Chiral zirconium complexes with bianiline-based N4-donor ligands

Article abstract of DOI:10.1021/om040011r

Syntheses of new tetradentate ligands, containing a bianiline backbone and two additional heterocyclic N-donors, and of chiral zirconium complexes containing these ligands as dianions are reported. Crystal structures of some of these complexes show a preference for coordinating the two remaining ligands in a trans- rather than cis-orientation. Nevertheless, these complexes are moderately active in MAO-activated olefin polymerization in toluene solution at 50°C. With propene, partly isotactic polypropene (55% mmmm) is obtained. These observations indicate that in cationic species generated in these reaction systems, the growing polymer chain and the olefin substrate occupy cis-coordination sites, while the heterocyclic N ligands adopt a screw-like trans orientation suitable to favor one of the enantiofacial orientations of the entering olefin substrate.

Full text of DOI:10.1021/om040011r

3800
Organometallics 2004, 23, 3800-3807
Ch ir a l Zir con iu m Com p lexes w ith Bia n ilin e-Ba sed
N4-Don or Liga n d s
Mika Kettunen,† Christoph Vedder,‡ Frank Schaper,‡ Markku Leskela¨,†
Ilpo Mutikainen,† and Hans-Herbert Brintzinger*,‡
Laboratory of Inorganic Chemistry, University of Helsinki, FIN-00014 Helsinki, Finland, and
Fachbereich Chemie, Universita¨t Konstanz, D-78457 Konstanz, Germany
Received J anuary 26, 2004
Syntheses of new tetradentate ligands, containing a bianiline backbone and two additional
heterocyclic N-donors, and of chiral zirconium complexes containing these ligands as dianions
are reported. Crystal structures of some of these complexes show a preference for coordinating
the two remaining ligands in a trans- rather than cis-orientation. Nevertheless, these
complexes are moderately active in MAO-activated olefin polymerization in toluene solution
at 50 °C. With propene, partly isotactic polypropene (55% mmmm) is obtained. These
observations indicate that in cationic species generated in these reaction systems, the growing
polymer chain and the olefin substrate occupy cis-coordination sites, while the heterocyclic
N ligands adopt a screw-like trans orientation suitable to favor one of the enantiofacial
orientations of the entering olefin substrate.
In tr od u ction
bianiline backbone, prepared by Scott and co-workers,8
have been reported only once.9
Earlier studies on olefin polymerization catalysts
based on group IV metal complexes with substituted,
annelated, and/or bridged cyclopentadienyl ligands1,2
have been followed more recently by investigations on
polymerization catalysts derived from a great variety
of other transition metal complexes.3 For group IV
transition metals, various complexes with two bidentate
N,N ligands4 or O,N ligands or with a tetradentate
O,N,N,O ligand have been studied with regard to MAO-
activated olefin polymerization catalysis,5 some with
remarkable activities,4a,6 recently even without MAO
activation.7 Nevertheless, the polymerization activities
for MAO-activated titanium and zirconium complexes
with Schiff-base O,N,N,O ligands containing a chiral
Other complexes containing ligands with N-donor
atoms only, which include amidinato,10 diamido,11 tria-
midoamine,12 and diamido-diamine13 complexes, among
these also chiral zirconium complexes containing biden-
tate14 and tetradentate15 diamido ligands with a bi-
(6) (a) Matsui, S.; Fujita, T. Catal. Today 2001, 66 (1), 63. (b) Mitani,
M.; Mohri, J .-I.; Yoshida, Y.; Saito, J .; Ishii, S.; Tsuru, K.; Matsui, S.;
Furuyama, R.; Nakano, T.; Tanaka, H.; Kojoh, S.-I.; Matsugi, T.;
Kashiwa, N.; Fujita, T. J . Am. Chem. Soc. 2002, 124, 3327. (c)
Furuyama, R.; Saito, J .; Ishii, S.-I.; Mitani, M.; Matsui, S.; Tohi, Y.;
Makio, H.; Matsukawa, N.; Tanaka, H.; Fujita, T. J . Mol. Catal. A:
Chem. 2003, 200, 31.
(7) (a) Bando, H.; Nakayama, Y.; Sonobe, Y.; Fujita, T. Macromol.
Rapid Commun. 2003, 24 (12), 732. (b) Ishii, S.; Saito, J .; Matsuura,
S.; Suzuki, Y.; Furuyama, R.; Mitani, M.; Nakano, T.; Kashiwa, N.;
Fujita, T. Macromol. Rapid Commun. 2002, 23 (12), 693. (c) Nakayama,
Y.; Bando, H.; Sonobe, Y.; Kaneko, H.; Kashiwa, N.; Fujita, T. J . Catal.
2003, 215 (1), 171. (d) Nakayama, Y.; Bando, H.; Sonobe, Y.; Kaneko,
H.; Kashiwa, N.; Fujita, T. J . Catal. 2003, 215 (1), 171. (e) Saito, J .;
Suzuki, Y.; Fujita, T. Chem. Lett. 2003, 32 (3), 236. (f) Younkin, T. R.;
Connor, E. F.; Henderson, J . I.; Friedrich, S. K.; Grubbs, R. H.;
Bansleben, D. A. Science 2000, 287, 460. (g) Zuideveld, M. A.;
Wehrmann, P.; Ro¨hr, C.; Mecking, S. Angew. Chem., Int. Ed. 2004,
43, 869.
† University of Helsinki.
‡ Universita¨t Konstanz.
(1) Brintzinger, H. H.; Fischer, D.; Mulhaupt, R.; Rieger, B.;
Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143.
(2) Resconi, L.; Cavallo, L.; Fait, A.; Piemontesi, F. Chem. Rev. 2000,
100, 1253.
(3) (a) Britovsek, G. J . P.; Gibson, V. C.; Wass, D. F. Angew. Chem.,
Int. Ed. 1999, 38, 428. (b) Gibson, V. C.; Spitzmesser, S. K. Chem. Rev.
2003, 103, 285. (c) Ittel, S. D.; J ohnson, L. K.; Brookhart, M. Chem.
Rev. 2000, 100, 1169.
(4) (a) Yoshida, Y.; Matsui, S.; Takagi, Y.; Mitani, M.; Nakano, T.;
Tanaka, H.; Kashiwa, N.; Fujita, T. Organometallics 2001, 20, 4793.
(b) Tsurugi, H.; Yamagata, T.; Tani, K.; Mashima, K. Chem. Lett. 2003,
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J .; Scott, P. J . Chem. Soc., Dalton Trans. 2000, 3340. (b) Woodman, P.
R.; Sanders, C. J .; Alcock, N. W.; Munslow, I. J .; Hitchcock, P. B.; Scott,
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N.; Munslow, I. J .; Kimberley, B. S.; Scott, P. J . Organomet. Chem.
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Scott, P. Chem. Commun. 2002, 352.
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138, 37. (b) Tian, J .; Hustad, P. D.; Coates, W. J . Am. Chem. Soc. 2001,
123, 5134. (c) Tian, J .; Hustad, P. D.; Coates, W. J . Am. Chem. Soc.
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10.1021/om040011r CCC: $27.50 © 2004 American Chemical Society
Publication on Web 07/10/2004

Chiral Zirconium Complexes
Organometallics, Vol. 23, No. 16, 2004 3801
Sch em e 1
aniline backbone, as well as complexes with tetraaza-
macrocyclic ligands,16 have been prepared but not
always tested in polymerization. Here, we report on the
synthesis of new 6,6′-dimethyl-bianiline-based tetraden-
tate ligands containing two additional heterocyclic N-
donors and the preparation of several chiral zirconium
complexes derived from their dianionic deprotonation
products, their structures, and their properties as
precatalysts for olefin polymerization.
cis-coordination sites, precludes the coordination of an
extra THF ligand molecule.
To study the effects of varying sidearm functionalities
on structures and reactivities of these bianiline-based
complexes, we next replaced the pyrrole by pyridyl
moieties. The dipyridine diimines, obtained by conden-
sation of dimethylbianiline with pyridine aldehyde and
6-methylpyridine aldehyde, respectively, had to be
reduced to the diamines 2H2 and 3H2 first, to make
dianionic ligands accessible from them. While attempts
to reduce the dipyridine diimines with NaBH4 or LiAlH4
were unsuccessful or gave low isolated yields, complete
conversion to the oily products 2H2 and 3H2, respec-
tively, was achieved, as judged from 1H NMR, by Pd-
(OH)2-catalyzed hydrogenation under H2 pressure at 80
°C (Scheme 3).
Resu lts a n d Discu ssion
Com p lex Syn t h esis a n d Ch a r a ct er iza t ion . The
dipyrrole diimine ligand 1H2 was readily prepared by
condensation of 6,6′-dimethyl-bianiline with pyrrole
aldehyde in methanol (Scheme 1). With a few drops of
formic acid being added as a catalyst, the product was
isolated with 85% yield after reacting 1 h at room
temperature. Upon stirring the reaction mixture over-
night in n-pentane, the product precipitated cleanly and
no further purification was needed.
Sch em e 3
Deprotonation of the pyrrole rings of ligand 1H2 was
achieved by reaction with NaH in THF. The disodium
salt 1Na2 thus formed was reacted with ZrCl4(THF)2 in
THF at room temperature to give complex 1-ZrCl2(THF)
(Scheme 1). Washing the crude product with toluene,
in which it is only slightly soluble, followed by extraction
with CH2Cl2 gave analytically pure 1-ZrCl2(THF), the
crystal structure of which is to be discussed below. The
coordinated THF was not removable in vacuo at 100 °C
or by coevaporation with toluene. To obtain a more solu-
ble complex, 1Na2 was reacted also with (tBu4biphenO2)-
ZrCl2(THF)2,17 to give the biphenolate complex
1-Zr(tBu4biphenO2) (Scheme 2). Apparently, the bulky
Reacting 2H2 or 3H2 with NaH and then with ZrCl4
or ZrCl4(THF)2 did not allow isolation of any zirconium
n
complexes. When BuLi was used instead, a few crystals
of 3-ZrCl2 were isolated (Scheme 4),18 which allowed us
Sch em e 4
Sch em e 2
to determine its structure by single-crystal X-ray dif-
fractometry. The biphenolate complex 2-Zr(tBu4biphenO2)
was obtained by reacting (tBu4biphenO2)Zr(NMe2)2 (4)
with ligand 2H2 in toluene at room temperature for 2
days and then under reflux for 2 h (Scheme 5). Again,
only a few crystals of 2-Zr(tBu4biphenO2) were isolated
from this reaction, but allowed determination of the
biphenolate ligand, which must necessarily occupy two
(15) (a) O’Shaughnessy, P. N.; Gillespie, K. M.; Morton, C.; West-
moreland, I.; Scott, P. Organometallics 2002, 21 (21), 4496. (b)
Westmoreland, I.; Munslow, I. J .; O’Shaughnessy, P. N.; Scott, P.
Organometallics 2003, 22 (14), 2972.
(16) (a) Uhrhammer, R.; Black, D. G.; Gardner, T. G.; Olsen, J . D.;
J ordan, R. F. J . Am. Chem. Soc. 1993, 115, 8493. (b) Martin, A.;
Uhrhammer, R.; Gardner, T. G.; J ordan, R. F. Organometallics 1998,
17, 382.
(17) Damrau, H.-R. H.; Royo, E.; Obert, S.; Schaper, F.; Weeber, A.;
Brintzinger, H.-H. Organometallics 2001, 20, 5258.
(18) Clegg, W.; Dunbar, L.; Horsburgh, L.; Mulvey, R. E. Angew.
Chem. 1996, 108, 815.

3802 Organometallics, Vol. 23, No. 16, 2004
Kettunen et al.
Sch em e 5
solid state structure of this complex by single-crystal
X-ray diffraction. Finally, we observed that 2H2 and
3H2 readily reacted with Zr(CH2Ph)4 to give complexes
2-Zr(CH2Ph)2 and 3-Zr(CH2Ph)2, respectively, in accept-
able yields (Scheme 6).
F igu r e 1. Molecular strucure of 1-ZrCl2(THF). Thermal
ellipsoids are at 50% probability, hydrogen atoms omitted
for clarity.
Sch em e 6
All complexes containing ligands 1, 2, or 3 gave room-
temperature NMR spectra in accord with a structure
of time-averaged C2-symmetry (see Experimental Sec-
tion). NMR patterns of the AB type were observed
for the diastereotopic N-CH2 and Zr-CH2 protons of
2-Zr(CH2Ph)2 and 3-Zr(CH2Ph)2, in accord with the
chiral geometry of these complexes.
F igu r e 2. Molecular strucure of 3-ZrCl2. Thermal el-
lipsoids are at 50% probability, hydrogen atoms omitted
for clarity.
Ta ble 1. Bon d Len gth s (Å) a n d An gles (d eg) a t Zr
Cen ter for 1-Zr Cl2(THF )
Molecu la r Str u ctu r es of 1-Zr Cl2(THF ), 3-Zr Cl2,
3-Zr (CH2P h )2, a n d 2-Zr (tBu 4bip h en O2). In complex
1-ZrCl2(THF), the zirconium center is coordinated to the
four nitrogen atoms of ligand 1, to two chloride ions,
and to the THF molecule (Figure 1, Table 1). The
coordination polyhedron can be described as a distorted
pentagonal bipyramid, where the chloride ions take the
pseudoaxial positions with a Cl-Zr-Cl angle of 169°,
while the four nitrogen atoms and the THF oxygen atom
occupy a distorted N4O mid-plane. The mean plane
defined by the two pyrrole-N atoms and by the Zr and
O atoms, which lie on the crystallographically imposed
C2 axis, is practically perpendicular to the ZrCl2
plane and might thus be taken to be the base plane of
a pentagonal bipyramide. The two imine-N atoms
deviate by (0.72 Å from this base plane due to a
dihedral angle of 67° in the biphenyl backbone. Never-
theless, the O-Zr-N(pyrrole), N(pyrrole)-Zr-N(imine),
and N(imine)-Zr-N(imine) angles (76°, 71°, and 77°,
respectively) are all close to the value of 72° expected
for a pentagonal coordination geometry. The Zr-
N(imine) and Zr-N(pyrrole) bond lengths are close to
those observed for Zr-Schiff-base and Zr-amido com-
plexes, respectively.8,10-16
Zr-N(1)
Zr-N(2)
Zr-O(1)
Zr-Cl(1)
2.252(3)
2.335(2)
2.268(3)
2.463(1)
N(1)-Zr-N(1A)
N(1)-Zr-N(2)
N(1)-Zr-O(1)
N(2)-Zr-N(2A)
Cl(1)-Zr-Cl(1A)
151.10(13)
71.03(9)
75.55(7)
76.57(12)
169.08(4)
except that the THF ligand is missing here, due to the
steric shielding of the fifth in-plane position by the
o-methyl groups on each of the pyridine ligand moieties.
The absence of a fifth ligand in the base plane results
in a somewhat smaller Cl-Zr-Cl angle of 138°, the
Cl-Zr-Cl plane still being close to perpendicular to
the N(pyridyl)-Zr-N(pyridyl) base plane. The two
N(amido) atoms deviate again by (0.6 Å from this base
plane; the N(pyridyl)-Zr-N(amido) and N(amido)-Zr-
N(amido) angles (71-72° and 84°) as well as the large
N(pyridyl)-Zr-N(pyridyl) angle of 141° are again close
to the values expected for pentagonal coordination. The
Zr-N(pyridyl) and Zr-N(amido) bond distances of 2.45
and 2.07 Å, respectively, are in the range of those
reported for other Zr-imine and Zr-amido complexes.8,10-16
The interchange of anionic and neutral N ligand atoms
between the inner and outer positions of the coordina-
tion base plane in 1-ZrCl2(THF) and 3-ZrCl2 thus seems
to have little effect on the overall coordination geom-
etries of these complexes.
Surprisingly similar to the structure just discussed
for 1-ZrCl2(THF) is that of 3-ZrCl2 (Figure 2, Table 2),

Chiral Zirconium Complexes
Organometallics, Vol. 23, No. 16, 2004 3803
Ta ble 2. Bon d Len gth s (Å) a n d An gles (d eg) a t Zr Cen ter s for 3-Zr Cl2, 3-Zr (CH2P h )2, a n d
2-Zr (tBu 4bip h en O2)
3-ZrCl2
3-Zr(CH2Ph)2
2-Zr(tBu4biphenO2)
Zr-N(3, amide)
Zr-N(2, amide)
Zr-N(1, pyridyl)
Zr-N(4, pyridyl)
Zr-X
2.073(3)
2.079(3)
2.446(3)
2.446(4)
2.475(1), X ) Cl(1)
2.470(1), X ) Cl(2)
140.8(1)
84.1(1)
71.4(1)
72.0(1)
144.0(1)
2.114(2)
2.084(2)
2.526(2)
2.521(2)
2.322(3), X ) C(36)
2.322(3), X ) C(29)
136.0(1)
85.4(1)
70.7(1)
69.6(1)
154.0(1)
151.29(8)
134.5(1), X ) C(36), C(29)
2.100(3)
2.097(3)
2.406(3)
2.412(3)
2.037(2), X ) O(2)
2.070(2), X ) O(1)
161.7(1)
86.5(1)
68.8(1)
69.1(1)
103.6(1)
125.7(1)
90.9(1), X ) O(1), O(2)
Zr-X
N(1)-Zr-N(4)
N(2)-Zr-N(3)
N(1)-Zr-N(2)
N(3)-Zr-N(4)
N(1)-Zr-N(3)
N(2)-Zr-N(4)
X-Zr-X
144.9(1)
138.4(1), X ) Cl(1), Cl(2)
Even more striking is the structural similarity be-
tween complexes 3-ZrCl2 and 3-Zr(CH2Ph)2 (Figure 3,
sufficient to displace the two pyridyl ligands from their
positions close to the molecular mid-plane into axial
positions.
A structure with axially placed pyridyl ligands is
brought about, however, by the biphenolate ligand in
2-Zr(tBu4biphenO2), in which the O ligand atoms must
necessarily occupy cis-coordination positions (Figure 4,
F igu r e 3. Molecular strucure of 3-Zr(CH2Ph)2. Thermal
ellipsoids are at 50% probability, hydrogen atoms omitted
for clarity.
F igu r e 4. Molecular strucure of 2-Zr(tBu4biphenO2).
Thermal ellipsoids are at 50% probability, hydrogen atoms
omitted for clarity.
Table 2). The bipyramidal coordination geometries are
very similar, with a C(benzyl)-Zr-C(benzyl) angle of
134° and N(pyridyl)-Zr-N(amido) and N(amido)-Zr-
N(amido) angles of 71° and 85°, respectively, and a large
N(pyridyl)-Zr-N(pyridine) angle of 136°. The Zr-N
distances are in the same range as noted before for
3-ZrCl2.
Bianiline-bridged N4 ligands in complexes of the type
N4ZrX2 thus tend to have all four N ligand atoms close
to the mid-plane, which bisects the rather large X-Zr-X
angle, so that the two X ligands occupy axial-type
positions. Due to a rather short distance between the
bianiline N atoms, associated with rather small dihedral
angles of 62-67° between the two phenyl rings, the four
N atoms leave a rather large open space in the molec-
ular mid-plane, opposite the bridging biphenylene unit.
This position, which corresponds to an equatorial corner
of a distorted pentagonal bipyramide, can either be
occupied by an additional ligand molecule, as in 1-ZrCl2-
(THF), or remain open, as in the sterically congested
complexes of the type 3-ZrX2 (X ) Cl, benzyl). While
repulsive contacts (3.6 Å) between the methyl groups
at the pyridyl rings might stabilize the large N(py-
ridyl)-Zr-N(pyridyl) angles, they are apparently not
Table 2). This complex adopts a slightly distorted
octahedral geometry, with an N(pyridyl)-Zr-N(pyridyl)
angle of 162° and N-Zr-N, N-Zr-O, and O-Zr-O
angles all close to 90°. Remarkably, the dihedral angle
between the two phenyl rings in the bianiline backbone,
61°, is even smaller than in complexes that have all four
N ligand atoms in equatorial positions. By analogy, we
would assume that the bis-pyrrole complex 1-Zr(tBu4-
biphenO2), discussed above, likewise has an octahedral
geometry with pyrrole rings in axial positions.
P olym er iza tion Stu d ies. Complex 1-ZrCl2(THF)
was found to catalyze, after activation with MAO, the
polymerization of ethene (6.2 kg/mol‚h‚bar) and of
propene (7.8 kg/mol‚h‚bar), under conditions that were
not optimized (50 °C, 2 bar propene pressure, 20 bar
ethene pressure, 5.8-20.8 µmol Zr, Al(MAO):Zr ) 1000)
(Table 3). The polypropene obtained with 1-ZrCl2(THF)/
MAO was found to be partially isotactic with 55%
mmmm pentads, in distinction to atactic polypropene
obtained with a chiral zirconium complex containing a
bidentate bianiline-diamido ligand.14 After activation
with [PhNMe2H]+[B(C6F5)4]-, complex 2-Zr(CH2Ph)2

3804 Organometallics, Vol. 23, No. 16, 2004
Kettunen et al.
and ROESY spectra. (3,3′,5,5′-tBu4-1,1′-bi-2-phenolate)ZrCl2-
Ta ble 3. P olym er iza tion Resu lts
(THF)2 and N,N′-(6,6′-dimethylbiphenyl-2,2′-diyl)diamine20
17
complex
activator
monomer activitya
were prepared according to literature procedures. Zr(CH2Ph)4
was obtained from MCAT GmbH (www.MCAT.de). All other
chemicals were purchased from commercial suppliers and used
without further purification.
1-ZrCl2(THF)b MAO
ethene
propene
6.2
7.8
0.4
1-ZrCl2(THF)c MAO
d
2-Zr(CH2Ph)2
[PhNMe2H]+[B(C6F5)4]- propene
a
b
Given as kg polymer/[mol(catalyst)‚h‚bar]. In toluene (100
N,N′-(6,6′-Dim e t h ylb ip h e n yl-2,2′-d iyl)b is(2-p yr r ole -
m eth yl)d iim in e (1H2). A solution of N,N′-(6,6′-dimethylbi-
phenyl-2,2′-diyl)diamine (1.0 g, 4.71 mmol), pyrrole-2-carbox-
aldehyde (0.90 g, 9.42 mmol), and HCOOH (0.25 mL) in
methanol (40 mL) was stirred at room temperature for 1 h.
Volatiles were evaporated, 30 mL of n-pentane added, and the
reaction mixture stirred for another 12 h. The product, which
precipitated in the form of a light red powder, was collected
by filtration and washed with n-pentane to yield 1.46 g (85%)
of 1H2 (mp 120 °C). 1H NMR (250 MHz, CD2Cl2): δ 1.97 (s,
6H, CH3), 6.19 (m, 2H, pyrrole-CH), 6.50 (m, 2H, pyrrole-CH),
6.86 (m, 4H, NCCH and pyrrole-CH), 7.10 (d, 3J ) 7.5 Hz, 2H,
CH3CCH), 7.24 (m, 2H, NCCHCH), 7.95 (s, 2H, NdCH) ppm.
1H NMR (250 MHz, C6D6): δ 2.12 (s, 6H, CH3), 6.04 (m, 4H,
mL) at 50 °C for 1 h, Al/Zr ) 1000, p(ethene) ) 20 bar. c In toluene
d
(500 mL) at 50 °C for 2 h, Al/Zr ) 1500, p(propene) ) 2 bar. In
toluene (500 mL) at 50 °C for 2 h, anilinium borate/Zr ) 1,
p(propene) ) 2 bar, Al(i-Bu)3 added as scavanger.
catalyzed the polymerization of propene with rather low
activity (0.44 kg/mol‚h‚bar). Complex 3-Zr(CH2Ph)2,
however, showed no propene polymerization activity at
all when activated with [PhNMe2H]+[B(C6F5)4]-.19
The preliminary results presented above indicate that
species of the type 1- or 2-Zr(pol)(olefin)+ are generated
in these reaction systems, in which the growing polymer
chain and the olefin substrate occupy cis-coordination
sites. This requires that the heterocyclic N ligands adopt
a screw-like trans-orientation similar to that observed
for 2-Zr(tBu4biphenO2) and might thus be suitable to
induce a preferential orientation of the last-inserted
polymer-chain segment and/or the entering olefin sub-
strate. This would explain the preference for isotactic
enchainment observed in these reaction systems.
Molecu la r Mod elin g Stu d ies. To investigate the
accessibility of complex configurations with monoden-
tate ligands in cis-position, we calculated the relative
energies of trans-2-ZrCl2 and of hypothetical cis-2-ZrCl2
using molecular mechanics models (see Experimental
Section). For our model complexes, the cis-configuration
turned out to be less stable than the trans-configuration
by only 4 kJ /mol. We thus conclude that isomerization
into a cis-coordinated complex is a feasible process
during polymerization with 2-ZrX2 as a precatalyst. For
cis-3-ZrCl2, on the other hand, we found a much greater
energy difference of 23 kJ /mol relative to trans-3-ZrCl2.
One explanation for the lack of activity of 3-Zr(CH2Ph)2
in polymerization might thus be that this complex is
not able to adopt the cis-configuration required for the
insertion reaction.
3
NHCHCH), 6.35 (m, 2H, NHCCH), 6.75 (d, J ) 7.7 Hz, 2H,
NCCH), 7.05 (d, 3J ) 7.2 Hz, 2H, CH3CCH), 7.16 (m, 2H,
NCCHCH), 7.88 (s, 2H, NdCH) ppm. 13C NMR (151 MHz,
C6D6): 20.28 (CH3), 110.11, 115.95, 116.59, 122.59, 126.86,
128.31, 133.54, 149.72, 152.06 ppm. Anal. Calcd for C24H22N4
(366.44): C, 78.66; H, 6.05; N, 15.29. Found: C, 78.32; H, 6.04;
N, 15.20.
N ,N ′-(6,6′-Dim e t h ylb ip h e n yl-2,2′-d iyl)b is(2-p yr id yl-
m eth yl)d iim in e. A solution of N,N′-(6,6′-dimethylbiphenyl-
2,2′-diyl)diamine (6.03 g, 28.4 mmol) and pyridine-2-carbox-
aldehyde (5.40 mL, 6.08 g, 56.8 mmol) in ethanol (100 mL)
was stirred at room temperature for 1 h. The volatiles were
then evaporated, 100 mL of n-pentane was added, and the
reaction mixture was stirred for another 12 h. During this
time, a light yellow powder (mp 80 °C) precipitated, which was
collected by filtration and washed with n-pentane. Yield: 10.1
g (91%). IR (KBr): ν 3053, 3014 (m, w, Ar-H), 2982, 2953, 2913,
2867 (w, m, m, w, C-H), 1632, 1585, 1567 (s, s, s, CdN, CdC),
1469, 1435 (s, s, C-Hdef), 1219 (m), 993 (m) cm-1. IR (PE): ν
597 (w), 590 (s), 580 (w), 570 (m), 549 (m), 530 (w), 520 (m),
475 (s), 440 (m), 404 (s), 381 (w), 368 (m), 316 (m), 260 (s),
241 (m) cm-1. 1H NMR (600 MHz, CDCl3): δ 2.04 (s, 6H, CH3),
6.92 (d, 3J 3/3′-4/4′ 7.7 Hz, 2H, 3-H/3′-H), 7.13 (d, 3J 5/5′-4/4′ 7.4 Hz,
3
2H, 5-H/5′-H), 7.22 (pt, J 5′′-4′′/6′′ 5.8 Hz, 2H, 5′′-H), 7.26 (pt,
3J 4/4′-3/3′/5/5′ 7.6 Hz, 2H, 4-H/4′-H), 7.59 (pt, 3J 4′′-3′′/5′′ 7.4 Hz, 2H,
3
4′′-H), 7.66 (d, J 3′′-4′′ 7.7 Hz, 2H, 3′′-H), 8.37 (s, 2H, NdCH),
3
8.55 (d, J 6′′-5′′ 3.8 Hz, 2 H, 6′′-H) ppm. 13C NMR (151 MHz,
In further experimental and molecular modeling
studies, we intend to investigate relative energies and
interconversion rates for the cis- and trans-isomers of
cationic complexes of the type (2,3)-Zr(alkyl)+ as well
as polymerization activities and polymer tacticities with
respect to temperature, so as to corroborate the respec-
tive roles of alternative complex geometries in polym-
erization catalysis.
CDCl3): δ 19.87 (CH3), 115.08 (C-3/C-3′), 121.32 (C-3′′), 124.70
(C-5′′), 127.36 (C-5/C-5′), 127.90 (C-4/C-4′), 132.64 (C-1/C-1′),
136.49 (C-4′′), 137.10 (C-6/C-6′), 149.13 (C-6′′), 149.73 (C-2/C-
2′), 154.90 (s, C-2′′), 159.52 (CdN) ppm. MS (EI, 70 eV): m/z
390 (100) [M+], 312 (55) [M+ - C5H4N], 285 (46) [312 - HCN],
208 (77) [C14H12N2+]. Anal. Calcd for C26H22N4 (390.49 g/mol):
C, 79.97; H, 5.68; N, 14.35. Found: C, 79.50; H, 5.75; N, 14.14.
N,N′-(6,6′-Dim eth ylbip h en yl-2,2′-d iyl)bis[(6-m eth yl-2-
p yr id yl)m eth yl]d iim in e. A solution of N,N′-(6,6′-dimethyl-
biphenyl-2,2′-diyl)diamine (3.50 g, 16.5 mmol) and 6-meth-
ylpyridine-2-carboxaldehyde (3.99 g, 32.9 mmol) in ethanol (60
mL) was stirred at room temperature for 1 h. Volatiles were
evaporated, n-pentane was added, and the mixture was stirred
for a further 12 h. The product, which precipitated as a white
powder (mp 130 °C), was collected by filtration and washed
with n-pentane. Yield: 6.15 g (89%). IR (KBr): ν 3058 (m,
Ar-H), 2966, 2917 (m, m, C-H), 1649, 1627, 1590, 1569 (m, m,
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were performed under
argon with Schlenk-line techniques or under N2 in a glovebox.
Solvents were dried prior to use by refluxing over and
distillation from sodium (hydrocarbons), magnesium (alcohols),
or calcium hydride (CH2Cl2). Deuterated solvents were dried
over 4 Å molecular sieves and used without further purifica-
tion. NMR spectra were recorded on Bruker AC 250 and DRX
600 spectrometers, 1H NMR chemical shifts were calibrated
by residual 1H solvent peaks. Signals were assigned by HMQC
1
m, m, CdN, CdC), 1456 (m, C-Hdef), 1218 (m) cm-1. H NMR
(600 MHz, CDCl3): δ 2.05 (s, 6H, 6-CH3/6′-CH3), 2.54 (s, 6 H,
3
6′′-CH3), 6.92 (d, J 3/3′-4/4′ ) 7.8 Hz, 2H, 3-H/3′-H), 7.10 (d,
3
3J 5′′-4′′ ) 7.1 Hz, 2H, 5′′-H), 7.13 (d, J 5/5′-4/4′ ) 7.5 Hz, 2H,
(19) Since satisfactory elemental analyses were obtained for the
catalyst precursors used, we can exclude that other complexes or
starting materials, such as ZrCl4 or ZrCl4(THF)2, were contributing to
the observed polymerization catalysis.
(20) Kanoh, S.; Goka, S.; Murose, N.; Kubo, H.; Kondo, M.; Sugino,
T.; Motoi, M.; Suda, H. Polym. J . 1987, 19, 1047.

Chiral Zirconium Complexes
Organometallics, Vol. 23, No. 16, 2004 3805
3
5-H/5′-H), 7.26 (pt, J 4/4′-3/3′/5/5′ ) 7.6 Hz, 2H, 4-H/4′-H), 7.47
washed with toluene and extracted with CH2Cl2, the filtrate
evaporated, and the remaining yellow powder dried in vacuo.
Yield: 0.38 g (50%). Crystals for X-ray diffraction were
obtained by slow evaporation of a toluene solution at room
3
3
(d, J 3′′-4′′ ) 7.4 Hz, 2H, 3′′-H), 7.49 (pt, J 4′′-3′′/5′′ 7.5 Hz, 2H,
4′′-H), 8.35 (s, 2H, NdCH) ppm. 13C NMR (151 MHz, CDCl3):
δ 19.85 (6-CH3/6′-CH3), 24.21 (6′′-CH3), 114.95 (C-3/C-3′),
118.44 (C-3′′), 124.30 (C-5′′), 127.21 (C-5/C-5′), 127.84 (C-4/C-
4′), 132.85 (C-1/C-1′), 136.66 (C-4′′), 137.03 (C-6/C-6′), 149.92
(C-2/C-2′), 154.46 (C-2′′), 157.74 (C-6′′), 159.74 (CdN) ppm. MS
(EI, 70 eV): m/z 418 (84) [M+], 326 (29) [M+ - C6H6N], 299
(56) [326 - HCN], 208 (100) [C14H12N2+]. Anal. Calcd for
1
temperature. H NMR (600 MHz, CD2Cl2): δ 1.99 (m, THF),
2.07 (s, 6H, CH3), 4.13 (b, 4H, THF) 6.27 (s, 2H, pyrrole-
NCHCH), 6.79 (s, 2H, pyrrole-NCCH), 7.14 (d, 3J ) 7.5 Hz,
2H, bianiline-NCCH), 7.23 (m, 2H, CH3CCH), 7.23-7.29 (m,
2H H-Ar) 7.28 (m, 2H, bianiline-CHCHCH), 7.91 (s, 2H, Nd
CH) ppm. 13C NMR (151 MHz, CD2Cl2): δ 19.6 (s, CH3), 20.1,
26.2 (s, THF), 73.4 (b, THF), 114.0 (s, pyrrole-NCHCH), 121.5
(s, pyrrole-NCCH), 124.5 (s, bianiline-NCCH), 125.6, 128.3 (s,
bianiline-CHCHCH), 128.5, 129.3 (s, bianiline-CH3CCH), 132.3
(s, bianiline-NCC), 138.4, 139.7, 160.6 (s, CdN) ppm. Anal.
Calcd for C28H28Cl2N4OZr (598.66 g/mol): C, 56.17; H, 4.71;
N, 9.36. Found: C, 55.86; H, 4.73; N, 9.23.
C
28H26N4 (418.54 g/mol): C, 80.35; H, 6.26; N, 13.39. Found:
C, 80.03; H, 6.25; N, 13.38.
N,N′-(6,6′-Dim et h ylb ip h en yl-2,2′-d iyl)-N,N′-b is(2-p y-
r id ylm eth yl)d ia m in e (2H2). N,N′-(6,6′-Dimethylbiphenyl-
2,2′-diyl)bis(2-pyridylmethyl)diimine (1.3 g, 3.33 mmol) was
dissolved in toluene (20 mL) and transferred to a 30 mL
autoclave. Pd(OH)2 on charcoal (10 mg) was added as a
catalyst, autoclave charged with 50 bar of H2, and the reaction
mixture stirred at 80 °C for 16 h. After venting the gases the
mixture was filtered, the filtrate evaporated to dryness, and
the residue dried in vacuo to yield a light yellow oil (1.24 g,
N,N′-(6,6′-Dim e t h ylb ip h e n yl-2,2′-d iyl)b is(2-p yr r ole -
m et h yl)d iim in e-Zr (3,3′,5,5′-t Bu 4-1,1′-b i-2-p h en ola t e) (1-
Zr (tBu 4bip h en O2)). THF (30 mL) was added to a mixture of
1Na2 (0.30 g, 0.74 mmol) and (3,3′,5,5′-tBu4-1,1′-bi-2-phenolate)-
ZrCl2(THF)2 (0.53 g, 0.74 mmol) at -50 °C. The yellowish
mixture was stirred at room temperature for 16 h, after which
the volatiles were evaporated in vacuo and the residue
extracted with CH2Cl2. The red extract was filtered and
evaporated to dryness and the solid residue dried in vacuo to
yield a yellow powder (0.48 g, 78%). 1H NMR (600 MHz,
C6D6): δ 1.30 (s, 18H, 5,5′-tBu), 1.62 (s, 18H, 3,3′-tBu), 1.92
(s, 6H, bianiline-CH3), 5.91 (s, 2H, pyrrole-NCHCH), 6.26 (d,
J 3.2 Hz, 2H, pyrrole-NCCH), 6.75 (m, 4H, bianiline-CH3-
CCHCH), 6.84 (s, 2H, HCdN), 7.18 (b, 2H, bianiline-NCCH),
7.27 (s, 2H, pyrrole-NCH), 7.37 (d, J 1.9 Hz, 2H, biphenolat-
1
94%). H NMR (250 MHz, CD2Cl2): δ 1.95 (s, 6H, CH3), 4.39
(d, J 5.2 Hz, 4H, N-CH2), 4.43 (t, J 5.5 Hz, 2H, NH), 6.47 (d,
J 8.1 Hz, 2H, H-Ar), 6.69 (d, J 7.4 Hz, 2H, H-Ar), 7.10 (m, 4H,
H-Ar), 7.23 (d, J 7.9 Hz, 2H, H-Ar) 7.49 (m, 2H, H-Ar), 8.44
1
(m, 2H, pyr-NCH) ppm. H NMR (250 MHz, C6D6): δ 2.10 (s,
6H, CH3), 4.14 (m, 4H, N-CH2), 4.59 (m, 2H, NH), 6.52 (m,
2H, H-Ar), 6.56 (d, J 8.1 Hz, 2H, H-Ar), 6.79 (d, J 7.5 Hz, 2H,
H-Ar), 6.95 (m, 2H, H-Ar) 7.13 (m, 4H, H-Ar), 8.34 (m, 2H,
pyr-NCH) ppm. MS (FAB): m/z 395 (100) [(M + H)+], 302 (31)
[M+ - C6H6N ], 208 (18) [C14H12N2+]. Anal. Calcd for C26H26N4
(394.51 g/mol): C, 79.15 H, 6.64; N, 14.21. Found: C, 77.44;
H, 9.86; N, 13.75.
6,6′H-Ar) 7.49 (d, J 1.6 Hz, 2H, biphenolat-4,4′H-Ar) ppm. 13
C
NMR (151 MHz, C6D6): δ 20.08, 25.6, 29.9, 30.8, 31.8, 34.4,
35.7, 67.8, 110.0, 114.0 (s, pyrrole-NCHCH), 121.4 (s, bianiline-
NCCH), 121.9 (s, pyrrole-NCCH), 123.6 (biphenolate-4,4′C-Ar),
128.4 (bianiline-CH3CHCH), 129.6 (biphenolate-6,6′C-Ar), 130.6,
132.4, 135.7, 138.5 (d), 142.5 142.8 (d, pyrrole-NCH), 147.6,
155.2, 161.8 (s, CdN) ppm. Anal. Calcd for C52H60N4O2Zr
(864.26 g/mol): C, 72.26; H, 7.00; N, 6.48. Found: C, 71.63;
H, 7.55; N, 6.28.
N,N′-(6,6′-Dim eth ylbiph en yl-2,2′-diyl)-N,N′-bis[(6-m eth -
yl-2-p yr id yl)m eth yl]d ia m in e (3H 2). N,N′-(6,6′-Dimethylbi-
phenyl-2,2′-diyl)bis[(6-methyl-2-pyridyl)methyl]diimine (1.0 g,
2.39 mmol) was dissolved in toluene (20 mL) and transferred
to a 30 mL autoclave. Pd(OH)2 (10 mg) on charcoal was added
as a catalyst, the autoclave charged with 10 bar of H2, and
the mixture stirred at 80 °C for 16 h. After venting the gases,
the mixture was filtered, the filtrate evaporated to dryness,
and the residue dried in vacuo to yield a colorless oil (0.95 g,
94%). 1H NMR (250 MHz, CD2Cl2): δ 2.01 (s, 6H, bianiline-
CH3), 2.43 (s, 6H, pyridyl-CH3), 4.35 (d, J ) 5.5 Hz, 4H,
N-CH2), 4.69 (m, 2H, NH), 6.54 (d, J ) 8.1 Hz, 2H, H-Ar), 6.74
(d, J ) 7.6 Hz, 2H, H-Ar), 6.95 (d, J ) 0.6 Hz, 2H, H-Ar), 7.03
(d, J ) 7.6 Hz, 2H, H-Ar) 7.17 (m, 2H, H-Ar), 7.35 (m, 2H,
H-Ar) ppm. 1H NMR (250 MHz, C6D6): δ 2.15 (s, 6H, bianiline-
CH3), 2.31 (s, 6H, pyridyl-CH3) 4.16 (m, 4H, N-CH2), 4.86 (m,
2H, NH), 6.49 (d, J ) 7.4 Hz, 2H, H-Ar), 6.64 (d, J ) 8.1 Hz,
2H, H-Ar), 6.82 (m, 2H, H-Ar), 6.90 (m, 4H, H-Ar) 7.21 (m,
2H, H-Ar) ppm. MS (FAB): m/z 423 (98) [(M + H)+], 316 (28)
[M+ - C7H8N], 208 (19) [C14H12N2+]. Anal. Calcd for C26H26N4
(422.56 g/mol): C, 79.58; H, 7.16; N, 13.26. Found: C, 77.95;
H, 7.52; N, 12.62.
[N,N′-(6,6′-Dim et h ylb ip h en yl-2,2′-d iyl)b is(2-p yr r ole-
m eth yl)d iim in e]Na 2 (1Na 2). A solution of 1H2 (2.7 g, 6.8
mmol) in THF (30 mL) was stirred with NaH (1.6 g, 67 mmol)
at room temperature for 2 h and then filtered, the filtrate
evaporated to dryness, and the residue dried in vacuo to yield
a light yellow powder (2.6 g, 94%), which was used in the next
step without purification. 1H NMR (250 MHz, CD2Cl2): δ 1.72
(s, 6H, CH3), 1.80 (m, THF), 3.64 (m, THF), 6.32 and 6.36 (m,
4H, Ar-H), 6.77 (m, 4H, Ar-H), 6.89 (m, 2H, Ar-H), 8.20 (s,
2H, NdCH) ppm.
N,N′-(6,6′-Dim et h ylb ip h en yl-2,2′-d iyl)-N,N′-b is(2-p y-
r id ylm eth yl)d ia m id o-Zr (CH2P h )2 (2-Zr (CH2P h )2). A solu-
tion of 2H2 (0.40 g, 1.01 mmol) in hexane/toluene (13 + 5 mL)
was added to a suspension of Zr(CH2Ph)4 (0.46 g, 1.01 mmol)
in hexane (15 mL) at room temperature. The reaction mixture
was stirred in the dark for 48 h, during which a yellow
precipitate was formed. This was collected by filtration,
washed three times with hexane (5 mL), and dried in vacuo.
Yield: 0.35 g (52%). 1H NMR (600 MHz, C6D6): δ 2.07 (d, J )
9.4 Hz, 2H, ZrCHAHB), 2.28 (s, 6H, CH3), 2.39 (d, J ) 9.4 Hz,
2H, ZrCHAHB), 4.42 (d, J 18.8 Hz, 2H, NCHAHB), 4.70 (d, J )
18.8 Hz, 2H, NCHAHB), 6.43 (m, 4H, ZrCH2CCH), 6.45 (m, 2H,
pyridine-NCCH), 6.64 (m, 4H, ZrCH2Ph-para-H and pyridine-
NCHCH), 6.86 (m, 4H, ZrCH2Ph-meta-H), 6.91 (m, 2H, pyri-
dine-para-H), 6.99 (m, 2H, bianiline-NCCH), 7.01 (m, 2H,
bianiline-CH3CCH), 7.23 (m, 2H, bianiline-NCCHCH), 8.40 (b,
2H, pyridine-NCH) ppm. 13C NMR (151 MHz, C6D6): δ 20.9
(CH3), 64.7 (N-CH2), 66.2 (Zr-CH2), 119.5 and 121.3 (ZrCH2-
Ph-para-C and pyridine-NCHCH), 120.9 (pyridine-NCCH),
121.1 (bianiline-NCCH), 123.9 (bianiline-CH3CCH), 125.7
(ZrCH2CCH), 127.5 (ZrCH2Ph-meta-C), 127.6 (bianiline-
NCCHCH), 129.3, 136.5 (pyridine-para-C), 136.8, 146.9
(pyridine-NCH), 149.9, 153.0, 165.1 ppm. Anal. Calcd for
C
40H38N4Zr (665.96 g/mol): C, 72.10; H, 5.75; N, 8.41. Found:
C, 71.74; H, 5.77; N, 8.41.
[N ,N ′-(6,6′-D im e t h y lb ip h e n y l-2,2′-d iy l)b is (2-p y r -
r olem eth yl)d iim in e]Zr Cl2(THF ) (1-Zr Cl2(THF )). A solu-
tion of 1Na2 (0.52 g, 1.3 mmol) in THF (15 mL) was added to
a stirred suspension of ZrCl4(THF)2 (0.48 g, 1.3 mmol) in THF
(20 mL) at -78 °C. The reaction mixture was allowed to reach
room temperature and stirred for another 20 h. The resulting
dark red solution was evaporated to dryness, the solid residue
N,N′-(6,6′-Dim eth ylbiph en yl-2,2′-diyl)-N,N′-bis[(6-m eth -
yl-2-p yr id yl)m eth yl]d ia m id o-Zr (CH2P h )2 (3-Zr (CH2P h )2).
This complex was prepared in the same manner as 2-Zr(CH2-
Ph)2 except that only hexane was used as solvent. Yield: 0.60
g, 72%. 1H NMR (600 MHz, C6D6): δ 2.09 (d, J 9.2 Hz, 2H,
ZrCHAHB), 2.28 (s, 6H, bianiline-CH3), 2.53 (d, J ) 9.2 Hz,

3806 Organometallics, Vol. 23, No. 16, 2004
Ta ble 4. Deta ils of th e Cr ysta l Str u ctu r e Deter m in a tion s
Kettunen et al.
2-Zr(tBu4biphenO2)‚
1-ZrCl2(THF)
0.5 NHMe2
3-ZrCl2‚toluene
228863
3-Zr(CH2Ph)2
CCSD no.
228862
228865
228864
formula
fw
C
28H28Cl2N4OZr
C54H64N4O2Zr‚(C2H7N)0.5
914.85
C28H28Cl2N4Zr‚C7H8
674.80
C42H42N4Zr
694.02
598.66
temperature (K)
cryst syst
space group
unit cell a (Å)
b (Å)
153
monoclinic
C2/c
16.754(3)
13.906(3)
12.633(3)
90
117.23(3)
90
173(2)
monoclinic
C2/c
35.332(1)
12.226(1)
23.289(1)
90
92.950(1)
90
173(2)
triclinic
P1h
173(2)
monoclinic
P21/c
17.6380(14)
13.8130(18)
15.9220(8)
90
116.330(6)
90
10.7740(9)
12.3440(11)
12.7330(11)
106.110(6)
94.849(7)
95.488(7)
1608.5(2); 2
1.393
0.538; 696
0.1 × 0.1 × 0.1
5.03 to 27.50
17 704/5668
[R(int) ) 0.0659]
0.948, 0.948a
5668/0/379
0.995
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3); Z
2617.2(9); 4
1.519
10046.8(11); 8
1.210
3476.7(6); 4
1.326
dcalcd (g/cm3)
µ (mm-1), F(000)
cryst size (mm)
θ range (deg)
no. of reflns collected/unique
0.654; 1224
0. 5 × 0.1 × 0.1
2.00 to 25.02
4732/2295
[R(int) ) 0.0466]
0.940, 0.845b
2295/0/164
1.030
0.263; 3880
0.24 × 0.2 × 0.2
5.02 to 27.51
37 895/11 406
[R(int) ) 0.0961]
0.949, 0.940a
11 406/36/565
1.017
0.352; 1448
0.2 × 0.2 × 0.15
5.00 to 27.50
36 747/7921
[R(int) ) 0.0687]
0.949, 0.933a
7921/0/424
1.028
T
max, Tmin
no. of data/restraints/params
GoF(F2)
final R indices [I>2σ(I)]
R1 ) 0.0314,
wR2 ) 0.0692
R1 ) 0.0573,
wR2 ) 0.0765
0.375
R1 ) 0.0636,
wR2 ) 0.1295
R1 ) 0.1389,
wR2 ) 0.1530
0.753
R1 ) 0.0504,
wR2 ) 0.1003
R1 ) 0.0982,
wR2 ) 0.1203
0.572
R1 ) 0.0452,
wR2 ) 0.0974
R1 ) 0.0856,
wR2 ) 0.1103
0.507
R indices (all data)
largest diff peak (e Å-3
)
a
b
Absorption correction semiempirical from equivalents. Absorption correction using psi-scan data.
2H, ZrCHAHB), 2.60 (s, 6H, pyridine-CH3), 4.47 (d, J ) 22.4
Hz, 2H, NCHAHB), 4.58 (d, J ) 18.8 Hz, 2H, NCHAHB), 6.03
(m, 4H, ZrCH2CCH), 6.24 (m, 2H, pyridine-NCCH), 6.42 (m,
2H, pyridine-CH3CCH), 6.51 (m, 2H, ZrCH2Ph-para-H), 6.66
(m, 4H, ZrCH2Ph-meta-H), 6.81 (m, 2H, pyridine-para-H), 6.93
(m, 2H, bianiline-NCCH), 7.01 (m, 2H, bianiline-CH3CCH),
7.18 (m, 2H, bianiline-NCCHCH) ppm. 13C NMR (151 MHz,
C6D6): δ 20.9 (bianiline-CH3), 25.3 (pyridine-CH3), 61.7
(Zr-CH2), 67.2 (N-CH2), 118.7 (pyridine-CH2CCH), 119.3
(ZrCH2Ph-para-C), 122.4 (pyridine-CH3CCH), 122.7 (bianiline-
NCCH), 124.2 (bianiline-CH3CCH), 125.0 (ZrCH2CCH), 127.5
(ZrCH2Ph-meta-C), 127.8 (bianiline-NCCHCH), 134.3, 136.4,
136.9 (pyridine-para-C), 149.6, 155.7, 156.2, 163.6 ppm. Anal.
Calcd for C42H42N4Zr (694.02 g/mol): C, 72.68; H, 6.10; N, 8.07.
Found: C, 72.28; H, 6.26; N, 8.43.
N,N′-(6,6′-Dim eth ylbiph en yl-2,2′-diyl)-N,N′-bis[(6-m eth -
yl-2-p yr id yl)m eth yl]d ia m id o-Zr Cl2 (3-Zr Cl2). A solution of
ligand 3H2 (0.56 g, 1.3 mmol) in hexane (20 mL) was stirred
with excess CaH2 at room temperature for 0.5 h and filtered.
N-BuLi (2.7 mmol) was added dropwise to the filtrate at 0 °C.
The reaction mixture was stirred at room temperature for 5
h, dilluted with 4 mL of THF, and added to a suspension of
ZrCl4 (0.3 g, 1.3 mmol) in toluene (20 mL). The reaction
mixture was stirred at room temperature for 20 h and
evaporated and the residue extracted with toluene. Only a few
milligrams of yellow crystals were obtained from the toluene
filtrate, which were subjected to X-ray crystallography. As
judged from 1H NMR, further extraction of the solid evapora-
tion residue with CH2Cl2 yielded an inseparable mixture of
products.
evaporation to dryness. J udging from its 1H NMR, the solid
residue appeared to be a mixture of products. Recrystallization
from toluene yielded only a few milligrams of crystalline 2-Zr-
(tBu4biphenO2), which was identified by X-ray crystallogra-
phy.
Cr ysta l Str u ctu r e Deter m in a tion s. Single crystals of
3-Zr(CH2Ph)2, 3-ZrCl2, and 2-Zr(tBu4biphenO2) were selected
for the X-ray measurements and mounted on a glass fiber
using the oil drop method. Data were collected on a Nonius
KappaCCD diffractometer using Mo KR radiation (71.073 pm)
and a graphite monochromator. Data for 1-ZrCl2(THF) were
collected on a Enraf Nonius CAD4 four-circle diffractometer.
The structures were solved by direct methods. All nonhydrogen
atoms were refined anisotropically.21 Hydrogen atoms were
introduced at calculated positions and refined with fixed
geometry with respect to their carrier atoms. Cell parameters
and the specific data collection parameters are summarized
in Table 4.
Molecu la r Mod elin g Ca lcu la tion s. All calculations were
done using the MM+ force field in the Hyperchem 5.0 program
package. The geometry of the ZrN4 fragment was imported
from the crystal structures of 3-ZrCl2 and 2-Zr(tBu4biphenO2),
respectively. The ZrN4 fragment was kept frozen while the
geometry of the remaining atoms, including the chloride atoms,
was optimized. Energy differences for cis- and trans-coordina-
tions were determined from single-point calculations, in which
all interactions with zirconium were neglected.
P olym er iza tion of P r op en e w ith 1-Zr Cl2(THF )/MAO.
In a Bu¨chi 1 L autoclave, 500 mL of toluene containing 2.75
mL (4.4 mmol) of methylaluminoxane (MAO, Witco, 1.6 M
solution in toluene, 5.2 mass % Al, molar mass ca. 800) was
saturated with propene (2 bar at 50 °C). In a Schlenk tube,
complex 1-ZrCl2(THF) (3.5 mg, 5.8 µmol) was stirred in 15 mL
of toluene and 2.75 mL (4.4 mmol) of MAO for 15 min, after
which it was transferred to the autoclave. During the poly-
merization reaction, the total pressure was kept constant at
N,N′-(6,6′-Dim et h ylb ip h en yl-2,2′-d iyl)-N,N′-b is(2-p y-
r id ylm e t h yl)d ia m id o-Zr (3,3′,5,5′-t Bu 4-1,1′-b i-2-p h e n o-
late) (2-Zr (tBu 4biph en O2)). 3,3′,5,5′-tBu4-1,1′-bi-2-phenol (0.39
g, 0.9 mmol) was added to a solution of Zr(NMe)4 (0.25 g, 0.9
mmol) in toluene (20 mL), and the reaction mixture was stirred
at room temperature for 20 h.The volatiles were evaporated,
and the residue was dried in vacuo for 6 h. Without further
purifications, the (3,3′,5,5′-tBu4-1,1′-bi-2-phenolate)Zr(NMe2)2
(4) thus obtained was dissolved in toluene (5 mL) and a toluene
solution of ligand 2H2 was added. The solution was stirred for
48 h at room temperature and refluxed for 2 h followed by
(21) Sheldrick, G. M. SHELXTL; University of Go¨ttingen: Ger-
many, 1990, 1997. Sheldrick, G. M. SADABS; University of Go¨ttin-
gen: Germany, 1996. Sheldrick, G. M. SHELX97; University of
Go¨ttingen: Germany, 1997.

Chiral Zirconium Complexes
Organometallics, Vol. 23, No. 16, 2004 3807
2 bar by further addition of propene. After 2 h, the autoclave
was vented and the reaction mixture drained into 1 L of
methanol acidified with 10 mL of concentrated aqueous HCl.
The precipitated polymer was collected by filtration, washed
with methanol, and dried at 50 °C to constant weight. Yield:
180 mg of a white powder, corresponding to an activity of 7.76
kg(polymer)/(mol(cat)‚h‚bar). Polymer 13C NMR spectra were
measured in C2D2Cl4 (δ 74.1 ppm) at 120 °C on a 600 MHz
spectrometer. Comparing the integral of the CH3 resonance
at δ 21.65 (365.5) to the sum of integrals of all CH3 resonances
at δ 19.59-21.65 (662.9) ppm gives 55% [mmmm] as a
measure of isotacticity of the polymer.
(10.4 mmol) of methylaluminoxane MAO (1.6 M) were stirred
in a Schlenk tube with 3.5 mL of toluene for 5 min and then
added to a 100 mL autoclave which already contained 38 mL
toluene and another 6.5 mL of MAO. The autoclave was
preheated to 45 °C, charged with ethylene (20 bar), and stirred
for 1 h. The autoclave was then vented and the reaction
mixture quenched by pouring it into 150 mL of a MeOH/HCl
solution. The white precipitate was filtered, washed with
MeOH, and dried at 60 °C to yield 2.6 g of polyethylene,
corresponding to an activity of 6.17 kg(polymer)/(mol(cat)‚h‚
bar).
P olymerization ofP ropene with 2-Zr(CH2P h)2/[P hNMe2H]-
[B(C6F 5)4]. In a Bu¨chi 1 L autoclave 500 mL of toluene was
saturated with propene (2 bar) and 11.3 mL (11.3 mmol) of
Al(i-Bu)3 was added at 50 °C. In a Schlenk flask, complex 2-Zr-
(CH2Ph)2 (7.5 mg, 11.3 µmol) in 15 mL of toluene was mixed
with 3.75 mL (11.3 µmol) of a 4 mM solution of [PhNMe2H]-
[B(C6F5)4] in toluene and transferred to the autoclave. The
reaction then proceeded as described above to yield 20 mg of
polypropene as a white powder, corresponding to an activity
of 0.44 kg(polymer)/(mol(cat)‚h‚bar).
Ack n ow led gm en t. Financial support from the foun-
dation of Fortum Oy (for M.K.) and from BASELL
GMBH is gratefully acknowledged. We thank Ms. Anke
Friemel for 2D NMR measurements.
Su p p or tin g In for m a tion Ava ila ble: Details of the crys-
tal structure determinations are available free of charge via
the Internet at http://pubs.acs.org.
P olym er iza tion of Eth en e w ith 1-Zr Cl2(THF )/MAO.
Complex 1-ZrCl2(THF)/MAO (11.1 mg, 21.07 µmol) and 6.5 mL
OM040011R