Formation and structural properties of salicylaldiminato complexes of zirconium and titanium

Article abstract of DOI:10.1016/S0020-1693(99)00573-3

The metallocene cation [Cp₂ZrCH₃(THF)+] (2, with BPh₄^- anion) reacts with N-isopropylsalicylaldimine (1a) by liberation of methane and formation of the pseudotetrahedral [(κO,κN-salicylaldiminato)ZrCp₂⁺] complex 3 that was characterized by X-ray diffraction. Deprotonation of 1a by treatment with n-butyllithium yields the corresponding lithiated reagent 4a, that exhibits a tetrameric structure in the crystal, featuring a cubic Li₄O₄ core structure. Treatment of 4a with Zr(NMe₂)₂Cl₂(dme) (5) yields the octahedral bis(N-isopropylsalicylaldiminato)Zr(NMe₂)₂ complex 7a. The X-ray crystal structure analysis of 7a has revealed that the aldiminato oxygen atoms of the κO,κN-chelate ligand are oriented trans to each other at the central metal atom. Treatment of the N-isopropyl, the N-cyclohexyl- and the N-(2,6-diisopropylphenyl)salicylimines (1a,b,d) with the reagent Zr(NMe₂)₄ (6) directly results in the formation of the respective octahedral (lig)₂Zr(NMe₂)₂ complexes 7a, 7b (also characterized by X-ray diffraction), and 7d in good yields. Treatment of 7b and 7d with Me₃Si-Cl replaced the -NMe₂ substituents by chloride to yield the corresponding lig₂ZrCl₂ complexes 8b and 8d, respectively. The X-ray crystal structure analysis of 8d showed an octahedral coordination with the aldiminato nitrogen atoms of the κO,κN-chelate ligands now being trans-oriented at zirconium. Complex 8b undergoes an enantiomerization process that is followed by dynamic NMR spectroscopy (ΔG(enant.)/≠ (268 K) ? 12 kcal mol^-1). Titanium tetrachloride forms a neutral 1:2 adduct with 1d. The NMR analysis and X-ray crystal structure analysis of the resulting bisbetaine-type adduct 9d reveals the formation of an octahedral titanium complex that contains two trans-Ti-O(aryl) bonds. The phenolic hydrogen atoms were transferred to the aldimine nitrogens to form an intramolecular iminium salt. Two equivalents of HCl are removed from 9d by treatment with NEt₃ to yield the bis[N-(2,6-diisopropylphenyl)salicylaldiminato]TiCl₂ complex 10d (characterized by X-ray diffraction). In a one-pot procedure TiCl₄ reacts with N-phenylsalicylaldimine (1c) and triethylamine in a 1:2:2 ratio to directly yield the corresponding (κO,κN-lig)₂ TiCl₂ complex 10c. The X-ray crystal structure analysis of 10c reveals a trans-orientation of ligand oxygen atoms, just like in the adduct intermediate 9. Upon activation with methylalumoxane the complexes 8d, 10c, and 10d form catalysts for the polymerization of ethene. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(99)00573-3

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 300–302 (2000) 810–821
Formation and structural properties of salicylaldiminato complexes
of zirconium and titanium
Joachim Strauch, Timothy H. Warren 1, Gerhard Erker *, Roland Fro¨hlich 2,
Pauli Saarenketo2
Organisch-Chemisches Institut der Uni6ersita¨t Mu¨nster, Corrensstraße 40, D-48149 Mu¨nster, Germany
Received 23 November 1999; accepted 26 November 1999
Abstract
The metallocene cation [Cp2ZrCH3(THF)+] (2, with BPh4− anion) reacts with N-isopropylsalicylaldimine (1a) by liberation of
methane and formation of the pseudotetrahedral [(kO,kN-salicylaldiminato)ZrCp2+] complex 3 that was characterized by X-ray
diffraction. Deprotonation of 1a by treatment with n-butyllithium yields the corresponding lithiated reagent 4a, that exhibits a
tetrameric structure in the crystal, featuring a cubic Li4O4 core structure. Treatment of 4a with Zr(NMe2)2Cl2(dme) (5) yields the
octahedral bis(N-isopropylsalicylaldiminato)Zr(NMe2)2 complex 7a. The X-ray crystal structure analysis of 7a has revealed that
the aldiminato oxygen atoms of the kO,kN-chelate ligand are oriented trans to each other at the central metal atom. Treatment
of the N-isopropyl, the N-cyclohexyl- and the N-(2,6-diisopropylphenyl)salicylimines (1a,b,d) with the reagent Zr(NMe2)4 (6)
directly results in the formation of the respective octahedral (lig)2Zr(NMe2)2 complexes 7a, 7b (also characterized by X-ray
diffraction), and 7d in good yields. Treatment of 7b and 7d with Me3Si-Cl replaced the ꢀNMe2 substituents by chloride to yield
the corresponding lig2ZrCl2 complexes 8b and 8d, respectively. The X-ray crystal structure analysis of 8d showed an octahedral
coordination with the aldiminato nitrogen atoms of the kO,kN-chelate ligands now being trans-oriented at zirconium. Complex
8b undergoes an enantiomerization process that is followed by dynamic NMR spectroscopy (DG"enant. (268 K):12 kcal mol−1).
Titanium tetrachloride forms a neutral 1:2 adduct with 1d. The NMR analysis and X-ray crystal structure analysis of the resulting
bisbetaine-type adduct 9d reveals the formation of an octahedral titanium complex that contains two trans-TiꢀO(aryl) bonds. The
phenolic hydrogen atoms were transferred to the aldimine nitrogens to form an intramolecular iminium salt. Two equivalents of
HCl are removed from 9d by treatment with NEt3 to yield the bis[N-(2,6-diisopropylphenyl)salicylaldiminato]TiCl2 complex 10d
(characterized by X-ray diffraction). In a one-pot procedure TiCl4 reacts with N-phenylsalicylaldimine (1c) and triethylamine in
a 1:2:2 ratio to directly yield the corresponding (kO,kN-lig)2TiCl2 complex 10c. The X-ray crystal structure analysis of 10c reveals
a trans-orientation of ligand oxygen atoms, just like in the adduct intermediate 9. Upon activation with methylalumoxane the
complexes 8d, 10c, and 10d form catalysts for the polymerization of ethene. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Octahedral bis-chelate complexes; Salicylaldiminato ligands; Betaine complex; Ethene polymerization; Zirconium; Titanium
1. Introduction
development, either in the form of bridged Cp-amido
systems [3] or completely Cp-free complexes of the early
and late transition metals [4]. We have checked the
potential of easily available ‘classical’ ligand systems in
early transition metal chemistry, and for that reason
studied the formation and the chemical and structural
properties of a variety of zirconium and titanium com-
plexes that contain the readily prepared salicylaldimi-
nato ligands [5,6]. This has revealed some remarkable
features of such systems that will be presented and
discussed in this account with the aid of a number of
typical examples of this class of compounds.
Homogeneous Ziegler catalysis has made significant
advances past the metallocene era [1,2]. Nitrogen-con-
taining ligands have played an important role in this
* Corresponding author. Tel.: +49-251-833 3221; fax: +49-251-
833 6503.
E-mail address: erker@uni-muenster.de (G. Erker)
1 New address: Department of Chemistry, Georgetown University,
Washington DC, USA.
2 X-ray crystal structure analyses.
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00573-3

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
811
2. Results and discussion
pseudotetrahedral coordination geometry at Zr. The
Cp(centroid)ꢀZrꢀCp(centroid) angle amounts to 132.1°.
The Zr(salicylaldiminato) moiety exhibits an almost
planar six-membered metallacyclic ring system with
2.1. Reaction of [Cp2ZrCH3(THF)+] cation with
salicylaldimines
,
typical bonding parameters of ZrꢀO1 1.986(1) A,
Salicylaldehyde was converted to the corresponding
aldimines 1a–c by treatment with isopropylamine (a),
cyclohexylamine (b) or aniline (c) in toluene in the
presence of anhydrous sodium sulfate [7]. The corre-
sponding condensation reaction of salicylaldehyde with
2,6-diisopropylaniline to yield the sterically more en-
cumbered aldimine (1d) was carried out in formic acid/
methanol [8].
,
ZrꢀN9 2.265(1) A, angle O1ꢀZr2ꢀN9 82.4(1). The short
zirconiumꢀoxygen bond and the rather large ZrꢀO1ꢀC2
angle (136.3(1)°) point to some p-bonding component
of the ZrꢀO linkage inside the distorted six-membered
ring system (angles O1ꢀC2ꢀC7 120.1(2)°, C2ꢀC7ꢀC8
124.2(2)°) [11]. The bond angles at the iminium nitro-
gen center amount to ZrꢀN9ꢀC8 123.6(1)°, ZrꢀN9ꢀC10
120.1(1)°, and C8ꢀN9ꢀC10 116.2(1)° (Fig. 1).
The salicylaldimine (1a) (R=isopropyl) was treated
with [Cp2ZrCH3(THF)+BPh4−] (2) [9] in dichloro-
methane. At 0°C a rapid reaction takes place with
evolution of methane [10] that leads to the formation of
the Cp2Zr(kN,kO-salicylaldiminato) complex 3 (ca.
80% isolated). Complexation of the aldimine moiety to
the Lewis acidic zirconium center has only resulted in a
small shifting of the ꢀCHꢁNꢀ NMR resonances to
higher l values (1H/13C NMR of 1a: l 7.79/162.4; 3: l
8.19/171.5 in CD2Cl2).
2.2. Preparation and structures of neutral
bis(salicylaldiminato)zirconium complexes
Two different protocols were followed in the prepa-
ration of the (salicylaldiminato)2ZrX2-type complexes.
First, the neutral salicylaldimine (1a) (R=isopropyl)
was deprotonated. Treatment of 1a with n-butyllithium
in THF gave the corresponding anion 4a. Diffusion of
pentane into a solution of 4 in THF furnished single
crystals of the lithiated reagent that was characterized
by X-ray diffraction (see Fig. 2). A tetrameric structure
was found, as it is often observed for Li-alkoxide or
Li-amide reagents, in which lithium and oxygen atoms
are alternately occupying the corner positions of a
slightly distorted cube [12]. The edges of the central
cubic structure are then spanned by the remaining parts
of the four salicylaldiminato moieties. The imino-nitro-
gen atom binds strongly to the corresponding lithium
center in this array, thereby completing the pseudo-
tetrahedral coordination sphere of the lithium atom
(for selected bond lengths and angles see Fig. 2).
The anion 4a was reacted with the new reagent
Zr(NMe2)2Cl2·dme (5) [13,14] in diethylether at 0°C in a
2:1 ratio. The octahedral bis-chelate complex 7a was
isolated in \80% yield as a bright orange-colored solid
(see Scheme 1). Alternatively, 6a was also prepared by
treatment of the neutral salicylaldimine (1a) (R=iso-
propyl) with Zr(NMe2)4 (6) [15] in a 2:1 ratio. Two
equiv. of dimethylamine were cleaved off to give a good
yield (ca. 80%) of 7a. Analogously, treatment of the
salicylaldimines (1b) (R=cyclohexyl) and 1d (R=2,6-
diisopropylphenyl) with Zr(NMe2)4 furnished the com-
plexes 7b and 7d, respectively. The bis(salicylal-
diminato)Zr(NMe2)2 complexes 7b and 7d were subse-
quently converted to the corresponding bis(salicyl-
aldiminato)ZrCl2 systems (8b, 8d) by treatment with a
slight excess of trimethylchlorosilane in dichloro-
methane [16].
Complex 3 was characterized by an X-ray crystal
structure analysis. The cation of 3 features a typical
Fig. 1. Molecular structure of 3 (cation only) with unsystematic atom
,
numbering scheme. Selected bond length (A) and angles (°): ZrꢀO1
1.986(1), ZrꢀN9 2.265(1), ZrꢀCCp 2.500(2), O1ꢀC2 1.328(2), C2ꢀC7
1.405(2), C7ꢀC8 1.438(2), C8ꢀN9 1.291(2); O1ꢀZrꢀN9 82.4(1),
ZrꢀO1ꢀC2 136.3(1), O1ꢀC2ꢀC7 120.1(2), C2ꢀC7ꢀC8 124.2(2),
C7ꢀC8ꢀN9 128.3(2), C8ꢀN9ꢀZr 123.6(1).
Complexation of the salicylaldiminato moiety to the
zirconium center has again resulted only in a marginal
1
shifting of the aldimine ꢀCHꢁNꢀ H/13C NMR signals

812
J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
The onset of the NꢀC(aryl) rotational processes
could be experimentally followed with the correspond-
ing bis(salicylaldiminato)ZrCl2 complex 8d, because of
its lower activation energy. From the dynamic 1H
NMR spectra DG"(NꢀC
(344 K):16.890.3 kcal
aryl)rot
mol−1 was deduced [17].
Complex 8b (R=cyclohexyl) undergoes a \ X Z
enantiomerization process in solution that is readily
followed by dynamic 1H or 13C NMR spectroscopy
[18]. The skeletal degenerate rearrangement of 8b be-
comes for instance apparent by the temperature-depen-
dent coalescence of the pairs of cyclohexyl CH2
resonances (A, B) in the 13C NMR spectrum of this
complex in the temperature range between 228 and 288
K (see Fig. 3). A Gibbs activation energy of DG"enant.
(268 K)=12.190.3 kcal mol−1 was obtained. The
related bis(salicylaldiminato)Zr(NMe2)2 complex 7b
(R=cyclohexyl) exhibits analogous dynamic behavior,
but with a higher activation energy (7b DG"enant. (353
K)=17.390.3 kcal mol−1 [19].
Fig. 2. A view of the associated tetrameric structure of 4a in the
Three examples of this series of complexes were
characterized by X-ray crystal structure analyses,
namely the systems 7a, 7b, and 8d. The bis(dimethyl-
amido)bis(N-isopropylsalicylaldiminato)zirconium com-
plex 7a is close to C2-symmetric in the crystal. The
coordination geometry around the central zirconium
atom in 7a is close to octahedral [20]. The aldiminato
oxygen atoms are oriented trans to each other (ZrꢀO11
,
crystal. Selected bond lengths (A) and angles (°): Li1ꢀLi2 2.607(10),
Li1ꢀLi3 2.663(11), Li1ꢀLi4 2.657(11), Li2ꢀLi3 2.687(12), Li2ꢀLi4
2.661(11), Li3ꢀLi4 2.551(11), Li1ꢀO11 1.885(8), Li1ꢀO21 1.953(8),
Li1ꢀN18 2.001(8), Li1ꢀO41 2.001(9), Li2ꢀO21 1.896(8), Li2ꢀO31
1.996(9), Li2ꢀN28 1.971(9), Li2ꢀO11 1.946(9), Li3ꢀO31 1.885(8),
Li3ꢀO41 1.955(8), Li3ꢀN38 1.992(9), Li3ꢀO11 1.989(9), Li4ꢀO41
1.902(8), Li4ꢀO21 1.988(9), Li4ꢀN48 1.978(9), Li4ꢀO31 1.949(8),
O11ꢀC11 1.315(5), C11ꢀC16 1.405(6), C16ꢀC17 1.460(6), C17ꢀN18
1.281(6), O21ꢀC21 1.314(5), C21ꢀC26 1.412(6), C26ꢀC27 1.461(7),
C27ꢀN28 1.273(6), O31ꢀC31 1.320(5), C31ꢀC36 1.411(6), C36ꢀC37
1.454(7), C37ꢀN38 1.270(6), O41ꢀC41 1.324(5), C41ꢀC46 1.412(7),
C46ꢀC47 1.447(7), C47ꢀN48 1.277(6); Li2ꢀLi1ꢀLi3 61.3(3),
Li2ꢀLi1ꢀLi4 60.7(3), Li3ꢀLi1ꢀLi4 57.3(3), Li1ꢀLi2ꢀLi3 60.4(3),
Li1ꢀLi2ꢀLi4 60.6(3), Li3ꢀLi2ꢀLi4 57.0(3), Li1ꢀLi3ꢀLi2 58.3(3),
Li1ꢀLi3ꢀLi4 61.2(3), Li2ꢀLi3ꢀLi4 61.0(3), Li1ꢀLi4ꢀLi2 58.7(3),
Li1ꢀLi4ꢀLi3 61.5(3), Li2ꢀLi4ꢀLi3 62.0(3), Li1ꢀO11ꢀC11 128.5(4),
O11ꢀC11ꢀC16 123.0(4), C11ꢀC16ꢀC17 123.9(4), C16ꢀC17ꢀN18
,
,
2.034(1) A, ZrꢀO31 2.026(1) A). The O11ꢀZrꢀO31 an-
gle amounts to 162.8(1)°, and the corresponding ZrꢀO
vectors are leaning away from the NMe2 ligands. The
ZrꢀNMe2 linkages exhibit bond lengths of 2.073(1) and
,
2.078(1) A and the ZrꢀN51 and ZrꢀN61 vectors com-
prise an angle of N51ꢀZrꢀN61=104.9(1)°. In contrast,
127.7(4),
O21ꢀC21ꢀC26 122.6(4), C21ꢀC26ꢀC27 125.5(4), C26ꢀC27ꢀN28
127.7(5), C27ꢀN28ꢀLi2 120.0(4), Li3ꢀO31ꢀC31 126.1(4),
O31ꢀC31ꢀC36 122.9(4), C31ꢀC36ꢀC37 125.1(4), C36ꢀC37ꢀN38
128.3(4), C37ꢀN38ꢀLi3 119.7(4), Li4ꢀO41ꢀC41 125.7(4),
C17ꢀN18ꢀLi1
121.5(4),
Li2ꢀO21ꢀC21
125.8(4),
O41ꢀC41ꢀC46 123.2(4), C41ꢀC46ꢀC47 124.8(4), C46ꢀC47ꢀN48
128.1(4), C47ꢀC48ꢀLi4 120.8(4).
(7b: l 7.79/163.5; 8b: 8.19/171.9, cf.: 1b: l 7.82/163.0).
The NMR spectra point to C2-symmetry of the systems
in solution. The chirality of the complexes 7 is evident
from the observation of a pair of diastereotopic iso-
propyl-CH3 1H NMR signals for 7a (l=1.08, 0.79, br.
s. at 298 K in CD2Cl2, 600 MHz), a total of six
cyclohexyl CH and CH2 13C NMR signals for 7b (at
l=61.7, 33.4, 32.4, 26.1, 25.7, and 25.5 ppm in
1
toluene-d8 at 208 K, 150 MHz), and a total of four H
NMR isopropyl doublets (l 1.41, 1.25, 1.14, 1.03, in
CD2Cl2 at 298 K, 600 MHz; 13C NMR signals at l
26.4, 26.3, 23.2, 22.4 ppm) for 7d. The latter spectral
appearance indicates frozen rotation about the
NꢀC(aryl) vector in 7d on the NMR time scale.
Scheme 1.

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
813
the ZrꢀN(imine) bond lengths are much longer at
,
,
2.434(1) A (ZrꢀN19) and 2.483(1) A (ZrꢀN39). The
corresponding N19ꢀZrꢀN39 angle amounts to 82.5(1)°,
whereas the bite angle inside the salicylaldiminato lig-
and of 7a is found at 76.3(1)° (O11ꢀZrꢀN19; 75.8(1)
O31ꢀZrꢀN39) (for additional values see Fig. 4 and
Table 1).
The bis[N-(2,6-diisopropylphenyl)salicylaldiminato]-
ZrCl2 complex 8d also exhibits a distorted octahedral
structure, but here the iminato nitrogen atoms are
oriented trans to each other. The N19ꢀZrꢀN1* angle
,
amounts to 177.0(2)°, and the ZrꢀN19 (2.346(3) A) and
ZrꢀN1* vectors are slightly leaning over towards the
,
chloride ligands (ZrꢀCl1 2.422(1) A, Cl1ꢀZrꢀCl2
96.3(1)°). Again, the geometry of the salicylaldiminato
ligand enforces the chelate angles to deviate markedly
from the ideal octahedral situation with N19ꢀZrꢀO11
being 77.8(1)°. Without this geometric restriction, the
remaining interligand angles around zirconium are all
around the expected octahedral values (N19ꢀZrꢀO11*:
104.4(1)°, O11ꢀZrꢀO11* 88.4(2)°, Cl1ꢀZrꢀO11*
90.4(1)°, Cl1ꢀZrꢀO11* 161.7(1)°). The ZrꢀO11
Fig. 3. Dynamic 13C NMR spectra of 8b (cyclohexyl resonances only;
in CD2Cl2, 150 MHz).
,
(1.980(2) A) bond in complex 8d is markedly shorter
than the zirconium-oxygen linkages in 7a and 7b, al-
though the corresponding bond angles at the oxygen
atoms are comparable (8d: ZrꢀO11ꢀC12 144.0(2)°; see
for a comparison: 7a 144.1(1)°, 144.6(1)°, 7b: 143.5(2)°,
144.0(2)°). Thus, there is a pronounced trans effect
operative at the octahedral zirconium complexes 7 and
8.
2.3. Bis(salicylaldiminato)titanium systems
A different method was used for the preparation of
the corresponding titanium complexes, because we have
observed that TiCl4 forms readily and selectively 1:2
complexes with a variety of salicylaldimines [21]. Thus,
the reaction of two molar equivalents of N-(2,6-diiso-
propylphenyl)salicylimine (1d) with titanium tetrachlo-
ride results in the clean formation of the corresponding
2:1 addition product 9d which was isolated in approxi-
mately 90% yield from dichloromethane.
The product 9d shows a single set of 1H and 13C
NMR signals for the two symmetry-equivalent ligands.
A single 1H NMR doublet (l 1.16, 3J=6.8 Hz) is
observed for the isopropyl methyl groups of 9d, which
indicates a non-chiral structure in solution and rapid
conformational equilibration. The aldimine ꢀCHꢁ
N(H)ꢀ resonances are observed at l 169 (13C) and l
8.05 (1H NMR). The latter signal is split into a doublet
(3J=16.1 Hz). This indicates that the aldimine nitrogen
atom in the adduct 9d is protonated. Consequently a
Fig. 4. A view of the molecular structure of 7a. Selected bond lengths
,
(A) and angles (°): ZrꢀO11 2.034(1), ZrꢀO31 2.026(1) ZrꢀN19
2.434(1), ZrꢀN39 2.483(1), ZrꢀN51 2.078(1), ZrꢀN61 2.073(1),
O11ꢀC12 1.325(2), C12ꢀC17 1.409(2), C17ꢀC18 1.452(2), C18ꢀN19
1.278(2), O31ꢀC32 1.325(2), C32ꢀC37 1.401(2), C37ꢀC38 1.449(2),
C38ꢀN39 1.286(2); O11ꢀZrꢀO31 162.8(1), O11ꢀZrꢀN19 76.3(1),
O11ꢀZrꢀN39 93.0(1), O11ꢀZrꢀN51 93.6(1), O11ꢀZrꢀN61 97.8(1),
O31ꢀZrꢀN19 89.1(1), O31ꢀZrꢀN39 75.8(1), O31ꢀZrꢀN51 94.2(1),
O31ꢀZrꢀN61 95.0(1), N19ꢀZrꢀN39 82.5(1), N19ꢀZrꢀN51 84.7(1),
N19ꢀZrꢀN61 169.2(1), N39ꢀZrꢀN51 163.8(1), N39ꢀZrꢀN61 88.8(4),
N51ꢀZrꢀN61 104.9(1), ZrꢀO11ꢀC12 144.1(1), O11ꢀC12ꢀC17 121.2(1),
C12ꢀC17ꢀC18 122.9(1), C17ꢀC18ꢀN19 127.6(1), C18ꢀN19ꢀZr
1
broad ꢁNHꢀ resonance is observed by H NMR spec-
126.9(1),
ZrꢀO31ꢀC32
144.6(1),
O31ꢀC32ꢀC37
120.4(1),
troscopy at l 13.7. The iminium salt NH infrared
C32ꢀC37ꢀC38 123.2(1), C37ꢀC38ꢀN39 128.6(1), C38ꢀN39ꢀZr
124.5(1).
band of complex 9d is observed at w˜ =3070 cm−1 as a

814
J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
Table 1
A comparison of selected structural data between the complexes 7a, 7b, 8d (M=Zr), 10c, and 10d (M=Ti) a
Compound
7a
7b
8d
10c
1.854(1)
2.223(2)
2.299(1)
10d
1.861(1)
2.223(1)
2.302(1)
88.5(1)
171.7(1)
82.5(1)
93.8(1)
MꢀO
2.030(1)
2.459(1)
2.076(1)
162.8(1)
82.5(1)
76.1(1)
104.9(1)
2.028(2)
2.436(2)
2.069(2)
157.9(1)
82.5(1)
76.3(1)
102.0(1)
1.980(2)
2.346(3)
2.422(2)
88.4(2)
177.0(2)
77.8(1)
96.3(1)
b
MꢀN
MꢀR c
OꢀMꢀO
NꢀMꢀN b
OꢀMꢀN b
RꢀMꢀR
165.1(1)
80.7(1)
81.7(1)
97.6(1)
a
,
Averaged bond lengths in A, angles in °.
b Aldiminato-nitrogen.
c R=NMe2 (7a, 7b); R=Cl (8a, 10c, 10d).
broad feature. The corresponding IR heterocarbonyl
stretching band is at 1635 cm−1 (Scheme 2).
Single crystals suited for the X-ray crystal structure
analysis of complex 9d were obtained from dichloro-
methane. The molecule contains a central TiCl4 core
the dynamic 1H NMR spectra at DG"rot. (330 K)=
16.390.3 kcal mol−1
.
Complex 10d was also characterized by X-ray diffrac-
tion. It shows a similar structure as the zirconium
analogue 8d (see Figs. 5 and 6). The aldiminato nitro-
gen atoms in 10d are also oriented trans to each other
in the distorted octahedral coordination environment at
the central titanium atom (for details see Figs. 7 and 8
and Table 1).
,
that is near to square-planar (TiꢀCl2 2.340(1) A, TiꢀCl1
,
2.373(1) A). The ClꢀTiꢀCl angles are close to 90°. In
the crystal, the molecules of 9d are C1-symmetric. The
salicyl–oxygen atoms are oriented trans to each other
Following these observations we have prepared the
related complex 10c in a one-pot procedure by treat-
ment of titanium tetrachloride with 2 equiv. of N-
phenylsalicylaldimine (1c) in dichloromethane in the
presence of triethylamine (2 equiv.). With loss of 2
equiv. of HCl the bis(N-phenylsalicylaldiminato)TiCl2
complex 10c was formed and isolated in \60% yield.
Single crystals of complex 10c were obtained from
toluene. The titanium complex 10c is also distorted
octahedral; it is C2-symmetric and thus chiral. In con-
,
at the central titanium atom (TiꢀO 1.895(1) A). The
adjacent ortho-phenylene ring system is found in a
coplanar orientation with the iminium cation function-
ality. In 9d the CꢁN bond length is 1.292(2) A (C8ꢀN9),
,
the C8ꢀN9ꢀC10 angle amounts to 122.2(2)°, and the
N9ꢀC8ꢀC7 angle is 127.6(2)° [22] (for a comparison,
the analogous angles in the zirconium complex 8d are
113.2(6)° (C18ꢀN19ꢀC20) and 128.3(3)° (N19ꢀC18ꢀ
,
C17), the CꢁN double length in 8d is 1.298(4) A
(C18ꢀN19)). The 2,6-diisopropylphenyl substituent at
nitrogen is significantly rotated relative to the plane of
the salicylaldiminium core (q C8ꢀN9ꢀC10ꢀC11
74.2(2)°).
Treatment of the dipolar adduct complex 9d with 2
molar equiv. of the base triethylamine resulted in clean
double deprotonation and elimination of two HꢀCl
units to yield the bis[N-(2,6-diisopropylphenyl)salicylal-
diminato]zirconium dichloride system 10d (ca. 60% iso-
1
lated). The H NMR spectrum of complex 10d shows
only a singlet for the aldiminato ꢀCHꢁNꢀ proton at l
8.41 (the corresponding 13C NMR resonance is at l
169.0 ppm). Complex 10d is chiral and the rotation
around the N-aryl linkage is frozen on the NMR time
1
scale. Thus it exhibits the H/13C NMR resonances of a
total of four diastereotopic methyl groups of the 2,6-di-
isopropyl moieties (1H: doublets at l 1.40, 1.25, 1.12,
1.11, at 298 K in dichloromethane-d2, 600 MHz; 13C:
25.3, 25.2, 23.3, 22.9, at 298 K, 150 MHz). The coales-
1
cence temperature of the two H NMR isopropyl sep-
tets (Dw in the slow exchange: 53 Hz) is at 330 K. The
NꢀC(aryl) rotational barrier of 10d was deduced from
Scheme 2.

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
815
,
Fig. 5. Molecular geometry of complex 7b. Selected bond lengths (A)
,
Fig. 6. Molecular structure of complex 8d. Selected bond lengths (A)
and angles (°): ZrꢀO11 2.024(2), ZrꢀO31 2.033(2) ZrꢀN19 2.423(2),
ZrꢀN39 2.448(2), ZrꢀN51 2.072(2), ZrꢀN61 2.065(2), O11ꢀC12
1.326(3), C12ꢀC17 1.401(4), C17ꢀC18 1.451(4), C18ꢀN19 1.285(4),
O31ꢀC32 1.329(3), C32ꢀC37 1.405(4), C37ꢀC38 1.446(4), C38ꢀN39
1.283(3); O11ꢀZrꢀO31 157.9(1), O11ꢀZrꢀN19 76.1(1), O11ꢀZrꢀN39
87.0(1), O11ꢀZrꢀN51 96.1(1), O11ꢀZrꢀN61 97.4(1), O31ꢀZrꢀN19
87.1(1), O31ꢀZrꢀN39 76.5(1), O31ꢀZrꢀN51 98.0(1), O31ꢀZrꢀN61
96.3(1), N19ꢀZrꢀN39 82.5(1), N19ꢀZrꢀN51 89.4(1), N19ꢀZrꢀN61
167.5(1), N39ꢀZrꢀN51 170.4(1), N39ꢀZrꢀN61 86.5(1), N51ꢀZrꢀN61
and angles (°): ZrꢀCl1 2.422(1), ZrꢀO11 1.980(2), ZrꢀN19 2.346(3),
O12ꢀC12 1.343(4), C12ꢀC17 1.384(5), C17ꢀC18 1.426(5), C18ꢀN19
1.298(4); Cl1ꢀZrꢀCl1* 96.3(1), Cl1ꢀZrꢀN19 93.2(1), Cl1ꢀZrꢀN19*
84.8(1), Cl1ꢀZrꢀO11 90.4(1), Cl1ꢀZrꢀO11* 161.7(1), Cl1*ꢀZrꢀN19
84.8(1),
Cl1*ꢀZrꢀN19*
93.2(1),
Cl1*ꢀZrꢀO11
161.7(1),
Cl1*ꢀZrꢀO11* 90.4(1), N19ꢀZrꢀN19* 177.0(2), N19ꢀZrꢀO11 77.8(1),
N19ꢀZrꢀO11* 104.4(1), N19*ꢀZrꢀO11 104.4(1), N19*ꢀZrꢀO11*
77.8(1), O11ꢀZrꢀO11* 88.4(2), ZrꢀO11ꢀC12 144.0(2), O11ꢀC12ꢀC17
119.5(3),
C12ꢀC17ꢀC18
123.5(3),
C17ꢀC18ꢀN19
128.3(3),
102.0(1),
C12ꢀC17ꢀC18 123.1(3), C17ꢀC18ꢀN19 127.2(3), C18ꢀN19ꢀZr
126.5(2), ZrꢀO31ꢀC32 144.0(2), O31ꢀC32ꢀC37 121.6(2),
ZrꢀO11ꢀC12
143.5(2),
O11ꢀC12ꢀC17
120.6(3),
C18ꢀN19ꢀZr 125.7(3).
C32ꢀC37ꢀC38 123.0(2), C37ꢀC38ꢀN39 127.7(2), C38ꢀN39ꢀZr
126.3(2).
trast to the related bis(salicylaldiminato)MCl2 com-
plexes 8d and 10d this titanium dichloride complex
(10c) features the oxygen atoms trans to each other at
the central metal atom. The TiꢀO1 bond length is
,
,
1.854(1) A, and the TiꢀN9 distance is 2.223(2) A. These
rather short bonds bring the ligand systems in the
titanium system in a closer contact to each other than
in the related Zr complexes. The Ti-O vectors in 10c are
again oriented away from the positions of the chloride
ligands (see Fig. 9 and Table 1). The OꢀTiꢀO* angle
amounts to 165.1(1)°. The TiꢀO1ꢀC2 angle is rather
large at 143.0(1)°. In 10c the aldiminato CꢁN bond
,
length amounts to 1.292(2) A (C8ꢀN9). The corre-
sponding bond angles TiꢀN9ꢀC8 (126.4(1)°) and
N9ꢀC8ꢀC7 (126.5(2)°) are in the typical range.
,
Fig. 7. Molecular structure of complex 9d. Selected bond lengths (A)
and angles (°): TiꢀO1 1.895(1), TiꢀCl1 2.373(1), TiꢀCl2 2.340(1),
O1ꢀC2 1.318(2), C2ꢀC7 1.412(3), C7ꢀC8 1.419(2), C8ꢀN9 1.292(2),
N9ꢀC10 1.447(2), N9ꢀH9 0.81(2), H9ꢀCl1* 2.53(2); O1ꢀTiꢀO1*
180.0, O1ꢀTiꢀCl1 92.4(1), O1ꢀTiꢀCl1* 87.6(1), O1ꢀTiꢀCl2 90.3(1),
O1ꢀTiꢀCl2* 89.7(1), Cl1ꢀTiꢀCl1* 180.0, Cl1ꢀTiꢀCl2 90.0(1),
Cl1ꢀTiꢀCl2* 90.0(1), Cl2ꢀTiꢀCl2* 180.0, TiꢀO1ꢀC2 149.9(1),
O1ꢀC2ꢀC7 118.9(2), C2ꢀC7ꢀC8 122.9(2), C7ꢀC8ꢀN9 127.6(2),
C8ꢀN9ꢀC10 122.2(2), N9ꢀH9...Cl1* 147(2).
It appears that the favored coordination geometry
(oxygens or aldiminato nitrogens trans to each other) is
controlled by a delicate balance of electronic and steric
effects. In the L2M(NMe2)2 series the trans-N situation
seems to be favored on electronic grounds as is appar-
ently the trans-O alternative in the L2ZrCl2 systems. On
going to the titanium series of complexes steric factors

816
J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
tally observable in an L2TiCl2 complex. The third alter-
native, featuring the C1-symmetric trans-O,N coor-
dination geometry was not observed so far.
2.4. Ethene polymerization reactions
Scouting ethene polymerization reactions were car-
ried out with the complexes 8d (M=Zr), 10c and 10d
(M=Ti), that all contain a cis-MeCl2 unit. In situ
activation of these systems was achieved by treatment
with a \1000fold excess of methylalumoxane [23]. The
systems tested showed only moderate ethene polymer-
ization activities (see Table 2), but a few trends became
visible. Exchange of the N-phenyl for the N-(2,6-diiso-
propylphenyl) substituent in the Ti series resulted in a
decrease of the catalyst activity. The Zr system, even in
the presence of this bulky substituent showed a higher
activity as compared to the Ti-catalyst system. It may
be that such catalysts might be suited for ethene poly-
merization at elevated temperatures. However, further
developments and modifications of the systems are
needed before new homogeneous Ziegler-type catalyst
systems based on bis(salicylaldiminato) Group 4 metal
halide complexes will find practical application.
,
Fig. 8. Molecular structure of complex 10d. Selected bond lengths (A)
and angles (°): TiꢀO1A 1.857(1), TiꢀO1B 1.864(1) TiꢀN9A 2.215(2),
TiꢀN9B 2.230(2), TiꢀCl1 2.304(1), TiꢀCl2 2.300(1), O1AꢀC2A
1.334(2), C2AꢀC7A 1.403(3), C7AꢀC8A 1.436(3), C8AꢀN9A
1.292(2), O1BꢀC2B 1.333(2), C2BꢀC7B 1.395(3), C7BꢀC8B 1.435(3),
C8BꢀN9B 1.292(2); O1AꢀTiꢀO1B 88.5(1), O1AꢀTiꢀN9A 82.6(1),
O1AꢀTiꢀN9B 104.5(1), O1AꢀTiꢀCl1 167.2(1), O1AꢀTiꢀCl2 89.5(1),
O1BꢀTiꢀN9A 102.4(1), O1BꢀTiꢀN9B 82.4(1), O1BꢀTiꢀCl1 91.1(1),
O1BꢀTiꢀCl2 166.4(1), N9AꢀTiꢀN9B 171.7(1), N9AꢀTiꢀCl1 85.0(1),
N9AꢀTiꢀCl2 90.7(1), N9BꢀTiꢀCl1 88.1(1), N9BꢀTiꢀCl2 85.2(4),
Cl1ꢀTiꢀCl2 93.8(1), TiꢀO1AꢀC2A 133.4(1), O1AꢀC2AꢀC7A 120.2(2),
C2AꢀC7AꢀC8A 121.8(2), C7AꢀC8AꢀN9A 127.2(2), C8AꢀN9AꢀTi
3. Experimental
All reactions were carried out under argon using
Schlenk-type glassware or in a glovebox. Solvents (in-
cluding the deuterated solvents used for NMR spec-
troscopy) were dried and distilled under argon prior to
use. NMR spectra were recorded on a Bruker AC 200
P NMR spectrometer (1H: 200 MHz, 13C: 50 MHz) at
298 K, on a Bruker AM 400 (1H: 400 MHz, 13C: 100
MHz) spectrometer at 298 K or on a Varian Unity Plus
600 NMR spectrometer (1H: 600 MHz, 13C: 150 MHz)
at variable temperature. Labeling of the NMR signals
in the experimental section is as depicted in formula
1, Schemes 1 and 2. Salicylaldimines 1a–d [7,8], the
reagents Zr(NMe2)4 (6) [24], [Cp2ZrCH3(THF)+-
(BPh4−)] (2) [25], and Zr(NMe2)2Cl2(dme) (5) [13] were
prepared according to literature procedures.
121.5(1),
TiꢀO1BꢀC2B
135.6(1),
O1BꢀC2BꢀC7B
119.6(2),
C2BꢀC7BꢀC8B 122.4(2), C7BꢀC8BꢀN9B 127.7(2), C8BꢀN9BꢀTi
121.3(1).
Table 2
Ethene polymerisation reactions with bis(N-arylsalicylaldiminato)
MCl2/MAO Ziegler-type catalyst systems a
Fig. 9. A view of the molecular geometry of 10c. Selected bond
,
lengths (A) and angles (°): TiꢀO1 1.854(1), TiꢀN9 2.223(2), TiꢀCl
cat.
T (°C)
mg/mmol cat.
Al/M
PE[g]
act b
2.299(1), O1ꢀC2 1.339(2), C2ꢀC7 1.399(3), C7ꢀC8 1.439(3), C8ꢀN9
1.292(2); O1ꢀTiꢀO1* 165.1(1), O1ꢀTiꢀN9 81.7(1), O1ꢀTiꢀN9*
87.0(1), O1ꢀTiꢀCl 93.7(1), O1ꢀTiꢀCl* 96.1(1), N9ꢀTiꢀN9* 80.7(1),
N9ꢀTiꢀCl 170.6(1), N9ꢀTiꢀCl* 91.0(1), ClꢀTiꢀCl* 97.6(1), TiꢀO1ꢀC2
143.0(1), O1ꢀC2ꢀC7 120.0(2), C2ꢀC7ꢀC8 122.1(2), C7ꢀC8ꢀN9
126.5(2), C8ꢀN9ꢀTi 126.4(1).
10c
10d
8d
60
60
60
80
14/27
15/22
18/22
18/22
1200
1500
1500
1500
1.18
0.56
2.96
3.56
22
13
67
81
8d
a Reactions carried out in toluene after MAO activation, all reac-
tions were run for 1 h.
seem to become determinant and override the electronic
control, now making the trans-O situation experimen-
b In g polymer/mmol [cat]·bar·h.

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
817
3.1. Bis(p5-cyclopentadienyl)(sN,sO-N-isopropyl-
salicylaldiminato)zirconium tetraphenylborate (3)
Calc. for C10H12NOLi (169.15): C, 71.01; H, 7.15; N,
8.28. Found: C, 71.28; H, 7.28; N, 7.87%. H NMR
1
(tetrahydrofuran-d8, 400.1 MHz, 298 K): l 8.08 (s, 1H,
3
To a suspension of [Cp2ZrCH3(THF)+(BPh4−)] (2)
(500 mg, 875 mmol) in dichloromethane (20 ml) was
added slowly at 0°C a solution of N-isopropylsalicyl-
aldimine (1a) (143 mg, 875 mmol) in dichloromethane
(10 ml). During the addition formation of a gas could
be observed and the color of the reaction mixture
turned yellow. After warming up to r.t. the reaction
mixture was stirred for 3 h. The solvent was removed
under reduced pressure and the residue was washed
twice with pentane (10 ml) and dried in vacuo. 3 was
obtained as a yellow solid, Yield: 541 mg (79%). M.p.
94°C. Anal. Calc. for C44H42NOZrBCl2·CH2Cl2
(787.79): C, 68.61; H, 5.63; N, 1.78. Found: C, 70.44;
H, 6.36; N, 1.62%. 1H NMR (dichloromethane-d2,
599.8 MHz, 298 K): l 8.19 (s, 1H, 7-H), 7.59 (t, 1H,
ArꢀCH), 6.73 (d, 1H, ArꢀCH), 6.37 (s, 10H, CpꢀH),
3.37 (sept., 1H, iPr-CH), 1.31 (d, 6H, iPr-CH3), the
other two aromatic signals of the salicylaldimine ligand
are covered by signals of the tetraphenylborate;
[BPh4]−: 7.40 (m, 8H, o-H), 7.07 (m, 8H, m-H), 6.92
(m, 4H, p-H); THF: 3.70 (m, 4H, a-H), 1.84 (m, 4H,
b-H). 13C NMR (dichloromethane-d2, 50 MHz, 298 K):
l 171.5 (C7), 163.0 (C1), 138.9 (C5), 136.1 (C3), 121.8
(C4), 119.0 (C6), 117.5 (CpꢀC), 115.5 (C2), 56.4 (iPr-
CH), 23.4 (iPr-CH3); [BPh4]−: 164.9, 136.7, 126.1,
122.2. X-ray crystal structure analysis of 3: formula
C44H42NOBZr·CH2Cl2, M=787.74, yellow crystal
0.35×0.30×0.20 mm, a=12.203(1), b=12.433(1),
7-H), 6.97–7.00 (m, 2H, 5-H, 3-H), 6.57 (d, JHH=8.2
3
Hz, 1H, 6-H), 6.28 (t, JHH=7.1 Hz, 1H, 4-H), 3.33
3
3
(sept, 1H, JHH=6.2 Hz, iPr-CH), 1.21 (d, JHH=6.5
Hz, 6H, iPr-CH3). 13C NMR (tetrahydrofuran-d8, 100.6
MHz, 298 K): l 165.3 (C7), 136.1 (C5), 133.8 (C3),
123.8 (C2), 123.4 (C6), 11.3 (C4), 62.7 (iPr-CH), 24.9
(iPr-CH3). X-ray crystal structure analysis of 4: for-
mula C10H12NOLi, M=169.15, light yellow crystal
0.15×0.15×0.10 mm, a=10.426(3), b=10.335(2),
3
,
,
c=19.271(6) A, i=104.40(2)°, V=2011.3(9) A ,
zcalc=1.117 g cm−3, v=5.53 cm−1, empirical absorp-
tion correction via „ scan data (0.9225T50.947),
Z=8, monoclinic, space group Pn (No. 7), u=1.54178
,
A, T=223 K, ꢀ/2q scans, 4218 reflections collected
(9h, −k, −l), [(sinq)/u]=0.62 A−1, 4218 indepen-
,
dent and 2702 observed reflections [I]2|(I)], 477
refined parameters, R=0.049, wR2=0.116, max resid-
ual electron density 0.17 (−0.24) e A−3, hydrogens
,
calculated and refined as riding atoms.
3.3. Bis(dimethylamido)bis(sN,sO-N-
isopropylsalicylaldiminato)zirconium (7a)
Method a: To a solution of Zr(NMe2)2Cl2(dme) (5)
(654 mg, 1.92 mmol) in ether (20 ml) was slowly added
at 0°C over 30 min a solution of N-isopropylsalicyl-
aldiminatolithium (4a) (650 mg, 3.84 mmol) in ether.
During the addition the color of the reaction mixture
turned orange and a white solid began to precipitate.
The reaction mixture was allowed to warm up to room
temperature, stirred for additional 2 h and filtered to
remove LiCl. The solvent of the clear filtrate was
removed under reduced pressure. The residue was
washed three times with pentane (10 ml) and dried in
vacuo. 7a was obtained as an orange solid. Yield: 896
mg (83%). M.p. 84°C. Anal. Calc. for C24H36N4O2Zr
(503.80): C, 57.22; H, 7.20; N, 11.12. Found: C, 57.33;
H, 7.48; N, 10.72%. 1H NMR (dichloromethane-d2,
599.8 MHz, 298 K): l 8.24 (s, 2H, 7-H), 7.41 (ddd,
,
c=13.916(1) A, h=109.84(1), i=91.19(1), k=
3
102.51(1)°, V=1928.6(3) A , zcalc=1.356 g cm−3, v=
,
4.59 cm−1, empirical absorption correction via SORTAV
(
(0.8565T50.914), Z=2, triclinic, space group P1
,
(No. 2), u=0.71073 A, T=198 K, ꢀ and € scans,
26373 reflections collected (9h, 9k, 9l), [(sinq)/u]=
0.71 A−1, 11448 independent (Rint=0.042) and 9913
,
observed reflections [I]2 |(I)], 462 refined parameters,
R=0.038, wR2=0.077, max. residual electron density
0.47 (−0.68) e A−3, hydrogens calculated and refined
,
as riding atoms.
3
4
3JHH=9.0 Hz, JHH=7.2 Hz, JHH=1.9 Hz, 2H, 5-H),
3.2. N-Isopropylsalicylaldiminatolithium (4a)
7.32–7.30 (m, 2H, 3-H), 6.93–6.91 (m, 2H, 6-H), 6.83
3
3
4
(ddd, JHH=8.4 Hz, JHH=7.2 Hz, JHH=1.1 Hz, 2H,
3
4
To a stirred solution of N-isopropylsalicylaldimine
(1a) (0.50 g, 3.05 mmol) in toluene (20 ml) was slowly
added at 0°C a solution of n-butyllithium (1.74 ml, 3.05
mmol, 1.77 M in hexane). During the addition the color
of the reaction solution changed from yellow to color-
less and a white solid started to precipitate. The reac-
tion mixture was allowed to warm to room
temperature. After stirring for additional 2 h the reac-
tion mixture was concentrated (10 ml) and a white solid
could be isolated by filtration. The product was charac-
terized as 4a. M.p. 95°C. Yield: 0.43 g (82%). Anal.
4-H), 3.95 (dsept, JHH=6.7 Hz, JHH=0.8 Hz, 2H,
iPr-CH), 2.88 (s, 12H, N(CH3)2), 1.08, 0.79 (br s, 6H,
iPr-CH3). 13C NMR (dichloromethane-d2, 150.8 MHz,
298 K): d 163.8 (C7), 161.9 (C1), 134.6 (C3), 134.4 (C5),
123.6 (C2), 120.5 (C6), 117.9 (C4), 55.5 (iPr-CH), 45.5
(N(CH3)2), 21.2 (br, iPr-CH3).
Method b: To a solution of Zr(NMe2)4 (6) (500 mg,
1.87 mmol) in toluene (20 ml) was slowly added at 0°C
a solution of N-isopropylsalicylaldimine (1a) (609 mg,
3.74 mmol). After warming up to room temperature the
orange reaction mixture was stirred for 2 h and NMe2H

818
J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
orange reaction mixture was stirred for 2 h and NMe2H
was allowed to escape via an oil bubbler. The solvent
was removed under reduced pressure. The residue was
washed twice with pentane (10 ml) and dried in vacuo.
7a was obtained as an orange solid. Yield: 744 mg
(79%). X-ray crystal structure analysis of 7a: formula
C24H36N4O2Zr, M=503.79, yellow crystal 0.30×
0.20×0.20 mm, a=9.644(1), b=10.203(1), c=
method b. Scale: Zr(NMe2)4 (6) (600 mg, 2.24 mmol),
N-2,6-diisopropylphenylsalicylaldimine (1d) (911 mg,
4.48 mmol). The desired compound 7d was isolated as
a yellow solid in 76% yield (1.25 g). 1H NMR
(dichloromethane-d2, 599.8 MHz, 298 K): l 8.19 (s, 2H,
3
3
4
7-H), 7.37 (ddd, JHH=8.7 Hz, JHH=6.9 Hz, JHH
=
3
4
1.8 Hz, 2H, 5-H), 7.29 (dd, JHH=7.8 Hz, JHH=1.7
3
Hz, 2H, 3-H), 7.26 (t, JHH=4.6 Hz, 2H, Ar-H), 7.19–
3
,
13.091(1) A, h=80.97(1), i=77.93(1), k=88.25(1)°,
7.20 (m, 8H, Ar-H), 6.71 (t, JHH=7.3 Hz, 2H, 4-H),
3
V=1244.0(2) A , zcalc=1.345 g cm−3, v=4.68 cm−1
,
6.61 (d, 3JHH=8.4 Hz, 2H, 6-H), 3.97, 3.17 (sept,
3JHH=6.8 Hz, 2H, iPr-CH), 2.90 (br s, 12H, N(CH3)2),
,
empirical absorption correction via SORTAV (0.8725
3
(
T50.912), Z=2, triclinic, space group P1 (No. 2),
1.41, 1.25, 1.14, 1.03 (d, JHH=6.8 Hz, 3H, iPr-CH3).
u=0.71073 A, T=198 K, ꢀ and € scans, 16773 reflec-
13C NMR (dichloromethane-d2, 150.8 MHz, 298 K): l
171.9 (C7), 165.5 (C1), 150.8 (Ar-C), 141.7, 141.1 (Ar-
C), 136.4 (C5), 135.9 (C3), 126.4, 123.4 (Ar-C), 123.9
(Ar-C), 121.1 (C2), 120.5 (C6), 116.6 (C4), 41.6
(N(CH3)2), 27.9, 27.7 (iPr-CH), 26.4, 26.3, 23.2, 22.4
(iPr-CH3).
,
−1
,
tions collected (9h, 9k, 9l), [(sinq)/u]=0.71 A
,
7503 independent (Rint=0.036) and 6836 observed
reflections [I]2|(I)], 288 refined parameters, R=
0.028, wR2=0.065, max residual electron density 0.36
(−0.53) e A−3, hydrogens calculated and refined as
,
riding atoms.
3.6. Dichlorobis(sN,sO-N-cyclo-
hexylsalicylaldiminato)zirconium (8b)
3.4. Bis(dimethylamido)bis(sN,sO-N-
cyclohexylsalicylaldiminato)zirconium (7b)
A stirred solution of bis(dimethylamido)bis(kN,kO-
N-cyclohexylsalicylaldiminato)zirconium (7b) (500 mg,
856 mmol) in dichloromethane (30 ml) was treated with
Me3SiCl (272 ml, 233 mg, 2.14 mmol). During the
addition the initially yellow reaction mixture lost its
color. It was stirred for additional 4 h at room temper-
ature, afterwards concentrated (10 ml) under reduced
pressure and cooled to −20°C. Filtration afforded 8b
as colorless crystals. Yield: 340 mg (69%). M.p. 87°C.
Anal. Calc. for C26H32N2O2ZrCl2·CH2Cl2 (651.61): C,
49.77; H, 5.26; N, 4.30. Found: C, 47.33; H, 5.07; N,
Procedure see method b. Scale: Zr(NMe2)4 (6) (600
mg, 2.24 mmol), N-cyclohexylsalicylaldimine (1b) (911
mg, 4.48 mmol). 7b was obtained as a light orange solid
in 83% yield (1.09 g). M.p. 132°C. Anal. Calc. for
C30H44N4O2Zr (583.9): C, 61.71; H, 7.60; N, 9.59.
Found: C, 61.57; H, 7.78; N, 9.01%. 1H NMR (toluene-
d8, 599.8 MHz, 208 K): l 7.79 (s, 2H, 7-H), 7.21 (t,
3
3JHH=7.7 Hz, 2H, 5-H), 7.10 (d, JHH=8.3 Hz, 2H,
3
3
6-H), 6.94 (d, JHH=7.1 Hz, 2H, 3-H), 6.75 (t, JHH
=
7.3 Hz, 2H, 4-H), 3.71 (m, 2H, cyclohexyl-H), 3.46 (s,
12H, N(CH3)2), 1.86–1.84, 1.62–1.61, 1.44–1.42, 1.25–
1.21, 0.86–0.80 (each m, 4H, cyclohexyl-H). 13C NMR
(toluene-d8, 150.8 MHz, 208 K): l 163.5 (C7), 161.5
(C1), 137.4 (C5), 134.3 (C3), 123.4 (C2), 120.7 (C6),
117.7 (C4), 61.7 (cyclohexyl-C), 45.2 (N(CH3)2), 33.4,
32.4, 26.1, 25.7, 25.5 (cyclohexyl-C). X-ray crystal
structure analysis of 7b: formula C30H44N4O2Zr, M=
583.91, yellow crystal 0.20×0.10×0.05 mm, a=
1
3.97%. H NMR (dichloromethane-d2, 150.8 MHz, 208
3
K): l 8.19 (s, 2H, 7-H), 7.52 (t, JHH=7.4 Hz, 2H,
3
3
5-H), 7.34 (d, JHH=2H, 3-H), 7.03 (d, JHH=8.3 Hz,
3
2H, 6-H), 7.00 (t, JHH=7.5 Hz, 4-H), 3.83, 2.07–2.05,
1.71–1.68, 1.50–1.48, 1.31–1.29, 1.27–1.23, 1.06–1.02,
1.02–1.00, 0.98–0.95, 0.90–0.86, 0.14–0.11 (m, 2H,
cyclohexyl-H). 13C NMR (dichloromethane-d2, 150.8
MHz, 208 K): l 166.7 (C7), 157.8 (C1), 135.7 (C5),
134.0 (C3), 122.6 (C2), 120.7 (C4), 118.0 (C6), 62.5,
33.8, 31.6, 35.4, 24.8, 24.7 (cyclohexyl-C).
,
17.863(1), b=16.678(1), c=10.134(1) A, i=91.62(1)°,
3
V=3017.9(4) A , zcalc=1.285 g cm−3, v=3.96 cm−1
,
,
empirical absorption correction via SORTAV (0.9255
T50.981), Z=4, monoclinic, space group P21/c (No.
3.7. Dichlorobis(sN,sO-N-2,6-diisopropyl-
phenylsalicylaldiminato)zirconium (8d)
,
14), u=0.71073 A, T=198 K, ꢀ and € scans, 15860
reflections collected (9h, 9k, 9l), [(sinq)/u]=0.62
,
A
−1, 6076 independent (Rint=0.045) and 4600 ob-
Procedure analogous to the preparation of com-
pound 8b. Scale: Bis(dimethylamido)bis(kN,kO-N-2,6-
diisopropylphenylsalicylaldiminato)zirconium (7d) (500
mg, 675 mmol), Me3SiCl (214 ml, 183 mg, 1.69 mmol).
Crystallization from dichloromethane afforded 8d as
light yellow crystals in 65% yield (317 mg). M.p. 258°C.
Anal. Calc. for C38H44N2O2ZrCl2·CH2Cl2 (807.80): C,
58.60; H, 5.74; N, 3.42. Found: C, 58.82; H, 6.03; N,
served reflections [I]2|(I)], 338 refined parameters,
R=0.042, wR2=0.079, max residual electron density
0.39 (−0.43) e A−3, hydrogens calculated and refined
,
as riding atoms.
3.5. Bis(dimethylamido)bis(sN,sO-N-2,6-
diisopropylphenylsalicylaldiminato)-zirconium (7d)
1
Procedure analogous to the preparation of 7a,
3.63%. H NMR (toluene-d8, 599.8 MHz, 298 K): l

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
819
3
,
,
8.03 (s, 2H, 7-H), 7.10–7.04 (m, 6H, Ar-H), 7.02 (t, 2H,
14.027(1) A, i=92.27(1)°, V=1892.7(3) A , zcalc
=
1.320 g cm−3, v=5.43 cm−1, no absorption correction
(0.8545T50.923), Z=2, monoclinic, space group
P21/n (No. 14), u=0.71073 A, T=198 K, ꢀ and €
5-H), 6.78 (dd, 3JHH=7.9 Hz, 4JHH=1.8 Hz, 2H, 3-H),
3
3
6.70 (d, JHH=8.3 Hz, 2H, 6-H), 6.46 (pt, JHH=7.8
Hz, 2H, 4-H), 3.66, 3.56 (sept, 3JHH=6.7 Hz, 2H,
iPr-CH), 1.46, 1.39, 1.07, 0.96 (d, JHH=6.8 Hz, 6H,
,
3
scans, 8077 reflections collected (9h, 9k, 9l),
[(sinq)/u]=0.65 A−1, 4351 independent (Rint=0.027)
iPr-CH3). 13C NMR (toluene-d8, 150.8 MHz, 298 K): l
171.7 (C7), 161.1 (C1), 151, 141.3, 140.5 (Ar-C), 136.8
(C5), 135.0 (C3), 127.1, 124.3, 123.0 (Ar-C), 121.8 (C2),
119.6 (C4), 118.3 (C6), 28.4, 27.9 (iPr-CH), 25.0, 24.8,
23.0, 23.1 (iPr-CH3). X-ray crystal structure analysis of
8d: formula C38H44N2O2Cl2Zr·CH2Cl2, M=807.80, yel-
,
and 3438 observed reflections [I]2|(I)], 221 refined
parameters, R=0.039, wR2=0.093, max residual elec-
tron density 0.37 (−0.28) e A−3, hydrogen at N9 from
,
difference Fourier map, others calculated and all
refined as riding atoms.
low crystal 0.40×0.30×0.10 mm, a=13.722(1), c=
3
18.589(1) A, V=3031.2(5) A , zcalc=1.328 g cm−3
,
3.9. Dichlorobis(sN,sO-N-2,6-diisopropyl-
phenylsalicylaldiminato)titanium (10d)
,
,
v=5.70 cm−1, empirical absorption correction via „
scan data (0.8045T50.945), Z=3, trigonal, space
A
solution of tetrachlorobis(kN,kO-N-2,6-diiso-
,
group P3121(No. 152), u=0.71073 A, T=223 K, ꢀ/2q
propylphenylsalicylaldiminium)titanium (9d) (1.50 g,
2.00 mmol) in dichloromethane (50 ml) was treated
with NEt3 (588 ml, 405 mg, 4.00 mmol). The reaction
mixture was stirred 4 h at r.t. and the solvent was
removed under reduced pressure. Toluene (100 ml) was
added to the residue and the mixture was filtered to
remove NH4Cl. The solvent of the clear filtrate was
removed under reduced pressure and the remaining
solid was washed twice with pentane (10 ml). The
product 10d was isolated as an orange solid. Yield: 856
scans, 3381 reflections collected (+h, 9k, −l),
[(sinq)/u]=0.62 A−1, 3312 independent (Rint=0.042)
,
and 2490 observed reflections [I]2|(I)], 232 refined
parameters, R=0.035, wR2=0.077, max. residual elec-
tron density 0.22 (−0.22) e A−3, Flack Parameter
,
−0.04(6), hydrogens calculated and refined as riding
atoms.
3.8. Tetrachlorobis(sN,sO-N-2,6-diisopropyl-
phenylsalicylaldiminium)titanium (9d)
mg
(63%).
M.p.
272°C.
Anal.
Calc.
for
C38H44N2O2Cl2Ti (679.59): C, 67.16; H, 6.53; N, 4.12.
Found: C, 66.16; H, 6.54; N, 3.78%. 1H NMR
(dichloromethane-d2, 599.8 MHz, 298 K): l 8.41 (s, 2H,
To a stirred solution of TiCl4 (500 mg, 2.64 mmol) in
dichloromethane (30 ml) was added slowly a solution of
N-2,6-diisopropylphenylsalicylaldimine (1d) (1.48 g,
5.27 mmol) in dichloromethane (20 ml). During the
addition the color of the reaction mixture turned into
deep purple. After stirring for 2 h at room temperature
the solvent was removed under reduced pressure. The
residue was washed twice with pentane (10 ml) and
dried in vacuo. 9d was obtained as a red solid. Yield:
1.80 g (91%). M.p. 273°C (dec.). Anal. Calc. for
C38H46N2O2Cl4Ti·CH2Cl2 (837.44): C, 55.94; H, 5.78;
3
3
4
7-H), 7.64 (ddd, JHH=8.4 Hz, JHH=7.3 Hz, JHH
=
3
4
1.7 Hz, 2H, 5-H), 7.58 (dd, JHH=7.8 Hz, JHH=1.7
3
Hz, 2H, 3-H), 7.29 (t, JHH=7.7 Hz, 2H, Ar-H), 7.24
(dd, 3JHH=7.7 Hz, 4JHH=1.6 Hz, 2H, Ar-H), 7.20 (dd,
3JHH=7.6 Hz, 4JHH=7.6 Hz, 2H, Ar-H), 7.12 (dt,
3JHH=7.5 Hz, 4JHH=1.1 Hz, 2H, 4-H), 6.75 (d,
3
3JHH=8.4 Hz, 2H, 6-H), 3.56, 3.54 (sept, JHH=6.8
3
Hz, 2H, iPr-CH), 1.40, 1.25, 1.12, 1.11 (d, JHH=6.8
Hz, 6H, iPr-CH3). 13C NMR (dichloromethane-d2,
150.8 MHz, 298 K): l 169.0 (C7), 163.6 (C1), 153.0
(C8), 141.4, 141.0 (Ar-C), 136.8 (C5), 134.8 (C3), 127.2,
124.2 (Ar-C), 123.0 (C2), 122.8 (Ar-C), 121.7 (C4),
115.3 (C6), 28.0, 27.8 (iPr-CH), 25.3, 25.2, 23.3, 22.9
(iPr-CH3). IR (KBr): w˜ =3069 (w), 2953 (s), 2867 (m),
1601 (vs), 1550 (vs), 1474 (m), 1438 (m), 1378 (m), 1331
(w), 1283 (vs), 1165 (w), 1154 (m), 927 (m), 858 (s), 794
(s), 703 (w), 628 (s) cm−1. X-ray crystal structure
analysis of 10d: formula C38H44N2O2Cl2Ti·1.5 C7H8,
M=817.75, red crystal 0.35×0.20×0.10 mm, a=
1
N, 3.34. Found: C, 55.66; H, 6.47; N, 1.95%. H NMR
(dichloromethane-d2, 599.8 MHz, 298 K): l 13.72 (br s,
3
2H, NH), 8.15 (d, JHH=8.66 Hz, 2H, 6-H), 8.05 (d,
3
3JHH=16.1 Hz, 2H, 7-H), 7.83 (t, JHH=7.9 Hz, 2H,
3
3
5-H), 7.46 (d, JHH=7.8 Hz, 2H, 3-H), 7.45 (t, JHH
=
3
7.9 Hz, 2H, Ar-H), 7.28 (d, JHH=7.8 Hz, 4H, Ar-H),
7.09 (t, 3JHH=7.9 Hz, 2H, 4-H), 3.33 (s, 3JHH=6.7 Hz,
3
4H, iPr-CH), 1.16 (d, JHH=6.8 Hz, 24H, iPr-CH3).
13C NMR (dichloromethane-d2, 150.8 MHz, 298 K): l
171.0 (C1), 169.0 (C7), 144.6 (Ar-C), 141.0 (C5), 135.8
(C3), 134.1 (Ar-C), 130.6 (Ar-C), 125.5 (C6), 124.4
(Ar-C), 121.0 (C4), 114.8 (C2), 28.6 (iPr-CH), 23.7 (br,
iPr-CH3). IR (KBr): w˜ =3070 (br), 2964 (vs), 1635 (vs),
1549 (s), 1469 (vs), 1386 (m), 1332 (w), 1283 (vs), 1144
(m), 1098 (w), 916 (m), 798 (s), 753 (m), 613 (s), 535 (m)
cm−1. X-ray crystal structure analysis of 9d: formula
C38H46N2O2Cl4Ti, M=752.47, red crystal 0.30×
0.20×0.15 mm, a=9.715(1), b=13.900(1), c=
,
10.344(1), b=14.462(1), c=16.013(1) A, h=89.12(1),
3
,
i=72.80(1), k=76.56(1)°, V=2222.0(3) A , zcalc
=
1.222 g cm−3, v=3.52 cm−1, empirical absorption
correction via SORTAV (0.8875T50.966), Z=2, tri-
(
,
clinic, space group P1 (No. 2), u=0.71073 A, T=198
K, ꢀ and € scans, 17283 reflections collected (9h,
9k, 9l), [(sinq)/u]=0.65 A−1, 10179 independent
(Rint=0.035) and 7427 observed reflections [I]2|(I)],
,

820
J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
548 refined parameters, R=0.047, wR2=0.095, max.
SORTAV, structure solution SHELXS-97, structure refine-
ment SHELXL-97, graphics SCHAKAL [26].
residual electron density 0.60 (−0.37) e A−3, solvent
,
heavily disordered and some parts refined with isotropic
thermal displacement parameters, hydrogens calculated
and refined as riding atoms.
3.11. Ethylene polymerization reactions
General procedure: An 1-l glass autoclave was
charged with toluene (300 ml) and a solution of methy-
lalumoxane (MAO) (0.033 mol, 10.5%) in toluene (20
ml). The mixture was stirred (800 rpm), thermostated at
the desired temperature and saturated with the gaseous
monomer at 2 bar. The polymerization reaction was
started by the injection of a solution of the catalyst 8d,
10c or 10d (22–27 mmol) in toluene (5 ml). After a
given time the reaction was stopped by the addition of
methanol (15 ml), acidified with HCl (aq, 2 N, 15 ml).
The polymer was isolated by filtration, washed with
HCl (aq, 6 N, 50 ml), water (200 ml), and acetone (30
ml), and dried in vacuo to constant weight (Table 2).
3.10. Dichlorobis(sN,sO-N-phenylsalicylaldiminato)-
titanium (10c)
To a stirred solution of TiCl4 (500 mg, 2.64 mmol) in
dichloromethane (30 ml) was added slowly a solution of
N-phenylsalicylaldimine (1c) (1.48 g, 5.27 mmol) in
dichloromethane (20 ml). The purple reaction mixture
was stirred for 10 min and NEt3 (735 ml, 534 mg, 5.27
mmol) was added. After stirring for 2 h at room
temperature the solvent was removed under reduced
pressure. Toluene (100 ml) was added to the residue
and the mixture was filtered to remove NH4Cl. The
clear solution was concentrated (10 ml). 10c was al-
lowed to crystallize at −20°C. and was obtained as
purple crystals. Yield: 891 mg (66%). M.p. 257°C. Anal.
Calc. for C26H20N2O2Cl2Ti·C7H8 (603.40): C, 65.59; H,
4. Supplementary material
1
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data
Centre as supplementary publication. Copies of the
data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (fax: int. code +44(1223)336 033, e-mail:
deposit@ccdc.cam.ac.uk).
4.68; N, 4.64. Found: C, 64.97; H, 4.50; N, 4.66%. H
NMR (dichloromethane-d2, 599.8 MHz, 188 K): l 8.01
(s, 2H, 7-H), 7.68, 7.28 (br s, 2H, Ar-H), 7.22–7.20 (m,
3
2H, toluene), 7.19 (d, JHH=7.5 Hz, 2H, 3-H), 7.14 (t,
3
2H, JHH=8.2 Hz, 5-H), 7.13–7.12 (m, 3H, Tol-H),
3
3
6.93 (t, JHH=7.4 Hz, 2H, Ar-H), 6.81 (t, JHH=7.4
Hz, 2H, 4-H), 6.81, 6.49 (br s, 2H, Ar-H), 6.12 (d,
3JHH=8.2 Hz, 2H, 6-H), 2.27 (s, 3H, toluene). 13C
NMR (dichloromethane-d2, 150.8 MHz, 188 K): l
165.1 (C7), 159.3 (C1), 151.7 (Ar-C), 137.5 (toluene),
136.2 (C5), 134.1 (C3), 128.4 (toluene), 127.8 (br, Ar-
C), 127.7 (toluene), 127.3, 126.5 (Ar-C), 124.7 (toluene),
124.6 (br, Ar-C), 123.1 (C2), 121.4 (C4), 121.3 (br,
Ar-C), 115.7 (C6), 20.9 (toluene). IR (KBr): w˜ =3051
(w), 2927 (w), 1602 (vs), 1552 (s), 1473 (m), 1444 (m),
1383 (m), 1279 (s), 1153 (m), 1026 (w), 911 (m), 807
(m), 698 (s), 639 (s), 575 (w) cm−1. X-ray crystal
structure analysis of 10c: formula C26H20N2O2Cl2Ti·
Acknowledgements
Financial support by the Fonds der Chemischen In-
dustrie and the Deutsche Forschungsgemeinschaft is
gratefully acknowledged. P.S. thanks the Finnish
Academy for financial support.
References
C6H6, M=589.35, red crystal 0.30×0.25×0.20 mm,
3
,
,
a=13.170(1), c=16.586(1) A, V=2876.8(4) A ,
zcalc=1.361 g cm−3, v=5.15 cm−1, empirical absorp-
tion correction via SORTAV (0.8615T50.904), Z=4,
[1] H.H. Brintzinger, D. Fischer, R. Mu¨lhaupt, B. Rieger, R.M.
Waymouth, Angew. Chem. 107 (1995) 1255; Angew. Chem. Int.
Ed. Engl. 34 (1995) 1143.
[2] (a) C.M. Killian, D.J. Tempel, L.K. Johnson, M. Brookhart, J.
Am. Chem. Soc. 118 (1996) 11664. C.M. Killian, L.K. Johnson,
M. Brookhart, Organometallics 16 (1997) 2005. B.L. Small, M.
Brookhart, A.M.A. Bennett, J. Am. Chem. Soc. 120 (1998) 4049,
and references cited in these articles. (b) G.J.P. Britousek, V.C.
Gibson, D.F. Wass, Angew. Chem. 111 (1999) 448; Angew.
Chem. Int. Ed. Engl. 38 (1999) 428.
,
tetragonal, space group P42/n (No. 86), u=0.71073 A,
T=198 K, ꢀ and € scans, 10244 reflections collected
(9h, 9k, 9l), [(sinq)/u]=0.71 A−1, 4332 indepen-
,
dent (Rint=0.042) and 2936 observed reflections [I]
2|(I)], 177 refined parameters, R=0.048, wR2=0.092,
−3
,
max residual electron density 0.38 (−0.42) e A
,
hydrogens calculated and refined as riding atoms. Data
sets were collected with Nonius CAD4, MACH3 or
KappaCCD diffractometers, using sealed tube or ro-
tating anode generator. Programs used: data collec-
[3] W.E. Piers, P.J. Shapiro, E.E. Bunel, J.E. Bercaw, Synlett, 2
(1990) 74. J.C. 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 416815-A2, 1991 (Dow Chemical). J.M. Canich,
Eur. Patent Appl. EP 429436-A1, 1991 (Exxon Chemical). J.M.
Canich, G.G. Hlatky, H.W. Turner, PCT Appl. WO 92-00333,
1992. P.J. Shapiro, W.D. Cotter, W.P. Schaefer, J.A. Labinger,
tion Express or Collect, data reduction MO
lEN or
DENZO-SMN, absorption correction for CCD data

J. Strauch et al. / Inorganica Chimica Acta 300–302 (2000) 810–821
821
J.E. Bercaw, J. Am. Chem. Soc. 116 (1994) 4623. L. Duda, G.
Erker, R. Fro¨hlich, F. Zippel, Eur. J. Inorg. Chem. (1998) 1153.
[4] (a) J.D. Scollard, D.H. McConville, J. Am. Chem. Soc. 118
(1996) 10008. J.D. Scollard, D.H. McConville, S.J. Rettig,
Organometallics 16 (1997) 1810. T.H. Warren, R.R. Schrock,
W.M. Davis, Organometallics 15 (1996) 562. D.D. Graf, R.R.
Schrock, W.M. Davis, R. Stumpf, Organometallics 18 (1999)
843. B. Tsuie, D.C. Swenson, R.F. Jordan, J.L. Petersen,
Organometallics 16 (1997) 1392. (b) D. Walther, R. Fischer, H.
Go¨rls, J. Koch, B. Schweder, J. Organomet. Chem. 508 (1996)
13. J.R. Hagadorn, J. Arnold, Angew. Chem. 110 (1998) 1813;
Angew. Chem., Int. Ed. Engl. 37 (1998) 1729. V. Volkis, M.
Shulinson, C. Averbuj, A. Lisovskii, F.T. Edelmann, M.S. Eisen,
Organometallics 17 (1998) 3155. L.R. Sita, J.R. Babcock,
Organometallics 17 (1998) 5228. N. Etkin, C.M. Ong, D.W.
Stephan, Organometallics 17 (1998) 3656. C. Averbuj, E. Tish,
M.S. Eisen, J. Am. Chem. Soc. 120 (1998) 8640.
[5] For recent use of salicylaldiminato ligands in catalysis see e.g.: S.
Chang, L. Jones II, C. Wang, L.M. Henling, R.H. Grubbs,
Organometallics 17 (1998) 3460. Y.N. Belokon, S. Caveda-Ce-
pas, B. Green, N.S. Ikonnikov, V.N. Khrustalev, V.I. Tararov,
M. Tasinazzo, G.I. Timofeeva, L.V. Yashkina, J. Am. Chem.
Soc. 121 (1999) 3968. T.M. Ovitt, G.W. Coates, J. Am. Chem.
Soc. 121 (1999) 4072. C.A. Krueger, K.W. Kuntz, C.D. Dzierba,
W.G. Wirschun, J.D. Gleason, M.L. Snapper, A.H. Hoveyda, J.
Am. Chem. Soc. 121 (1999) 4284. See also: E. Solari, C. Maltese,
F. Franceschi, C. Floriani, A. Chiesi-Villa, C. Rizzoli, J. Chem.
Soc., Dalton Trans. (1997) 2903. Review: L. Canali, D.C. Sher-
rington, Chem. Soc. Rev. 28 (1999) 85.
[14] S. Brenner, R. Kempe, P. Arndt, Z. Anorg. Allg. Chem. 621
(1995) 2021.
[15] J.N. Christopher, R.F. Jordan, J.L. Petersen, V.G. Young,
Organometallics 16 (1997) 3044. G.M. Diamond, R.F. Jordan,
J.L. Petersen, Organometallics 15 (1996) 4030. G.M. Diamond,
R.F. Jordan, J.L. Petersen, J. Am. Chem. Soc. 118 (1996) 8024,
G.M. Diamond, S. Rodewald, R.F. Jordan, Organometallics 14
(1995) 5.
[16] J.N. Christopher, G.M. Diamond, R.F. Jordan, J.L. Petersen,
Organometallics 15 (1996) 4038. G.M. Diamond, R.F. Jordan,
J.L. Petersen, Organometallics 15 (1996) 4045.
[17] S. Sternhell, Rotation about Single Bonds in Organic Molecules,
in: L.M. Jackman, F.A. Cotton (Eds.), Dynamic Nuclear Mag-
netic Resonance Spectroscopy, Academic Press, New York,
1975, pp. 163–201.
[18] X. Bei, D.C. Swenson, R.F. Jordan, Organometallics, 16 (1997)
3282. T. Tsukahara, D.C. Swenson, R.F. Jordan, Organometal-
lics 16 (1997) 3303. I. Kim, Y. Nishihara, R.F. Jordan, R.D.
Rogers, A.L. Rheingold, G.P.A. Yap, Organometallics 16 (1997)
3314. P.B. Hitchcock, M.F. Lappert, D.S. Liu, J. Chem. Soc.,
Chem. Commun. (1994) 2637. M.F. Lappert, D.-S. Liu, J.
Organomet. Chem. 500 (1995) 203. B.-J. Deelman, P.B. Hitch-
cock, M.F. Lappert, H.-K. Lee, W.-P. Leung, J. Organomet.
Chem. 513 (1996) 281. M. Rahim, N.J. Taylor, S. Xin, S.
Collins, Organometallics 17 (1998) 1315. J.P. Corden, W. Erring-
ton, P. Moore, M.G.H. Wallbridge, J. Chem. Soc., Chem.
Commun. (1999) 323. K. Klaß, L. Duda, N. Kleigrewe, G.
Erker, R. Fro¨hlich, E. Wegelius, Eur. J. Inorg. Chem. (1999) 11.
Review: U. Knof, A. v. Zelewsky, Angew. Chem. 111 (1999) 312;
Angew. Chem., Int. Ed. Engl. 38 (1999) 302.
[6] T. Repo, M. Klinga, P. Pietiko¨inen, M. Leskela¨, A.-M. Unsitalo,
T. Pakkanen, K. Hakala, P. Aalbonen, B. Lo¨fgren, Macro-
molecules, 30 (1997) 171.
[19] M.L.H. Green, L.-L. Wong, A. Seela, Organometallics 11 (1992)
2660, and references cited therein.
[7] R. Moors, F. Vo¨gtle, Chem. Ber. 126 (1993) 2133.
[20] E.B. Tjaden, D.C. Swenson, R.F. Jordan, J.L. Petersen,
Organometallics 14 (1995) 371.
[21] Review: V.S. Shambayati, W.E. Crowe, S.L. Schreiber, Angew.
Chem. 102 (1990) 273; Angew. Chem., Int. Ed. Engl. 29 (1990)
256.
[22] See for a comparison: B. Ahrens, P.G. Jones, A.K. Fischer, Eur.
J. Inorg. Chem. (1999) 1103.
[23] H. Sinn, W. Kaminsky, Adv. Organomet. Chem. 18 (1980) 99.
[24] D.C. Bradley, I.M. Thomas, J. Chem. Soc. (1960) 3857.
[25] S. Borkowsky, R.F. Jordan, G.D. Hinch, Organometallics 10
(1991) 1268.
[26] Programs used: Data collection: EXPRESS: Nonius B.V., 1994;
COLLECT: Nonius B.V., 1998. Data reduction: MolEN: K. Fair,
Enraf–Nonius B.V., 1990. DENZO-SMN: Z. Otwinowski, W.
Minor, Methods in Enzymology 276 (1997) 307; Absorption
Correction: SORTAV: R.H. Blessing, Acta Crystallogr., Sect. A 51
(1995) 33; J. Appl. Cryst. 30 (1997) 421; Structure Solution:
SHELXS-97: G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990)
467; Structure refinement: SHELXL-97: G.M. Sheldrick, Univer-
sity Go¨ttingen, Germany, 1997. Graphics: SCHAKAL-92: E.
Keller, University Freiburg, Germany, 1997.
[8] C. Wang, S. Friedrich, T.R. Younkin, R.T. Li, R.H. Grubbs,
D.A. Bansleben, M.W. Day, Organometallics 17 (1998) 3149.
[9] R.F. Jordan, Adv. Organomet. Chem. 32 (1991) 325.
[10] For other reactions of methylzirconocene cation systems that
proceed with loss of methane, see e.g.: D. Ro¨ttger, G. Erker, R.
Fro¨hlich, S. Kotila, J. Organomet. Chem. 518 (1996) 17. A.
Bertuleit, C. Fritze, G. Erker, R. Fro¨hlich, Organometallics 16
(1997) 2891. J. Pflug, A. Bertuleit, G. Kehr, R. Fro¨hlich, G.
Erker, Organometallics 18 (1999) 3818. J. Wonnemann, M.
Oberhoff, G. Erker, R. Fro¨hlich, K. Bergander, Eur. J. Inorg.
Chem. (1999) 1111.
[11] G. Erker, U. Dorf, C. Kru¨ger, Y.-H. Tsay, Organometallics 6
(1987) 680 and references cited therein. See also: T. Cuenca, P.
Go´mez-Sal, C. Martin, B. Royo, P. Royo, J. Organomet. Chem.
588 (1999) 134.
[12] For recent examples see e.g.: B. Goldfuss, S.I. Khan, K.N.
Honk, Organometallics 18 (1999) 2927. K.B. Aubrecht, B.L.
Lucht, D.B. Collum, Organometallics 18 (1999) 2981.
[13] T.H. Warren, G. Erker, R. Fro¨hlich, B. Wibbeling,
Organometallics 19 (2000) 127.
.
.