Zirconium and hafnium mono(alkyl) complexes containing a tridentate linked amido-tetramethylcyclopentadienyl ligand. Molecular structure of Hf(η5:η1:η1-C5Me4SiMe2NCH2CH2OCH3)Cl2

Article abstract of DOI:10.1016/S0022-328X(98)00372-6

Zirconium and hafnium complexes M(η⁵:η¹:η¹-C₅Me₄SiMe₂NCH₂CH₂OMe)Cl₂ (M=Zr, Hf) containing the tridentate 2-methoxyethylamido-functionalized tetramethylcyclopentadienyl ligand C₅Me₄SiMe₂NCH₂CH₂OMe have been synthesized by the reaction of the dilithium derivative Li₂[C₅Me₄SiMe₂NCH₂CH ₂OMe] with MCl₄(THF)₂. Selective monoalkylation of the dichloro complexes gave complexes of the type M(η⁵:η¹:η¹-C₅Me₄SiMe₂NCH₂CH₂OMe)(R)Cl (R=CH₂Ph, o-C₆H₄CH₂NMe₂). The crystal structure of the hafnium dichloro complex Hf(η⁵:η¹:η¹-C₅Me₄SiMe₂NCH₂CH₂OMe)Cl₂ has been determined by X-ray crystal diffraction and shows a trigonal bipyramidal structure in which the five-membered ring and the methoxy function adopt the apical positions. Crystal data: monoclininc P2₁/c, a=12.069(2) A, b=15.362(3) A, c=9.949(2) A, β=92.04(1)°, V=1843.4(6) A³, Z=4, R=0.0471, R_w=0.0952.

Full text of DOI:10.1016/S0022-328X(98)00372-6

Journal of Organometallic Chemistry 558 (1998) 139–146
Zirconium and hafnium mono(alkyl) complexes containing a tridentate
linked amido-tetramethylcyclopentadienyl ligand. Molecular structure
of Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OCH3)Cl2
Francisco Amor, Karen E. du Plooy, Thomas P. Spaniol, Jun Okuda *
Institut fu¨r Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Uni6ersita¨t, J.-J.-Becher-Weg 24, D-55099, Mainz, Germany
Received 31 October 1997
Abstract
Zirconium and hafnium complexes M(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)Cl2 (M=Zr, Hf) containing the tridentate 2-
methoxyethylamido-functionalized tetramethylcyclopentadienyl ligand C5Me4SiMe2NCH2CH2OMe have been synthesized by the
reaction of the dilithium derivative Li2[C5Me4SiMe2NCH2CH2OMe] with MCl4(THF)2. Selective monoalkylation of the dichloro
complexes gave complexes of the type M(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)(R)Cl (R=CH2Ph, o-C6H4CH2NMe2). The
crystal structure of the hafnium dichloro complex Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)Cl2 has been determined by X-ray
crystal diffraction and shows a trigonal bipyramidal structure in which the five-membered ring and the methoxy function adopt
˚
˚
˚
the apical positions. Crystal data: monoclininc P21/c, a=12.069(2) A, b=15.362(3) A, c=9.949(2) A, i=92.04(1)°, V=
3
˚
1843.4(6) A , Z=4, R=0.0471, Rw=0.0952. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Zirconium; Hafnium; Linked amido-cyclopentadienyl ligand; Alkyl complex
1. Introduction
electrons are expected to be even more electrophilic and
their generation by the alkyl abstraction from dialkyls
M(p5:p1-C5R4SiMe2NR%)R¦ are currently under intense
Since Bercaw et al. utilized the linked amido-cy-
clopentadienyl ligand C5Me4SiMe2NtBu in scandium
chemistry to successfully develop the first single-compo-
nent h-olefin polymerization catalysts with living char-
acteristics [1], extensive efforts have recently been
devoted to the synthesis and study of group 4 metal
2
scrutiny [6]. One possible route would be the halide
abstraction from mono(alkyl) complexes of the type
M(p5:p1-C5R4SiMe2NR%)(R)X. Here we describe the
preparation and characterization of zirconium and
hafnium complexes containing the 2-methoxyethy-
lamido-functionalized tetramethylcyclopentadienyl lig-
and C5Me4SiMe2NCH2CH2OMe. This tridentate ligand
was developed to attenuate the strong electrophilic
metal centers through the presence of an additional
2-electron donor function attached to the amido-nitro-
gen atom [2]c, [7].
complexes
of
general
formula
M(p5:p1-
C5R4SiMe2NR%)X2 (M=Ti, Zr, Hf; X=halide, amido,
alkyl) [2,3]. A major technological breakthrough was
the commercial introduction of ethylene polymerization
catalysts on the basis of such complexes resulting in
novel types of polyethylene materials [4]. In contrast to
the conventional 14-electron metallocene catalysts
[M(p5-C5R5)2R%]+ [5], the surmised active species
2. Results and discussion
[M(p5:p1-C5R4SiMe2NR%)R¦]+
with
12
valence
When (chlorodimethylsilyl)tetramethylcyclopenta-di-
ene is treated with lithium 2-methoxyethylamide in
* Corresponding author. Fax: +49 6131 395605.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00372-6

140
F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
Scheme 1.
hexane, (C5Me4H)SiMe2NHCH2CH2OMe is obtained
as a yellow, distillable oil in good yield (Scheme 1). The
1H NMR spectrum of (C5Me4H)SiMe2NHCH2-
CH2OMe shows a singlet for the methyl groups of the
silicon bridge at −0.01 ppm and the methyl groups of
the cyclopentadienyl ring appear as two singlets at 1.84
and 1.99 ppm. The CH2 protons of the side chain are
recorded as two AA%XX% multiplets centered at 2.91
and 3.34 ppm and the methoxy group as a singlet at
3.37 ppm. Thus, the molecule appears to contain a
mirror plane at room temperature.
complex 1b are located at lower field, the difference to
the corresponding groups in the zirconium homologue
1a being between 0.01 and 0.09 ppm. These data are in
agreement with a trigonal bipyramidal molecular struc-
ture possessing a mirror plane or with a three-legged
piano-stool structure in which the ether donor is
bonded in a flexible manner on the NMR time scale
[2]c,d. From the crystallographic study of the hafnium
complex 1b (vide infra) and of the related Zr(p5:p1:p1-
C5Me4SiMe2NCH2CH2NMe2)Cl2 [2]c, we believe that
the latter scenario is less likely for the more Lewis-
acidic zirconium and hafnium centers.
Double
deprotonation
of
(C5Me4H)SiMe2-
NHCH2CH2OMe with two equivalents of n-butyl
lithium in hexane gives crystalline Li2(C5Me4-
SiMe2NCH2CH2OMe), which reacts with MCl4(THF)2
(M=Zr, Hf) in toluene at low temperatures to afford
colorless, crystalline Zr(p5:p1:p1-C5Me4SiMe2NCH2-
CH2OMe)Cl2 (1a) and Hf(p5:p1:p1-C5Me4SiMe2NCH2-
CH2OMe)Cl2 (1b) in 78% and 58% yield, respectively
(Scheme 1).
Attempts to prepare mono(alkyl) complexes starting
from the dichloro complexes 1a and b using a variety of
alkylating reagents such as the THF adduct of diben-
zylmagnesium or phenyl lithium in the appropriate
stoichiometry has failed so far, leading to mixtures
consisting of di- and mono(alkyl) complexes besides the
starting material. The reaction of 1a with MeMgCl
resulted in an inseparable 4:1 mixture consisting of the
mono(methyl) zirconium derivative 2a and the unre-
acted starting dichloro complex. 2a can be easily recog-
nized by the lack of a mirror plane in the NMR
spectra. Thus, in the 1H NMR spectrum the methyl
group at Zr gives rise to a signal at −0.06 ppm, by 0.3
ppm lower field than that in the dimethyl complex
Zr(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)Me2 [2]c. The
13C NMR resonance is recorded at 31.5 ppm which is in
the expected range for related chloro(methyl)zir-
conocenes Zr(p5-C5R5)2(Me)Cl [8]. Similar to the zir-
conocene analogs, no fast scrambling between the
The 1H NMR spectra of the complexes 1a and b
show a pattern similar to that described for the 1H
NMR
spectrum
of
the
ligand
precursor
(C5Me4H)SiMe2NHCH2CH2OMe. For 1a the methyl
groups of the silicon bridge appear as a singlet at 0.35
ppm and the methyl groups of the cyclopentadienyl
ring appear as singlets at 2.12 and 2.13 ppm. The
protons of the lateral chain are recorded as two pseudo-
triplets of a typical AA%XX% system at 2.88 and 3.36
ppm. The signal of the methoxy group is recorded at
3.60 ppm as a singlet. The resonances of the hafnium

F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
141
As an indication for the tridentate bonding mode of
the C5Me4SiMe2NCH2CH2OMe ligand in 4a, the
methoxy signal is shifted to higher field to 2.85 as
compared to the dichloro complex 1a with 3.54 ppm.
Similar high field shift for this signal is observed in the
diphenyl or dibenzyl complexes M(p5:p1:p1-C5Me4-
SiMe2NCH2CH2OMe)X2 (M=Zr, Hf; X=Ph,
CH2Ph) [2]h, indicating the close proximity of the
methoxy group to the anisotropy region of the o-
C6H4CH2NMe2 group. Thus the linked amido-cy-
clopentadienyl ligand C5Me4SiMe2NCH2CH2OMe
preferably acts as a tridentate ligand and appears to
dichloro 1a, mono(methyl) 2a, and di(methyl) [2]h
seems to occur both on the NMR and laboratory time
scale.
The reaction of PhCH2MgCl with the dichlorides 1a
and 1b at 0°C gave the mono(benzyl) complexes 3a and
3b as pentane-soluble, colorless crystals in 80 and 66%
yield, respectively. In agreement with the presence of a
configurationally stable chiral metal center, two singlets
for the methyl groups at the silicon atom, and four
singlets for the five-membered ring methyl groups are
1
detected in the H NMR spectrum of 3. Each proton of
the lateral chain appears as a well separated six-line
multiplet of an ABCD spin system. The diastereotopic
methylene protons of the benzyl ligand in 3a appear in
exhibit
a
stronger chelate effect than the o-
C6H4CH2NMe2 ligand.
1
the H NMR spectrum as an AB spin system at 1.81
and 2.04 ppm with 2JHH=12 Hz. In the 13C NMR
spectrum, the resonance at 58.5 ppm can be assigned to
the methylene carbon of the benzyl group. None of
these data support any agostic bonding of the benzylic
group, as was suggested in the similar mono(benzyl)
complex M{p5:p1:p1-C5H4(CH2)3NMe}(CH2Ph)Cl [9].
Reaction of 1a and 1b with Li(o-C6H4CH2NMe2) [10]
at −78°C gave the mono(aryl) complexes M(p5:p1:
p1-C5 Me4SiMe2NCH2CH2OMe)(o-C6H4CH2NMe2)Cl
(M=Zr (4a), M=Hf (4b)) as colorless crystals in good
3. X-ray crystal structure determination for 1b
An X-ray crystal structure determination of the
hafnium dichloro complex 1b was carried out. Crystal-
lographic details are summarized in Table 1. Fractional
coordinates and equivalent isotropic temperature fac-
tors are listed in Table 2, selected bond distances and
angles in Table 3.
The molecular structure is depicted in Fig. 1. The
compound adopts a distorted trigonal bipyramidal
configuration with the tetramethylcyclopentadienyl lig-
and and the methoxy groups occupying the apical
positions, as is now established for a series of zirconium
and hafnium complexes with the C5Me4SiMe2NCH2-
CH2X ligand [2]c,d,h. The tetramethylcyclopentadienyl
ligand is bonded in a slightly distorted pentahapto
fashion as judged by the sum of the angles at the ring
(540°) and the metal ring-carbon distances ranging
1
yields. As was observed for 3a and 3b, the H and 13C
NMR spectra of the complexes 4a and 4b suggest a
molecular structure devoid of a mirror plane. Complete
assignment was achieved using 1D and 2D NMR spec-
troscopy. At room temperature, the resonance of the
NMe2 group of the N,N%-dimethylamino function to the
metal center appears as a singlet at 2.27 ppm, suggest-
ing a rapid inversion at the amino nitrogen atom on the
NMR time scale. Likewise, the 13C NMR spectrum
shows a singlet at 49.6 ppm for the two methyl carbon
atoms. The signal of the methylene protons of the
o-C6H4CH2NMe2 ligand are observed as two AB dou-
˚
from 2.428(7) to 2.585(8) A. The hafnium-nitrogen
˚
bond length of 2.038(6) A is in the range for an amido
ligand bonded to
a
d0-hafnium center such as
5
˚
Hf{N(SiMe3)2}3Cl (2.04(1) A) [11]a, Hf(p -C5Me5)2-
(H)NHMe2 (2.027(8) A) [11]b, Hf(p -C5Me5)(NiPr)3
(2.041(4), 2.065(3) A) [11]c or that observed in related
5
˚
3
blets with JHH=14 Hz at 2.73 and 3.83 ppm for 4a
˚
and the 13C NMR signal is observed at 70.7 ppm. For
4b the corresponding resonances are found in a similar
region.
hafnium complexes containing a linked amido-cy-
clopentadienyl ligand [2]h, [3]g. The nitrogen atom is
trigonal planar implying a three-electron ligand, the

142
F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
Table 2
sum of the angles at the nitrogen atom amounting to
360°. The hafnium–oxygen bond length of 2.324(5) A
Fractional coordinates (×104) and equivalent isotopic temperature
˚
factors [A ×103] for Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OCH3)Cl2
(1b)
2
˚
is slightly larger than those found in hafnium com-
plexes with a donor ligand such as THF ([Hf(p5-
˚
C5Me5)2CH2CHMe2(THF)][B(C6H5)4] [12], 2.221(6) A;
Atom
x
y
z
U(eq)
5
˚
Hf(p -C8H8)Cl2(THF) [13], 2.233(9) A). The averaged
Hf–Cl distance in 1b of 2.4 A is within the range
Hf
1948.5(2)
223.4(2)
−818(2)
632(2)
1185(2)
1073(3)
1272(4)
128(4)
7856.8(1)
7860(3)
5580(2)
10 217(2)
7398(5)
9113(6)
9434(7)
9611(9)
8457(11)
7565(10)
8160(8)
10 804(11)
8278(16)
6244(13)
7532(10)
12027(9)
10 057(13)
9122(8)
36(1)
73(1)
70(1)
47(1)
48(1)
42(1)
38(1)
53(2)
66(3)
62(2)
48(2)
90(4)
121(6)
115(5)
70(3)
91(4)
88(4)
49(2)
58(2)
61(2)
˚
Cl(1)
Cl(2)
Si
O
N
447(2)
2291(2)
3120(2)
387(4)
expected for (dichloro)hafnocene derivatives [14], sug-
gesting an electronically relatively saturated metal cen-
ter due to the presence of the strongly y-donating
amido ligand. However, the angle between the chlorine
atoms is 109.2(1)° and is significantly larger than in
hafnocene complexes with about 97° [14].
1987(5)
3526(6)
2906(7)
3026(8)
3679(7)
3999(7)
2245(9)
2610(11)
4037(11)
4756(7)
2776(10)
4131(9)
1144(7)
551(8)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
−660(5)
−1176(6)
−740(6)
70(5)
−903(8)
−2103(6)
−1084(9)
727(7)
1147(10)
2089(7)
1952(5)
1960(5)
993(6)
4. Experimental section
All experiments were performed under argon using
standard schlenk or glove box techniques. Pentane and
hexane were purified by distillation from sodium/
triglyme/benzophenone ketyl. Toluene was distilled
over sodium sand. C5Me4HSiMe2Cl [1], MCl4(THF)2
(M=Zr, Hf) [15] Li(o-C6H4CH2NMe2) were synthe-
sized according to published procedures [16]. MgMeCl,
7783(9)
6239(9)
−348(8)
Table 1
MgPhCH2Cl, and LinBu (Aldrich) were titrated prior
to use [17]. H2NCH2CH2OMe (Aldrich) was distilled
from CaH2 and stored over molecular sieves. NMR
spectra were recorded on a Bruker DRX 400 spectrom-
eter (l in ppm with respect to SiMe4 as internal refer-
ence), mass spectra on a Finigan 8230 spectrometer.
Elemental analyses were performed in Analytische Lab-
oratorien, Lindlar (Germany).
Crystallographic data for Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2-
OCH3)Cl2 (1b)
Crystal data
Empirical formula
Formula weight
Crystal color
C14H25Cl2HfNOSi
500.83
Colorless
0.40×0.30×0.30
Monoclinic
P21/c (no. 14)
12.069(2)
15.362(3)
9.949(2)
Crystal size, mm
Crystal system
Space group
˚
a, A
˚
b, A
Table 3
˚
c, A
Selected bond lengths [A] and angles [°] for Hf(p5:p1:p1-
˚
i (°)
Volume, A
Z
92.04(1)
1843.4(6)
4
C5Me4SiMe2NCH2CH2OCH3)Cl2 (1b)
3
˚
Bond lengths
Angles
Dcalc, Mg m−3
Abs. coeff., mm−1
F(000)
1.805
6.009
976
Hf–N
2.038(6)
2.417(2)
2.401(2)
2.324(5)
2.428(7)
2.466(8)
2.494(8)
2.572(9)
2.585(8)
1.728(6)
1.874(7)
1.426(9)
1.435(9)
1.459(9)
1.49(1)
N–Hf–Cl(1)
N–Hf–Cl(2)
Cl(2)–Hf–Cl(1)
N–Hf–O
O–Hf–Cl(1)
O–Hf–Cl(2)
N–Si–C(10)
N–Si–C(11)
N–Si–C(1)
C(11)–Si–C(10)
C(13)–O–C(14)
C(13)–O–Hf
C(14)–O–Hf
C(12)–N–Si
C(12)–N–Hf
Si–N–Hf
121.5(2)
111.8(2)
109.2(1)
71.2(2)
76.7(2)
80.4(2)
114.7(4)
113.2(4)
90.8(3)
106.0(6)
112.0(6)
112.3(4)
125.7(5)
126.0(5)
124.7(5)
109.2(3)
106.9(6)
108.3(6)
Hf–Cl(1)
Hf–Cl(2)
Hf–O
Hf–C(1)
Hf–C(2)
Hf–C(5)
Hf–C(3)
Hf–C(4)
Si–N
Si–C(1)
O–C(13)
O–C(14)
N–C(12)
C(12)–C(13)
Data collection
Temperature, K
Radiation
2q range
Reflns. measd.
296(2)
MoKh (u=0.71070 A)
3.01–29.96°
˚
−165h516; −215k50;
05l513
Refinement
No. reflns. measd.
No. indep. reflns.
No. obsd. reflns.
Goodness-of-fit
R
5675
5346 [Rint=0.0242]
3813 (I\2|(I))
1.143
0.0471
0.0952
wR2
Extinction coefficient
0.0005(2)
+1.671, −1.943
Largest e-max, e-min, e
O–C(13)–C(12)
N–C(12)–C(13)
−3
˚
A

F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
143
Fig. 1. ORTEP diagram of the molecular structure of Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OCH3)Cl2 (1b). Thermal ellipsoids are drawn at 50%
probability level. Hydrogen atoms are omitted for the sake of clarity.
white precipitate which was filtered. Toluene (40 ml)
was added at −78°C to a solid mixture of the dilithium
salt (1.00 g, 3.7 mmol) and the THF adduct of zirco-
nium tetrachloride (1.42 g, 3.7 mmol). The mixture was
stirred at room temperature and the yellow solution
was filtered and concentrated. Cooling the filtrate to
−30°C overnight gave 1a (1.19 g, 78%) as colorless
4.1. C5Me4HSiMe2NHCH2CH2OMe
A hexane solution of (C5Me4H)SiMe2Cl (17.5 g, 81.9
mmol) was added to
a
suspension of Li(N-
HCH2CH2OMe) (8.1 g, 100 mmol) in hexane (100 ml)
at −78°C. The reaction mixture was allowed to warm
to room temperature and stirred for 14 h. Filtration of
the resulting solution and removal of the solvent in
vacuo gave crude (C5Me4H)SiMe2NHCH2CH2OMe as
a yellow oil which was distilled at 75°C and 10−2 mbar;
1
crystals in two crops. H NMR (C6D6): l 0.35 (s, 6 H,
SiCH3), 2.12, 2.13 (s, 6 H, CCH3), 2.88 (t, 2 H, NCH2),
3.36 (t, 2 H, CH2O), 3.54 (s, 3 H, OCH3); 13C{1H}
NMR (C6D6): l 2.4 (SiCH3), 12.2, 14.7 (CCH3), 46.9
(NCH2), 62.5 (OCH3), 77.1 (CH2O), 101.1 (ring-C at
Si), 130.3, 130.9 (CCH3). EI MS: m/z (%) 413 (46)
1
yield: 11.4 g (55%). H NMR (CDCl3): l −0.01 (s, 6
H, SiCH3), 1.84, 1.99 (s, 6 H, CCH3), 2.91 (m, 2 H,
NCH2), 3.34 (m, 2 H, CH2O), 3.37 (m, 3 H, OCH3);
13C{1H} NMR (CDCl3): l −2.8 (SiCH3), 11.1, 14.2
(C5CH3), 41.4 (NCH2), 56.6 (ring-C at Si), 58.5
(OCH3), 75.5 (CH2O), 132.5, 135.4 (CCH3). EI MS:
m/z (%) 253 (20) [M+], 194 (15) [M+ −CH2CH2OMe].
Anal. Calcd. for C14H27NOSi: C, 66.34; H, 10.74; N,
5.53. Found: C, 65.74; H, 10.78; N, 5.64.
[M+], 366 (100) [M+ −C2H5O], 339 (38) [M+
−
C3H6NO]. Anal. Calcd. for C14H25Cl2NOSiZr: C,
40.60; H, 6.09; N, 3.38. Found: C, 40.37; H, 6.13; N,
3.29.
4.3. Zr(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)MeCl
(2a)
4.2. Zr(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)Cl2 (1a)
MeMgCl (0.62 ml of a 1.6 M solution in THF) were
added to a cooled at −78°C suspension of 1a (0.41 g,
0.99 mmol) and the mixture was stirred to room tem-
perature for 3 h. All solvents were removed and a pale
yellow solution was extracted in pentane (15 ml). This
solution was concentrated and cooled overnight to
−30°C to precipitate white crystals identified as a 4:1
To
a
cooled
at
0°C
solution
of
(C5Me4H)SiMe2NHCH2CH2OMe (3.14 g, 12.44 mmol)
in hexane (20 ml) was added LinBu (10.8 ml of a 2.3 M
solution in hexane) using
a
syringe to form
Li2(C5Me4SiMe2NCH2CH2OMe) (3.00 g, 91%) as a

144
F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
mixture consisting of Zr(p5:p1:p1-C5Me4SiMe2NCH2-
CH2OMe)MeCl and 1a. H NMR (C6D6): l −0.06 (s,
in C6H4, 2JHH=1.5 Hz, 3JHH=7 Hz), 7.12 (d, 1 H, H-5
3
1
or H-2 in C6H4, JHH=7 Hz), 7.67 (dd, 1 H, H-4 or
H-3 in C6H4, 2JHH=1.5 Hz, 3JHH=7 Hz); 13C{1H}
NMR (C6D6): l 2.4, 3.0 (SiCH3), 12.6, 12.7, 16.2, 16.6
(CCH3), 46.7 (NCH2), 49.6 (NCH3), 61.1 (OCH3), 70.9
(C6H4CH2NMe2) 76.2 (CH2O), 102.9 (ring-C at Si),
123.1, 125.5, 125.7 (C-2–C-4 C6H4CH2NMe2), 125.9,
3 H, ZrCH3), 0.35, 0.37 (s, 3 H, SiCH3), 2.00, 2.08,
2.11, 2.17 (s, 3 H, CCH3), 2.88, 3.0, 3.3, 3.4 (m, 1 H,
NCH2 and CH2O), 3.54 (s, 3 H, OCH3); 13C{1H} NMR
(C6D6): l 2.5, 2.9 (SiCH3), 11.5, 12.4, 13.8, 14.8
(CCH3), 31.5 (ZrCH3), 46.2 (NCH2), 62.1 (OCH3),
78.1 (CH2O), 98.76 (ring-C at Si), 126.6, 126.9, 127.7,
127.9 (CCH3). EI MS: m/z (%) 393 (5) [M+], 377 (100)
126.9,
128.0,
130.6
(CCH3),
142.6
(C-5
C6H4CH2NMe2), 145.9 (C-6 C6H4CH2NMe2), 189.3 (C-
1 C6H4CH2NMe2). EI MS: m/z (%) 513 (84) [M+], 469
(25) [M+ −NMe2], 455 (22) [M+ −CH2NMe2], 379
(23) [M+ −C6H4CH2NMe2]. Anal. Calcd. for
C23H37ClN2OSiZr: C, 53.94; H, 7.23; N, 5.47. Found:
C, 48.52; H, 7.51; N, 4.69.
[M+ −CH3], 357 (25) [M+ −Cl], 342 (46) [M+
−
CH3–Cl].
4.4. Zr(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)-
(CH2Ph)Cl (3a)
4.6. Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)Cl2 (1b)
A suspension of 1a (0.27 g, 0.65 mmol) in hexane (30
ml) was cooled at 0°C and then benzylmagnesium
chloride (0.45 ml of a 1.6 M solution in THF) was
added via syringe. The mixture was stirred and allowed
to warm to room temperature. After removing all
volatiles, pentane (15 ml) was added, the solution
filtered, and the filtrate concentrated to give 3a (0.24 g,
Following a procedure analogous to that described
for 1a, Li2[C5Me4SiMe2NCH2CH2OMe] (1.20 g, 4.52
mmol) was reacted with the THF adduct of hafnium
tetrachloride (2.10 g, 4.52 mmol) to give 1b as colorless
crystals in two crops; yield 1.31 g (58%). 1H NMR
(C6D6): l 0.35 (s, 6 H, SiCH3), 2.19, 2.2 (s, 6 H, CCH3),
2.97 (t, 2 H, NCH2), 3.28 (t, 2 H, CH2O), 3.54 (s, 3 H,
OCH3); 13C{1H} NMR (C6D6): l 2.4 (SiCH3), 11.9,
14.3 (CCH3), 45.7 (NCH2), 62.3 (OCH3), 77.5 (CH2O),
92.9 (ring-C at Si), 128.3, 129.3 (CCH3). EI MS: m/z
(%) 501 (1) [M+], 429 (1) [M+ −2Cl]. Anal. Calcd. for
C14H25Cl2HfNOSi: C, 33.57; H, 4.99; N, 2.79. Found:
C, 33.82; H, 4.91; N, 2.71.
1
80%) as, colorless crystals upon cooling to −30°C. H
NMR (C6D6): l 0.36, 0.43 (s, 3 H, SiCH3), 1.81 (d, 1 H,
2JHH=12 Hz, ZrCH2C6H5), 1.96 (s, 3 H, CCH3), 2.04
2
(d, JHH=12 Hz, 1 H, ZrCH2C6H5), 2.04, 2.16, 2.23 (s,
3 H, CCH3), 2.91, 2.99, 3.12 (m, 1 H, NCH2, CH2O),
3.17 (s, 3 H, OCH3), 3.24 (m, 1 H, NCH2 or CH2O),
6.87–7.19 (m, 5 H, CH2C6H5). 13C{1H} NMR (C6D6):
l 2.2, 2.9 (SiCH3), 11.2, 12.8, 13.6, 14.8 (CCH3), 46.5
(NCH2), 58.5 (ZrCH2C6H5), 63.5 (OCH3), 78.3
(CH2O), 100.2 (ring-C at Si), 121.4 (para-C6H5), 125.6,
126.9 (CCH3), 127.3 (meta-C6H5), 127.6 (ortho-C6H5),
129.0, 129.3 (CCH3), 150.1 (ipso-C6H5). EI MS: m/z
(%) 377 (24) [M+ −CH2Ph], 342 (41) [M+ −CH2Ph–
Cl]. Anal. Calcd. for C21H32ClNOSiZr: C, 53.76; H,
6.82; N, 2.96. Found: C, 46.30; H, 7.26; N, 2.57.
4.7. Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)-
(CH2Ph)Cl (3b)
Following a procedure analogous to that described
for the preparation of 3a, 1b (0.35 g, 0.69 mmol) was
reacted with benzylmagnesium chloride(0.42 ml of a 1.6
M solution in THF) to give 3b (0.25 g, 66%) as color-
1
less crystals. H NMR (C6D6): l 0.35, 0.42 (s, 3 H,
4.5. Zr(p5:p1:p1-C5Me4SiMe2NCH2CH2-
OMe)(o-C6H4CH2NMe2)Cl (4a)
2
SiCH3), 1.50, 1.87 (d, 1 H, HfCH2C6H5, JHH=13 Hz),
1.96, 2.09, 2.19, 2.24 (s, 3 H, CCH3), 2.87–3.10 (m, 4
H, NCH2 and CH2O), 3.08 (s, 3 H, OCH3), 6.8–7.2 (m,
5 H, CH2C6H5); 13C{1H} NMR (C6D6): l 2.2, 2.9
(SiCH3), 11.1, 12.5, 13.5, 14.7 (CCH3), 45.6 (NCH2),
62.7 (HfCH2C6H5), 63.4 (OCH3), 78.6 (CH2O), 99.8
(ring-C at Si), 121.7 (para-C6H5), 124.8, 125.5, 126.0,
128.5 (CCH3), 128.8 (meta-C6H5), 129.0 (ortho-C6H5),
150.5 (ipso-C6H5). EI MS: m/z (%) 557 (19) [M+], 467
(50) [M+ −C7H7], 431 (56) [M+ −C7H7–Cl]. Anal.
Calcd. for C21H32ClHfNOSi: C, 45.32; H, 5.75; N, 2.52.
Found: C, 42.32; H, 6.09; N, 2.39.
Hexane (40 ml) was added at −78°C to a mixture of
1a (0.26 g, 0.62 mmol) and Li(o-C6H4CH2NMe2) (0.1 g,
0.70 mmol). The mixture was stirred at room tempera-
ture overnight and then all volatiles were removed in
vacuo. The residue was extracted with pentane (3×15
ml), the yellow extracts were filtered and concentrated.
Cooling to −30°C overnight afforded 4a (0.20 g, 63%)
1
as colorless crystals. H NMR (C6D6): l 0.54, 0.63 (s, 3
H, SiCH3), 1.61, 1.82, 2.03 (s, 3 H, CCH3), 2.27 (s, 6 H,
N(CH3)2), 2.53 (s, 3 H, CCH3), 2.73 (d, 1 H,
C6H4CH2NMe, 2JHH=14 Hz), 2.85 (s, 3 H, OCH3),
3.21 (m, 2 H, NCH2 and CH2O), 3.67 (m, 1 H, NCH2
4.8. Hf(p5:p1:p1-C5Me4SiMe2NCH2CH2OMe)-
(p1-C6H4CH2NMe2)Cl (4b)
2
or CH2O), 3.83 (d, 1 H, C6H4CH2N(CH3)2, JHH=14
Hz), 3.88 (m, 1 H, NCH2 or CH2O), 6.87 (d, 1 H, H-2
Following a procedure analogous to that described
for the preparation of 4a, 1b (0.30 g, 0.59 mmol) was
or H-5 in C6H4, 3JHH=7 Hz), 7.08 (dt, 1 H, H-3 or H-4

F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
145
Acknowledgements
reacted with Li(o-C6H4CH2NMe2) (0.1 g, 0.70 mmol)
to give 4b (0.24 g, 69%) as colorless crystals from
pentane solution. H NMR (C6D6): l 0.57, 0.65 (s, 3
1
This work was supported by the Fonds der Chemis-
chen Industrie and the Volkswagen-Foundation. F. A.
is indebted to the European Community (TMR pro-
gram) and K.d.P. to the Humboldt Foundation for a
postdoctoral fellowship.
H, SiCH3), 1.63, 1.85, 2.01 (s, 3 H, CCH3), 2.27 (s, 6
H, NCH3), 2.58 (s, 3 H, CCH3), 2.79 (s, 3 H, OCH3),
2.81 (d, 1 H, C6H4CH2N, 2JHH=14 Hz), 3.33–3.53
(m, 3 H, NCH2 and CH2O), 3.83 (d, 1 H, C6H4CH2N,
2JHH=14 Hz), 3.87–3.93 (m, 1 H, NCH2 or CH2O),
3
6.93 (d, 1 H, H-2 or H-5 in C6H4, JHH=7 Hz), 7.11
References
2
3
(td, 1 H, H-3 or H-4 in C6H4, JHH=1.6 Hz, JHH=7
3
Hz), 7.19 (t, 1 H, H-4 or H-3 in C6H4, JHH=7 Hz),
[1] (a) P.J. Shapiro, E.E. Bunel, W.P. Schaefer, J.E. Bercaw,
Organometallics 9 (1990) 867. (b) P.J. Shapiro, W.D. Cotter,
W.P. Schaefer, J.A. Labinger, J.E. Bercaw, J. Am. Chem. Soc.
116 (1994) 4623. (c) W.E. Piers, P.J. Shapiro, E.E. Bunel, J.E.
Bercaw, Synlett 2 (1994) 74.
[2] (a) J. Okuda, Chem. Ber. 123 (1990) 1649. (b) J. Okuda, F.J.
Schattenmann, S. Wocadlo, W. Massa, Organometallics 14
(1995) 789. (c) K.E. du Plooy, U. Moll, S. Wocadlo, W. Massa,
J. Okuda, Organometallics 14 (1995) 3129. (d) J. Okuda, K.E. du
Plooy, W. Massa, H.C. Kang, U. Rose, Chem. Ber. 129 (1996)
275. (e) F. Amor, J. Okuda, J. Organomet. Chem. 520 (1996)
245. (f) J. Okuda, S. Verch, T.P. Spaniol, R. Stu¨rmer, Chem.
Ber. 129 (1996) 1429. (g) J. Okuda, T. Eberle, T.P. Spaniol,
Chem. Ber./Recueil, 130 (1997) 209. (h) F. Amor, T.P. Spaniol,
J. Okuda, Organometallics 16 (1997) 4765.
[3] (a) D.D. Devore, F.J. Timmers, D.L. Hasha, R.K. Rosen, T.J.
Marks, P.A. Deck, C.L. Stern, Organometallics 14 (1995) 3132.
(b) L. Kloppenburg, J.L. Peterson, Organometallics 15 (1996) 7.
(c) D.W. Carpenetti, L. Kloppenburg, J.T. Kupec, J.L. Petersen,
Organometallics 15 (1996) 1572. (d) L. Kloppenburg, J.L. Peter-
son, Organometallics 16 (1997) 3548. (e) S. Ciruelos, T. Cuenca,
P. G-mez-Sal, A. Manzanero, P. Royo, Organometallics 14
(1995) 177. (f) S. Ciruelos, T. Cuenca, R. Gomez, P. Gomez-Sal,
A. Manzanero, P. Royo, Organometallics 15 (1996) 5577. (g)
H.V.R. Dias, Z. Wang, S.G. Bott, J. Organomet. Chem. 508
(1996) 91.
[4] (a) J.M. Canich, G.G. Hlatky, H.W. Turner, PCT Appl. WO
92-00333, 1992. (b) J.M. Canich, Eur. Patent Appl. EP 420
436-A1, Exxon, 1991. (c) P.N. Stevens, F.J. Timmers, D.R.
Wilson, G.F. Schmidt, P.N. Nickias, R.K. Rosen, G.W. Knight,
S. Lai, Eur. Patent Appl. EP 416 815-A2, Dow, 1991. (d) F.G.
Sernetz, R. Mu¨lhaupt, F. Amor, T. Eberle, J. Okuda, J. Polym.
Sci. Part A 35 (1997) 1571. (e) F.G. Sernetz, R. Mu¨lhaupt, R.M.
Waymouth, Macromol. Chem. Phys. 197 (1996) 1071. (f) F.G.
Sernetz, R. Mu¨lhaupt, R.M. Waymouth, Polymer Bulletin 38
(1997) 141. (g) A.L. McKnight, Md.A. Masood, R.M. Way-
mouth, Organometallics 16 (1997) 2879. (h) T. Shiomura, T.
Asanuma, N. Inoue, Macromol. Rapid Commun. 17 (1996) 9. (i)
T. Shiomura, T. Asanuma, T. Sunaga, Macromol. Rapid Com-
mun. 18 (1997) 169. (j) H. Hagihara, T. Shiono, T. Ikeda,
Macromolecules 30 (1997) 4783. (k) K. Soga, T. Uozumi, S.
Nakamura, T. Toneri, T. Teranishi, T. Sano, T. Arai, Macro-
mol. Chem. Phys. 197 (1996) 4237.
7.79 (d, 1H, H-5 or H-2 in C6H4, 3JHH=7 Hz);
13C{1H} NMR (C6D6): l 2.5, 3.1 (SiCH3), 12.4, 12.5,
15.8, 16.5 (CCH3), 46.6 (NCH2), 49.6 (N(CH3)2), 59.9
(OCH3), 70.7 (C6H4CH2N), 75.9 (CH2O), 102.5 (ring-
C at Si), 123.4 (C-2 or C-5 C6H4CH2N), 124.7, 125.7
(CCH3), 125.8, 126.0 (C-3, C-4 C6H4CH2N), 127.1
(CCH3), 127.8 (C-5 or C-2 C6H4CH2N), 129.1 (CCH3,
143.7 (C-6 C6H4CH2N), 146.7 (C-1 C6H4CH2). EI MS:
m/z (%) 600 (66) [M+], 565 (35) [M+ −Cl], 468 (74)
[M+ −C6H4CH2NMe2], 435 (7) [M+ −Cl,
−
C6H4CH2NMe2]. Anal. Calcd. for C23H37ClHfN2OSi:
C, 46.00; H, 6.17; N, 4.67. Found: C, 45.93; H, 6.30;
N, 4.52.
4.9. X-ray crystal structure analysis of 1b
Crystal data for 1b are summarized in Table 1. The
compound, obtained as colorless crystals by cooling a
concentrated toluene solution, crystallizes in the mon-
oclinic space group P21/c. Data collection in the range
3.01B2qB29.96° was performed using ꢀ-scans on an
Enraf-Nonius CAD-4 diffractometer with graphite-
monochromated MoKh ratiation. Data correction for
Lorentz polarization and absorption (empirically using
C-scans) was carried out using the program system
MOLEN [18]a. From 5675 measured reflections, all
5346 independent reflections were used and 189
parameters were refined by full-matrix least-squares
against all F2o data (SHELXL-93) [18]b. The structure
was solved using direct methods (SHELXS-86) [18]c and
difference Fourier syntheses and refined with an-
isotropic thermal parameters for non-hydrogen atoms.
Hydrogen atoms were calculated at their idealized po-
sitions. The refinement converged with R=0.0471,
wR2=0.0952 for all observed Fo data, goodness of fit
1.143.
[5] R.F. Jordan, Adv. Organomet. Chem. 32 (1991) 325.
[6] (a) Y.X. Chen, C.C. Stern, S. Yang, T.J. Marks, J. Am. Chem.
Soc. 118 (1996) 12451. (b) Y.X. Chen, T.J. Marks, Organometal-
lics 16 (1997) 3649. (c) T.K. Woo, P.M. Margl, J.C. Lohrenz,
P.E. Blochl, T. Ziegler, J. Am. Chem. Soc. 118 (1996) 13021.
[7] (a) K.C. Hultzsch, T.S. Spaniol, J. Okuda, Organometallics 16
(1997) 4845. (b) K.C. Hultzsch, J. Okuda, Macromol. Rapid
Commun. 18 (1997) 809.
Further details of the crystal structure investigation
are available on request from the Fachinformation-
szentrum Karlsruhe, Gesellschaft fu¨r wissenschaftlich-
technische
Information,
D-76344
Eggenstein-
Leopoldshafen, Germany, on quoting the depository
number CSD408459, the names of the authors and the
journal citation.
[8] (a) P.J. Walsh, F.J. Hollander, R.G. Bergman, J. Am. Chem.
Soc. 110 (1988) 8729. (b) R.F. Jordan, J. Organomet. Chem. 294
(1985) 321.

146
F. Amor et al. / Journal of Organometallic Chemistry 558 (1998) 139–146
[9] A.K. Hughes, A. Meetsma, J.H. Teuben, Organometallics 12
Razavi, J. Ferrara, J. Organomet. Chem. 435 (1992) 299. (c) A.
Razavi, J.L. Atwood, J. Organomet. Chem. 459 (1993) 117. (d)
R.M. Shallout, J.Y. Corey, N.P. Roth, J. Organomet. Chem. 503
(1995) 205. (e) C.H. Saldarriga-Molina, A. Clearfield, I. Bernal,
Inorg. Chem. 13 (1974) 2880.
(1993) 1936.
[10] L. Manzer, J. Am. Chem. Soc. 100 (1978) 8068.
[11] (a) C. Airoldi, D.C. Bradley, H. Chudzynska, M.B. Hursthouse,
K.M. Abdul-Malik, P.R. Praistoly, J. Chem. Soc. Dalton Trans.
(1980) 2010–2015. (b) G.L. Hillhouse, A.R. Bulls, B.D. Santar-
siero, J.E. Bercaw, Organometallics 7 (1988) 1309. (c) Y. Bai,
H.W. Roesky, M. Noltemyer, M. Witte, Chem. Ber. 125 (1992)
825.
[15] L.E. Manzer, Inorg. Synth. 21 (1982) 135.
[16] J.T.B.H. Jastrzebski, G. van Koten, Inorg. Synth. 26 (1989) 152.
[17] (a) S.C. Watson, J.F. Eastham, J. Organomet. Chem. 9 (1967)
165. (b) J. Suffert, J. Org. Chem. 54 (1989) 509.
[12] Z. Gou, D.C. Swenson, R.F. Jordan, Organometallics 13 (1994)
1424.
[18] (a) C.K. Fair, MOLEN, An Interactive Structure Solution Proce-
dure, Enraf-Nonius, Delft, 1990. (b) G.M. Sheldrick, SHELXL-93
,
[13] P. Berno, C. Floriani, A. Chiesi-Villa, C. Rizzoli, J. Chem. Soc.
Dalton Trans. (1991) 3093.
[14] (a) R.D. Rogers, M.M. Benning, L.K. Kurihara, R.J. Moriarty,
M.D. Rausch, J. Organomet. Chem. 293 (1985) 51. (b) A.
Program for the Refinement of Crystal Structures, University of
Gsttingen, Germany, 1993. (c) G.M. Sheldrick, SHELXL-86, Pro-
gram for the Solution of Crystal Structures, University of Go¨t-
tingen, Germany, 1986.
.