Group 4 metal complexes of nitrogen-bridged dialkoxide ligands: Synthesis, structure, and polymerization activity studies

Article abstract of DOI:10.1021/om0505817

Neutral soluble titanium(IV) and zirconium(IV) complexes of new amino-dialkoxide ligands {OCR₂CH₂N(CH₂Ph) CH₂CR₂O}^2- ({ONOR}^2-) have been prepared. Alcohol and alkane elimination

Full text of DOI:10.1021/om0505817

5620
Organometallics 2005, 24, 5620-5633
Group 4 Metal Complexes of Nitrogen-Bridged
Dialkoxide Ligands: Synthesis, Structure, and
Polymerization Activity Studies
Laurent Lavanant,† Loic Toupet,‡ Christian W. Lehmann,§ and
Jean-Franc¸ois Carpentier*,†
Organome´talliques et Catalyse, UMR 6509 CNRS-Universite´ de Rennes 1,
Institut de Chimie de Rennes, 35042 Rennes Cedex, France, Groupe Matie`re Condense´e et
Mate´riaux, Cristallochimie, UMR 6626 CNRS-Universite´ de Rennes 1, 35042 Rennes Cedex,
France, and Max-Planck-Institut fu¨r Kohlenforschung, Chemical Crystallography,
Postfach 101353, 45466 Mu¨lheim/Ruhr, Germany
Received July 12, 2005
Neutral soluble titanium(IV) and zirconium(IV) complexes of new amino-dialkoxide ligands
{OCR2CH2N(CH2Ph)CH2CR2O}2- ({ONOR}2-) have been prepared. Alcohol and alkane
elimination reactions from {ONOR}H2 (R ) Me, 1; p-tol, 2) and salt metathesis routes from
Li2{ONOMe} in situ-generated afford {ONOMe}Ti(OiPr)2 (3), {ONOR}2M (R ) Me, M ) Ti, 5;
Zr, 6; R ) p-tol, M ) Zr, 7), {ONOMe}Zr(CH2Ph)2 (8), {ONOMe}ZrCl2(THF)n (n ) 0, 9; n ) 1,
10), {ONOMe}Zr(NMe2)2 (11), and {ONOR}TiCl2 (R ) Me, 13; R ) p-tol, 14) in good yields.
X-ray crystallographic studies showed that 3, 8, 13, and 14 adopt in the solid state
mononuclear structures, with coordination of the nitrogen atom to the metal center. Dinuclear
structures with bridging alkoxide and amido ligands were observed for 6 and a mixed amido-
{ONOMe}Zr complex (12) isolated in the preparation of 11. NMR data are consistent with
the existence of a single monomeric species in toluene solution for all complexes, except 11
and dichlorozirconium complexes 9 and 10, for which mixtures of monomeric and possibly
aggregated species are observed in toluene and THF. The dynamic behavior of monomeric
species 3, 8, 13, and 14 in toluene was investigated by variable-temperature NMR
spectroscopy. The activation parameters determined by line-shape analysis, in particular
for 8 (∆Hq ) 20.0 ( 1 kcal‚mol-1; ∆Sq ) 13.1 ( 2 cal‚mol-1‚K-1) and 13 (∆Hq ) 17.4 ( 1
kcal‚mol-1; ∆Sq ) 11.4 ( 2 cal‚mol-1‚K-1), suggest a process involving dissociation of nitrogen,
inversion of configuration at nitrogen, and amine re-coordination. The bulkiness of the R
substituents affects the fluxional behavior of {ONOR}TiCl2 (R ) Me, 13; R ) p-tol, 14). The
THF-free dichlorozirconium complex 9 in combination with MAO generates highly active
but very unstable ethylene polymerization catalyst systems.
Introduction
generally considered to contribute sufficient electron
density to be isolobal to the cyclopentadienyl ligand.1,4
This situation is more critical for alkoxides (O-C(sp3)),
as evidenced by the large tendency of these ligands to
form aggregated structures with early transition met-
als.4 Introduction of a heteroatom with additional donor
functionalities into a chelating multidentate alkoxide
ligand can tackle this problem.4 However, reports of
well-characterized group 4 metal complexes with mul-
tidentate dialkoxide ligand systems, such as amino-
dialkoxides5-,8 or sulfur-bridged dialkoxides,9 are lim-
ited. Most of these systems have been used for polymeri-
zation10 or fine chemicals catalysis,11,12 and the exact
nature of the precursors and active species remains
unclear.
In this contribution, we describe a series of soluble
titanium(IV) and zirconium(IV) complexes of the new
tridentate amino-dialkoxide ligand systems {OCR2CH2N-
(CH2Ph)CH2CR2O}2- ({ONOR}2-, R ) Me, p-tolyl). The
objectives of this work were to define the {ONOR}2-
coordination properties in simple group 4 {ONOR}MX2
complexes, to allow structural comparison, in the solid
Numerous examples of nonmetallocene group 4 com-
plexes have now been reported.1 Among these, a diverse
range of complexes that contain heteroatom-bridged
diaryloxide ligands {OZO}2- (e.g., Z ) N, S) have been
identified as promising olefin polymerization cata-
lysts.2,3 In these systems, the bridging heteroatom Z can
provide, if coordinated, the stereochemically rigid frame-
work essential for stereoregular polymer formation.1
First of all, the bridging heteroatom X may also provide
an increased stabilization of reactive, electron-deficient
metal centers. Indeed, aryloxides (O-C(sp2)) are not
* Corresponding author. Fax: (+33)(0)223-236-939. E-mail:
jean-francois.carpentier@univ-rennes1.fr.
† Organome´talliques et Catalyse.
‡ Groupe Matie`re Condense´e et Mate´riaux.
§ Max-Planck-Institut.
(1) For reviews on post-metallocene complexes of group 4 metals,
see: (a) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew. Chem.,
Int. Ed. 1999, 38, 428-447. (b) Coates, G. W. J. Chem. Soc., Dalton
Trans. 2002, 467-475. (c) Gibson, V. C.; Spitzmesser, S. K. Chem. Rev.
2003, 103, 283-315. (d) Suzuki, Y.; Terao, H.; Fujita, T. Bull. Chem.
Soc. Jpn. 2003, 76, 1493-1517. (e) Corradini, P.; Guerra, G.; Cavallo,
L. Acc. Chem. Res. 2004, 37, 231-241.
10.1021/om0505817 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 10/04/2005

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5621
state and solution, with related systems that differ in
the size of chelate ring, the nature of the alkoxide carbon
and nitrogen substituents, and the nature of the het-
eroatom.9 The ethylene polymerization properties of
{ONOR}MX2/MAO and {ONOR}MR+ in situ-generated
catalysts have also been investigated.
nearly quantitative yield via ring-opening of isobutylene
oxide by benzylamine (eq 1). The para-tolyl-substituted
diol {ONOtol}H2 (2) was obtained from the reaction of
an excess of the p-tolyl Grignard reagent with the
appropriate amino-diester13 (eq 2). This route proved
more efficient than the ring-opening of the diaryl-
substituted oxirane (p-tol)2COCH2 (2-5 equiv) by ben-
zylamine, which yielded only the 1:1 amino-alcohol
product (p-tol)2C(OH)CH2NHCH2Ph. Both diols 1 and
2 were obtained as microcrystalline powders.
Results and Discussion
Ligand Synthesis. Two new ligands were prepared
to explore the influence of the R substituents in
{OCR2CH2N(CH2Ph)CH2CR2O}2- ligands and Ti(IV)
and Zr(IV) complexes thereof. The dimethyl-substituted
nitrogen-bridged diol {ONOMe}H2 (1) was prepared in
(2) For examples see: (a) Kakugo, M.; Miyatake, T.; Mizunuma, K.
Chem. Express. 1987, 2, 445-448. (b) Miyatake, T.; Mizunuma, K.;
Seki, Y.; Kakugo, M. Macromol, Rapid Commun. 1989, 10, 349-352.
(c) Van der Linden, A.; Schaverien, C. J.; Meiboom, N.; Ganter, C.;
Orpen, A. G. J. Am. Chem. Soc. 1995, 117, 3008-3021. (c) Tshuva, E.
Y.; Goldberg, I.; Kol, M. J. Am. Chem. Soc. 2000, 122, 10706-10707.
(d) Tshuva, E. Y.; Goldberg, I.; Kol, M. Inorg. Chem. 2001, 40, 4263-
4270. (e) Tshuva, E. Y.; Goldberg, I.; Kol, M., Goldschmidt, Z.
Organometallics 2001, 20, 3017-3028. (f) Tshuva, E. Y.; Goldberg, I.;
Kol, M.; Goldschmidt, Z. Chem. Commun. 2001, 2120-2121. (g)
Tshuva, E. Y.; Groysman, S.; Goldberg, I.; Kol, M.; Goldschmidt, Z.
Organometallics 2002, 21, 662-670. (h) Balsells, J.; Carroll, P. J.;
Walsh, P. J. Inorg. Chem. 2001, 40, 5568-5574. (i) Tian, J. P.; Hustad,
D.; Coates, G. W. J. Am. Chem. Soc. 2001, 123, 5134-5135. (j) Boyd,
C. L.; Toupance, T.; Tyrell, B. R.; Ward, B. D.; Wilson, C. R.; Cowley,
A. R.; Mountford, P. Organometallics 2005, 24, 309-330. (k) Toupance,
T.; Dubberley, S. R.; Rees, N. H.; Tyrrell, B. R.; Mountford, P.
Organometallics 2002, 21, 1367-1382. (l) Fokken, S.; Spaniol, T. P.;
Kang, H.-C.; Massa, W.; Okuda, J. Organometallics 1996, 15, 5069-
5072. (m) Sernetz, F. G.; Muelhaupt, R.; Fokken, S.; Okuda, J.
Macromolecules 1997, 30, 1562-1569. (n) Capacchione, C.; Proto, A.;
Ebeling, H.; Mu¨lhaupt, R.; Mo¨ller, K.; Spaniol, T. P.; Okuda, J. J. Am.
Chem. Soc. 2003, 125, 4964-4965. (o) Natrajan, L. S.; Wilson, C.;
Okuda, J.; Arnold, P. L. Eur. J. Inorg. Chem. 2004, 3724-3732. (p)
Capacchione, C.; Manivannan, R.; Barone, M.; Beckerle, K.; Centore,
R.; Oliva, L.; Proto, A.; Tuzi, A.; Spaniol, T. P.; Okuda, J. Organome-
tallics 2005, 24, 2971-2982. (q) Takashima, Y.; Nakayama, Y.; Hirao,
T.; Yasuda, H.; Harada, A. J. Organomet. Chem. 2004, 689, 612-619.
(r) Janas, S.; Jerzykiewicz, L. B.; Przybylak, K.; Sobota, P.; Sczzegot,
K.; Wisniewska, D. Eur. J. Inorg. Chem. 2004, 1639-1645. (s) Janas,
S.; Jerzykiewicz, L. B.; Przybylak, K.; Sobota, P.; Sczzegot, K.;
Wisniewska, D. Eur. J. Inorg. Chem. 2005, 1063-1070.
Synthesis of Neutral Complexes. Several routes
to {ONOR}-Ti and {ONOR}-Zr complexes have been
explored: (a) σ-bond metathesis reactions between the
diols and an appropriate homoleptic metal precursor
enabling either alkane, alcohol, or amine elimination;
(b) salt elimination reactions between the Li2{ONOMe
}
salt in situ-generated and MCl4(THF)n. These results
are summarized in Schemes 1 and 2 and eq 3. The
prepared neutral complexes are all air- and moisture-
sensitive and were characterized in the solid state by
elemental analysis and X-ray diffraction studies for
some of them, and in solution by variable-temperature
1H and 13C NMR spectroscopy (vide infra).
(3) For theoretical studies on [(2-C6H4O)X(2′-C6H4O)]TiMe+ (X ) O,
S, Se, Te) systems, see: (a) Froese, R. D. F.; Musaev, D. G.; Matsubara,
T.; Morokuma, K. J. Am. Chem. Soc. 1997, 119, 7190-7196. (b) Froese,
R. D. F.; Musaev, D. G.; Morokuma, K. Organometallics 1999, 18, 373-
379.
The 1:1 σ-bond metathesis reaction of diol 1 and
Ti(OiPr)4 proceeded readily and selectively to yield
{ONOMe}Ti(OiPr)2 (3) (Scheme 1). Attempts to prepare
the parent zirconium complex {ONOMe}Zr(OtBu)2 (4)
with Zr(OtBu)4 and 1 under various conditions invari-
ably yielded mixtures of 4 and the bis-ligand complex
{ONOMe}2Zr (6), which could not be separated by
recrystallization.14 Both 6 and the analogous titanium
complex 5 were prepared efficiently by the reaction of
2 equiv of 1 with M(OR)4 complexes. Similar reaction
with the p-tolyl-substituted diol 2 afforded the parent
bis-ligand zirconium complex {ONOtol}2Zr (7) in quan-
titative yield. Complex 6 served as an efficient entry to
(4) (a) Bradley, D. C.; Mehrotra, R. M.; Rothwell, I. P.; Singh, A.
Alkoxo and Aryloxo Derivatives of Metals; Academic Press: London,
2001. (b) Mehrotra, R. M.; Singh, A. Prog. Inorg. Chem. 1997, 46, 239-
545. (c) Hubert-Pfalzgraf, L. G. Coord. Chem. Rev. 1998, 178-180,
967-997.
(5) Mack, H.; Eisen, M. J. Chem. Soc., Dalton Trans. 1998, 917-
921.
(6) (a) Shao, P.; Gendron, R. A. L.; Berg, D. J.; Bushnell, G. W.
Organometallics 2000, 19, 509-520. (b) Shao, P.; Gendron, R. A. L.;
Berg, D. J. Can. J. Chem. 2000, 78, 255-264.
(7) Gauvin, R. M.; Osborn, J. A.; Kress, J. Organometallics 2000,
19, 2944-2946.
(8) Lavanant, L.; Chou, T.-Y.; Chi, Y.; Lehmann, C. W.; Toupet, L.;
Carpentier, J.-F. Organometallics 2004, 23, 5450-5458.
the dibenzyl complex {ONOMe}Zr(CH2Ph)2
8 via
(9) Related group 4 sulfur-bridged dialkoxo complexes derived from
the parent sulfur-bridged ligand system {OCR2CH2SCH2CR2O}2-
({OSOR}2-, R ) Me, p-tolyl) have also been prepared. Lavanant, L.;
Silvestru, A.; Faucheux, A.; Toupet, L.; Jordan, R. F.; Carpentier, J.-
F. Organometallics 2005, 24, 5604-5619.
comproportionation with Zr(CH2Ph)4. Alcoholysis of
Zr(CH2Ph)4 with 1 affords a more direct and easier
synthesis of 8.
(10) (a) Manivannan, R.; Sundararajan, G. Macromolecules 2002,
35, 7883-7890. (b) Manivannan, R.; Sundararajan, G.; Kaminsky, W.
J. Mol. Catal. A: Chem. 2000, 160, 85-95. (c) Carone, C.; de Lima,
V.; Albuquerque, F.; Nunes, P.; de Lemos, C.; dos Santos, J. H. Z.;
Galland, G. B.; Stedile, F. C.; Einloft, S.; de S. Basso, N. R. J. Mol.
Catal. A: Chem. 2004, 208, 285-290.
(11) For use of amino- and pyridine-dialkoxide group 4 complexes,
see: (a) Manickam, G.; Sundararajan, G. Tetrahedron: Asymmetry
1999, 10, 2913-2925. (b) Sundararajan, G.; Prabagaran, N.; Varghese,
B. Org. Lett. 2001, 3, 1973-1976. (c) Hawkins, J. M. H.; Sharpless, B.
Tetrahedron Lett. 1987, 28, 2825-2828. (d) Zambrano, C. H.; Mc-
Mullen, A. K.; Kobriger, L. M., Fanwick, P. E.; Rothwell, I. P. J. Am.
Chem. Soc. 1990, 112, 6565-6570.
(12) Leading references for use of simple (without heteroatom
bridge) dialkoxide group 4 complexes: (a) Bachand, B.; Wuest, D.
Organometallics 1991, 10, 2015-2025. (b) Duthaler, R. O.; Hafner, A.
Chem. Rev. 1992, 92, 807-832. (c) Gothelf, K. V.; Jorgensen, A. J.
Organomet. Chem. 1994, 59, 5687-5691. (d) Yamasaki, S.; Kanai, M.;
Shibasaki, M. J. Am. Chem. Soc. 2001, 123, 1256-1257. (f) Ackermann,
L.; Bergman, R. G.; Loy, R. N. J. Am. Chem. Soc. 2003, 125, 11956-
11963.
(13) Cook, C. J.; Topich, J. Inorg. Chim. Acta 1988, 144, 81-87.
(14) The opposite trend was observed with the related sulfur-bridged
ligand {OSOMe 2-; that is, alcohol elimination reactions of {OSOMe}-
}
H2 were selective with Zr(OtBu)4 but not with Ti(OiPr)4; see ref 9.

5622 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
Scheme 1
yield. Complex 9 was also prepared in a one-pot
procedure by generating first “Zr(nBu)2Cl2” from ZrCl4
and nBuLi15 and then adding 2 equiv of 1 to perform
an alkane elimination. Salt metathesis between ZrCl4-
(THF)2 and the in situ-generated dilithium salt of 1, Li2-
{ONOMe}, proceeded readily in THF solution to give the
dichloro complex with a single THF ligand {ONOMe}-
ZrCl2(THF) (10). Alternatively, reaction of Zr(NMe2)4
with 2 equiv of 1 gave in quantitative yield the diamido
complex {ONOMe}Zr(NMe2)2 (11),16 which was further
converted to dichloro complex 10 upon treatment with
ClSiMe3 in THF solution.
THF-free dichlorotitanium complexes {ONOR}TiCl2
(13, R ) Me; 14, R ) p-tol) were prepared by alcohol
elimination between the corresponding diol (1 and 2,
respectively) and Ti(OiPr)2Cl2,10,17 in situ-generated
from TiCl4 and Ti(OiPr)4 (eq 3).
Solid-State Structures of Neutral Complexes.
The solid-state structures of 3, 6, 8, 12,16 13, and 14
were determined by single-crystal X-ray diffraction
studies. Crystallographic data and selected bond dis-
tances and angles are listed in Tables 1-7.
The solid-state structures of 3, 13, and 14 are quite
similar and will be discussed first (Figures 1-3). These
compounds all adopt five-coordinate, distorted trigonal
bipyramidal, monomeric structures in which the equa-
torial positions are occupied by the two oxygen atoms
of the chelating dialkoxide and an additional X ligand
(OiPr and Cl, respectively).18 The nitrogen atom is
coordinated on an axial position. A (noncrystallographic)
plane of symmetry embraces the Ti, N, and both X
atoms, which confers an approximate Cs symmetry to
these molecules. The Ti-O bond distances involving the
chelating dialkoxide ligand in the three compounds
differ within less than 0.02 Å in a given complex. In
the dichloro complexes 13 and 14, those distances are
similar (1.767(2)-1.792(1) Å), indicative of a minimal
steric influence of the R substituent R to O (Me vs p-tol),
and compare well with those observed in the related
complex {OSOMe}TiCl2(THF)2 (1.761(2), 1.765(2) Å).9
Somewhat longer Ti-O bond distances are observed in
the isopropoxide complex 3 (1.842(1)-1.852(1) Å), pos-
sibly reflecting the higher electron density at the metal
Scheme 2
(15) (a) Eisch, J. J.; Owuor, F. A.; Shi, X. Organometallics 1999,
18, 1583-1585. (b) Eisch, J. J.; Owuor, F. A.; Otieno, P. O. Organo-
metallics 2001, 20, 4132-4134.
(16) The identity of 11 was unambiguously confirmed by elemental
analysis and its reactivity (selective conversion to 10). The 1H NMR
spectra of 11 in toluene-d8 and THF-d8 featured many unresolved
resonances, indicative of the presence of several species in solution.
Upon recrystallization of 11 from toluene, X-ray suitable crystals of
{κ2-ONOMe}Zr(µ2-NMe2)(µ2,κ3-{ONOMe})Zr(κ2-{ONOMe})(NMe2) (12), a
dimeric species that results from the exchange of two NMe2 units by
Two {ONOMe}ZrCl2(THF)n complexes with a variable
number of THF ligands (n ) 0, 1) were prepared as
shown in Scheme 2. Comproportionation of bis-ligand
complex 6 with ZrCl4 in toluene gave the THF-free
complex {ONOMe}ZrCl2 (9) in virtually quantitative
2-
a {ONOMe
}
moiety, were isolated.
(17) Gothelf, K. V.; Jorgensen K. A. J. Org. Chem. 1994, 59, 5687-
5691.
(18) Dihedral angles: 3, Ti(1)-O(2)-O(8)-O(20) ) 37.79°; 8, Zr(1)-
C(23)-C(24)-N(1) ) 2.18°; 13, Ti(1)-O(1)-O(2)-Cl(1) ) 31.65°; 14,
Ti(1)-O(1)-O(2)-Cl(1) ) 33.03°.

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5623
Table 1. Crystal Data and Structure Refinement for 3, 6, 8, 12, 13, and 14
3
6‚C5H12
8‚C6H6
12
13‚2C6H6
14‚C7H8
formula
C
21H37NO4Ti
C60H92N4O8Zr2
0.35 × 0.33 ×
0.21
1251.96
orthorhombic
Pbca
25.9133(2)
21.78440(10)
23.7752(2)
90.00
90.00
90.00
13421.24(17)
8
C
29H37NO2Zr
C26.25H42.50N2.50O3Zr
0.07 × 0.03 ×
0.03
C15H23NO2TiCl2
0.25 × 0.22 ×
0.12
C
39H39NO2TiCl2
cryst size, mm
0.06 × 0.03 ×
0.25 × 0.10 ×
0.25 × 0.20 ×
0.01
0.10
0.18
M, g‚mol-1
cryst syst
space group
a, Å
415.42
orthothombic
Pbca
9.23220(10)
16.1665(2)
30(0860(5)
90.00
90.00
90.00
1526.9(5)
2
600.92
triclinic
P1h
532.35
524.36
764.62
triclinic
P1h
triclinic
P1h
monoclinic
P21/n
8.9747(2)
17.5058(4)
17.6712(4)
90.00
95.0630(10)
90.00
2765.48(11)
4
8.2126(15)
11.844(2)
15.873(3)
88.381(3)
82.016(3)
87.221(3)
1526.9(5)
2
10.2018(3)
15.2094(4)
19.0889(5)
75.4540(10)
76.6110(10)
80.5690(10)
2771.41(13)
4
11.6927(2)
12.8447(3)
13.5239(4)
93.4990(10)
103.2660(10)
97.669(2)
1950.37(8)
2
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
Dcalc, Mg/m3
T, Κ
1.307
100(2)
1.239
120(1)
2.06-27.49
0.363
1.307
100(2)
1.276
1.259
150(1)
1.302
120(1)
100
θ range, deg
1.72-28.32
0.391
1.72-28.32
0.391
3.11
1.64-27.50
0.525
2.13-27.51
0.396
µ, mm-1
31.01
no. of measd reflns
no. of indep reflns
no. of reflns I>2σ(I)
no. of params
goodness of fit
R {I > 2σ(I)}
wR2
18097
210699
15400
18097
48557
37757
25631
7157
7601
17693
6356
8976
6431
12611
6431
14018
4289
7155
356
687
356
582
353
470
1.034
1.125
1.034
1.089
1.029
1.027
0.0325
0.0756
0.398
0.0520
0.0325
0.0756
0.609
0.0585
0.0500
0.0481
0.1248
0.1430
0.1345
0.1230
lgst diff, e‚Å-3
1.192
2.427
0.575
0.499
Table 2. Selected Bond Lengths (Å) and Angles
(deg) for 3
Table 5. Selected Bond Lengths (Å) and Angles
(deg) for 8‚C6H6
N(5)-Ti(1)
2.4473(12) C(22)-O(20)-Ti(1) 135.99(10)
N(1)-Zr(1)
O(1)-Zr(1)
O(2)-Zr(1)
C(16)-Zr(1)
C(17)-Zr(1)
C(23)-Zr(1)
C(24)-Zr(1)
2.4056(15) C(24)-C(23)-Zr(1) 83.04(11)
1.9667(12) C(17)-C(16)-Zr(1) 101.81(11)
O(8)-Ti(1)
1.8518(11) O(10)-Ti(1)-N(5)
1.8418(11) O(8)-Ti(1)-N(5)
1.7856(11) O(2)-Ti(1)-N(5)
170.35(5)
75.77(4)
76.14(4)
O(2)-Ti(1)
1.9625(12) O(1)-Zr(1)-O(2)
2.3008(18) O(1)-Zr(1)-C(16)
144.96(5)
101.26(6)
103.04(6)
143.94(6)
123.54(6)
72.36(5)
O(10)-Ti(1)
O(20)-Ti(1)
C(7)-O(8)-Ti(1)
C(3)-O(2)-Ti(1)
1.8102(11) O(20)-Ti(1)-N(5) 86.47(4)
126.59(9) O(10)-Ti(1)-O(20) 103.16(5)
127.11(9) O(2)-Ti(1)-O(10) 100.35(5)
2.977(18)
2.2917(18) N(1)-Zr(1)-C(24)
2.561(18) N(1)-Zr(1)-C(16)
O(1)-Zr(1)-C(24)
C(12b)-O(10)-Ti(1) 159.6(3)
O(8)-Ti(1)-O(10) 99.45(5)
C(1)-O(1)-Zr(1) 129.47(11) N(1)-Zr(1)-O(1)
C(6)-O(2)-Zr(1) 130.23(10) N(1)-Zr(1)-O(2)
72.73(5)
Table 3. Selected Bond Lengths (Å) and Angles
Table 6. Selected Bond Lengths (Å) and Angles
(deg) for 13‚2C6H6
(deg) for 6‚C5H12
N(1)-Ti(1)
O(1)-Ti(1)
O(2)-Ti(1)
Cl(1)-Ti(1)
Cl(2)-Ti(1)
2.3743(17) Cl(2)-Ti(1)-N(1) 172.26(7)
1.7827(17) O(1)-Ti(1)-O(2)
1.7670(18) O(1)-Ti(1)-Cl(1)
118.83(9)
116.63(6)
116.78(7)
100.41(6)
76.26(7)
75.73(7)
O(1)-Zr(1)
O(2)-Zr(1)
O(3)-Zr(1)
O(3)-Zr(2)
O(4)-Zr(1)
O(4)-Zr(2)
O(5)-Zr(2)
O(6)-Zr(2)
O(7)-Zr(1)
O(7)-Zr(2)
O(8)-Zr(1)
Zr(1)-Zr(2)
N(2)-Zr(2)
O(2)-Zr(1)-O(4) 159.95(8)
O(1)-Zr(1)-O(7) 164.60(8)
O(3)-Zr(1)-O(8) 154.18(8)
O(3)-Zr(2)-O(5) 198.42(8)
O(4)-Zr(2)-O(6) 165.16(8)
O(7)-Zr(2)-N(2) 139.82(8)
1.957(2)
1.963(2)
2.223(2)
C(1)-O(1)-Zr(1)
C(5)-O(2)-Zr(1)
151.37(19)
151.6(2)
2.2610(8)
2.2852(7)
O(2)-Ti(1)-Cl(1)
O(2)-Ti(1)-Cl(2)
C(16)-O(3)-Zr(1) 140.18(17)
2.2159(19) C(16)-O(3)-Zr(2) 119.19(16)
2.2870(19) C(20)-O(4)-Zr(1) 131.49(16)
C(1)-O(1)-Ti(1) 131.64(14) O(1)-Ti(1)-N(1)
C(5)-O(2)-Ti(1) 133.13(15) O(2)-Ti(1)-N(1)
2.198(2)
1.941(2)
1.951(2)
C(20)-O(4)-Zr(2) 116.65(16)
C(35)-O(5)-Zr(2) 163.5(2)
C(31)-O(6)-Zr(2) 160.51(19)
Table 4. Selected Bond Lengths (Å) and Angles
(deg) for 14‚C7H8
2.3454(19) C(50)-O(7)-Zr(1) 128.45(16)
2.054(2)
1.949(2)
3.2342(4)
2.395(2)
C(50)-O(7)-Zr(2) 134.11(17)
C(46)-O(8)-Zr(1) 157.90(19)
N(1)-Ti(1)
O(1)-Ti(1)
O(2)-Ti(1)
Cl(1)-Ti(1)
Cl(2)-Ti(1)
2.3377(17) Cl(2)-Ti(1)-N(1) 164.52(5)
1.7917(15) O(2)-Ti(1)-O(1)
1.7924(14) O(1)-Ti(1)-Cl(1)
126.27(7)
113.27(5)
112.78(5)
97.73(5)
75.54(6)
75.52(6)
O(1)-Zr(1)-O(2)
O(1)-Zr(1)-O(8)
O(2)-Zr(1)-O(7)
O(2)-Zr(1)-O(8)
O(3)-Zr(2)-O(4)
O(3)-Zr(2)-O(6)
O(3)-Zr(2)-N(2)
97.89(9)
101.58(9)
93.67(8)
99.58(9)
73.53(7)
94.22(8)
70.00(8)
2.2496(6)
2.2684(6)
O(2)-Ti(1)-Cl(1)
O(2)-Ti(1)-Cl(2)
C(1)-O(1)-Ti(1) 131.17(12) O(1)-Ti(1)-N(1)
C(4)-O(2)-Ti(1) 131.93(12) O(2)-Ti(1)-N(1)
center. The Ti-O-C angles in 3 (126.59(9)°, 127.11(9)°),
13 (131.6(1)°, 133.1(1)°), and 14 (131.2(1)°, 131.9(1)°) are
bent to the same extent as in the diamino-dialkoxide-
Ti complex {{-CH2N(Me)CH2C(CF3)2O}2}TiCl2 (129.8(1)°,
129.4(1)°).8 It is reasonable to describe the oxygens in
complexes 3, 13, and 14 as sp2-hybridized and to regard
the alkoxides as four-electron (σ, π) donors; however,
because of the more acute M-O-C angles, the oxygens
in these complexes are less donor than in Berg’s six-
membered-ring amino-dialkoxide species {N{CH2-
CH2C(O)Me2}2}ZrX2, resulting in higher electron-defi-
ciency at the metal center. The five-membered chelate
rings in 3, 13, and 14 are rather flat and appear not to
be significantly strained. Due to the trans influence of
the OiPr ligand, the Ti-N bond distance (2.447(1) Å)
in 3 is longer than in chloro complexes 13 (2.374(2) Å)
and 14 (2.338(2) Å).
The solid-state structure of the dibenzyl complex 8
(Figure 4) follows the gross features of the compounds
previously discussed. The coordination of the {ONOMe
}
2-
ligand is meridional with the two oxygens occupying the
axial sites; the O-Zr-O angle (144.96(5)°) is, however,
significantly smaller than 180°.18 The Zr-O distances
(1.967(1), 1.963(1) Å) are ca. 0.15-0.20 Å longer than
the corresponding Ti-O bonds, reflecting the ca. 15%
difference in the metal ionic radii,19 and fall in the range

5624 Organometallics, Vol. 24, No. 23, 2005
Table 7. Selected Bond Lengths (Å) and Angles (deg) for 12
Lavanant et al.
O(2a)-Zr(1a)
O(8a)-Zr(1a)
O(2c)-Zr(1a)
1.931(2)
1.990(2)
2.273(2)
2.263(2)
1.950(2)
1.948(2)
2.224(2)
2.196(2)
2.094(3)
2.434(3)
2.157(3)
2.388(2)
3.2502(4)
163.20(9)
158.07(10)
163.93(9)
C(3a)-O(2a)-Zr(1a)
C(7a)-O(8a)-Zr(1a)
C(3c)-O(2c)-Zr(1a)
C(7c)-O(8c)-Zr(1a)
C(3b)-O(2b)-Zr(1b)
C(7b)-O(8b)-Zr(1b)
C(3c)-O(2c)-Zr(1b)
C(7c)-O(8c)-Zr(1b)
O(8b)-Zr(1b)-O(8c)
O(2b)-Zr(1b)-O(2c)
N(25)-Zr(1b)-O(5c)
O(2a)-Zr(1a)-O(8a)
O(2a)-Zr(1a)-N(22)
O(2a)-Zr(1a)-N(25)
O(2a)-Zr(1a)-O(8c)
O(8a)-Zr(1a)-O(8c)
164.4(2)
139.0(2)
131.82(17)
139.62(17)
159.63(19)
162.3(2)
114.74(17)
118.97(17)
169.64(8)
166.55(8)
141.87(9)
96.47(9)
95.40(10)
93.44(9)
96.78(9)
95.36(8)
O(8c)-Zr(1a)
O(2b)-Zr(1b)
O(8b)-Zr(1b)
O(2c)-Zr(1b)
O(8c)-Zr(1b)
N(22)-Zr(1a)
N(25)-Zr(1a)
N(25)-Zr(1b)
N(5c)-Zr(1b)
Zr(1a)-Zr(ab)
N(25)-Zr(1a)-O(8a)
N(22)-Zr(1a)-O(8c)
N(2a)-Zr(1a)-O(2c)
(ca. 1.95-2.08 Å) observed for alkoxy-Zr complexes.5-7,9,20
The Zr-N distance of 2.406(2) Å is similar to that of
2.419(12) Å found in the parent complex Zr{N{CH2-
CH2C(O)Me2}2{((S)-2-C6H4C(H)Me}}{CH2Ph}.6 As in
the latter complex, one benzyl group in 8 is η2-
coordinated, as evident from the acute Zr(1)-C(23)-
C(24) angle of 83.0(1)° and the short Zr(1)-C(24) contact
of 2.56(2) Å.7,21 We assume that η2-coordination of a
benzyl group in 8 reflects the electron-deficiency of this
compound (formally 14-e), as supported by acute Zr-
O-C angles (129.5(1)°, 130.2(1)°).5
The bis-ligand complex 6 adopts a dimeric structure
in which both zirconium atoms are in a highly distorted
octahedral coordination geometry (Figure 5). Two
2-
{ONOMe
}
ligands are in a terminal mode, while two
others bridge the zirconiums, with regular Zr-O bond
distances and Zr-O-C angles.22 Only one out of the four
Figure 1. ORTEP view of {ONOMe}Ti(OiPr)2 (3). El-
lipsoids are drawn at the 30% probability level; all hydro-
gen atoms have been omitted for clarity.
Figure 3. ORTEP structure of {ONOtol}TiCl2 (14). El-
lipsoids are drawn at the 30% probability level; all hydro-
gen atoms have been omitted for clarity.
Figure 2. ORTEP view of {ONOMe}TiCl2 (13). Ellipsoids
are drawn at the 50% probability level; all hydrogen atoms
have been omitted for clarity.
Figure 4. ORTEP view of {ONOMe}Zr(CH2Ph)2 (8). El-
lipsoids are drawn at the 30% probability level; all hydro-
gen atoms have been omitted for clarity.

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5625
Figure 5. ORTEP view of {ONOMe}2Zr (6). Ellipsoids are
drawn at the 30% probability level; all hydrogen atoms
have been omitted for clarity.
Figure 6. ORTEP view of 12. Ellipsoids are drawn at the
30% probability level; all hydrogen atoms have been
omitted for clarity.
nitrogens is coordinated to Zr, and the overall molecule
is dissymmetric. The dinuclear structure of 6 contrasts
with the mononuclear structures observed for the six-
membered bis(amino-dialkoxide) complex Zr{MeN{CH2-
CH2C(O)Ph2}2}2, in which both nitrogen atoms are
coordinated to the metal center,5b and the five-mem-
bered sulfur-birdged complex Ti{OSOMe}2, which has a
tetrahedral coordination.9 We assume that, in these
cases, larger substituents at the R-positions (R ) Ph vs
Me) and a smaller metal center (Ti vs Zr), respectively,
prevent dimerization. Unfortunately, no suitable X-ray
crystal of {ONOtol}2Zr (7) could be obtained to assess
this hypothesis.
2D COSY, HMQC, and HMBC experiments. NMR
studies were performed in toluene or benzene solvent
to avoid the formation of solvent adducts.
1
The 261 K H NMR spectrum of {ONOMe}TiCl2 (13)
in toluene-d8 features sharp signals (Figure 7). Key
resonances include one singlet for the NCH2Ph group,
two AB doublets for the NCHH groups, and two singlets
for the CMe2 groups. The 243 K 13C NMR spectrum of
13 contains one set of benzyl resonances, one NCH2
resonance, and one methyl resonance. These data are
consistent with overall Cs symmetry. Coordination of the
N atom to Ti in 13 is most likely, as expected from the
metal center’s electron deficiency and as observed in the
solid-state structure, but the NMR data give no defini-
tive evidence for it.23
Complex 12, isolated during the synthesis of amido
complex 11,16 exhibits a dimeric structure very similar
to that of 6 (Figure 6). Formally, the two structures are
As shown in Figure 7, raising the temperature results
in broadening and coalescence of the NCHH resonances
obtained by replacing the {ONOMe 2- ligand in a mixed
}
(Tcoal ) ca. 300 K) and the methyl resonances (Tcoal
)
terminal-bridging mode by two NMe2 groups playing
the same role.
285 K), and at 320 K singlets are observed for those
groups. These data establish that 13 undergoes an
exchange process, as shown in eq 4. Line-shape analysis
confirmed that both the NCH2CMe2 hydrogens and the
CMe2 hydrogens exchange at the same (or at least quite
similar) rates (Figure 7), as expected for the fluxional
process in eq 4. The activation parameters for this
fluxional behavior (∆Hq ) 17.4 ( 0.5 kcal‚mol-1; ∆Sq )
11.4 ( 2 cal‚mol-1‚K-1) were derived from an Eyring
analysis (Figure 8).24
The structures of 6 and 12 are similar to that
observed for {{OSOMe}Zr(OtBu)2}2, i.e., (OtBu)2Zr(µ2-
OtBu)(µ2,κ3-{OSOMe})Zr(κ2-{OSOMe})(OtBu);9 these struc-
2-
tures all display a bridging {OZOMe
}
ligand with a
singly coordinated Z atom (Zr(2)-N(2) ) 2.395(2) Å in
6; Zr(1b)-N(5c) ) 2.388(2) Å in 12; Zr-S ) 2.768(1) Å9).
Solution Structure and Dynamics of Neutral
Complexes. The solution structures and dynamic
behaviors of the prepared complexes have been inves-
tigated by variable-temperature NMR spectroscopy.
A similar fluxional behavior was observed for
{ONOMe}Ti(OiPr)2 (3). The 252 K 1H NMR spectrum of
3 features the same pattern of resonances for the
1
Assignment of H and 13C resonances was made from
{ONOMe 2- ligand as that observed for 13, together with
}
(19) Effective ionic radii for six-coordinate metal centers: Ti4+, 0.605
Å; Zr4+, 0.72 Å. Shannon, R. D. Acta Crystallogr., Sect. A 1976, A32,
751-767.
(20) (a) Howard, W. A.; Trnka, T. M.; Parkin, G. Inorg. Chem. 1995,
34, 5900-5909. (b) Stephan, D. W. Organometallics 1990, 9, 2718-
2723. (c) Tsukahara, T.; Swenson, D. C.; Jordan, R. F. Organometallics
1997, 16, 3303-3313.
(21) (a) Latesky, S. L.; McMullen, A. K.; Niccolai, G. P.; Rothwell,
I. P.; Huffman, J. C. Organometallics 1985, 4, 902-908. (b) Jordan,
R. F.; Lapointe, R. E.; Bajgur, C. S.; Echols, S. F.; Willett, R. J. Am.
Chem. Soc. 1987, 109, 4111-4113. (c) Bochmann, M.; Lancaster, S.
J.; Hursthouse, M. B.; Malik, K. M. A. Organometallics 1994, 13, 2235-
2243.
(22) For examples of dimeric Zr alkoxides, see: (a) Evans, W. J.;
Ansari M. A.; Ziller J. W. Inorg. Chem. 1999, 38, 1160-1164. (b)
Fleeting, K. A.; O’Brien P.; Jones, A. C.; Otway, D. J.; White, A. J. P.;
William, D. J. J. Chem. Soc., Dalton Trans. 1999, 2853-2859. (c)
Vaartstra, B. A.; Huffman, J. C.; Gradeff, P. S.; Hubert-Pfalzgraf, L.-
G.; Daran, J.-C.; Parraud, S.; Yunlu, K.; Caulton, K. G. Inorg. Chem.
1990, 29, 3126-3131.
(23) No clear trend was observed in the 1H and 13C chemical shifts
of the NCH2CR2 and NCH2Ph units in complexes prepared in this study
that could be related to coordination of N to the metal center.
(24) (a) These values correspond well with the free energies of
activation determined experimentally from the coalescence tempera-
tures for both the NCH2CMe2 (Tc ) 300 K; ∆Gcoal ) 13.9(3) kcal‚mol-1
;
)
q
∆Gcalc ) 14.0 kcal‚mol-1) and CMe2 hydrogens (Tc ) 285 K; ∆Gcoal
q
q
14.3(3) kcal‚mol-1; ∆Gcalc ) 14.2 kcal‚mol-1). Exchange barriers ∆Gq
were determined from the coalesence of the NCH2 AB patterns using
the following equations for an equally populated, two-site exchange:
∆Gq ) 4.576Tc{10.319 + log(Tc/kc)} (kcal‚mol-1), where Tc is the
q
coalesence temperature and kc is the exchange rate constant at
coalesence, which is given by kc ) π{(∆νAB2 + 6JAB
}
1/2/21/2. The errors
2
on ∆Gcoalq were estimated assuming (2% uncertainty in the chemical
shifts and coalescence temperature.b-d (b) Alexander, S. J. Chem. Phys.
1962, 37, 967-974. (c) Kurland, R. J.; Rubin, M. B.; Wise, W. B. J.
Chem. Phys. 1964, 40, 2426-2427. (d) Kost, D.; Zeichner, A. Tetrahe-
dron Lett. 1974, 4533-4536.

5626 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
Figure 7. Experimental (left) and simulated (right) variable-temperature 1H NMR spectra of {ONOMe}TiCl2 (13) showing
the NCH2CMe2 (δ 2.80 and 2.50) and CMe2 (δ 1.20 and 1.05) resonances (toluene-d8, 400 MHz). The vertical expansion is
different in each case for clarity. Best-fit first-order rate constants (k) are shown with the simulated spectra. The markers
* and Σ denote resonances for PhCH3 and PhCHD2, respectively.
coalescence temperature for the NCH2CMe2 hydrogens
in 3 (Tc ) 285 K; ∆Gcoal ) 13.0 ( 0.3 kcal‚mol-1) is
q
slightly lower than that obtained for 13 (∆Gq (285 K) )
14.3 kcal‚mol-1).24 The similarity of these data indicates
limited influence of the X (Cl, OiPr) ligands on the
overall dynamics of {ONOMe}TiX2 complexes 3 and 13.
The 298 K 1H NMR spectrum of the dichlorotitanium
complex {ONOtol}TiCl2 (14), which bears p-tolyl sub-
stituents at the R positions in place of the methyl groups
in 13, displays the same characteristic sharp resonances
as those observed for 13 at low temperature. The AB
system for the inequivalent NCHHC(p-tol)2 hydrogens,
a singlet for the NCH2Ph hydrogens, and two singlets
for the p-C6H4Me groups indicate also a Cs-symmetric
Figure 8. Eyring plot for {ONOMe}TiCl2 (13) (toluene-d8
solvent).
structure with a mirror plane including the Ti, N, and
both Cl atoms. Upon heating, the Me p-tol resonances
q
coalesce first (Tcoal ) 345 K; ∆Gcoal ) 17.7 ( 0.3
kcal‚mol-1) and then those of the NCHHC(p-tol)2 (Tcoal
) 357 K; ∆Gcoalq ) 17.6 ( 0.3 kcal‚mol-1) (see Support-
ing Information).
The dibenzyl complex {ONOMe}Zr(CH2Ph)2 (8) fea-
tures dynamics in toluene solution similar to those of
3, 13, and 14 (Figure 9). The room-temperature 1H NMR
spectrum of 8 is in the slow exchange regime, and
freezing/resolution is achieved at 250 K. In addition to
the sharp AB doublets (NCHHCMe2), the two singlets
(NCH2CMe2), and the singlet (NCH2Ph, δ 3.56, not
shown in Figure 9) observed for 13, the low-temperature
two doublets for inequivalent CH3 in the OiPr groups.
At 320 K, three sharp singlets are observed for the CH3,
NCH2CMe2, and NCH2Ph hydrogens of the ligand, and
the OCH(CH3)2 hydrogens appear as a sharp doublet.
The free energy of activation determined from the

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5627
1
Figure 9. Experimental (left) and simulated (right) variable-temperature H NMR spectra of {ONOMe}Zr(CH2Ph)2 (8)
showing the NCH2CMe2 (δ 3.15 and 2.00), ZrCH2Ph (δ 2.35 and 1.75), and CMe2 (δ 1.45 and 1.15) resonances (toluene-d8,
400 MHz). The vertical expansion is different in each case for clarity. Best-fit first-order rate constants (k) are shown with
the simulated spectra. The markers * and Σ denote resonances for PhCH3 and PhCHD2, respectively.
spectrum of 8 displays two singlets for the ZrCHHPh
hydrogens. The observation of two Cipso signals for the
benzyl rings in the 13C spectrum, with one high-field
and one low-field resonance (δ 147.3 and 141.4), is
diagnostic for the presence of one η2-benzyl group and
one normal η1-benzyl group,21 as observed in the solid
state. Also, two benzylic CH2 13C signals (δ 54.9 and
1
53.6) are observed. Upon warming, the H resonance
systems (except the singlet for NCH2Ph) coalesce and,
at 375 K, a total of four singlets (some still broadened)
are observed. These data establish that 8 undergoes
exchange of the η2/η1-benzyl ligands, as shown in eq 5.
A line shape analysis (Figure 9) combined with an
Eyring analysis (Figure 10) confirmed that the NCH2-
CMe2, ZrCH2Ph, and CMe2 spin systems exchange at
Figure 10. Eyring plot for {ONOMe}Zr(CH2Ph)2 (8) (toluene-
the same (or at least quite similar) rate, as expected
d8 solvent).
for the fluxional process in eq 5, and gave the corre-
sponding activation parameters (∆Hq ) 20.0 ( 0.5
The positive values for the entropy of activation
kcal‚mol-1; ∆Sq ) 13.1 ( 2 cal‚mol-1‚K-1).25
associated with the dynamic processes for 8 and 13 (∆Sq
) 13.1 and 11.4 ( 2 cal‚mol-1‚K-1, respectively) are
consistent with the proposed dissociative processes
(25) These values correspond well with the free energies of activation
determined experimentally from the coalescence temperature for the
q
q
NCH2CMe2 (Tc ) 345 K; ∆Gcoal ) 15.6(3) kcal‚mol-1; ∆Gcalc ) 15.5
kcal‚mol-1), ZrCH2Ph (Tc ) 335 K; ∆Gcoal ) 15.7(3) kcal‚mol-1; ∆Gcalc
q
q
) 15.6 kcal‚mol-1), and CMe2 hydrogens (Tc ) 330 K; ∆Gcoal ) 15.7(3)
q
kcal‚mol-1; ∆Gcalc ) 15.7 kcal‚mol-1). See ref 24 for calculation details.
q

5628 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
outlined in eqs 4 and 5.26 These processes imply dis-
sociation of nitrogen, inversion of configuration at
nitrogen, and amine re-coordination. A similar process
has been proposed to account for the fluxional behavior
of related zirconium bis(amino-dialkoxide)5 and amino-
diamido27 complexes. The observation of a higher free
energy exchange barrier in the bis-ligand complexes Zr-
{MeN{CH2CH2C(O)R2}2}2 bearing phenyl substituents
(R ) Ph, ∆Gq . 15.9 kcal‚mol-1) as compared to methyl-
Figure 11. Plausible structures for monomeric {ONOMe}-
ZrCl2 (9) (not considering isomers resulting from inversion
at nitrogen)
substituted systems (R ) Me, ∆Gq ) 15.9 kcal‚mol-1
)
has led Berg to propose that inversion at nitrogen is
more energy demanding than amine dissociation;6 in-
deed, amine dissociation should be logically favored with
bulkier R substituents. This hypothesis, proposed on
systems where complicated processes can take place due
to the presence of two amino-dialkoxide ligands on the
metal center, is confirmed by our results with mono-
ligand complexes. Both 8 and 13, which have methyl
substituents R to the alkoxides, show similar enthalpies
of activation (∆Hq ) 20.0 and 17.4 ( 0.5 kcal‚mol-1
,
respectively), while the exchange process for complex
14, which has p-tolyl substituents at the R positions,
Figure 12. Schematic representations of some plausible
dinuclear structures for 9.
requires more energy (∆Gq
) 17.6 ( 0.3
coal(357 K)
kcal‚mol-1 for 14, vs 15.3 and 13.3 ( 0.3 kcal‚mol-1 for
8 and 13, respectively).
structures for 9b include a C1-symmetric monomeric
species (e.g., C, Figure 11) or a dimeric species (Figure
12), as observed in the solid state for complexes 6 and
12 (vide supra). The 9a/9b ratio varies from one batch
to another in the range 50:50 to 40:60, but does not
change with time, even after prolonged heating. The
observation of several isomers or species that may have
different nuclearity for 9 contrasts with the single
mononuclear species observed in solution and in the
solid state for the parent dichlorotitanium complexes
{ONOR}TiCl2 13 and 14. Dimerization of 9 is plausible
since Zr normally prefers a higher coordination number
vs Ti.28
Complex 9 readily dissolves in THF to form the mono-
THF adduct {ONOMe}ZrCl2(THF) (10), which is slightly
soluble in benzene. Coordination of a THF ligand in 10
in the solid state was established by elemental analysis.
Also, the 1H and 13C NMR spectrum of 10 in C6D6
contains resonances for a coordinated THF ligand (δ
1H: 3.33, 1.71; δ 13C: 70.6, 26.9), shifted upfield and
downfield from free THF resonances (δ(C6D6) 1H: 3.57,
1.40; δ 13C: 67.8, 25.7).
1
The H and 13C NMR data for the bis-ligand com-
plexes {ONOR}2M (5-7) in toluene solution are consis-
tent with mononuclear structures and feature dynamic
behaviors similar to those observed for the related six-
membered-ring species Zr{RN{CH2CH2C(O)R′2}2}2 de-
scribed by Berg and co-workers.5 The high-temperature
(300-360 K) 1H NMR spectra, in the fast exchange
regime, all feature sharp singlets for the NCH2CR2,
NCH2Ph, CMe2, and p-MeC6H4 hydrogens. In the slow
exchange regime, i.e., below 250 K for 5 and 6 and below
300 K for 7, the NCH2Ph and NCHHCR2 hydrogens
appear as two doublets and four doublets, respectively;
also, all the methyl groups are inequivalent and appear
as four singlets. This fluxional behavior can also be
accounted for by amine dissociation and inversion at
nitrogen followed by re-coordination, a process that is
hindered by bulky substituents in the case of 7.
The NMR spectra of the dichloro complexes {ONOMe}-
ZrCl2(THF)n 9 and 10 are more complicated and indicate
the coexistence of several isomers and/or species in
1
solution. The room-temperature H NMR spectrum of
the THF-free complex 9 in toluene-d8 features several
series of resonances, of which two account for more than
80% of the total. The simplest series (9a) contains one
singlet for the NCH2CMe2 hydrogens and two sets of
overlapping doublets for the NCH2CMe2 and NCH2Ph
hydrogens, suggesting a mononuclear species of high
symmetry (on the NMR time scale) (e.g., A or B, Figure
11). The second series (9b) features four doublets for
the NCHHCMe2, four singlets for the NCH2CMe2, and
two doublets for the NCHHPh hydrogens. Possible
In benzene solution, two major isomers of 10 (that
account for more than 80% of the total) are also
observed, one with a dissymmetric structure (10a) and
the other with a symmetric structure (on the NMR time
scale) (10b). The ratio 10a/10b is ca. 70:30 and does not
vary over several weeks in benzene at room tempera-
1
ture. The H and 13C NMR spectra of 10-d8 in THF-d8
revealed the existence of three major species, 10a′-10c′.
The ratio 10a′/10b′/10c′ was variable according to the
batch and the origin of 10 (dissolution of 9 in THF or
direct synthesis via salt metathesis in THF) (see Ex-
perimental Section). However, in all cases, the kinetic
mixtures slowly transformed at room temperature in
THF-d8 to yield the thermodynamic isomer, 10c′, in
(26) Purely dissociative mechanisms are generally characterized by
∆Sq values above 10 eu. See: (a) Atwood, J. D. Inorganic and
Organometallic Reaction Mechanisms; Brooks/Cole: Monterey, CA,
1985; p 17. (b) Jordan, R. B. Reaction Mechanisms of Inorganic and
Organometallic Systems; Oxford University: New York, 1991; pp 56-
57.
1
more than 90% selectivity after one week. The H and
(27) (a) Clark, H. C. S.; Cloke, F. G. N.; Hitchcock, P. B.; Love, J.
B.; Wainwright, A. P. J. Organomet. Chem. 1995, 501, 333-340. (b)
Horton, A. D.; de With, J.; van der Linden, A. J.; van de Weg, H.
Organometallics 1996, 15, 2672-2674.
(28) The complex ZrCl2{OSOMe}, which derives from the parent
sulfur-bridged dialkoxide, is completely insoluble in aromatic hydro-
carbons, also suggesting aggregated structures; see ref 9.

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5629
Figure 13. Some plausible structures for mononuclear {ONOMe}ZrCl2(THF) (10) (not considering isomers resulting from
inversion at nitrogen).
Table 8. Ethylene Polymerization Dataa
activityb
c
entry
catalyst precursor
activator (equiv)
time (min) yield (g) (kgPE‚mol-1‚h-1
)
Mwc (10-3
)
Mw/Mn
Tmd (°C)
1
2
3
4
5
6
{ONOMe}TiCl2 (13)
{ONOMe}TiCl2 (13)
{ONOtol}TiCl2 (14)
{ONOtol}TiCl2 (14)
{ONOMe}ZrCl2 (9)
{ONOMe}ZrCl2 (9)
MAO (500)
5
40
5
0.018
0.646
0.025
0.473
0.088
0.070
4.4
4.7
5.0
8.1
nd
606
136
625
262
375
nd
100
7.1
6.5
2.4
5.4
130.0
135.1
132.7
134.2
138.4
141.4
MAO (500)
MAO (500)
MAO (500)
30
MAO (500)
0.08
0.08
1780
[Ph3C][B(C6F5)4] (3)/
Al(iBu)3 (10)
1415
7
8
{ONOMe}ZrCl2(THF) (10) MAO (500)
{ONOMe}ZrCl2(THF) (10) [Ph3C][B(C6F5)4] (3)/
Al(iBu)3 (10)
30
30
0.000
0.000
0
0
9e
10
{ONOMe}Zr(CH2Ph)2 (8)
{ONOMe}Zr(CH2Ph)2 (8)
B(C6F5)3 (1)
[Ph3C][B(C6F5)4] (1)
30
30
0.000
0.000
0
0
a Polymerization experiments were conducted under 5 atm of ethylene using 30-140 µmol of catalyst precursor in 30-80 mL of toluene;
the results shown for each entry are representative of at least two reproducible runs. b Average activity calculated over the whole
polymerization time. c Determined by GPC. d Determined by DSC. e Conducted in the presence of 100 equiv of Al(iBu)3 as scavenger.
13C NMR spectra of 10c′ feature resonances for equiva-
lent NCH2CMe2, NCH2CMe2, and NCH2Ph groups,
reflecting a high-symmetry structure on the NMR time
scale. Because dimerization/aggregation is less probable
for six-coordinate species, as we observed for the related
species {OSOMe}TiCl2(THF)2 and {OSOMe}ZrCl2(THF)2,9
and obviously less probable in a strongly coordinating
solvent such as THF, we reasonably assume that the
different species observed both in benzene (10a, 10b)
and in THF (10a′, 10b′, 10c′) are all mononuclear
isomers. Possible structures are depicted in Figure 13.
Ethylene Polymerization. The prepared complexes
were briefly investigated in ethylene polymerization.
Neutral {ONOR}MCl2(THF)n complexes 9, 10, 13, and
14 were activated with MAO or a combination of [Ph3C]-
[B(C6F5)4] with Al(iBu)3,29 while molecular Lewis acidic
activators were used to generate cationic benzyl-
zirconium species from 8 in situ. The results are
summarized in Table 8.
orange-yellow reaction mixture was observed over 40
min and ethylene consumption continued over this
period,31 suggesting that the active species are quite
stable under these conditions. The nature of the R
substituent in these {OCR2CH2N(CH2Ph)CH2CR2O}-Ti
systems had a minor influence on polymerization per-
formance under the conditions investigated, as judged
by the similarity of apparent activities, molecular
weights, and melting points. The molecular weight of
polyethylene increased over the reaction time, while the
molecular weight distribution and melting points re-
mained almost constant (entries 3 and 4).
Catalysts based on the THF-free complex {ONOMe}-
ZrCl2 (9) are much more active than {ONOR}-Ti cata-
lysts but deactivate very fast (entries 5 and 6). Under
the conditions investigated, all of the polyethylene is
formed within 5 s, and no more ethylene is consumed
after this time. Minor changes in polymerization activity
and polymer characteristics arose on changing the
nature of the activator. The apparent activity of systems
based on 9 is higher than those reported for related
catalysts based on discrete zirconium precursors having
amino-alkoxide or amino-dialkoxide ligands,32 although
direct comparisons are difficult due to differences in
polymerization time and conditions. In contrast, the
THF-adduct {ONOMe}ZrCl2(THF) (10) (entry 6) gave no
activity, whatever the activation procedure, suggesting
Titanium complexes 13 and 14 activated by MAO in
toluene solution are poorly active for ethylene polym-
erization (entries 1-4).30 No discoloration of the pale
(29) (a) Chien, J. C. W.; Xu, B. Makromol. Chem. Rapid Commun.
1993, 14, 109-114. (b) Chien, J. C. W.; Tsai, W. M. Makromol. Chem.
Macromol. Symp. 1993, 66, 141-155. (c) Chen, Y. X.; Rausch, M. D.;
Chien, J. C. W. Organometallics 1994, 13, 748-749. (d) Chien, J. C.
W.; Rausch, M. D. J. Polym. Sci. Part A: Polym. Chem. 1994, 32, 2387-
2393. (e) Song, F. S.; Cannon, R. D.; Lancaster, S. J.; Bochmann M. J.
Mol. Catal. A 2004, 218, 21-28.
(30) Eisen and co-workers have reported that the Ti[Py{CPh2O)2]-
Cl2/MAO combination exhibits modest ethylene polymerization activity
(20 °C, 1 atm); see ref 5.
(31) In these experiments, polyethylene was recovered in virtually
the same amount as that of ethylene consumed; oligomers (if any) are
therefore negligible.

5630 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
that THF could act as poison. Also, no activity was
observed with discrete in situ-generated ionic zirconium-
benzyl species (entries 9 and 10). Berg6 and Kress7
observed similar insignificant or no ethylene polymer-
ization activity with [RN{CH2CH2C(O)R′2}2]Zr(CH2Ph)2/
B(C6F5)3 and Zr(CH2Ph)2(2,6-bis{menthoxo}pyridyl)/
B(C6F5)3 combinations, respectively, and attributed it
to the formation of tight ion pairs.
The polyethylenes produced under these conditions
have relatively high molecular weights and melting
temperatures, indicative of essentially linear long chain
microstructures. The molecular weight distributions
were generally broad,32 especially for Ti systems, al-
though all of them feature monomodal shapes (see
Supporting Information).
Experimental Section
General Considerations. All manipulations were per-
formed under a purified argon atmosphere using standard
high-vacuum Schlenk techniques or in a glovebox. Solvents
(toluene, pentane, THF, diethyl ether) were freshly distilled
from Na/K alloy under nitrogen and degassed thoroughly by
freeze-thaw-vacuum cycles prior to use. Deuterated hydro-
carbon solvents (>99.5% D, Eurisotop) were freshly distilled
from sodium/potassium amalgam under argon and degassed
prior to use. Ethyl N-benzyl(ethoxycarbonyl)methylami-
noacetate was prepared according to the literature.13 Zirco-
nium and titanium precursors ZrCl4, Zr(OtBu)4, TiCl4, and
Ti(OiPr)4 were purchased from Aldrich and were used as
received. Zr(CH2Ph)4 was prepared following the literature
procedure.33 {Ph3C}{B(C6F5)4} (Boulder) and MAO (30 wt %
solution in toluene, Albermale) were used as received. B(C6F5)3
(Boulder) was sublimed twice before use.
NMR spectra of complexes were recorded on Bruker AC-
200, AC-300, DRX-400, DRX-500, and AM-500 spectrometers
at ambient probe temperature (23 °C) unless otherwise
Conclusions
A variety of soluble chloro, alkoxy, amido, and benzyl
{ONOR}MX2 complexes of Zr and Ti based on the
new tridentate ligand system {OCR2CH2N(CH2Ph)
CH2CR2O}2-, as well as bis-ligand complexes, have been
prepared. The routes employed proved to be effective
with both ligands bearing either methyl or p-tolyl R
substituents. The coordination properties of these simple
neutral group 4 complexes {ONOR}MX2 have been
investigated in the solid state and in solution and
compared to related systems that vary in the nature of
the heteroatom donor and/or size of the metalacycles.
Notably, most of the {ONOMe}MX2 complexes studied,
which derived from the methyl-substituted ligand sys-
tem, adopt mononuclear structures in the solid state and
in solution, despite the modest steric crowding of the
ligand. Also, the nature of the R substituents affects
strongly the fluxional behavior of the complexes.6
The coordination of the nitrogen atom on metal
centers in {ONOR}MX2 complexes, even those bearing
bulky p-tolyl substituents, has been established unam-
biguously. These results cut short the proposed nonco-
ordination of nitrogen in related amino-dialkoxide tita-
niumcomplexes,suggestedfromMM2computations.10a,11a
The effective N‚‚‚metal interaction in {ONOR}MX2
complexes seems not to decrease too dramatically the
metal Lewis acidity, as demonstrated by the high
ethylene polymerization activity with some {ONOR}-
ZrCl2/MAO combinations. As anticipated, however, the
activity of the {ONOR}ZrCl2/MAO combinations is some-
what lower than that observed with the parent systems
{OSOR}ZrCl2/MAO derived from the less-donating sulfur-
1
indicated. H and 13C chemical shifts are reported in ppm vs
SiMe4 and were determined by reference to the residual solvent
1
peaks. Assignment of signals was made from H-1H COSY,
1H-13C HMQC, and HMBC NMR experiments (the markers
a, b, ..., in assignments of NMR data refer to bound H and C
atoms). NMR probe temperatures were calibrated by a MeOH
thermometer.34 All coupling constants are given in hertz.
Elemental analyses were performed by the Microanalytical
Laboratory at the Institute of Chemistry of Rennes and are
the average of two independent determinations. Melting points
are uncorrected.
Gel permeation chromatography (GPC) was performed on
a Polymer Laboratories PL-GPC 220 instrument using 1,2,4-
trichlorobenzene solvent (stabilized with 125 ppm BHT) at 150
°C. A set of three PLgel 10 µm Mixed-B or Mixed-B LS columns
was used. Samples were prepared at 160 °C. Polyethylene
molecular weights were determined vs polystyrene standards
and are reported relative to polyethylene standards, as cal-
culated by the universal calibration method using Mark-
Houwink parameters (K ) 14.1 × 10-5, R ) 0.70 for PSt, K )
14.1 × 10-5, R ) 0.70 for PE).35 DSC measurements were
performed on a TA Instruments DSC 2920 differential scan-
ning calorimeter. Polyethylene samples (10 mg) were annealed
by heating to 170 °C at 20 °C/min, followed by cooling to 40
°C at 40 °C/min, then heating to 170 °C at 20 °C/min.
{ONOMe}H2 (1). A solution of isobutene oxide (3.00 g, 41.6
mmol) and benzylamine (1.11 g, 10.4 mmol) in methanol (50
mL) was heated under reflux for 15 days. The mixture was
cooled to room temperature and filtered. The white powder
collected was dissolved in CH2Cl2 (30 mL) and dried for 48 h
over MgSO4. After filtration, volatiles were removed under
vacuum, leaving 1 as a white powder (2.61 g, 98%). Mp ) 95
°C. Anal. Calcd for C15H25NO2: C, 71.67; H, 10.02; N, 5.57.
Found: C, 71.29; H, 10.06; N, 5.47. 1H NMR (C6D6, 500
bridged ligands {OCR2CH2SCH2CR2O}2- 9 Reasons for
.
2
MHz): δ 7.36 (d, 2H, J ) 7.5 Hz, o-H), 7.28 (t, 2H, 7.3 Hz,
the high instability of the {ONOR}ZrCl2/MAO catalysts,
also observed with the parent {OSOR}-M systems, are
still unclear. Current investigations are directed toward
understanding of these phenomena, assessing in par-
ticular possible transfer of {OXOR}2- ligands between
group 4 metal and Al centers.
m-H), 7.21 (t, 1H, 7.2 Hz, p-H), 4.59 (s, 2H, OH), 3.70 (s, 2H,
NCH2Ph), 2.70 (s, 4H, NCH2CMe2), 1.24 (s, 12H, CH3). 1H
NMR (CDCl3, 200 MHz): δ 7.32-7.40 (m, 5H, phenyl), 3.77
(s, 2H, NCH2Ph), 3.46 (s, 2H, OH), 2.66 (s, 4H, NCH2CMe2),
1.13 (s, 12H, CH3). 1H NMR (THF-d8, 200 MHz): δ 7.02-7.17
(m, 5H, phenyl), 3.76 (s, 2H, OH), 3.43 (s, 2H, NCH2Ph), 2.58
(s, 4H, NCH2CMe2), 1.09 (s, 12H, CH3). 13C{1H} NMR (C6D6,
125 MHz): δ 140.1 (ipso-C), 129.1 (o-C), 128.2 (m-C), 127.0
(p-C), 71.6 (NCH2CMe2), 68.1 (NCH2CMe2), 64.0 (NCH2Ph),
27.9 (Me).
(32) (a) [RN{CH2CH2C(O)R′2}2]Zr(CH2Ph)2/MAO (1:500) gave at 50
°C, 5 atm 136-384 kg PE‚mol-1‚h-1 with Mw ) 143-452 000, Mw/Mn
) 3.4-5.7; see ref 6a. (b) Zr[PyC(CF3)2O]2[CH2Ph]2/MAO (1:1000) gave
at 30 °C, 8 atm 10 kg PE‚mol-1‚h-1 with Mw ) 375 000, Mw/Mn ) 28;
Zr[PyC(CF3)2O]2[CH2Ph]2/B(C6F5)3 (1:1) gave at 40 °C, 3 atm 96 kg
PE‚mol-1‚h-1 with Mw ) 16 000, Mw/Mn ) 2.6. Tsukahara, T.; Swenson,
D. C.; Jordan, R. F. Organometallics 1997, 16, 3303-3313. (c)
Combinations of Zr(CH2Ph)2(2,6-bis{menthoxo}pyridyl) with MAO or
B(C6F5)3 are not active for ethylene polymerization at 20 °C, 1-6 atm;
see ref 7.
(33) Zucchini, U.; Albizzati, E.; Giannini, U. J. Organomet. Chem.
1971, 26, 357-372.
(34) Van Geet, A. L. Anal. Chem. 1970, 42, 679-680.
(35) Scholte, Th. G.; Meijerink, N. L. J.; Schofelleers, H. M.; Brands,
A. M. G. J. Appl. Polym. Sci. 1984, 29, 3763-3782.

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5631
{ONOtol}H2 (2). Et2O (50 mL) and a few drops of CH3I were
introduced in a Schlenk flask containing magnesium turnings
(2.27 g, 97.5 mmol) under argon. After a pale yellow color
appeared, 4-bromotoluene (8.00 g, 48.8 mmol) was added
dropwise to maintain gentle ebullition of the mixture. The
mixture was stirred at room temperature for 4 h. The Grignard
solution was filtered and titrated with a 1.0 M solution of
2-butanol in toluene in the presence of o-phenantroline,
indicating a 90% yield. The solution was cooled to -5 °C, and
ethyl (N-benzylethoxycarbonylmethylamino)acetate (1.95 g, 7.0
mmol) was added by portion over 1 h. The mixture was
refluxed for 2 h, then cooled to 0 °C and quenched with an
aqueous solution of NH4Cl (20 mL of a 2.15 mol/L solution, 43
mmol). The aqueous phase was washed with ether (3 × 20
mL), and the organic phase was washed with water (2 × 10
mL). The organic phases were combined and dried over MgSO4
for 24 h. After filtration, volatiles were removed under vacuum
and the resulting white powder was recrystallized from ethanol
to yield 2 as a colorless microcrystalline powder (1.80 g, 47%).
Mp ) 177 °C. Anal. Calcd for C39H41NO2: C, 84.29; H, 7.44;
(0.170 g, 0.59 mmol). Workup afforded 4 as a white powder
(0.282 g, 86%). Anal. Calcd for C30H46N2O4Ti: C, 65.92; H, 8.48;
N, 5.13. Found: C, 66.26; H, 8.57; N, 5.08. 1H NMR (toluene-
d8, 300 MHz, 298 K): δ 7.23-7.18 (m, 10H, phenyl), 4.25 (s,
1
4H, CH2Ph), 2.83 (s, 8H, CH2NCMe2), 1.37 (s, 24H, CH3). H
NMR (toluene-d8, 300 MHz, 193 K): δ 7.35-7.20 (m, 10H,
2
2
phenyl), 4.69 (d, J ) 9.0 Hz, 2H, CHHPh), 4.12 (d, J ) 9.0
Hz, 2H, CHHPh), 3.08 (d, 2J ) 7.9 Hz, 1H, CHHNCMe2), 2.85
(d, J ) 7.9 Hz, 1H, CHHNCMe2), 2.53 (d, J ) 7.9 Hz, 1H,
CHHNCMe2), 2.35 (d, J ) 7.9 Hz, 1H, CHHNCMe2), 1.87 (s,
2
2
2
3H, CH3), 1.57 (s, 3H, CH3), 1.32 (s, 3H, CH3), 1.21 (s, 3H,
CH3). 3C{1H} NMR (toluene-d8, 75 MHz, 298 K): δ 137.1 (ipso-
C, Ph), 130.5 and 128.1 (o- and m-C, Ph), 127.3 (p-C, Ph), 81.7
(NCH2C(Me)2), 68.3 (NCH2C(Me)2), 63.6 (CH2Ph), 27.9 (CH3).
13C{1H} NMR (toluene-d8, 300 MHz, 203 K): δ 136.6 (ipso, Ph),
131.3 and 128.4 (o- and m-C, Ph), 127.7 (p-C, Ph), 81.7
(NCH2C(Me)2), 80.8 (NCH2C(Me)2), 69.3 (NCH2C(Me)2), 64.9
(NCH2C(Me)2), 63.8 (CH2Ph), 32.0 (CH3), 30.7 (2C, 2 CH3), 29.7
(CH3).
{ONOMe}2Zr (6). This complex was prepared as described
above for 3 starting from 1 (0.400 g, 1.54 mmol) and Zr(OtBu)4
(0.296 g, 0.77 mmol). Workup afforded 5 as a white powder
(0.361 g, 80%). Anal. Calcd for C30H46N2O4Zr: C, 61.08; H, 7.87;
N, 4.75. Found: C, 62.77; H, 8.42; N, 4.65. 1H NMR (THF-d8,
500 MHz): δ 7.49-7.34 (m, 5H, phenyl), 4.39 (s, 2H, CH2Ar),
2.94 (s, 4H, CH2NCMe2), 1.34 (s, 12H, CH3). 1H NMR (toluene-
d8, 500 MHz, 243 K): δ 7.48-7.18 (m, 5H, phenyl), 4.74 (d, 2J
1
N, 2.52. Found: C, 84.36; H, 7.51; N, 2.61. H NMR (CDCl3,
3
300 MHz): δ 7.17 (d, J ) 8.2 Hz, 8H, p-tol), 6.16-6.91 (m,
5H, Ph), 7.05 (d, 3J ) 8.2 Hz, 8H, p-tol), 4.28 (s, 2H, OH), 3.58
(s, 4H, NCH2C(p-tol)2), 3.32 (s, 2H, NCH2Ph), 2.30 (s, 12H,
1
3
CH3, p-tol). H NMR (toluene-d8, 500 MHz): δ 7.33 (d, J )
8.2 Hz, 8H, p-tol), 7.15-6.91 (m, 5H, Ph), 6.92 (d, 3J ) 8.2 Hz,
8H, p-tol), 4.50 (s, 2H, OH), 3.62 (s, 4H, NCH2C(tol)2), 3.34 (s,
2H, NCH2Ar), 2.12 (s, 12H, CH3, p-tol). 13C{1H} NMR (toluene-
d8, 125 MHz): δ 143.8 (ipso-C, p-tol), 138.5 (ipso-C, Ph), 135.7
(p-C, p-tol), 129.8 (o-C, p-tol), 128.8 (m-C, Ph), 128.1 (m-C,
p-tol), 127.9 (o-C, Ph), 127.0 (p-C, Ph), 77.3 (NCH2C(p-tol)2),
65.6 (NCH2C(p-tol)2), 61.8 (CH2Ph), 20.5 (CH3 p-tol).
2
) 15.0 Hz, 1H, CHHPh), 4.28 (d, J ) 15.0 Hz, 1H, CHHPh),
3.09 (d, 2J ) 13.3 Hz, 1H, CHHNCMe2), 2.96 (d, 2J ) 13.3 Hz,
1H, CHHNCMe2), 2.64 (d, 2J ) 13.3 Hz, 1H, CHHNCMe2), 2.53
(d, 2J ) 13.3 Hz, 1H, CHHNCMe2), 1.60 (s, 3H, CH3), 1.42 (s,
3H, CH3), 1.36 (s, 3H, CH3), 1.25 (s, 3H, CH3). 1H NMR
(toluene-d8, 500 MHz, 340 K): δ 7.17-7.32 (m, 5H, phenyl),
4.48 (s, 2H, CH2Ph), 2.89 (s, 4H, CH2NCMe2), 1.36 (s, 12H,
CH3). 13C{1H} NMR (toluene-d8, 125 MHz, 330 K): δ 137.74
(ipso, Ph), 131.19 (o-C, Ph), 128.1 and 127.5 (p- and m-C, Ph),
77.1 (NCH2C(Me)2), 68.4 (NCH2C(Me)2), 63.0 (CH2Ph), 32.2
(CH3).
{ONOMe}Ti(OiPr)2 (3). A solution of 1 (0.250 g, 0.879 mmol)
in toluene (3 mL) at -30 °C was added dropwise over 5 min
to a stirred solution of Ti(OiPr)4 (0.274 g, 0.879 mmol) in
toluene (2 mL) at -30 °C. Stirring was maintained for 5 h,
letting the mixture warm to room temperature. Removal of
volatiles under vacuum left a white powder, which was
recrystallized from pentane at -30 °C to give 3 as colorless
crystals (0.355 g, 87%). Anal. Calcd for C21H37O4NTi: C, 60.72;
{ONOtol}2Zr (7). This complex was prepared as described
above for 3 starting from 2 (0.100 g, 0.18 mmol) and Zr(OtBu)4
(0.034 g, 0.090 mmol). Workup afforded a white powder, which
was recrystallized from pentane at -30 °C to give colorless
crystals of 7 (0.110 g, 91%). Anal. Calcd for C78H78N2O4Zr: C,
1
H, 8.92; N, 3.37. Found: C, 60.29; H, 8.97; N, 3.42. H NMR
(toluene-d8, 500 MHz, 320 K): δ 7.22-7.16 (m, 5H, phenyl),
3
4.85 (sept, J ) 6.1 Hz, 2H, CH (OiPr)), 4.39 (s, 2H, CH2Ar),
2.84 (s, 4H, CH2NCMe2), 1.40 (d, 3J ) 6.1 Hz, 12H, CH3 (OiPr)),
1
78.15; H, 6.56; N, 2.34. Found: C, 78.38; H, 6.43; N, 2.24. H
1
3
1.30 (s, 12H, CH3). H NMR (toluene-d8, 500 MHz, 252 K): δ
NMR (toluene-d8, 500 MHz): δ 7.90 (d, J ) 7.3 Hz, 4H, o-H
7.24-7.16 (m, 5H, phenyl), 4.93 (sept, 3J ) 4.4 Hz, 2H, CH
(OiPr)), 4.40 (s, 2H, CH2Ph), 3.05 (d, 2J ) 12.7 Hz, 2H,
CHHNCMe2), 2.42 (d, 2J ) 12.7 Hz, 2H, CHHNCMe2), 1.48
(d, 3J ) 4.4 Hz, 6H, CH3 (OiPr)), 1.44 (d, 2J ) 4.4 Hz, 6H, CH3
(OiPr)), 1.42 (s, 6H, CH3), 1.24 (s, 6H, CH3). 13C{1H} NMR
(toluene-d8, 125 MHz, 320 K): δ 135.7 (ipso, Ph), 131.0 and
128.1 (o- and m-C, Ph), 127.5 (p-C, Ph), 81.4 (NCH2C(Me)2),
76.0 (CH (OiPr)), 68.7 (NCH2C(Me)2), 63.6 (CH2Ph), 31.1 (CH3
(OiPr)), 27.9 (CH3).
3
3
p-tol), 7.63 (d, J ) 7.3 Hz, 4H, o-H p-tol), 7.50 (d, J ) 7.3
3
Hz, 4H, o-H p-tol), 7.34 (d, J ) 7.1 Hz, 4H, o-H p-tol), 7.10-
7.20 (m, 10H, m-H Bz, p-H Bz and m-H ptol), 6.91 (d, 3J ) 8.0
Hz, 4H, m-H p-tol), 6.86-6.84 (m, 8H, o-H Bz and m-H p-tol),
3
2
6.82 (d, J ) 8 Hz, 4H, m-H p-tol), 4.79 (d, J ) 14.2 Hz, 2H,
CHHPh), 4.63 (d, 2J ) 14.2 Hz, 2H, CHHPh), 4.03 (d, 2J )
12.7 Hz, 2H, NCHHC(p-tol)2), 4.01 (d, 2J ) 12.7 Hz, 2H,
NCHHC(p-tol)2), 3.91 (d, J ) 12.7 Hz, 2H, NCHHC(p-tol)2),
3.75 (d, J ) 12.7 Hz, 2H, NCHHC(p-tol)2), 2.24 (s, 6H, CH3
2
2
Reaction of Zr(OtBu)4 with Diol 1: Generation of
{ONOMe}Zr(OtBu)2 (4) and {ONOMe}2Zr (6). This reaction
was carried out as described above for the synthesis of 3
starting from 1 (0.100 g, 0.39 mmol) and Zr(OtBu)4 (0.148 g,
0.39 mmol). Workup afforded a white powder, which was
recrystallized from pentane at -30 °C to give a mixture of
colorless crystals of 4 and 6 (0.172 g), in a 1:2 ratio according
to 1H NMR. Further crystallization did not allow recovering 4
in an analytically pure form. Complex 4: 1H NMR (THF-d8,
300 MHz): δ 7.49-7.34 (m, 5H, phenyl), 4.32 (s, 2H, CH2Ar),
2.87 (s, 4H, CH2NCMe2), 1.27 (s, 12H, CH3), 1.25 (s, 18H,
OtBu). 13C{1H} NMR (THF-d8, 75 MHz): δ 138.1 (ipso-C, Ph),
130.2 (o-C, Ph), 128.0 and 127.1 (p- and m-C), Ph), 78.2
(OC(CH3)2), 72.9 (C(CH3)3), 62.1 (NCH2Ph), 52.2 (NCH2), 33.0
(C(CH3)3), 31.0 (OC(CH3)2).
p-tol), 2.20 (s, 12H, 2 CH3 p-tol), 2.00 (s, 6H, CH3 p-tol). 13C-
{1H} NMR (toluene-d8, 125 MHz, 298 K): δ 149.0 (ipso-C,
p-tol), 148.3 (ipso-C, p-tol), 147.9 (ipso-C, p-tol), 147.1 (ipso-C,
p-tol), 134.9 (p-C, p-tol), 134.6 (p-C, p-tol), 134.5 (p-C, p-tol),
134.1 (ipso-C, bz), 134.0 (p-C, p-tol), 131.19 (o-C, bz), 128.7
and 128.4 (m-C, p-tol), 128.3 and 128.2 (m-C and p-C, bz), 85.4
(NCH2C(Me)2), 84.8 (NCH2C(Me)2), 66.7 (NCH2C(Me)2), 66.3
(NCH2C(Me)2), 60.3 (CH2Ph), 20.7 (CH3), 20.6 (CH3), 20.4 (2
overlapping signals, 2 CH3).
{ONOMe}Zr(CH2Ph)2 (8). Synthesis by Alkane Elimina-
tion. A solution of 1 (0.200 g, 0.795 mmol) in toluene (20 mL)
was added at -20 °C to a solution of Zr(CH2Ph)4 (0.354 g, 0.795
mmol) in toluene (20 mL). The mixture was stirred for 2 h at
room temperature. The clear solution was concentrated under
vacuum to ca. 1/4 of the initial volume and placed at -30 °C
to afford 8 as a colorless microcrystalline powder (0.380 g,
91%). Anal. Calcd for C29H37NO2Zr: C, 66.62; H, 7.13; N, 2.68.
{ONOMe}2Ti (5). This complex was prepared as described
above for 3 starting from 1 (0.300 g, 1.19 mmol) and Ti(OiPr)4

5632 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
1
Found: C, 66.21; H, 7.01; N, 2.59. H NMR (toluene-d8, 500
vacuum of the filtrate offered 10 as a white powder (0.691 g,
52%). This product was soluble in benzene, toluene, and THF.
1H NMR spectroscopy of 10 in benzene-d6 or toluene-d8
indicated a mixture of isomers, of which two major ones, 10a
and 10b, account for more than 80% of the total, with a ratio
10a/10b ) 70:30. Isomer 10a: 1H NMR (C6D6, 300 MHz): δ
7.28-7.01 (m, 5H, phenyl), 4.70 (d, 2J ) 15.2 Hz, 1H, CHHAr),
4.54 (d, 2J ) 15.2 Hz, 1H, CHHAr), 3.33 (m, 4H, OCH2 THF),
3.29 (d, 2J ) 13.1 Hz, 1H, CHHNCMe2), 2.99 (d, 2J ) 13.1 Hz,
1H, CHHNCMe2), 2.86 (d, 2J ) 13.1 Hz, 1H, CHHNCMe2), 2.61
(d, 2J ) 13.1 Hz, 1H, CHHNCMe2), 2.01 (s, 3H, CH3), 1.79 (s,
3H, CH3), 1.71 (m, 4H, CH2CH2 THF), 1.40 (s, 3H, CH3), 1.36
(s, 3H, CH3). 13C{1H} NMR (C6D6, 125 MHz): δ 133.8 (ipso-
C), 81.2 (C(CH3)2), 80.2 (C(CH3)2), 71.7 (NCH2(CH3)2), 70.6
(OCH2, THF), 66.2 (NCH2(CH3)2), 60.6 (NCH2Ar), 32.6 (CH3),
31.2 (CH3), 28.0 (CH3), 27.7 (CH3), 26.9 (CH2CH2, THF). Isomer
10b: 1H NMR (C6D6, 75 MHz): δ 7.28-7.01 (m, 5H, phenyl),
4.00 (m, 2H, CH2Ar), 3.05 (m, 4H, CH2NCMe2), 1.47 (s, 6H,
MHz, 295 K): δ 7.14-6.95 (m, 15H, Ar), 3.56 (s, 2H, NCH2-
Ar), 3.14 (d, J ) 13.5 Hz, 2H, NCHH), 2.34 (s, 2H, CH2Ar-
2
(a)), 2.05 (d, 2J ) 13.5 Hz, 2H, NCHH), 1.76 (s, 2H, CH2Ar(b)),
1.43 (s, 6H, CH3), 1.15 (s, 6H, CH3). 1H NMR (toluene-d8, 500
MHz, 375 K): δ 7.07-6.95 (m, 15H, Ar), 3.58 (s, 2H, NCH2-
Ar), 2.66 (s, 4H, NCH2), 2.04 (s, 4H, ZrCH2), 1.19 (s, 12H, CH3).
13C{1H} NMR (toluene-d8, 125 MHz, 295 K): δ 147.3 (ipso-
C(b)), 141.4 (ipso-C(a)), 138.3, 132.2, 129.6 (o-C(b)), 129.0 (o-
C(a)), 122.3 (p-C(a)), 121.3 (p-C(b)), δ 82.8 (s, C), 69.1 (NCH2),
55.1 (CH2Ar(b)), 54.3 (CH2Ar(a)), 53.3 (NCH2Ar), 34.1 (CH3),
32 (CH3).
Synthesis by Comproportionation. Zr(CH2Ph)4 (0.042 g,
0.167 mmol) and 6 (0.076 g, 0.167 mmol) were introduced in
a Teflon-valved NMR tube, and toluene-d8 (ca. 1.5 mL) was
vacuum-transferred in at -180 °C. The tube was sealed and
warmed to room temperature. 1H NMR spectroscopy revealed
90% conversion of the starting reagents to 8.
1
{ONOMe}ZrCl2 (9). Synthesis by Alkane Elimination
from “Zr(n-Bu)2Cl2”. n-BuLi (3.5 mL of a 1.6 M solution in
hexane, 5.62 mmol) was added dropwise, over 10 min, to a
stirred solution of ZrCl4 (0.656 g, 2.81 mmol) in toluene (15
mL) at -78 °C. The mixture was slowly warmed to room
temperature and stirred for 8 h, resulting in a brown slurry.
This mixture of “Zr(n-Bu)2Cl2” and LiCl was cooled at -40 °C,
and a solution of diol 1 (0.708 g, 2.81 mmol) in toluene (5 mL)
was added dropwise under stirring over 30 min. The brown
mixture was slowly warmed to room temperature and stirred
for 8 h. Gas evolution (butane) was observed without change
in the color. The precipitate (LiCl) was removed by filtration
over a frit and washed with toluene (2 × 30 mL). The filtrate
was concentrated under vacuum to leave a white powder,
which was washed with pentane (2 × 5 mL) and dried under
vacuum (0.656 g, 56%). This product was very poorly soluble
in toluene and readily soluble in THF.
Synthesis via Comproportionation of ZrCl4 and
{ONOMe}2Zr. In the glovebox, a solution of complex 6 (0.050
g, 0.085 mmol) in toluene (2 mL) and a solution of ZrCl4 (0.020
g, 0.085 mmol) in toluene (2 mL) were cooled at -30 °C and
rapidly mixed. The mixture was stirred at room temperature
for 24 h. Volatiles were removed under vacuum to leave 9 as
a white powder (0.069 g, 100%). Anal. Calcd for C15H23Cl2NO2-
Zr: C, 43.78; H, 5.63; N, 3.40. Found: C, 44.12; H, 5.48; N,
3.20. This product was sparingly soluble in toluene and readily
soluble in THF. 1H NMR spectroscopy of 9 in toluene indicated
it is a mixture of isomers of which two major ones, 9a and 9b,
account for more than 80% of the total, with a ratio 9a/9b )
53:47. Isomer 9a: 1H NMR (toluene-d8, 500 MHz): δ 7.28-
7.01 (m, 5H, phenyl), 4.00 (m, 2H, CHHAr), 2.88 (m, 4H,
CHHNCMe2), 1.38 (s, 12H, CH3). Isomer 9b: 1H NMR (toluene-
d8, 500 MHz): δ 7.28-7.01 (m, 5H, phenyl), 4.71 (d, 2J ) 15.2
Hz, 1H, CHHAr), 4.53 (d, 2J ) 15.2 Hz, 1H, CHHAr), 3.32 (d,
2J ) 13.1 Hz, 1H, CHHNCMe2), 3.05 (d, 2J ) 13.1 Hz, 1H,
CHHNCMe2), 2.87 (d, 2J ) 13.1 Hz, 1H, CHHNCMe2), 2.65
(d, 2J ) 13.1 Hz, 1H, CHHNCMe2), 2.02 (s, 3H, CH3), 1.78 (s,
3H, CH3), 1.39 (s, 3H, CH3), 1.37 (s, 3H, CH3). 1H NMR
spectroscopy of 9 in THF-d8 indicated a mixture of isomers, of
which three major ones, 10a′, 10b′, and 10c′, account for more
than 90% of the total, with a ratio 10a′/10b′/10c′ ) 30:7:63.
{ONOMe}ZrCl2(THF) (10). Synthesis by Salt Elimina-
tion. n-BuLi (2.49 mL of a 1.6 M solution in hexane, 3.98
mmol) was added dropwise, under stirring, to a solution of 1
(0.500 g, 1.99 mmol) in THF (7 mL) at -78 °C. The mixture
was warmed to room temperature and stirred for 24 h. It was
then cooled at -40 °C and slowly transferred over 30 min into
a solution of ZrCl4 (0.463 g, 1.99 mmol) in THF (3 mL) at -40
°C (previously prepared 3 h before addition). The mixture
turned yellow upon addition of the dialkoxide and was stirred
at room temperature overnight. Volatiles were removed under
vacuum, and the residue was extracted with toluene (4 × 15
mL). Filtration of the solution and concentration under
CH3), 1.36 (s, 6H, CH3) and the same H resonances of THF
as above for 10a. 13C{1H} NMR (C6D6, 300 MHz): δ 140.6 (ipso-
C), 83.1 (C(CH3)2), 71.7 (NCH2(CH3)2), 63.4 (NCH2Ar), 31.2
(CH3) and the same 13C resonances of THF as above for 10a.
1H NMR spectroscopy of 10 in THF-d8 indicated a mixture of
isomers, of which three major ones, 10a′, 10b′, and 10c′,
account for more than 80% of the total, with a ratio 10a′/10b′/
10c′ ) 34:13:53. A 1H NMR monitoring indicated that isomers
10a′ and 10b′ slowly convert into isomer 10c′ in THF solution
at room temperature (90% conversion within 1 week). Isomer
3
10a′: 1H NMR (THF-d8, 500 MHz): δ 7.47 (d, J ) 10.1 Hz,
2
2H, o-H), 7.41 (m, 1H, p-H), 7.38 (m, 2H, m-H), 4.72 (d, J )
15.0 Hz, 1H, CHHAr), 4.53 (d, 2J ) 15.0 Hz, 1H, CHHAr), 3.55
(d, 2J ) 13.0 Hz, 1H, CHHNCMe2), 3.19 (d, 2J ) 13.0 Hz, 1H,
CHHNCMe2), 3.04 (d, 2J ) 13.0 Hz, 1H, CHHNCMe2), 2.78
(d, 2J ) 13.0 Hz, 1H, CHHNCMe2), 1.93 (s, 3H, CH3), 1.65 (s,
3H, CH3), 1.59 (s, 3H, CH3), 1.39 (s, 3H, CH3). 13C{1H} NMR
(THF-d8, 500 MHz): δ 133.6 (ipso-C), 132.0 (o-C), 128.2 (p-C),
128.1 (m-C), 81.4 (C(CH3)2), 80.5 (C(CH3)2), 70.6 (NCH2(CH3)2),
65.9 (NCH2(CH3)2), 60.5 (NCH2Ar), 32.2 (CH3), 30.7 (2 CH3),
28.8 (CH3) (THF resonances were not clearly identified because
of multiple overlapping resonances). Isomer 10b′: 1H NMR
(THF-d8, 500 MHz): δ 7.48-7.18 (m, 5H, phenyl), 3.99 (m,
2H, CH2Ar), 2.91 (m, 4H, CH2NCMe2), 1.18 (s, 6H, CH3), 1.22
(s, 6H, CH3). 13C{1H} NMR (THF-d8, 125 MHz): δ 140.4 (ipso-
C), 128.6 (o-C), 127.2 (p-C), 126.8 (m-C), 82.5 (C(CH3)2), 71.4
(NCH2(CH3)2), 63.2 (NCH2Ar), 27.1 (CH3). Isomer 10c′: 1H
NMR (THF-d8, 500 MHz): δ 7.48-7.18 (m, 5H, phenyl), 3.99
(s, 2H, CH2Ar), 2.91 (s, 4H, CH2NCMe2), 1.15 (s, 12H, CH3).
13C{1H} NMR (THF-d8, 125 MHz): δ 140.4 (ipso-C), 128.6 (o-
C), 127.2 (p-C), 126.8 (m-C), 82.5 (C(CH3)2), 71.4 (NCH2(CH3)2),
63.2 (NCH2Ar), 27.1 (CH3).
{ONOMe}Zr(NMe2)2 (11). A solution of 1 (0.245 g, 0.974
mmol) in toluene (5 mL) at -30 °C was slowly transferred to
a stirred solution of Zr(NMe2)4 (0.261 g, 0.974 mmol) in toluene
(5 mL) at -30 °C. The reaction mixture was warmed to room
temperature and stirred for 48 h under partial vacuum.
Volatiles were removed under vacuum, and the residue was
washed with pentane (2 × 5 mL), leaving 11 as a white powder
(0.381 g, 91%). Anal. Calcd for C19H35N3O2Zr: C, 53.23; H, 8.23;
N, 9.80. Found: C, 52.87; H, 8.13; N, 9.45. 1H NMR spectros-
copy in toluene-d8 at room temperature and 60 °C featured
many resonances.
{ONOMe}ZrCl2(THF) (10). Synthesis from 11. In a Tef-
lon-valved NMR tube containing a solution of complex 7 (0.040
g, 0.093 mmol) in THF-d8 (1.5 mL) at -30 °C was added
ClSiMe3 (0.020 g, 0.018 mmol). The reaction mixture was
gently warmed to room temperature, while vigorously shaken
for 10 min, and then left standing for 12 h. A 1H NMR
spectrum showed complete and selective transformation of 11
to 10. Volatiles were removed under vacuum, and the residue
was washed with pentane and finally dried in a vacuum to
afford 11 as a white powder (0.038 g, 84%). Anal. Calcd for

Group 4 Metal Complexes of Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5633
C19H31Cl2NO3Zr: C, 47.19; H, 6.46; N, 2.90. Found: C, 47.74;
H, 6.56; N, 2.90. H NMR in THF-d8 showed the presence of
three isomers, 10a′, 10b′, and 10c′, in a 33:21:46 ratio.
of 8 one benzene molecule, that of 12 two benzene molecules,
and that of 14 one toluene molecule. Crystal data and details
of data collection and structure refinement are given in Table
1. Crystallographic data are also available as cif files (see
Supporting Information).
1
{K2-ONOMe}Zr(µ2-NMe2)(µ2,K3-{ONOMe})Zr(K2-{ONOMe})-
(NMe2) (12). A small amount of X-ray quality crystals of the
dimeric species 12, which results from the exchange of two
Line Shape Analysis and NMR Simulations. NMR
spectral simulations were performed using “gNMR” (Cherwell
Scientific). Simulations of the NCHHCMe2, NCH2CMe2, and
ZrCHHPh hydrogens of 8 and NCHHCMe2 and NCH2CMe2
hydrogens of 13 were performed in a two-step procedure. First,
the chemical shifts observed in the slow limit exchange (below
240 K) were used to set up the spin systems. The relative
population ratio was fixed at 1:1:3:3:1:1 for 8 and 1:1:3:3 for
13. The natural line-width in the absence of exchange (W0 )
2.5 Hz for 8, 2.6 Hz for 13) was measured for the Me hydrogens
at 250 K. The chemical shifts of the different hydrogens vary
slightly in the slow limit exchange, and a linear extrapolation
was used to estimate the chemical shifts at higher tempera-
tures. We checked that the observed and calculated chemical
shifts for the collapsed resonances are identical. Then, for
different temperatures, the exchange rate was varied to get
the best fit between the simulated and the experimental
spectra; for each complex, all spin systems were processed
simultaneously. Activation parameters were determined by a
standard Eyring analysis, and the standard deviations from
the least-squares fit were used to estimate the uncertainties
in ∆Hq and ∆Sq.37
Ethylene Polymerization. Polymerization experiments
(Table 8) were performed in a 150 or 320 mL high-pressure
glass reactor equipped with a mechanical stirrer and exter-
nally heated with a double mantle with a circulating oil bath
as desired. In a typical experiment, the reactor was filled with
toluene (25 or 70 mL, depending on the size of the reactor)
and MAO (30 wt % solution in toluene, 2-3 or 6-8 mL, 500
equiv) or AliBu3 (0.5-0.8 mL, 10 equiv) and pressurized at 5
atm of ethylene (Air Liquide, 99.99%). The reactor was
thermally equilibrated at the desired temperature for 1 h.
Ethylene pressure was decreased to 1 atm, and the catalyst
precursor (30-50 or 120-150 µmol) in toluene (5 or 10 mL)
was added by syringe. The ethylene pressure was immediately
increased to 5 atm, and the solution was stirred for the desired
time. Ethylene consumption was monitored using an electronic
manometer connected to a secondary 100 mL ethylene tank,
which feeds the reactor by maintaining constant the total
pressure. The polymerization was stopped by venting of the
vessel and quenching with a 10% HCl solution in methanol
(30 or 80 mL). The polymer was collected by filtration, washed
with methanol and acetone (2 × 20 mL), and dried under
vacuum overnight.
NMe2 units by a {ONOMe 2- moiety in 11, was isolated from a
}
toluene solution of a sample of 11 (prepared as described
above) placed at -30 °C.
{ONOMe}TiCl2 (13). TiCl4 (0.059 g, 0.315 mmol) was added
dropwise at room temperature to a stirred solution of Ti(OiPr)4
(0.089 g, 0.315 mmol) in toluene (2 mL). The mixture was
stirred for 1 h, and a solution of 1 (0.163 g, 0.629 mmol) in
toluene (3 mL), cooled at -30 °C, was added dropwise over 2
min. The mixture was stirred for 12 h at room temperature,
and volatiles were removed under vacuum. The residue was
washed with pentane (2 × 2 mL) and dried under vacuum to
leave 13 as a white powder (0.065 g, 78%). Anal. Calcd for
C15H23O2NCl2Ti: C, 48.94; H, 6.30; N, 3.80. Found: C. 49.49;
H, 7.02; S, 3.58. 1H NMR (toluene-d8, 300 MHz, 243 K): δ
7.92-7.17 (m, 5H, aryl), 4.09 (s, 2H, CH2Ar), 2.91 (d, 2J ) 13.4
Hz, 2H, CHHNCMe2), 2.50 (d, 2J ) 13.4 Hz, 2H, CHHNCMe2),
1.16 (s, 6H, CH3), 1.06 (s, 6H, CH3). 1H NMR (toluene-d8, 500
MHz, 340 K): δ 6.95-7.15 (m, 5H, phenyl), 4.15 (s, 2H, CH2-
Ar), 2.86 (s, 4H, CH2NCMe2), 1.16 (s, 12H, CH3). 13C{1H} NMR
(toluene-d8, 75 MHz, 243 K): δ 137.0 (ipso-C, Ph), 133.3 and
131.5 (o- and m-C, Ph), 129.2 (p-C, Ph), 91.3 (NCH2C), 68.1
(NCH2), 65.3 (NCH2Ph), 30.0 (CH3).
{ONOtol}TiCl2 (14). This complex was prepared as de-
scribed above for 13, starting from TiCl4 (0.040 g, 0.21 mmol),
Ti(OiPr)4 (0.059 g, 0.21 mmol), and 2 (0.232 g, 0.42 mmol).
Workup afforded 14 as a white powder (0.241 g, 86%). Anal.
Calcd for C39H39Cl2NO2Ti: C, C, 69.65; H, 5.85; N, 2.08.
1
Found: C, 69.79; H, 5.66; N, 2.22. H NMR (toluene-d8, 300
3
MHz): δ 7.43 (d, J ) 8.1 Hz, 4H, o-H p-tol), 7.08-7.15 (m,
3
3H, m-H bz and p-H bz), 6.95 (d, J ) 8.1 Hz, 4H, o-H p-tol),
6.92 (d, 3J ) 8.1 Hz, 4H, m-H p-tol), 6.63 (d, 3J ) 8.1 Hz, 4H,
m-H p-tol), 6.44 (d, 3J ) 6.1 Hz, 2H, o-H Bz), 4.09 (s, 2H, CH2-
Ar), 3.91 (d, 2J ) 12.8 Hz, 2H, NCHHCMe2), 3.82 (d, 2J ) 12.8
Hz, 2H, NCHHCMe2), 2.08 (s, 6H, CH3), 2.04 (s, 6H, CH3). 13C-
{1H} NMR (toluene-d8, 75 MHz): δ 143.1 (ipso-C, p-tol), 143.0
(ipso-C, p-tol), 136.8 (p-C, p-tol), 136.1 (p-C, p-tol), 133.0 (ipso-
C, Bz), 131.5 (o-C, Bz), 129.0 and 128.9 (m-C, p-tol), 128.5 and
128.6 (m-C and p-C, Bz), 124.8 and 124.6 (o-C, p-tol), 97.0
(NCH2C(p-tol)2), 67.76 (NCH2C(p-tol)2), 63.3 (CH2Ph), 20.5
(CH3 p-tol).
Crystal Structure Determination of Complexes 3, 6,
8, 12, 13, and 14. Suitable single crystals were mounted onto
glass fibers using the “oil-drop” method. Diffraction data were
collected at 100-150 K using a NONIUS Kappa CCD diffrac-
tometer with graphite-monochromatized Mo KR radiation (λ
) 0.71073 Å). A combination of ω- and æ-scans was carried
out to obtain at least a unique data set. Crystal structures
were solved by means of the Patterson method, and remaining
atoms were located from difference Fourier synthesis, followed
by full-matrix least-squares refinement based on F2 (programs
SHELXS-97 and SHELXL-97).36 Many hydrogen atoms could
be found from the Fourier difference. Carbon-bound hydrogen
atoms were placed at calculated positions and forced to ride
on the attached carbon atom. The hydrogen atom contributions
were calculated but not refined. All non-hydrogen atoms were
refined with anisotropic displacement parameters. The loca-
tions of the largest peaks in the final difference Fourier map
calculation as well as the magnitude of the residual electron
densities were of no chemical significance. The cell of 6 was
found to contain one pentane molecule of crystallization, that
Acknowledgment. This work was supported by the
Ministe`re de la Recherche et de l’Enseignement Su-
pe´rieur (Ph.D. grant to L.L.) and the Centre National
de la Recherche Scientifique (ATIPE fellowship to
J.F.C.). We gratefully thank Dr. Ian Steele (The Uni-
versity of Chicago) for the X-ray crystal diffraction
analysis of 8, and Prof. Richard F. Jordan (The Univer-
sity of Chicago) for GPC analyses and valuable discus-
sions.
Supporting Information Available: Crystallographic
data for 3, 6, 8, 12, 13, and 14 in CIF format; additional VT
1H NMR data for 5 and 14; representative GPC and DSC
profiles of polyethylenes prepared. This material is available
free of charge via the Internet at http://pubs.acs.org
OM0505817
(36) (a) Sheldrick, G. M. SHELXS-97, Program for the Determina-
tion of Crystal Structures; University of Goettingen: Germany, 1997.
(b) Sheldrick, G. M. SHELXL-97, Program for the Refinement of
Crystal Structures; University of Goettingen: Germany, 1997.
(37) (a) Bevington, P. R. Data Reduction and Error Analysis for the
Physical Sciences; McGraw-Hill: New York, 1969. (b) Skoog, D. A.;
Leary, J. J. Principles of Instrumental Analysis, 4th ed.; Saunders
College, 1992; pp 13-14.