C6D5Br (0.5 mL) was added
to an equimolar mixture of 2b (30 mg, 80.5 µmol) and B(C6F5)3
(41 mg, 80.5 µmol) in an NMR tube at -78 °C. The reaction
mixture turned yellow at -30 °C: 1H NMR (C6D5Br, 253 K) δ
-0.21 (br s, 3 H, ZrCH3), 0.21 (br s, 6 H, SiCH3), 0.81 (br s, 3
H, CH3B(C6F5)3), 1.8 (br s, 12 H, C5(CH3)4), 3.1 (br, 2 H, NCH2),
3.19 (br s, 3 H, OCH3), 3.67 (br, 2 H, CH2O); 13C{1H} NMR
(C6D5Br, 253 K) δ 1.9 (SiCH3), 10.0 (br, C5(CH3)4), 20.0 (CH3B-
(C6F5)3), 34.8 (ZrCH3), 47.4 (NCH2), 62.3 (OCH3), 80.4 (CH2O),
102.2 (ring C at Si); 11B NMR (C6D5Br, 253 K) δ -15.00; 19F
NMR (C6D5Br, 253 K) δ -130.3 (ortho C6F5), -160.0 (para
C6F5), -163.7 (meta C6F5).
501 (3, M+ - CH3), 428 (76, M+ - CH2SiMe3), 340 (16, M+
-
2CH2SiMe3). Anal. Calcd for C22H47NOSi3Zr: C, 51.14; H, 9.10;
N, 2.71. Found: C, 50.87; H, 9.06; N, 2.82.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)P h 2 (8b). Follow-
ing a procedure analogous to that described for the preparation
of 2a , 1b (0.54 g, 1.30 mmol) was reacted with phenyllithium
(1.5 mL of a 1.8 M solution in cyclohexane/ether) to give color-
less crystals: yield 0.45 g (70%); 1H NMR δ 0.53 (s, 6 H, SiCH3),
1.71, 2.01 (s, 6 H, C5(CH3)4), 2.17 (s, 3 H, OCH3), 3.21 (“t”, 2
H, NCH2), 3.34 (“t”, 2 H, CH2O), 7.11-7.44 (m, 10 H, C6H5);
13C{1H} NMR δ 3.0 (SiCH3), 12.1, 14.8 (C5(CH3)4), 46.8 (NCH2),
61.3 (OCH3), 78.3 (CH2O), 97.7 (ring C at Si), 126.0 (para
C6H5), 126.2 (C5(CH3)4), 126.5 (meta C6H5), 128.7 (C5(CH3)4),
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)n P r 2 (4b). Follow-
ing a procedure similar to that described for the preparation
of 2a , 1b (0.46 g, 1.11 mmol) was reacted with n-propyllithium
(6.18 mL of a 0.36 M solution in pentane) to afford a brownish
134.1 (ortho C6H5), 191.1 (ipso C6H5); EI MS m/z 341 (1, M+
-
2C6H5), 328 (1, M+ - 2C7H7). Anal. Calcd for C26H35NOSiZr:
C, 62.80; H, 7.05; N, 2.82. Found: C, 62.57; H, 7.20; N, 2.73.
Zr (η5:η1:η1-C5Me4SiMe2NCH 2CH 2OMe){C(dNt Bu )E t }-
Cl (12b). Following a procedure analogous to that described
for 12a , ethylmagnesium chloride (0.93 mL of a 1.7 M solution
in THF) was added to a mixture of 1b (0.66 g, 1.59 mmol) and
tert-butyl isonitrile (0.18 mL, 1.59 mmol) in hexane (30 mL)
at -78 °C to give colorless crystals after cooling a concentrated
1
2
oil: yield 0.36 g (77%); H NMR δ -0.14 (td, 2 H, J HH ) 12
3
Hz, J HH ) 5 Hz, ZrCH2), 0.40 (s, 6 H, SiCH3), 0.60 (td, 2 H,
2J HH ) 12 Hz, J HH ) 5 Hz, ZrCH2), 1.14 (t, 6 H, J HH ) 7 Hz,
γ-CH3), 1.3-1.5 (m, 4 H, â-CH2), 2.00, 2.09 (s, 6 H, C5(CH3)4),
3.08 (“t”, 2 H, NCH2), 3.36 (s, 3 H, OCH3), 3.47 (“t”, 2 H, CH2O);
13C{1H} NMR δ 2.9 (SiCH3), 11.3, 14.1 (C5(CH3)4), 21.9 (â-CH2,
γ-CH3), 46.0 (NCH2), 54.8 (ZrCH2), 60.9 (OCH3), 79.4 (CH2O),
96.8 (ring C at Si), 123.7, 125.4 (C5(CH3)4); EI MS m/z 384 (2,
M+ - C3H7), 340 (3, M+ - C3H7, - C3H8), 342 (6, M+ - C3H7,
- C3H6).
3
3
1
pentane solution: yield 0.50 g (64%); H NMR δ 0.58 (s, 6 H,
3
SiCH3), 1.11 (t, 3 H, J HH ) 7 Hz, CH2CH3), 1.26 (s, 9 H,
C(CH3)3), 1.47, 2.18, 2.19 (s, 3 H, C5(CH3)4), 2.29 (m, 1 H, CH2-
CH3), 2.58 (s, 3 H, C5(CH3)4), 2.67 (m, 1 H, CH2CH3), 3.00 (m,
1 H, NCH2), 3.10 (m, 1 H, CH2O), 3.19 (s, 3 H, OCH3), 3.25
(m, 2 H, NCH2, CH2O); 13C{1H} NMR δ 3.0, 3.2 (SiCH3), 12.2,
12.5 (C5(CH3)4), 12.7 (CH2CH3), 15.0, 15.2 (C5(CH3)4), 28.9
(CH2CH3), 31.4 (C(CH3)3), 46.8 (NCH2), 60.4 (C(CH3)3), 62.0
(OCH3), 78.3 (CH2O), 102.8 (ring C at Si), 123.5, 128.6 (C5-
(CH3)4), 247.6 (CN). Anal. Calcd for C21H39N2ClOSiZr: C,
51.46; H, 7.96; N, 5.72. Found: C, 51.22; H, 7.87; N, 5.85.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Me2 (2c). Follow-
ing a procedure analogous to that described to prepare 2a , 1c
(0.40 g, 0.79 mmol) was treated with methylmagnesium
chloride (0.88 mL of a 1.9 M solution in THF) to give 2c as
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)n Bu 2 (5b). A sus-
pension of 1b (0.48 g, 1.16 mmol) in hexane (30 mL) was
treated with n-butyllithium (1.0 mL of a 2.3 M solution in hex-
ane) at 0 °C. After stirring for 16 h at room temperature, all
volatiles were removed in vacuo. The residue was extracted
into pentane and filtered. Recrystallization from pentane at
-78 °C afforded colorless crystals: yield 0.35 g (67%); mp (dec)
60 °C; 1H NMR δ -0.18 (m, 2 H, ZrCH2), 0.41 (s, 6 H, SiCH3),
3
0.54 (m, 2 H, ZrCH2), 1.04 (t, 6 H, J HH ) 7 Hz, δ-CH3), 1.2-
1.5 (overlap. m, 8 H, â-, γ-CH2), 2.06, 2.14 (s, 6 H, C5(CH3)4),
3.1 (“t”, 2 H, NCH2), 3.42 (s, 3 H, OCH3), 3.49 (“t”, 2 H, CH2O);
13C NMR δ 2.9 (q, 1J CH ) 117 Hz, SiCH3), 11.3, 14.1 (q, 1J CH
)
125 Hz, C5(CH3)4), 14.3 (q, 1J CH ) 123 Hz, δ-CH3), 30.1 (t, 1J CH
) 124 Hz, â-CH2), 30.7 (t, 1J CH ) 124 Hz, γ-CH2), 45.9 (t, 1J CH
) 133 Hz, NCH2), 51.0 (t, 1J CH ) 112 Hz, ZrCH2), 60.8 (q, 1J CH
colorless crystals: yield 0.22 g (60%); H NMR δ -0.46 (s, 6
1
H, HfCH3), 0.42 (s, 6 H, SiCH3), 2.08, 2.12 (s, 6 H, C5(CH3)4),
3.12 (“t”, 2 H, NCH2), 3.30 (s, 3 H, OCH3), 3.39 (“t”, 2 H, CH2O);
13C{1H} NMR δ 2.9 (SiCH3), 11.9, 14.0 (C5(CH3)4), 41.8
(HfCH3), 45.3 (NCH2), 60.8 (OCH3), 72.9 (CH2O), 96.7 (ring C
at Si), 123.4, 124.7 (C5(CH3)4); EI MS m/z 446 (100, M+ - CH3),
431 (21, M+ - 2CH3). Anal. Calcd for C16H31NHfOSi: C, 41.78;
H, 6.74; N, 3.04. Found: C, 41.62; H, 6.61; N, 2.91.
1
) 143 Hz, OCH3), 79.4 (t, J CH ) 142 Hz, CH2O), 96.8 (s, ring
C at Si), 123.6, 125.4 (s, C5(CH3)4); EI MS m/z 398 (10, M+
-
C4H9), 344 (37, M+ - C4H9, - C4H7), 342 (100, M+ - C4H9,
-C4H8), 340 (48, M+ - C4H9, - C4H10). Anal. Calcd for C22H43
-
NOSiZr: C, 57.86; H, 9.42; N, 3.06. Found: C, 57.60; H, 9.25;
N, 3.16.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)Et2 (3c). Follow-
ing a procedure analogous to that described to prepare 2a , 1c
(0.30 g, 0.59 mmol) was reacted with ethyllithium (11.4 mL of
a 0.11 M solution in hexane) to give 3c as colorless crystals:
yield 0.19 g (66%); 1H NMR δ -0.27 (m, 2 H, HfCH2), 0.42 (s,
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(CH2P h )2 (6b). Fol-
lowing a procedure analogous to that described to prepare 6a ,
1b (1.0 g, 2.42 mmol) was reacted with dibenzylmagnesium
THF adduct (0.84 g, 2.42 mmol) to give colorless crystals: yield
1
3
0.83 g (66%); H NMR δ 0.37 (s, 6 H, SiCH3), 1.37, 1.85 (d, 2
6 H, SiCH3), 0.48 (m, 2 H, HfCH2), 1.21 (t, J HH ) 8 Hz, 6 H,
H, 2J HH ) 12 Hz, ZrCH2), 1.97, 1.98 (s, 6 H, C5(CH3)4), 2.63 (s,
3 H, OCH3), 3.02 (“t”, 2 H, NCH2), 3.26 (“t”, 2 H, CH2O), 6.63-
7.15 (m, 10 H, C6H5); 13C{1H} NMR δ 2.7 (SiCH3), 11.6, 14.4
CΗ2CH3), 2.04, 2.16 (s, 6 H, C5(CH3)4), 3.11 (“t”, 2 H, NCH2),
3.34 (s, 3 H, OCH3), 3.42 (“t”, 2 H, CH2O); 13C{1H} NMR δ 2.8
(SiCH3), 11.3 (C5(CH3)4), 11.6 (HfCH2), 13.9 (C5(CH3)4), 45.5

5846 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
(NCH2), 49.5 (CΗ2CH3), 60.6 (OCH3), 79.5 (CH2O), 97.5 (ring
H, NCH2), 3.32 (“t”, 2 H, CH2O), 7.15-7.47 (m, 10 H, C6H5);
13C{1H} NMR δ 2.9 (SiCH3), 12.0, 14.6 (C5(CH3)4), 46.3 (NCH2),
61.2 (OCH3), 78.6 (CH2O), 98.1 (ring C at Si), 125.5 (C5(CH3)4),
125.9 (para C6H5), 126.9 (meta C6H5), 127.2 (C5(CH3)4), 135.4
(ortho C6H5), 202.6 (ipso C6H5); EI MS m/z 585 (30, M+), 508
C at Si), 123.1, 124.1 (C5(CH3)4); EI MS m/z 460 (10, M+
-
C2H6), 431 (80, M+ - 2C2H6). Anal. Calcd for C18H35NHfOSi:
C, 44.31; H, 7.17; N, 2.87. Found: C, 44.19; H, 7.07; N, 2.76.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)n P r 2 (4c). Follow-
ing a procedure analogous to that described to prepare 2a , 1c
(0.56 g, 1.12 mmol) was reacted with n-propyllithium (7.5 mL
of a 0.3 M solution in pentane) to give 4c as pale yellow needles
(100, M+ - C7H7), 431 (18, M+ - 2C7H7). Anal. Calcd for C26H35
-
NHfOSi: C, 53.47; H, 5.99; N, 2.39. Found: C, 53.13; H, 6.08;
N, 2.25.
1
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(COMe)Me (9c).
Toluene (15 mL) was added to a 50 mL flask containing 2c
(0.20 g, 0.43 mmol), and the argon atmosphere was replaced
by carbon monoxide. The solution was stirred overnight, and
toluene was completely removed to give 9c as a yellow oil:
yield 0.17 g (80%); 1H NMR δ -0.08 (s, 3 H, HfCH3), 0.53, 0.54
(s, 3 H, SiCH3), 1.30 (s, 3 H, HfCOCH3), 1.99, 2.27, 2.45, 2.46
(s, 3 H, C5(CH3)4), 2.68 (s, 3 H, OCH3), 2.9-3.2 (m, 4 H, NCH2-
that melt at room temperature: yield 0.36 g (63%); H NMR
2
3
δ -0.37 (td, 2 H, J HH ) 12 Hz, J HH ) 5 Hz, HfCH2), 0.40 (s,
6 H, SiCH3), 0.49 (td, 2 H, 2J HH ) 12 Hz, 3J HH ) 5 Hz, HfCH2),
1.16 (t, 6 H, J HH ) 6 Hz, γ-CH3), 1.2-1.5 (m, 4 H, â-CH2),
3
2.04, 2.13 (s, 6 H, C5(CH3)4), 3.10 (“t”, 2 H, NCH2), 3.33 (s, 3
H, OCH3), 3.42 (“t”, 2 H, CH2O); 13C{1H} NMR δ 2.8 (SiCH3),
11.2, 14.0 (C5(CH3)4), 22.5 (γ-CH3), 23.0 (â-CH2), 45.5 (NCH2),
60.7 (OCH3), 64.7 (HfCH2), 79.5 (CH2O), 98.0 (ring C at Si),
123.3, 124.2 (C5(CH3)4); EI MS m/z 474 (18, M+ - C3H7), 432
(28, M+ - C3H7, - C3H6), 431 (16, M+ - 2C3H7), 430 (29, M+
- C3H7, - C3H8).
1
CH2O); 13C NMR δ 2.9, 3.3 (q, J CH ) 118 Hz, SiCH3), 10.5,
1
1
11.2, 14.4, 14.7 (q, J CH ) 126 Hz, C5(CH3)4), 23.8 (q, J CH
)
1
111 Hz, HfCOCH3), 35.0 (q, J CH ) 125 Hz, HfCH3), 45.1 (t,
1J CH ) 133 Hz, NCH2), 58.6 (q, 1J CH ) 144 Hz, OCH3), 78.9 (t,
1J CH ) 143 Hz, CH2O), 98.5 (s, ring C at Si), 121.1, 121.5, 123.9,
125.3 (s, C5(CH3)4), 342.3 (s, HfCOCH3); EI MS m/z 489 (11,
M+), 446 (41, M+ - COCH3), 431 (78, M+ - COCH3, - CH3).
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)n Bu 2 (5c). This
compound was prepared analagously to 5b. From 1c (0.40 g,
0.79 mmol) and n-butyllithium (0.62 mL of a 2.7 M solution
in hexane), 5c was obtained as colorless crystals: yield 0.23 g
(55%); mp (dec) 90 °C; 1H NMR δ -0.47 (m, 2 H, HfCH2), 0.42
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(COnBu )nBu (10c).
An NMR tube containing a solution of 5c (27 mg, 0.05 mmol)
in C6D6 (0.5 mL) was placed into a flask, and the argon
atmosphere was replaced by carbon monoxide. The NMR tube
was left overnight under carbon monoxide, during which time
the color of the solution changed from colorless to slightly
3
(s, 6 H, SiCH3), 0.49 (m, 2 H, HfCH2), 1.06 (t, 6 H, J HH ) 7
Hz, δ-CH3), 1.20 (m, 2 H, â-CH2), 1.50 (overlap. m, 6 H, â-,
γ-CH2), 2.06, 2.14 (s, 6 H, C5(CH3)4), 3.13 (“t”, 2 H, NCH2),
3.39 (s, 3 H, OCH3), 3.45 (“t”, 2 H, CH2O); 13C NMR δ 2.8 (q,
1J CH ) 117 Hz, SiCH3), 11.3, 13.9 (q, 1J CH ) 125 Hz, C5(CH3)4),
14.3 (q, 1J CH ) 123 Hz, δ-CH3), 31.1 (t, 1J CH ) 124 Hz, â-CH2),
1
yellow. H NMR spectra indicated complete conversion of 5c
1
1
31.2 (t, J CH ) 124 Hz, γ-CH2), 45.9 (t, J CH ) 133 Hz, NCH2),
into 10c. Removal of all the volatiles resulted in a yellow oil;
1H NMR δ 0.35 (m, 2 H, HfCH2), 0.53, 0.55 (s, 3 H, SiCH3),
0.55-1.20 (overlap. m, 10 H, HfCOCH2, â-, γ-CH2), 0.89, 1.23
60.4 (t, 1J CH ) 110 Hz, HfCH2), 60.8 (q, 1J CH ) 144 Hz, OCH3),
1
79.6 (t, J CH ) 141 Hz, CH2O), 97.4 (s, ring C at Si), 123.4,
124.2 (s, C5(CH3)4); EI MS m/z 488 (26, M+ - C4H9), 432 (83,
M+ - C4H8, - C4H9), 430 (100, M+ - C4H9, - C4H10). Anal.
Calcd for C22H43NHfOSi: C, 48.57; H, 7.91; N, 2.57. Found:
C, 48.30; H, 7.75; N, 2.43.
3
(t, 3 H, J HH ) 7 Hz, δ-CH3), 1.32, 1.99, 2.26, 2.48 (s, 3 H,
C5(CH3)4), 2.5 (m, 2 H, NCH2), 2.69 (s, 3 H, OCH3), 2.7 (m, 2
H, CH2O); 13C{1H} NMR δ 2.8, 3.3 (SiCH3), 10.6, 11.1, 14.2,
14.4 (C5(CH3)4), 14.5, 14.6 (δ-CH3), 23.3, 26.2, 32.1, 33.4 (â-
and γ-CH2), 43.2 (HfCOCH2), 45.1 (NCH2), 49.1 (HfCH2), 58.8
(OCH3), 79.1 (CH2O), 98.6 (ring C at Si), 121.1, 121.2, 123.7,
125.3 (C5(CH3)4), 343.0 (HfCOCH2).
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(CH2P h )2 (6c). Fol-
lowing a procedure analogous to that described to prepare 6a ,
1c (0.30 g, 0.59 mmol) was reacted with dibenzylmagnesium
THF adduct (0.27 g, 0.77 mmol) to give colorless crystals: yield
1
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)I2 (11c). C6D6 (0.5
mL) was added to an NMR tube containing 5c (30 mg, 0.05
mmol) and I2 (28 mg, 0.11 mmol). Complete conversion of 5c
to 11c with concomitant signals for nBuI was observed within
0.24 g (67%); H NMR δ 0.40 (s, 6 H, SiCH3), 1.04, 1.73 (d, 2
H, 2J HH ) 13 Hz, HfCH2), 2.01, 2.07 (s, 6 H, C5(CH3)4), 2.58 (s,
3 H, OCH3), 3.09 (“t”, 2 H, NCH2), 3.18 (“t”, 2 H, CH2O), 6.8-
7.1 (m, 10 H, C6H5); 13C{1H} NMR δ 2.7 (SiCH3), 11.5, 14.3
(C5(CH3)4), 45.9 (NCH2), 62.4 (OCH3), 66.6 (HfCH2), 79.2
(CH2O), 98.4 (ring C at Si), 121.7 (para C6H5), 124.9, 125.3
(C5(CH3)4), 127.7 (meta C6H5), 128.8 (ortho C6H5), 151.0 (ipso
C6H5); EI MS m/z 522 (1, M+ - C7H7), 431 (35, M+ - 2C7H7).
Anal. Calcd for C28H39NHfOSi: C, 54.94; H, 6.39; N, 2.28.
Found: C, 54.68; H, 6.20; N, 2.14.
1
5 min by H NMR spectroscopy. After removing all the vola-
tiles, the dark yellow solid was washed with pentane (2 mL)
and dried: yield 32 mg (95%); 1H NMR δ 0.28 (s, 6 H, SiCH3),
2.19, 2.42 (s, 6 H, C5(CH3)4), 2.89 (“t”, 2 H, NCH2), 3.44 (“t”, 2
H, CH2O), 3.72 (s, 3 H, OCH3); 13C{1H} NMR δ 2.2 (SiCH3),
12.9, 15.2 (C5(CH3)4), 46.5 (NCH2), 65.8 (OCH3), 77.5 (CH2O),
100.7 (ring C at Si), 129.6, 130.6 (C5(CH3)4); EI MS m/z 685
(14, M+), 558 (37, M+ - I). Anal. Calcd for C14H25NHfI2OSi:
C, 24.58; H, 3.65; N, 2.04. Found: C, 22.16; H, 3.94; N, 2.78.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)(CH2SiMe3)2 (7c).
Following a procedure analogous to that described to prepare
2a , 1c (0.30 g, 0.59 mmol) was reacted with trimethylsilyl-
methylmagnesium chloride (1.25 mL of a 1 M solution in Et2O)
to give 7c as colorless crystals: yield 0.25 g (71%); 1H NMR δ
H f(η5:η1:η1-C5Me4SiMe2NCH 2CH 2OMe){C(dNt Bu )E t }-
Cl (12c). Following a procedure analogous to that described
for 12a , ethylmagnesium chloride (0.42 mL, 0.84 mmol, 2 M
in THF) was added to a mixture of 1c (421 mg, 0.84 mmol)
and tert-butyl isonitrile (0.09 mL, 0.84 mmol) in hexane (30
mL) at -78 °C to give colorless crystals: yield 247 mg (51%);
2
-1.17, -0.20 (d, 2 H, J HH ) 12 Hz, HfCH2), 0.17 (s, 18 H,
Si(CH3)3), 0.41 (s, 6 H, Si(CH3)2), 2.07, 2.13 (s, 6 H, C5(CH3)4),
3.17 (“t”, 2 H, NCH2), 3.41 (“t”, 2 H, CH2O), 3.43 (s, 3 H, OCH3);
13C{1H} NMR δ 2.7 (Si(CH3)2), 4.9 (Si(CH3)3), 12.3, 14.7 (C5-
(CH3)4), 45.4 (HfCH2), 48.6 (NCH2), 62.6 (OCH3), 78.9 (CH2O),
98.5 (ring C at Si), 124.1, 124.4 (C5(CH3)4); EI MS m/z 605 (1,
M+), 518 (4, M+ - CH2SiMe3), 431 (21, M+ - 2CH2SiMe3).
Anal. Calcd for C22H47NHfOSi3: C, 43.74; H, 7.78; N, 2.32.
Found: C, 43.64; H, 7.66; N, 2.27.
3
1H NMR δ 0.59 (s, 6 H, SiCH3), 1.15 (t, 3 H, J HH ) 7.0 Hz,
CH2CH3), 1.25 (s, 9 H, C(CH3)3), 1.54, 2.22, 2.23 (s, 3 H, C5-
(CH3)4), 2.28 (m, 1 H, CH2CH3), 2.63 (s, 3 H, C5(CH3)4), 2.80
(m, 1 H, CH2CH3), 3.09 (m, 2 H, CH2O, 1 H, SiNCH2), 3.12 (br
s, 3 H, OCH3), 3.24 (m, 1 H, SiNCH2); 13C{1H} NMR δ 3.4, 3.6
(SiCH3), 12.4, 12.8 (C5(CH3)4), 13.3 (CH2CH3), 15.1, 15.5 (C5-
(CH3)4), 30.3 (CH2CH3), 31.6 (C(CH3)3), 46.5 (SiNCH2), 60.3
(C(CH3)3), 61.8 (OCH3), 78.4 (CH2O), 102.3 (ring C at Si), 121.8,
123.9 (C5(CH3)4), 223.9 (CN); EI MS m/z 578 (6, M+), 549 (13,
M+ - C2H5), 521 (24, M+ - CMe3), 502 (23, M+ - NCH2CH2-
OMe), 466 (38, M+ - CNCMe3, - C2H5), 458 (100, M+ - C5-
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OMe)P h 2 (8c). Follow-
ing a procedure analogous to that described to prepare 2a , 1c
(0.41 g, 0.82 mmol) was reacted with phenyllithium (0.92 mL
of a 1.8 M solution in cyclohexane/ether) to give 8c as yellow
1
crystals: yield 0.32 g (68%); H NMR δ 0.53 (s, 6 H, SiCH3),
1.76, 2.04 (s, 6 H, C5(CH3)4), 2.14 (s, 3 H, OCH3), 3.25 (“t”, 2

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5847
3
Me4). Anal. Calcd for C21H39N2ClHfOSi: C, 43.66; H, 6.82; N,
4.85. Found: C, 43.62; H, 6.79; N, 4.95.
δ 0.60, 0.73 (s, 3 H, SiCH3), 1.03 (t, 3 H, J HH ) 7.4 Hz,
CH2CH3), 1.34 (s, 3 H, C5(CH3)4), 1.36 (s, 9 H, C(CH3)3), 1.97
(s, 3 H, C5(CH3)4), 2.03 (s, 6 H, NCH3), 2.12 (s, 3 H, C5(CH3)4),
2.26 (m, 2 H, CH2CH3, 1 H, CH2NMe2), 2.62 (m, 1 H, CH2-
NMe2), 2.64 (s, 3 H, C5(CH3)4), 3.37, 3.59 (m, 1 H, SiNCH2);
13C{1H} NMR δ 4.3, 5.0 (SiCH3), 11.9, 12.0 (C5(CH3)4), 12.4
(CH2CH3), 15.8, 16.6 (C5(CH3)4), 28.4 (CH2CH3), 30.4 (C(CH3)3),
45.7 (NCH3), 51.1 (SiNCH2), 61.7 (C(CH3)3), 63.4 (CH2NMe2),
104.7 (ring C at Si), 125.7, 127.4, 128.6, 133.8 (C5(CH3)4), 238.8
(CN); EI MS m/z 403 (18, M+ - C4H9), 385 (5, M+ - CH2CH2-
Ti(η5:η1-C5Me4SiMe2NCH2CH2NMe2)Cl2 (1d ). The same
procedure as that described for the preparation of 1a was
followed, to prepare 1d from TiCl3(THF)3 and Li2[C5Me4SiMe2-
1
NCH2CH2NMe2]: orange crystals; yield 57%; mp 142 °C; H
NMR δ 0.34 (s, 6 H, SiCH3), 2.06, 2.14 (s, 6 H, C5(CH3)4), 2.31
(s, 6 H, NCH3), 2.61 (“t”, 2 H, CH2NMe2), 3.49 (“t”, 2 H, CH2-
NSi); 13C{1H} NMR (C6D6, 25 °C) δ 2.2 (SiCH3), 13.2, 15.9 (C5-
(CH3)4), 47.1 (NCH3), 53.4 (SiNCH2), 60.7 (CH2NMe2), 105.3
(ring C at Si), 136.7, 137.6 (C5(CH3)4); EI MS: m/z 382 (1, M+),
295 (1, M+ - NCH2CH2NMe2), 178 (2, C5Me4SiMe2), 119 (1,
C9H11+), 58 (100, C3H8N+). Anal. Calcd for C15H28Cl2N2SiTi:
C, 47.00; H, 7.36; N, 7.31. Found: C, 47.00; H, 7.32; N, 6.83.
Ti(η5:η1-C5Me4SiMe2NCH2CH2NMe2)Me2 (2d ). The same
procedure as that described for the preparation of 2a was
followed, to prepare 2d from 1d : pale beige-yellow crystals;
NMe2), 348 (28, M+ - CNCMe3, - C2H5), 290 (100, M+
-
CNCMe3, - C2H5, - SiMe2). Anal. Calcd for C22H42N3ClSiTi:
C, 57.43; H, 9.22; N, 9.14. Found: C, 57.05; H, 8.85; N, 9.18.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Cl2 (1e). Toluene
(55 mL) was added to a solid mixture of ZrCl4(THF)2 (1.71 g,
4.0 mmol) and Li2(C5Me4SiMe2NCH2CH2NMe2) (1.26 g, 4.0
mmol) at -78 °C. The mixture was stirred at room tempera-
ture overnight and filtered. The product was obtained as
colorless crystals after concentrating the filtrate and cooling
it to -30 °C: yield 1.08 g (56%); 1H NMR δ 0.36 (s, 6 H, SiCH3),
2.09, 2.12 (s, 6 H, C5(CH3)4), 2.35 (s, 6 H, NCH3), 2.52 (“t”, 2
H, CH2NMe2), 2.92 (“t”, 2 H, CH2NSi); 13C{1H} NMR δ 2.3
(SiCH3), 12.2, 14.4 (C5(CH3)4), 46.9 (SiNCH2), 47.3 (NCH3), 62.3
(CH2NMe2), 102.2 (ring C at Si), 129.1, 131.3 (C5(CH3)4); EI
1
yield 43%; mp 45 °C; H NMR δ 0.33 (s, 6 H, TiCH3), 0.40 (s,
6 H, SiCH3), 1.92 (s, 6 H, C5(CH3)4), 2.03 (s, 6 H, C5(CH3)4),
2.15 (s, 6 H, NCH3), 2.52 (“t”, 2 H, CH2NMe2), 4.05 (“t”, 2 H,
1
CH2NSi); 13C NMR δ 3.4 (q, J CH ) 121 Hz, SiCH3), 12.1 (q,
1
1J CH ) 126 Hz, C5(CH3)4), 15.0 (q, J CH ) 127 Hz, C5(CH3)4),
45.8 (q, 1J CH ) 133 Hz, NCH3), 48.8 (q, 1J CH ) 118 Hz, TiCH3),
1
1
49.1 (t, J CH ) 134 Hz, SiNCH2), 63.3 (t, J CH ) 131 Hz, CH2-
NMe2), 98.5 (s, ring C at Si), 128.2, 132.3 (s, C5(CH3)4); EI MS
m/z 340 (5, M+ - 2H), 327 (3, M+ - CH3), 311 (9, M+ - 2CH3,
- H), 283 (1, M+ - NMe3), 266 (4, M+ - NMe3, - CH3, - 2H),
252 (2, M+ - NMe3, - 2CH3), 240 (9, C11H18NSiTi+), 58 (100,
C3H8N+). Anal. Calcd for C17H34N2SiTi: C, 59.62; H, 10.01; N,
8.18. Found: C, 58.33; H, 9.75; N, 8.30.
MS m/z 426 (3, MH2+), 424 (2, M+), 368 (10, MH2 - CH2-
+
NMe2), 366 (10, M+ - CH2NMe2), 339 (3, C11H19Cl2SiZr+), 58
(100, C3H8N+). Anal. Calcd for C15H28Cl2N2SiZr: C, 42.23; H,
6.62; N, 6.57. Found: C, 43.19; H, 6.08; N, 6.16.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Me2 (2e). Follow-
ing a procedure analogous to that described for 2b, 1e (1.07 g,
2.5 mmol) was reacted with methylmagnesium chloride (1.67
mL, 5.0 mmol, 3 M in THF) in hexane (40 mL) at -78 °C to
give colorless crystals; mp 58 °C: yield 500 mg (55%); 1H NMR
δ -0.39 (s, 6 H, ZrCH3), 0.42 (s, 6 H, SiCH3), 2.03, 2.06 (s, 6
H, C5(CH3)4), 2.19 (s, 6 H, NCH3), 2.50 (“t”, 2 H, CH2NMe2),
Ti(η5:η1-C5Me4SiMe2NCH2CH2NMe2)(CH2C6H5)2 (6d). Fol-
lowing a procedure analogous to that described to prepare 6a ,
1d (500 mg, 1.3 mmol) was reacted with the THF adduct of
dibenzylmagnesium (600 mg, 1.71 mmol) to give orange-red
1
needles: yield 322 mg (50%); H NMR δ 0.39 (s, 6 H, SiCH3),
1
3.05 (“t”, 2 H, SiNCH2); 13C NMR δ 3.0 (q, J CH ) 118 Hz,
1.73, 1.83 (s, 6 H, C5(CH3)4), 1.89 (s, 6 H, NCH3), 1.93 (“t”, 2
H, CH2NMe2), 2.05, 2.18 (d, 2 H, 2J HH ) 10.3 Hz, TiCH2), 3.69
(“t”, 2 H, SiNCH2), 6.87, 7.14 (m, 5 H, C6H5); 13C{1H} NMR δ
4.2 (SiCH3), 11.4, 15.0 (C5(CH3)4), 45.4 (NCH3), 49.8 (SiNCH2),
61.9 (CH2NMe2), 79.2 (TiCH2), 99.5 (ring C at Si), 121.9 (para
C6H5), 126.8 (meta C6H5), 128.5 (ortho C6H5), 129.2, 135.2 (C5-
(CH3)4), 149.3 (ipso C6H5); EI MS m/z 312 (9, M+ - 2C7H7),
240 (13, M+ - 2C7H7, - CH2CH2NMe2), 211 (15, TiC5Me4-
SiMe2). Anal. Calcd for C29H42N2SiTi: C, 70.40; H, 8.57; N,
5.66. Found: C, 69.83; H, 8.45; N, 5.78.
1
1
SiCH3), 11.7 (q, J CH ) 126 Hz, C5(CH3)4), 14.1 (q, J CH ) 126
Hz, C5(CH3)4), 32.7 (q, J CH ) 112 Hz, s, 6 H, ZrCH3), 45.4 (t,
1
SiNCH2), 46.2 (q, NCH3), 64.8 (t, CH2NMe2), 97.9 (s, ring C at
Si), 124.5, 124.9 (s, C5(CH3)4). Anal. Calcd for C17H34N2SiZr:
C, 52.93; H, 8.88; N, 7.26. Found: C, 52.55; H, 8.76; N, 7.13.
Rea ction of 2e w ith B(C6F 5)3. C6D5Br (0.5 mL) was added
to a equimolar mixture of 2e (28 mg, 72 µmol) and B(C6F5)3
(37 mg, 72 µmol) in a NMR tube at -78 °C and allowed to
warm to -20 °C: 1H NMR (253 K, C6D5Br) δ -0.14 (br s, 3 H,
ZrCH3), 0.25, 0.32 (s, 3 H, SiCH3), 0.94 (br s, 3 H, CH3B(C6F5)3),
1.45, 1.72, 1.84 (br s, 3 H, C5(CH3)4), 1.87, 1.89 (br s, 3 H,
NCH3), 1.99 (br s, 3 H, C5(CH3)4), 2.97 (br s, 2 H, CH2NMe2),
3.15 (br s, 2 H, SiNCH2); 13C{1H} NMR (253 K, C6D5Br) δ 1.2,
2.2 (SiCH3), 10.1, 10.9, 12.5, 14.6, (C5(CH3)4), 35.3 (ZrCH3),
42.7 (CH3B(C6F5)3), 46.6 (SiNCH2), 47.4 (NCH3), 62.6 (CH2-
NMe2), 102.4 (ring C at Si); 19F NMR (253 K, C6D5Br) δ -133.5
(ortho C6F5), -160.7 (para C6F5), -165.9 (meta C6F5).
Rea ction of 6d w ith B(C6F 5)3. C6D5Br (0.5 mL) was added
to an equimolar mixture of 6d (20 mg, 40 µmol) and B(C6F5)3
(21 mg, 40 µmol) in an NMR tube at -78 °C. The color turned
dark red at room temperature: 1H NMR (C6D5Br) δ 0.21, 0.36
(s, 3 H, SiCH3), 1.16 (s, 3 H, C5(CH3)4), 1.58 (s, 6 H, NCH3),
1.69, 1.78 (s, 3 H, C5(CH3)4), 2.09 (dd, 1 H, SiNCH2), 2.15 (s, 3
2
H, C5(CH3)4), 2.27, 2.51 (d, 1 H, J HH ) 11.4 Hz, TiCH2), 3.19
(m, 1 H, CH2NMe2), 3.30 (br s, 2 H, CH2B(C6F5)3), 3.40 (m, 1
H, CH2NMe2), 3.86 (dd, 1 H, SiNCH2), 6.35 (d, 2 H, 2J HH ) 7.2
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Et2 (3e). Ethyl-
lithium (8.13 mL, 2.36 mmol, 0.29 M in pentane) was added
to a suspension of 1e (503 mg, 1.18 mmol) in hexane (30 mL)
at -78 °C. The mixture was allowed to warm to 0 °C over a
period of 3 h under stirring. All volatiles were removed in vac-
uo, and the residue was extracted with pentane (30 mL). Fil-
tration, followed by concentrating the yellow filtrate and
cooling the concentrated pentane solution to -35 °C, afforded
2
Hz, CH2C6H5), 6.83 (t, J HH ) 7.2 Hz, 1 H, CH2C6H5), 6.80-
7.12 (signals overlap. with solvent signals, 7 H, CH2C6H5); 13C-
{1H} NMR (C6D5Br) δ -0.6, 2.2 (SiCH3), 10.5, 12.5, 15.3, 15.8
(C5(CH3)4), 31.8 (CH2B(C6F5)3), 45.9, 46.4 (NCH3), 49.9 (SiNCH2),
59.5 (CH2NMe2), 78.7 (TiCH2), 104.7 (ring C at Si), 122.9,
127.2, 128.1, 128.3, 128.9, 129.1, 130.6, 132.6, 134.0, 139.1,
141.6, 143.7 (ring C), 136.0, 137.5, 138.5, 147.0 (C6F5), 148.8
(ipso CH2C6H5), 149.9 (ipso C6F5); 19F NMR (C6D5Br) δ -130.4
(d, 3J FF ) 22.2 Hz, ortho C6F5), -163.7 (t, 3J FF ) 20.2 Hz, para
1
yellow crystals: yield 68 mg (14%); H NMR (C6D5Br, 253 K)
δ 0.09 (m, 4 H, ZrCH2), 0.38 (s, 6 H, SiCH3), 1.06 (t, 6 H, J HH
3
3
C6F5), -166.5 (t, J FF ) 20.2 Hz, meta C6F5).
) 7.8 Hz, CH2CH3), 2.03 (s, 6 H, C5(CH3)4), 2.06 (s, 6 H, NCH3),
2.31 (s, 6 H, C5(CH3)4), 2.59 (br s, 2 H, CH2NMe2), 3.09 (br s,
2 H, SiNCH2); 13C{1H} NMR (C6D5Br, 253 K) δ 2.8 (SiCH3),
11.2 (C5(CH3)4), 13.3 (ZrCH2), 14.2 (C5(CH3)4), 42.3 (br s,
NCH3), 45.2 (CH2CH3), 46.3 (SiNCH2), 64.3 (CH2NMe2), 97.7
(ring C at Si), 122.9, 123.8 (C5(CH3)4). Anal. Calcd for C17H38N2-
SiZr: C, 55.13; H, 9.27; N, 6.77. Found: C, 51.58; H, 7.87; N, 6.95.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)n P r 2 (4e). Follow-
Ti(η5:η1-C5Me4SiMe2NCH2CH2NMe2){C(dNtBu)Et}Cl(12d).
Following a procedure analogous to that described to prepare
12a , ethylmagnesium chloride (0.73 mL, 1.44 mmol, 2 M in
THF) was added to a mixture of 1d (553 mg, 1.44 mmol) and
tert-butyl isonitrile (0.16 mL, 1.44 mmol) in hexane (35 mL)
at -78 °C. After cooling a concentrated pentane solution,
1
yellow crystals were obtained: yield 179 mg (27%); H NMR

5848 Organometallics, Vol. 17, No. 26, 1998
Amor et al.
ing a procedure analogous to that described to prepare 3e, 1e
(550 mg, 1.29 mmol) was treated with n-propyllithium (10.4
mL, 2.6 mmol, 0.25 M in hexane) in hexane (35 mL) at -78
°C to give a pale yellow solid: yield 140 mg (25%); 1H NMR δ
2.57 (s, 3 H, C5(CH3)4), 2.63 (m, 1 H, CH2CH3), 2.63 (m, 1 H,
CH2NMe2), 3.04, 3.14 (m, 1 H, SiNCH2), signal for NMe2 not
observed; 13C{1H} NMR δ 2.3, 3.6 (SiCH3), 12.2, 12.5 (C5-
(CH3)4), 13.4 (CH2CH3), 15.2, 15.4 (C5(CH3)4), 29.6 (CH2CH3),
31.5 (C(CH3)3), 45.9 (SiNCH2), 61.5 (C(CH3)3), 64.4 (CH2NMe2),
103.6 (ring C at Si), 122.9, 123.9, 124.8, 127.1 (C5(CH3)4), 246.6
0.17 (m, 4 H, ZrCH2), 0.40 (s, 6 H, SiCH3), 1.11 (t, 6 H, 3J HH
)
7 Hz, γ-CH3), 1.26, 1.43 (m, 2 H, â-CH2), 2.04, 2.08, (s, 6 H,
C5(CH3)4), 2.22 (s, 6 H, NCH3), 2.50 (“t”, 2 H, CH2NMe2), 3.05
(“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.8 (SiCH3), 11.2, 14.2 (C5-
(CH3)4), 22.7 (γ-CH3), 23.5 (â-CH2), 45.6 (SiNCH2), 46.5 (NCH3),
56.9 (ZrCH2), 64.9 (CH2NMe2), 98.6 (ring C at Si), 124.2, 124.5
(C5(CH3)4); EI MS m/z 442 (2, M+), 398 (15, M+ - NMe2), 356
(83, M+ - NCH2CH2NMe2). Anal. Calcd for C21H42N2SiZr: C,
57.06; H, 9.60; N, 6.34. Found: C, 55.84; H, 9.29; N, 6.68.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)n Bu 2 (5e). A sus-
pension of 1e (436 mg, 1 mmol) in hexane (35 mL) was treated
with n-butyllithium (1.15 mL, 2 mmol, 1.8 M in hexane) at 0
°C. After stirring for 3 h at this temperature all volatiles were
removed in vacuo. The residue was extracted into hexane (20
mL) to afford a yellow-brown oil: yield 268 mg (56%); 1H NMR
δ 0.16 (m, 4 H, ZrCH2), 0.39 (s, 6 H, SiCH3), 1.01 (t, 6 H,
δ-CH3), 1.21 (m, 2 H, â-CH2), 1.38 (m, 2 H, â-CH2, 4 H γ-CH2),
2.04, 2.07 (s, 6 H, C5(CH3)4), 2.23 (s, 6 H, NCH3), 2.49 (“t”, 2
H, CH2NMe2), 3.03 (“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.9
(SiCH3), 11.3, 14.3 (C5(CH3)4), 14.1 (δ-CH3), 30.8 (â-CH2), 32.3
(γ-CH2), 45.6 (SiNCH2), 46.6 (NCH3), 53.2 (ZrCH2), 64.9 (CH2-
NMe2), 98.1 (ring C at Si), 124.1, 124.5 (C5(CH3)4). Anal. Calcd
for C23H46N2SiZr: C, 58.77; H, 9.88; N, 5.96. Found: C, 52.97;
H, 8.80; N, 5.69.
1
(CN), signal for NMe2 not observed; H NMR (C6D5CD3, -70
°C) δ 0.64, 0.66 (s, 3 H, SiCH3), 1.12 (br s, 3 H, CH2CH3), 1.19
(s, 9 H, C(CH3)3), 1.35 (s, 3 H, C5(CH3)4), 1.37 (s, 3 H, NCH3),
1.53 (m, 1 H, CH2NMe2), 1.85 (m, 1 H, CH2CH3), 2.15, 2.27 (s,
3 H, C5(CH3)4), 2.38 (s, 3 H, NCH3), 2.49 (m, 1 H, CH2CH3),
2.60 (m, 1 H, CH2NMe2), 2.69 (s, 3 H, C5(CH3)4), 2.99, 3.12
(m, 1 H, SiNCH2); 1H NMR (C6D5CD3, +30 °C) δ 0.54 (s, 6 H,
3
SiCH3), 1.20 (t, 3 H, J HH ) 7.4 Hz, CH2CH3), 1.27 (s, 9 H,
C(CH3)3), 1.46 (s, 3 H, C5(CH3)4), 1.92 (m, 1 H, CH2NMe2), 2.07,
2.20 (s, 3 H, C5(CH3)4), 2.23 (m, 1 H, CH2CH3), 2.47 (s, 3 H,
C5(CH3)4), 2.60 (m, 1 H, CH2CH3), 2.66 (m, 1 H, CH2NMe2),
3.04, 3.14 (m, 1 H, SiNCH2), signal for NMe2 not observed; 1H
NMR (C6D5CD3, +70 °C) δ 0.50, 0.52 (s, 3 H, SiCH3), 1.23 (t,
3 H, 3J HH ) 7.4 Hz, CH2CH3), 1.30 (s, 9 H, C(CH3)3), 1.49 (s, 3
H, C5(CH3)4), 2.01 (br s, 7 H, NCH3, CH2NMe2), 2.04, 2.19 (s,
3 H, C5(CH3)4), 2.30 (m, 1 H, CH2CH3), 2.42 (s, 3 H, C5(CH3)4),
2.57 (m, 1 H, CH2NMe2), 2.71 (m, 1 H, CH2CH3), 3.04, 3.15
(m, 1 H, SiNCH2); EI MS m/z 446 (22, M+ - C4H9), 391 (100,
M+ - CNCMe3, - C2H5), 347 (5, M+ - CNCMe3, - C2H5, -
NMe2), 305 (14, M+ - CNCMe3, - C2H5, - NCH2CH2NMe2).
Anal. Calcd for C22H42N3ClSiZr: C, 52.48; H, 8.43; N, 8.35.
Found: C, 52.41; H, 8.38; N, 8.47.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Cl2 (1f). Follow-
ing a procedure analogous to that described to prepare 1e,
toluene (30 mL) was added to a solid mixture of HfCl4(THF)2
(1.69 g, 3.64 mmol) and Li2(C5Me4SiMe2NCH2CH2NMe2) (1.01
g, 3.64 mmol) at -78 °C to afford colorless crystals: yield 1.12
g (60%); 1H NMR δ 0.37 (s, 6 H, SiCH3), 2.18, 2.19 (s, 6 H,
C5(CH3)4), 2.33 (s, 6 H, NCH3), 2.46 (“t”, 2 H, CH2NMe2), 3.03
(“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.4 (SiCH3), 12.0, 14.1 (C5-
(CH3)4), 45.5 (SiNCH2), 47.3 (NCH3), 62.8 (CH2NMe2), 102.3
(ring C at Si), 126.1, 129.7 (C5(CH3)4); EI MS m/z 514 (9, M+),
456 (11, M+ - CH2NMe2), 428 (21, M+ - NCH2CH2NMe2).
Anal. Calcd for C15H28N2Cl2HfSi: C, 35.05; H, 5.50; N, 5.45.
Found: C, 35.08; H, 5.41; N, 6.19.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Me2 (2f). Meth-
ylmagnesium chloride (0.83 mL, 1.32 mmol, 1.6 M in THF)
was added to a suspension of 1f (340 mg, 0.66 mmol) in hexane
(30 mL) at -78 °C. The mixture was allowed to warm to 0 °C
over 3 h under stirring. All volatiles were removed in vacuo,
and the residue extracted with pentane (15 mL). The extracts
were filtered and concentrated. Cooling to -30 °C gave a
colorless microcrystalline powder: yield 150 mg (48%); 1H
NMR δ -0.51 (s, 6 H, HfCH3), 0.43 (s, 6 H, SiCH3), 2.06, 2.10
(s, 6 H, C5(CH3)4), 2.15 (s, 6 H, NCH3), 2.46 (“t”, 2 H, CH2-
NMe2), 3.11 (“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.9 (SiCH3),
11.6, 13.9 (C5(CH3)4), 42.5 (HfCH3), 45.0 (SiNCH2), 46.1
(NCH3), 65.3 (CH2NMe2), 98.4 (ring C at Si), 123.4, 123.9 (C5-
(CH3)4); EI MS m/z 443 (23, M+ - 2CH3), 300 (52, 443 - SiMe2-
NCH2CH2NMe2). Anal. Calcd for C17H40N2HfSi: C, 43.15; H,
8.54; N, 5.92. Found: C, 42.92; H, 8.32; N, 6.62.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)Et2 (3f). Follow-
ing a procedure analogous to that described to prepare 3e,
ethyllithium (9.36 mL, 2.72 mmol, 0.29 M in pentane) was
reacted with a suspension of 1f (698 mg, 1.36 mmol) in hexane
(30 mL) to give colorless crystals: yield 68 mg (26%); 1H NMR
δ 0.05 (qq, 4 H, HfCH2), 0.41 (s, 6 H, SiCH3), 1.31 (t, 6 H, 3J HH
) 8.0 Hz, CH2CH3), 2.11, 2.14, 2.19 (s, 6 H, C5Me4, NCH3),
2.46 (“t”, 2 H, CH2NMe2), 3.09 (“t”, 2 H, SiNCH2); 13C{1H} NMR
δ 2.7 (SiCH3), 6.9 (HfCH2), 11.3, 14.2 (C5(CH3)4), 45.1 (SiNCH2),
45.5 (NCH3), 46.5 (CH2CH3), 65.3 (CH2NMe2), 99.75 (ring C
at Si), 123.3, 123.7 (C5(CH3)4). Anal. Calcd for C17H38N2SiHf:
C, 45.53; H, 7.66; N, 5.59. Found: C, 43.70; H, 6.79; N, 5.67.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)n P r 2 (4f). Follow-
ing a procedure analogous to that described to prepare 4e, 1f
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)(CH2C6H5)2 (6e).
Following a procedure analogous to that described to prepare
6a , 1e (427 mg, 1 mmol) was reacted with dibenzylmagnesium
THF adduct (560 mg, 1.6 mmol) to give yellow crystals: yield
1
250 mg (47%); H NMR δ 0.40 (s, 6 H, SiCH3), 1.71 (d, 2 H,
2J HH ) 11.2 Hz, ZrCH2), 1.80 (s, 6 H, NCH3), 1.91, 2.01 (s, 6
H, C5(CH3)4), 1.92 (d, 2 H, 2J HH ) 11.2 Hz, ZrCH2), 2.22 (“t”, 2
H, CH2NMe2), 2.97 (“t”, 2 H, SiNCH2), 6.90-7.18 (m, 10 H,
C6H5); 13C{1H} NMR δ 2.3 (SiCH3), 11.8, 14.2 (C5(CH3)4), 45.7
(NCH3), 45.9 (SiNCH2), 60.9 (ZrCH2), 65.4 (CH2NMe2), 101.1
(ring C at Si), 121.3 (para C6H5), 125.7, 127.3 (C5(CH3)4), 127.9
(meta C6H5), 128.2 (ortho C6H5), 151.4 (ipso C6H5); EI MS m/z
356 (71, M+ - 2C7H7), 295 (4, M+ - 2C7H7, - SiMe2). Anal.
Calcd for C29H42N2SiZr: C, 64.73; H, 7.88; N, 5.21. Found: C,
63.48; H, 7.96; N, 5.38.
Zr (η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)P h 2 (8e). Phenyl-
lithium (2.25 mL, 4.1 mmol, 1.8 M in cyclohexane/Et2O ) 7/3)
was added to a suspension of 1e (866 mg, 2.0 mmol) in diethyl
ether (30 mL) at -78 °C. The mixture was allowed to warm
to 0 °C over a period of 4.5 h under stirring. All volatiles were
removed in vacuo, and the residue was extracted with hexane
(25 mL). Filtration followed by concentrating the yellow filtrate
and cooling the concentrated hexane solution to -35 °C
afforded a colorless microcrystalline solid: yield 470 mg (44%);
1H NMR δ 0.54 (s, 6 H, SiCH3), 1.45 (s, 6 H, C5(CH3)4), 1.56 (s,
6 H, NCH3), 2.08 (s, 6 H, C5(CH3)4) 2.52 (br s, 2 H, CH2NMe2),
3.19 (“t”, 2 H, SiNCH2), 7.17-7.59 (m, 10 H, C6H5); 13C{1H}
NMR δ 2.9 (SiCH3), 11.7, 15.2 (C5(CH3)4), 46.5 (SiNCH2), 48.0
(NCH3), 63.5 (CH2NMe2), 97.7 (ring C at Si), 125.8, 126.5,
126.5, 127.9, 128.2 (o-, m-, p-C6H5, C5(CH3)4), signal for ipso
C6H5 not observed; EI MS m/z 510 (2, M+), 433 (98, M+
-
C6H5), 356 (10, M+ - 2C6H5). Anal. Calcd for C27H38N2SiZr:
C, 63.58; H, 7.53; N, 5.49. Found: C, 60.15; H, 6.91; N, 5.22.
Zr (η5:η1:η1-C5Me4SiMe2NCH 2CH 2NMe2){C(dNt Bu )E t }-
Cl (12e). Following a procedure analogous to that described
for 12a , ethylmagnesium chloride (1.04 mL, 2.07 mmol, 2 M
in THF) was added to a mixture of 1e (885 mg, 2.07 mmol)
and tert-butyl isonitrile (0.23 mL, 2.07 mmol) in hexane (50
mL) at -78 °C to give colorless crystals after cooling a
concentrated pentane solution: yield 713 mg (68%); 1H NMR
3
δ 0.58 (s, 6 H, SiCH3), 1.18 (t, 3 H, J HH ) 7.4 Hz, CH2CH3),
1.27 (s, 9 H, C(CH3)3), 1.46 (s, 3 H, C5(CH3)4), 1.90 (m, 1 H,
CH2NMe2), 2.13 (s, 3 H, C5(CH3)4), 2.20 (m, 1 H, CH2CH3), 2.24,

Alkyl Complexes of Group 4 Metals
Organometallics, Vol. 17, No. 26, 1998 5849
(449 mg, 0.87 mmol) was treated with n-propyllithium (7 mL,
1.75 mmol, 0.25 M in pentane) in hexane (30 mL) at -78 °C
to give a colorless solid: yield 174 mg (38%); 1H NMR δ -0.01
MS m/z 426 (24, M+ + 2H), 424 (18, M+), 368 (38, M+ - C4H8),
366 (32, M+ - C3H8N), 58 (100, C3H8N+), 42 (44, C2H4N+).
Anal. Calcd for C15H28N2Cl2SiZr: C, 42.23; H, 6.62; N, 6.57.
Found: C, 41.59; H, 7.36; N, 6.45.
3
(m, 4 H, HfCH2), 0.40 (s, 6 H, SiCH3), 1.14 (t, 6 H, J HH ) 8.0
Hz, γ-CH3), 1.28, 1.43 (m, 2 H, â-CH2), 2.09, 2.11 (s, 6 H, C5-
(CH3)4), 2.19 (s, 6 H, NCH3), 2.46 (“t”, 2 H, CH2NMe2), 3.09
(“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.7 (SiCH3), 11.2, 14.1 (C5-
(CH3)4), 23.8 (γ-CH3), 24.2 (â-CH2), 45.1 (SiNCH2), 46.4 (NCH3),
65.3 (CH2NMe2), 66.2 (HfCH2), 99.1 (ring C at Si), 123.3, 123.8
Zr (η5:η1:η1-C5H 3t Bu SiMe2NCH 2CH 2NMe2)(CH 2SiMe3)2
(7g). Following a procedure similar to that to prepare 7b, 7g
was prepared from 1g and trimethylsilylmethylmagnesium
chloride to give colorless crystals: yield 31%; 1H NMR δ -0.63
2
2
(d, J HH ) 11.5 Hz, 1 H, ZrCH2), -0.21 (d, J HH ) 11.0 Hz, 1
(C5(CH3)4); EI MS m/z 485 (3, M+ - NMe2), 443 (52, M+
-
H, ZrCH2), -0.14 (d, J HH ) 11.0 Hz, 1 H, ZrCH2), 0.57 (d,
2
NCH2CH2NMe2), 357 (12, M+ - NCH2CH2NMe2, - 2 C3H7).
Anal. Calcd for C21H42N2SiHf: C, 47.66; H, 8.02; N, 5.29.
Found: C, 46.16; H, 7.37; N, 5.98.
2J HH ) 11.5 Hz, 1 H, ZrCH2), 0.19, 0.22 (s, 9 H, SiCH3), 0.27,
0.39 (s, 3 H, SiCH3), 1.43 (s, 9 H, C(CH3)3), 2.17 (br s, 6 H,
NCH3), 1.96, 3.30 (m, 1 H, CH2NMe2), 2.91, 3.08 (m, 1 H, Si-
NCH2), 6.09 (m, 1 H, C5H3), 6.31 (m, 1 H, C5H3), 7.03 (m, 1 H,
C5H3); 13C{1H} NMR δ -2.3, -1.5 (Si(CH3)2), 4.5, 4.7 (Si(CH3)3),
32.0 (C(CH3)3), 33.1 (C(CH3)3), 41.5, 42.2 (ZrCH2), signal for
N(CH3)2 not observed, 45.9 (SiNCH2), 64.6 (CH2NMe2), 102.7
(ring C attached to Si), 110.7, 116.0, 117.7 (ring C), 144.1 (ring
H f(η5:η1:η1-C5Me4SiMe2NCH2CH 2NMe2)n Bu 2 (5f). Fol-
lowing a procedure analogous to that described to prepare 5e,
1f (405 mg, 0.79 mmol) was treated with n-butyllithium (1.13
mL, 1.58 mmol, 1.38 M in hexane) in hexane (30 mL) at 0 °C
to give a yellow oil: yield 101 mg (23%); 1H NMR δ -0.01 (m,
t
3
C attached to Bu). Anal. Calcd for C23H50N2Si3Zr: C, 52.11;
4 H, HfCH2), 0.41 (s, 6 H, SiCH3), 1.02 (t, 6 H, J HH ) 7.4 Hz,
H, 9.51; N, 5.28. Found: C, 48.63; H, 9.01; N, 5.33.
δ-CH3), 1.23 (m, 2 H, â-CH2), 1.42 (m, 2 H, â-CH2, 4 H, γ-CH2),
2.11, 2.13 (s, 6 H, C5(CH3)4), 2.24 (s, 6 H, NCH3), 2.50 (“t”, 2
H, CH2NMe2), 3.11 (“t”, 2 H, SiNCH2); 13C{1H} NMR δ 2.7
(SiCH3), 11.3, 14.1 (C5(CH3)4), 14.2 (δ-CH3), 31.8 (γ-CH2), 32.9
(â-CH2), 45.2 (SiNCH2), 46.5 (NCH3), 62.4 (HfCH2), 65.4 (CH2-
NMe2), 99.2 (ring C at Si), 123.3, 123.7 (C5(CH3)4).
Eth ylen e P olym er iza tion . A 0.5 L Bu¨chi reactor was
charged with 200 mL of toluene. At a constant ethene pressure
of 3 bar (c ) 0.432 mol/L), a mixture of 5 µmol of catalyst (c )
25 µmol/L) and 1.5 mL (2.5 mmol) of MAO (c ≈ 1.658 mol/L)
was added at 3.5 bar pressure, followed by 1.5 h of stirring at
23 °C. After the reaction mixture was drained into 0.5 L of
methanol and acidified with 10 mL of concentrated hydrochlo-
ric acid, the polymer was collected by filtration, washed with
methanol, and dried to constant weight. Melting points were
determined by DSC.
Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2NMe2)(CH2C6H5)2 (6f).
Following a procedure analogous to that described to prepare
6a , 1f (388 mg, 0.76 mmol) was reacted with dibenzylmagne-
sium THF adduct (430 mg, 1.23 mmol) to give colorless
1
needles: yield 380 mg (81%); H NMR δ 0.42 (s, 6 H, SiCH3),
1.46 (d, 2 H, 2J HH ) 12.0 Hz, HfCH2), 1.69 (d, 2 H, 2J HH ) 12.0
Hz, HfCH2), 1.80, 1.97 (s, 6 H, C5(CH3)4), 2.08 (s, 6 H, NCH3),
2.18 (“t”, 2 H, CH2NMe2), 3.05 (“t”, 2 H, SiNCH2), 6.8-7.16
(m, 10 H, C6H5); 13C{1H} NMR δ 2.3 (SiCH3), 11.8, 14.1 (C5-
(CH3)4), 45.2 (SiNCH2), 45.7 (NCH3), 65.9 (CH2NMe2), 67.9
(HfCH2), 101.1 (ring C at Si), 121.8, (para C6H5), 124.2, 126.5
(C5(CH3)4), 129.2 (meta C6H5), 129.5 (ortho C6H5), 151.6 (ipso
C6H5); EI MS m/z 539 (15, M+ - NCH2CH2NMe2), 482 (21,
M+ - NCH2CH2NMe2, - SiMe2), 443 (7, M+ - 2C7H7). Anal.
Calcd for C29H42N2HfSi: C, 55.70; H, 6.78; N, 4.48. Found: C,
56.26; H, 6.29; N, 4.69.
X-r a y Cr ysta l Str u ctu r e An a lysis of 2b, 8b, a n d 12a .
Relevant crystallographic data for 2b, 8b, and 12a are sum-
marized in Table 1. Single crystals suitable for X-ray crystal
structure analysis were obtained by slow cooling of concen-
trated pentane solutions. Data were performed using ω-scans
on an Enraf-Nonius CAD-4 diffractometer with graphite-
monochromated Mo-KR radiation. Data correction for Lorentz
polarization and absorption (empirically using ψ-scans) was
carried out using the program system MolEN.37a From the
measured reflections, all independent reflections were used
and the parameters were refined by full-matrix least-squares
against all Fo2 data (SHELXL-93).37b The structure was solved
using direct methods (SHELXS-86)37c and difference Fourier
syntheses and refined with anisotropic thermal parameters
for non-hydrogen atoms. For 2b, hydrogen atoms were refined
with isotropic thermal parameters. The hydrogen atoms were
calculated at their idealized positions for 8b and 12a . For more
details see the Supporting Information.
H f(η5:η1:η1-C5Me4SiMe2NCH 2CH 2NMe2){C(dNt Bu )E t }-
Cl (12f). Following a procedure analogous to that described
to prepare 12a , ethylmagnesium chloride (1.44 mL, 2.88 mmol,
2 M in THF) was added to a mixture of 1f (1.48 g, 2.88 mmol)
and tert-butyl isonitrile (0.32 mL, 2.88 mmol) in hexane (50
mL) at -78 °C to give colorless crystals after cooling a
concentrated pentane solution: yield 460 mg (27%); 1H NMR
3
δ 0.58 (s, 6 H, SiCH3), 1.20 (t, 3 H, J HH ) 7.4 Hz, CH2CH3),
Ack n ow led gm en t . We thank the Volkswagen-
Foundation, BASF AG (Kunststofflaboratorium), and
the Fonds der Chemischen Industrie for financial sup-
port. F.A. is indebted to the European Community (TMR
program), K.dP. to the Alexander von Humboldt-
Foundation for a postdoctoral fellowship, and A.B. to
the Deutsche Forschungsgemeinschaft (Graduierten-
kolleg “Physik und Chemie supramolekularer Systeme”)
for a predoctoral fellowship. Some experiments were
performed by Dr. U. Moll (BASF AG).
1.26 (s, 9 H, C(CH3)3), 1.53 (s, 3 H, C5(CH3)4), 1.87 (m, 1 H,
CH2CH3), 2.00 (br s, 6 H, NCH3), 2.16 (s, 3 H, C5(CH3)4), 2.19
(m, 1 H, CH2CH3), 2.30, 2.63 (s, 3 H, C5(CH3)4), 2.77 (m, 2 H,
CH2NMe2), 3.19 (m, 2 H, SiNCH2); 13C{1H} NMR δ 2.1, 3.6
(SiCH3), 12.0, 12.5 (C5(CH3)4), 13.6 (CH2CH3), 15.0, 15.4 (C5-
(CH3)4), 30.0 (CH2CH3), 31.5 (C(CH3)3), 45.2 (SiNCH2), 48.3
(br s, NCH3), 61.2 (C(CH3)3), 64.8 (CH2NMe2), 103.0 (ring C
at Si), 121.1, 122.4, 124.1, 125.5 (C5(CH3)4), 256.0 (CN); EI MS
m/z 533 (5, M+ - CMe3), 477 (100, M+ - CNCMe3, - C2H5).
Anal. Calcd for C22H42N3ClHfSi: C, 44.73; H, 7.18; N, 7.12.
Found: C, 44.87; H, 7.21; N, 7.34.
Su p p or tin g In for m a tion Ava ila ble: Listings of all crys-
tal data and refinement parameters, atomic parameters
including hydrogen atoms, thermal parameters, and bond
lengths and angles for 2b, 8b, and 12a (10 pages). Ordering
information is given on any current masthead page.
Zr (η5:η1:η1-C5H3tBu SiMe2NCH2CH2NMe2)Cl2 (1g). Fol-
lowing a similar procedure that was used to prepare 1e,
reaction of ZrCl4(THF)2 with Li(C5H3tBuSiMe2NCH2CH2NMe2)
gave 1g as colorless crystals: yield 67%; 1H NMR δ 0.19, 0.25
(s, 3 H, SiCH3), 1.47 (s, 9 H, C(CH3)3), 2.08, 2.55 (s, 3 H, NCH3),
1.87 (m, 1 H, CH2NMe2), 3.19 (m, 6.2 Hz, 1 H, CH2NMe2), 2.79
(m, 1 H, SiNCH2), 2.90 (m, 1 H, SiNCH2), 6.04 (m, 1 H, C5H3),
6.30 (m, 1 H, C5H3), 7.03 (m, 1 H, C5H3); 13C{1H} NMR δ -3.4,
-2.1 (SiCH3), 31.3 (C(CH3)3), 33.2 (C(CH3)3), 44.8, 48.6 (NCH3),
47.2 (SiNCH2), 62.5 (CH2NMe2), 106.9 (ring C attached to Si),
115.5, 118.0, 126.3 (ring C), 146.8 (ring C attached to tBu); EI
OM980722N
(37) (a) Fair, C. K. MolEN, An Interactive Structure Solution
Procedure; Enraf-Nonius: Delft, 1990. (b) Sheldrick, G. M. SHELXL-
93, Program for the Refinement of Crystal Structures; University of
Go¨ttingen: Germany, 1993. (c) Sheldrick, G. M. SHELXS-86, Program
for the Solution of Crystal Structures; University of Go¨ttingen,
Germany, 1986.