Electron-deficient group 4 metal complexes of sulfur-bridged dialkoxide ligands: Synthesis, structure, and polymerization activity studies

Article abstract of DOI:10.1021/om050560c

Coordination of the sulfur-bridged dialkoxide ligands {OCR ₂CH₂SCH₂CR₂O}^2- ({OSOR}^2-, R = Me, p-tolyl) on titanium and zirconium centers has been studied. A variety of complexes having one

Full text of DOI:10.1021/om050560c

5604
Organometallics 2005, 24, 5604-5619
Electron-Deficient Group 4 Metal Complexes of
Sulfur-Bridged Dialkoxide Ligands: Synthesis,
Structure, and Polymerization Activity Studies
Laurent Lavanant,† Anca Silvestru,† Anne Faucheux,† Loic Toupet,‡
Richard F. Jordan,§ 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 Department of Chemistry, The University of Chicago, 5735 S. Ellis Avenue,
Chicago, Illinois 60637
Received July 6, 2005
Coordination of the sulfur-bridged dialkoxide ligands {OCR2CH2SCH2CR2O}2- ({OSOR}2-,
R ) Me, p-tolyl) on titanium and zirconium centers has been studied. A variety of complexes
having one or two ancillary {OSOMe 2- ligands, viz., M(OR)2{OSOMe} (M ) Zr, OR ) OtBu,
}
4; M ) Ti, OR ) OiPr, 5), M{OSOMe}2 (M ) Zr, 6; Ti, 7), Zr(CH2Ph)2{OSOMe} (8), and MCl2-
{OSOMe}(THF)n (M ) Zr, n ) 0, 9; n ) 1, 10; n ) 2, 11; M ) Ti, n ) 0, 12; n ) 2, 13), have
been prepared in good yields by alcohol or alkane elimination from {OSOMe}H2 (1a) or by
salt metathesis routes from alkali metal salts M{OSOMe} (M ) K, 2a; M ) Li, in
situ-generated). Coordination of the p-tolyl-substituted ligand by these and other routes
proved to be much more difficult, and only TiCl2{OSOtol} (14) was obtained. Crystallographic
studies showed that dichloro complexes 11 and 13 and bis-ligand complex 7 adopt in the
solid state mononuclear structures with no bonding interaction between the sulfur atom
and metal centers. The crystal structure of 4 contains two independent dinuclear molecules
that interconvert formally by exchange of tBuO and chelating {OSOMe} ligands between
terminal and bridging modes and feature normal Zr-S bonds. NMR data for 4 and 12 are
consistent with dinuclear C1-symmetric structures in toluene solution, while dibenzyl complex
8 has a mononuclear structure. Variable-temperature NMR studies combined with line-
shape analysis established that the fluxional behavior of 8 results from the exchange between
η2/ η1-benzyl ligands (∆Hq ) 10.6 ( 1 kcal‚mol-1; ∆Sq ) -2.7 ( 2 cal‚mol-1‚K-1). Abstraction
of one benzyl ligand of 4 with 1 equiv of [Ph3C][B(C6F5)4] or B(C6F5)3 proceeds cleanly to
give the corresponding thermally unstable, ionic species [Zr(CH2Ph){OSOMe}]+[BX(C6F5)3]-
(X ) C6F5, 15; CH2Ph, 16), which have been characterized by 1H, 11B, 13C, and 19F
NMR spectroscopy and show Cs symmetry in solution. The decomposition of 16 proceeds via
C6F5/benzyl exchange from Zr to B and generates the stable [Zr(C6F5){OSOMe}]+-
[η6-(PhCH2)B(CH2Ph)(C6F5)2]- (17). Cationic species in situ-generated from Zr chloro
complexes and MAO are highly active but very unstable ethylene polymerization catalysts.
Introduction
relatively more basic alkoxide ligands to act as bridging
ligands, resulting in di- or polynuclear structures.3 This
difficulty can be partly overcome by (i) increasing the
steric bulk of the -OR moieties, which is easy due to
Largely because of the search for new-generation
olefin polymerization catalysts, investigation into the
use of alkoxide (O-C(sp3)) and aryloxide (O-C(sp2))
ancillary ligands to replace the ubiquitous cyclopenta-
dienyl-type ligands in organo group 4 metal complexes
has become popular in recent years.1 While the synthetic
organometallic chemistry and catalytic applications of
group 4 metal complexes of chelating bis-aryloxide
ligands have been extensively explored,2 the chemistry
of alkoxide-based complexes proved to be more compli-
cated.3 This is inherent to the high tendency of the
(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.
(2) For examples in group 4 chemistry see: (a) Van der Linden, A.;
Schaverien, C. J.; Meiboom, N.; Ganter, C.; Orpen, A. G. J. Am. Chem.
Soc. 1995, 117, 3008-3021. (b) Tshuva, E. Y.; Goldberg, I.; Kol, M. J.
Am. Chem. Soc. 2000, 122, 10706-10707. (c) Balsells, J.; Carroll, P.
J.; Walsh, P. J. Inorg. Chem. 2001, 40, 5568-5574. (d) Tian, J. P.;
Hustad, D.; Coates, G. W. J. Am. Chem. Soc. 2001, 123, 5134-5135.
(3) (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.
* Corresponding author. Fax: (+33)(0)223-236-939. E-mail: jean-
francois.carpentier@univ-rennes1.fr.
† Organome´talliques et Catalyse, UMR 6509 CNRS.
‡ Groupe Matie`re Condense´e et Mate´riaux, Cristallochimie, UMR
6626 CNRS.
§ The University of Chicago.
10.1021/om050560c CCC: $30.25 © 2005 American Chemical Society
Publication on Web 09/23/2005

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5605
the large availability of alcohols, or (ii) modifying the
alkoxide ligand with additional donor functionalities.3
Several group 4 metal complexes based on tridentate
and tetradentate bis-aryloxide2 and bis-alkoxide4-7
ligands having additional coordinating heteroatom(s)
(N, O, S) have been described. Of special interest are
ligands having a sulfur bridge,2a,8-10 since the soft sulfur
atom may interact weakly with the hard metal center,
possibly stabilizing a reactive cationic metal center
without deactivating it, as a better donor atom would
do. Theoretical computations predicted that TiMe{(2-
C6H4O)X(2′-C6H4O)}+ (X ) O, S, Se, Te) systems act as
“breathing catalysts”, with the X heteroatom moving in
and out from the metal center as the electron density
changes, leading to a less stabilized π-olefin complex and
a lower activation (ethylene insertion) barrier.11 This
effect has been proposed to account for the higher
ethylene polymerization activity of some titanium sulfur-
bridged bis-aryloxide systems as compared to methyl-
ene-bridged or directly bridged analogues.2a,12 Predictive
computational work also suggested the possible ap-
propriateness of sulfur-bridged bis-alkoxide ligands of
Figure 1. ORTEP drawing of {OSOtol}H2 (1b). Ellipsoids
are drawn at the 50% probability level.
{OCR2CH2SCH2CR2O}2- ligands and Ti(IV) and Zr(IV)
complexes thereof. The known dimethyl-substituted
sulfur-bridged diol {OSOMe}H2 (1a)13 and the new
para-tolyl-substituted diol {OSOtol}H2 (1b) were pre-
pared in good yields by the reaction of sodium sulfide
with the corresponding tertiary chlorhydrine in boiling
ethanol (eq 1). Diol 1a was readily obtained in pure, dry
form. However, 1b was isolated by recrystallization as
the mono-water adduct, as evidenced by elemental anal-
ysis and a single X-ray diffraction study (Figure 1, Table
1). Treatment of 1b with drying agents (MgSO4, MS 4
Å, etc.) for long periods did not remove the water. The
strong interaction of water with 1b can be correlated
with the extensive hydrogen bonding in the solid state
(Figure 2). The higher acidity of -CAr2OH (pKa ) ca.
13.5) as compared to -CMe2OH (pKa ) ca. 15.3)14 makes
1b a better H-bond donor and presumably accounts for
the formation of the robust water adduct 1b‚H2O.
the type {OC2H2SC2H2O}2-
.
In this contribution, we describe the coordination
chemistry of titanium(IV) and zirconium(IV) complexes
of the tridentate ligand systems {OCR2CH2SCH2CR2O}2-
({OSOR}2-, R ) Me, p-tolyl). The objectives of this
work were to define the {OSOR}2- coordination proper-
ties in simple group 4 MX2{OSOR} complexes, to pre-
pare MR2{OSOR} and also [M(R){OSOR}]+ alkyl spe-
cies, and to explore the ethylene polymerization proper-
ties of MX2{OSOR}/MAO and [M(R){OSOR}]+ catalysts.
Results and Discussion
Ligands Synthesis. Two ligands were prepared
to explore the influence of the R substituents in
(4) Shao, P.; Gendron, R. A. L.; Berg, D. J.; Bushnell, G. W.
Organometallics 2000, 19, 509-520.
(5) Gauvin, R. M.; Osborn, J. A.; Kress, J. Organometallics 2000,
19, 2944-2946.
(6) (a) Manickam, G.; Sundararajan, G. Tetrahedron: Asymmetry
1999, 10, 2913-2925. (b) Mack, H.; Eisen, M. J. Chem. Soc., Dalton
Trans. 1998, 917-921.
(7) Related group 4 amino-dialkoxide complexes derived from the
parent N-bridged ligand system [OCR2CH2N(CH2Ph)CH2CR2O]2-
([ONOR]2-, R ) Me, p-tolyl) have also been prepared. Lavanant, L.;
Toupet, L.; Lehmann, C. W.; Carpentier, J.-F. Organometallics 2005,
accepted for publication.
(8) (a) Kakugo, M.; Miyatake, T.; Mizunuma, K. Chem. Express.
1987, 2, 445-448. (b) Miyatake, T.; Mizunuma, K.; Seki, Y.; Kakugo,
M. Macromol. Chem., Rapid Commun. 1989, 10, 349-352. (c) Miyatake,
T.; Mizunuma, K.; Kakugo, M. Makromol. Chem., Macromol. Symp.
1993, 66, 203-214.
Diols 1a and 1b were transformed into the cor-
responding dipotassium salts (eq 2). Treatment of 1a
with potassium in THF at room temperature gave
K2{OSOMe} (2a) in 94% yield. This procedure was not
effective for 1b, but K2{OSOtol} (2b) could be isolated
in 35% yield by reaction of 1b with potassium tert-
butoxide.
(9) (a) Fokken, S.; Spaniol, T. P.; Kang, H.-C.; Massa, W.; Okuda,
J. Organometallics 1996, 15, 5069-5072. (b) Sernetz, F. G.; Muelhaupt,
R.; Fokken, S.; Okuda, J. Macromolecules 1997, 30, 1562-1569. (c)
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.
(d) Fokken, S.; Reichwald, F.; Spaniol, T. P.; Okuda, J. J. Organomet.
Chem. 2002, 663, 158-163. (e) Natrajan, L. S.; Wilson, C.; Okuda, J.;
Arnold, P. L. Eur. J. Inorg. Chem. 2004, 3724-3732. (f) Capacchione,
C.; Proto, A.; Okuda, J. J. Polym. Sci. A: Polym. Chem. 2004, 42, 2815-
2822. (g) Capacchione, C.; Manivannan, R.; Barone, M.; Beckerle, K.;
Centore, R.; Oliva, L.; Proto, A.; Tuzi, A.; Spaniol, T. P.; Okuda, J.
Organometallics 2005, 24, 2971-2982.
(10) (a) Takashima, Y.; Nakayama, Y.; Hirao, T.; Yasuda, H.;
Harada, A. J. Organomet. Chem. 2004, 689, 612-619. (b) Janas, S.;
Jerzykiewicz, L. B.; Przybylak, K.; Sobota, P.; Sczzegot, K.; Wisniewska,
D. Eur. J. Inorg. Chem. 2004, 1639-1645. (c) Janas, S.; Jerzykiewicz,
L. B.; Przybylak, K.; Sobota, P.; Sczzegot, K.; Wisniewska, D. Eur. J.
Inorg. Chem. 2005, 1063-1070. (e) Janas, Z.; Jerzykiewicz, L. B.;
Sobota, P.; Sczzegot, K.; Wisniewska, D. Organometallics 2005, 24,
3987-3994.
The trimethylsilyl ethers {OSOR}(TMS)2 (3a,b) were
prepared in high yield by reaction of 1a,b with
(11) (a) Froese, R. D. J.; Musaev, D. G.; Matsubara, T.; Morokuma,
K. J. Am. Chem. Soc. 1997, 119, 7190-7196. (b) Froese, R. D. J.;
Musaev, D. G.; Matsubara, T.; Morokuma, K. Organometallics 1999,
18, 373-379.

5606 Organometallics, Vol. 24, No. 23, 2005
Table 1. Crystal Data and Structure Refinement for 1b, 3b, 4, 7, 11, and 13
Lavanant et al.
1b
3b
4
7
11
13
formula
cryst size, mm
M, g‚mol-1
cryst syst
space group
a, Å
C
32H36O3S
C38H50O2SSi2
C
16H34O4SZr
C16H32O4S2Ti
C16H32Cl2O4SZr
C16H32Cl2O4STi
0.30 × 0.17 × 0.15 0.42 × 0.40 × 0.22 0.17 × 0.14 × 0.05 0.25 × 0.08 × 0.08 0.50 × 0.42 × 0.40 0.54 × 0.45 × 0.32
500.67
monoclinic
P21/n
627.02
monoclinic
C2
413.71
triclinic
P1h
400.44
monoclinic
C2/c
482.60
monoclinic
P21/n
439.28
monoclinic
P21/n
13.0192(11)
12.2471(10)
17.7002(15)
90.00
22.692(1)
8.3884(5)
20.4111(1)
90.00
10.3427(3)
19.0944(6)
21.5341(7)
81.6410(10)
77.779(2)
84.072(2)
4100.6(2)
8
17.718(1)
12.194(1)
9.611(1)
90.00
10.2494(2)
10.8080(2)
20.4758(3)
90.00
10.0684(2)
10.7817(2)
20.2383(4)
90.00
b, Å
c, Å
R, deg
â, deg
99.614(2)
90.00
110.821(3)
90.00
94.447(3)
90.00
101.990(1)
90.00
101.938(1)
90.00
γ, deg
V, Å3
2782.6(4)
4
3631.5(3)
4
2070.2(3)
4
2218.73(7)
4
2149.44(7)
4
Z
Dcalc, Mg/m3
T, Κ
1.195
279(2)
1.147
110(1)
1.340
100
1.285
1.445
110
1.357
293(2)
120(1)
3.34-27.49
0.629
θ range, deg
1.81-26.37
0.147
1.84-27.49
0.186
2.91-31.00
0.651
2.07-2749
0.846
2.11-27.48
0.760
µ, mm-1
no. of measd reflns 21 988
no. of indep reflns 5689
no. of reflns with 4420
I > 2σ(I)
13 737
4434
3935
46 974
8389
24 761
5032
4883
31 872
23 443
23 54
4888
13 757
1989
4107
no. of params
goodness of fit
R [I > 2σ(I)]
338
390
827
106
218
218
1.032
0.0449
0.1176
0.224
1.121
0.0573
0.1414
0.308
1.013
0.0716
0.1497
2.548
1.065
0.0487
0.1284
0.794
1.082
0.0249
0.0653
1.567
1.001
0.0537
0.1495
1.661
2
Rw
lgst diff, e‚Å-3
Scheme 1
ClSiMe3 (eq 3). The use of DBU, instead of the usual
NEt3, and a large excess of ClSiMe3 were found to be
Figure 2. Hydrogen-bonding interactions involving water
in the crystal structure of 1b.
necessary to obtain a high yield of 3b. The identity of
3b was confirmed by an X-ray diffraction study (Figure
3, Table 1).
Synthesis of Neutral Complexes. Several routes
to Ti-{OSOR} and Zr-{OSOR} complexes have been
explored: (a) σ-bond metathesis reactions between the
diols and an appropriate homoleptic metal precursor
enabling either alkane or alcohol elimination; (b) salt
elimination reactions between a alkali metal dialkoxide
salt and MCl4(THF)n; (c) σ-bond metathesis reactions
between the diol trimethylsilyl ethers and MCl4(THF)n.
These results are summarized in Schemes 1-3. The
prepared neutral complexes are all air- and moisture-
sensitive and were characterized by variable-tempera-
ture 1H and 13C NMR spectroscopy, elemental analysis,
and, in several cases, X-ray diffraction (vide infra).
The 1:1 σ-bond metathesis reaction of 1a and
Zr(OtBu)4 proceeded readily to yield the corresponding
(12) (a) Nakayama, Y.; Watanabe, K.; Ueyama, N.; Nakamura, A.;
Harada, A.; Okuda, J. Organometallics 2000, 19, 2498-2503. See
also: (b) Oakes, D. C. H.; Kimberley, B. S.; Gibson, V. C.; Jones, D. J.;
White, A. J. P.; Williams, D. J. Chem. Commun. 2004, 2174-2175.
(13) (a) Idson, B.; Spoerri, P. E. J. Am. Chem. Soc. 1954, 76, 2902-
2906. (b) Gilbert, B. C.; Larkin, J. P.; Norman, R. O. C. J. Chem. Soc.,
Perkin Trans. 2 1973, 272-277.
(14) pKa Values calculated with the ACD software (CambridgeSoft)
for Ph2CHOH and Me2CHOH, respectively.

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5607
Scheme 2
Scheme 3
either the isolated dipotassium salt 2a or in situ-
generated Li2{OSOMe} proceeded readily in THF to
give ZrCl2{OSOMe}(THF) (10) with a single THF ligand.
The bis-THF complex ZrCl2{OSOMe}(THF)2 (11) was
obtained by recrystallization of 9 or 10 in THF. Complex
11 was converted to 10 upon removal of one molecule
of THF by vacuum-drying for several hours.
Similarly, alcohol elimination between 2 equiv of 1a
and Ti(OiPr)2Cl2, in situ-generated from TiCl4 and
Ti(OiPr)4,16 gave the THF-free dichloro titanium com-
plex 12 (Scheme 3). The elimination reaction of in situ-
generated Li2{OSOMe} with TiCl4 in THF afforded the
bis-THF analogue 13. In no case could a mono-THF
titanium complex be isolated.
The reactions in Schemes 1-3 were unsuccessful
when carried out with p-tolyl-substituted diol 1b or salts
thereof. The direct reaction of 1b with a slight excess
of TiCl4 in the absence of NEt32a did afford TiCl2{OSOtol}
(14), but this species could not be isolated in a pure form
(eq 4). Attempts to prepare similar compounds from the
reaction of TiCl4(THF)2 and the trimethylsilyl ether 3b
by elimination of trimethylsilyl chloride17 were unsuc-
cessful. The analogous dimethyl-substituted diol-ether
3a did afford 13, but the reactivity (maximum 15%
conversion) was quite poor (eq 5).
bis(tert-butoxide) complex 4 (Scheme 1). Attempts to
perform the same reaction with Ti(OiPr)4 and 1a under
various conditions invariably yielded mixtures of Ti-
(OiPr)2{OSOMe} (5) and the bis-ligand complex Ti-
{OSOMe}2 (7), which could not be separated by recrys-
tallization. Both 7 and the analogous Zr complex 6 were
prepared efficiently by the reaction of 2 equiv of 1a with
M(OR)4 complexes. Complex 6 served as an efficient
entry to the dibenzyl complex Zr(CH2Ph)2{OSOMe} (8)
via comproportionation with Zr(CH2Ph)4.4 Direct alco-
holysis of Zr(CH2Ph)4 with diol 1a also affords 8.
However, this alkane elimination route requires careful
addition at low temperature under diluted condition to
avoid the formation of insoluble products. The compro-
portionation route is easier and more reliable.
Several ZrCl2{OSOMe}(THF)n complexes with variable
number of THF ligands (n ) 0-2) were prepared as
shown in Scheme 2. Comproportionation of bis-ligand
complex 6 with ZrCl4 in toluene gave the THF-free
complex ZrCl2{OSOMe} (9) in virtually quantitative
yield. Complex 9 was also prepared in a one-pot
procedure by first generating “Zr(nBu)2Cl2” from ZrCl4
and nBuLi15 and then adding 2 equiv of 1a to perform
an alkane elimination. Again, the comproportionation
route proved to be easier and more efficient, although
it requires two steps. Salt metathesis between ZrCl4 and
Solid-State Structures of Neutral Complexes.
The solid-state structures of 4, 7, 11, and 13 were

5608 Organometallics, Vol. 24, No. 23, 2005
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 4
molecule a molecule b
Lavanant et al.
O(10a)-Zr(1a)
O(20a)-Zr(1a)
O(60a)-Zr(2a)
O(50a)-Zr(2a)
O(30a)-Zr(1a)
O(7a)-Zr(1a)
O(3a)-Zr(1a)
O(3a)-Zr(2a)
O(7a)-Zr(2a)
O(40a)-Zr(2a)
Zr(2a)-Zr(1a)
S(5a)-Zr(1a)
C(10a)-O(10a)-Zr(1a)
C(20a)-O(20a)-Zr(1a)
C(60a)-O(60a)-Zr(2a)
C(50a)-O(50a)-Zr(2a)
C(30a)-O(30a)-Zr(1a)
C(7a)-O(7a)-Zr(1a)
C(3a)-O(3a)-Zr(1a)
C(3a)-O(3a)-Zr(2a)
C(7a)-O(7a)-Zr(2a)
C(40a)-O(40a)-Zr(2a)
S(5a)-Zr(1a)-O(30a)
O(10a)-Zr(1a)-O(7a)
O(20a)-Zr(1a)-O(3a)
O(40a)-Zr(2a)-O(3a)
O(50a)-Zr(2a)-O(7a)
O(60a)-Zr(2a)-O(30a)
O(10a)-Zr(1a)-O(20a)
O(50a)-Zr(2a)-O(60a)
O(3a)-Zr(1a)-O(7a)
O(3a)-Zr(2a)-O(7a)
O(20a)-Zr(1a)-O(40a)
O(30a)-Zr(2a)-O(40a)
1.956(3)
1.930(3)
O(10b)-Zr(2b)
O(60b)-Zr(1b)
O(40b)-Zr(1b)
O(7b)-Zr(2b)
O(3b)-Zr(2b)
O(3b)-Zr(1b)
O(7b)-Zr(1b)
O(30b)-Zr(2b)
O(20b)-Zr(2b)
O(50b)-Zr(2b)
O(50b)-Zr(1b)
S(5b)-Zr(1b)
Zr(1b)-Zr(2b)
C(10b)-O(10b)-Zr(2b)
C(60b)-O(60b)-Zr(1b)
C(40b)-O(40b)-Zr(1b)
C(7b)-O(7b)-Zr(2b)
C(3b)-O(3b)-Zr(2b)
C(3b)-O(3b)-Zr(1b)
C(7b)-O(7b)-Zr(1b)
C(30b)-O(30b)-Zr(2b)
C(20b)-O(20b)-Zr(2b)
C(50b)-O(50b)-Zr(2b)
C(50b)-O(50b)-Zr(1b)
S(5b)-Zr(1b)-O(50b)
O(60b)-Zr(1b)-O(3b)
O(40b)-Zr(1b)-O(7b)
O(10b)-Zr(2b)-O(7b)
O(30b)-Zr(2b)-O(3b)
O(20b)-Zr(2b)-O(50b)
O(40b)-Zr(1b)-O(60(b)
O(20b)-Zr(2b)-O(30b)
O(3b)-Zr(1b)-O(7b)
O(3b)-Zr(2b)-O(7b)
1.933(3)
1.943(4)
1.933(3)
2.221(4)
2.353(3)
2.162(3)
2.251(3)
1.940(4)
1.957(3)
2.370(3)
2.059(4)
2.7682(14)
3.2601(7)
170.5(3)
155.8(4)
168.4(4)
138.9(3)
127.3(3)
122.9(3)
125.5(3)
159.8(4)
155.9(4)
130.2(3)
126.8(3)
139.51(10)
158.81(15)
167.50(14)
157.01(14)
160.55(14)
160.34(14)
98.68(16)
98.59(16)
73.80(12)
70.75(12)
1.950(3)
1.955(3)
2.054(3)
2.174(3)
2.242(3)
2.195(3)
2.371(3)
1.935(3)
3.2613(7)
2.7401(13)
153.8(3)
175.7(4)
156.3(4)
157.9(4)
130.6(3)
121.7(3)
125.9(3)
137.6(3)
128.7(3)
166.3(4)
140.71(10)
159.10(13)
170.05(14)
155.33(14)
158.60(14)
162.30(14)
97.60(15)
100.57(15)
73.20(12)
70.31(12)
105.13(14)
88.26(13)
Table 3. Selected Bond Lengths (Å) and Angles
(deg) for 7
Table 4. Selected Bond Lengths (Å) and Angles
(deg) for 11 and 13
S(1)-Ti(1)
O(1)-Ti(1)
O(2)-Ti(1)
C(5)-H(5A′)
3.480
1.7902(17) O(1)-Ti(1)-O(2) 113.23(8)
1.8008(16) C(4)-S(1)-C(5) 102.55(14)
C(6)-O(2)-Ti(1) 142.51(16)
11
13
O(1)-Zr(1)
O(2)-Zr(1)
O(3)-Zr(1)
O(4)-Zr(1)
Cl(1)-Zr(1)
Cl(2)-Zr(1)
S(1)-Zr(1)
1.9025(11)
1.9137(12)
2.3000(11)
2.3131(11)
2.5026(4)
2.4807(4)
4.072
O(1)-Ti(1)
O(2)-Ti(1)
O(3)-Ti(1)
O(4)-Ti(1)
Cl(1)-Ti(1)
Cl(2)-Ti(1)
S(1)-Ti(1)
1.761(2)
1.765(2)
2.2083(19)
2.2181(18)
2.3941(8)
2.3650 (8)
4.061
2.963
O(1)-Ti(1)-O(1′) 110.94(14)
O(2)-Ti(1)-O(2′) 104.02(11)
C(5)-H(5A)-S(1′) 169.23
C(1)-O(1)-Ti(1)
149.96(15) O(1)-Ti(1)-O(2′) 107.66(8)
determined by single-crystal X-ray diffraction. Crystal-
lographic data and selected bond distances and angles
are listed in Tables 1-5. For the sake of clarity, the bis-
THF adducts MCl2{OSOMe}(THF)2 (M ) Zr, 11; M )
Ti, 13) will be discussed first.
C(1)-O(1)-Zr(1) 161.43(11)
C(4)-O(2)-Zr(1) 154.72(11)
C(3)-S(1)-C(2)
O(2)-Zr(1)-O(4) 170.49(5)
O(1)-Zr(1)-O(3) 170.39(5)
O(1)-Zr(1)-O(2) 100.16(5)
C(1)-O(1)-Ti(1) 160.05(19)
C(4)-O(2)-Ti(1) 154.6(2)
C(3)-S(1)-C(2)
103.23(10)
103.3(2)
O(2)-Ti(1)-O(4) 168.86(9)
O(1)-Ti(1)-O(3) 169.03(8)
O(1)-Ti(1)-O(2) 101.76(9)
Both 11 and 13 adopt six-coordinate, distorted octa-
hedral, monomeric structures in the solid state (Figures
4 and 5). There is no bonding interaction between the
sulfur atom and metal centers (M‚‚‚S ) 4.06-4.07 Å),
probably due to the presence of the two THF ligands.
The chloride ligands are trans to each other and are cis
to the alkoxide ligand. The major distortions from
idealized octahedral geometry involve the chloride
ligands (Cl(1)-M(1)-Cl(2) ) 160.81(2)° for 11 and
163.66(3)° for 13). The Zr-O distances involving the
dialkoxide ligand of 11 (1.902(1), 1.914(1) Å) are similar
to those in the related complexes Zr[N{CH2CH2C(O)-
Me2}2{((S)-2-C6H4C(H)Me}][CH2Ph] (1.93(1), 1.938(9)
Å)4 and Zr[PhCH2N{CH2C(O)Me2}2][CH2Ph]2 (1.963(1),
1.967(1) Å)7 and somewhat shorter than those in the
O(3)-Zr(1)-O(4)
Cl(2)-Zr(1)-Cl(1) 160.810(15) Cl(2)-Ti(1)-Cl(1) 163.66(3)
81.33(4)
O(3)-Ti(1)-O(4)
79.80(7)
more sterically constrained Zr(CH2Ph)2(2,6-bis{menth-
oxo}pyridyl) (1.989(2), 2.001(3) Å)5 and in Zr(CH2Ph)2-
[{-CH2N(Me)CH2C(CF3)2O}2] (2.0214(8), 2.0471(8) Å),
which contains a fluorinated dialkoxide ligand.18 The
Ti-O distances in 13 are ca. 0.14 Å shorter than the
corresponding Zr-O distances in 11, reflecting the ca.
15% difference in the metal ionic radii.19 The M-O-C
units in 11 and 13 (range of M-O-C angles: 154.6-
161.4°) are slightly bent, but less so than those in
Zr[N{CH2CH2C(O)Me2}2{((S)-2-C6H4C(H)Me}][CH2-
(17) Mack, H.; Eisen, M. S. J. Chem. Soc., Dalton Trans. 1998, 917-
921.
(18) Lavanant, L.; Chou, T.-Y.; Chi, Y.; Lehmann, C. W.; Toupet,
L.; Carpentier, J.-F. Organometallics 2004, 23, 5450-5458.
(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.
(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) (a) Gothelf, K. V.; Jorgensen K. A. J. Org. Chem. 1994, 59,
5687-5691. (b) Manivannan, R.; Sundararajan, G. Macromolecules
2002, 35, 7883-7890.

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5609
Figure 3. ORTEP drawing of {OSOtol}(SiMe3)2 (3b).
Ellipsoids are drawn at the 50% probability level.
Figure 6. ORTEP drawing of Ti{OSOMe}2 (7). Ellipsoids
are drawn at the 50% probability level; all hydrogen atoms
have been omitted for clarity.
electron species (counting the alkoxides as four-electron
donors).
The structure of the bis-ligand titanium complex 7 is
shown in Figure 6. The Ti center has a slightly distorted
tetrahedral coordination geometry, with only the O
atoms bound to the metal center (range of O-Ti-O
angles ) 104.0(1)-113.23(8)°). The Ti-O distances are
similar to those in 13, while the Ti-O-C angles are
ca. 10° smaller (149.9(1)° and 142.5(2)°). The S atom in
7 is not coordinated (Ti‚‚‚S ) 3.480 Å). This contrasts
with the structure of the six-coordinate bis(amino-
dialkoxide) complex Zr[MeN{CH2CH2C(O)Ph2}2]2, in
which both N atoms are coordinated to the metal
center.20 This may not be surprising since (i) Zr nor-
mally prefers a higher coordination number vs Ti and
(ii) the hard metal ion (Ti, Zr) is expected to prefer
dative interactions with relatively harder nitrogen
atoms than soft sulfur atoms.21,22
Figure 4. ORTEP drawing of ZrCl2{OSOMe}(THF)2 (11).
Ellipsoids are drawn at the 50% probability level; all
hydrogen atoms have been omitted for clarity.
However, as shown in Figure 7, the S atoms are
involved in intermolecular S‚‚‚H‚‚‚C interactions with
methylene groups adjacent to sulfur in neighboring
molecules, which results in a linear chain packing
arrangement. The S‚‚‚H distance of 2.96 Å is close to
the sum of the S and H van der Waals radii (3.00 Å)
and is similar to the distances observed for intermo-
lecular C-H‚‚‚S interactions in tetrathiafulvalene de-
rivatives.23
The crystal structure of the heteroleptic complex
Zr(OtBu)2{OSOMe} (4) is more complicated than those
of 11, 13, and 7. It features two independent dinuclear
molecules that differ in the nature of the bridging
Figure 5. ORTEP drawing of TiCl2{OSOMe}(THF)2 (13).
Ellipsoids are drawn at the 50% probability level; all
hydrogen atoms have been omitted for clarity.
(20) Shao, P.; Gendron, R. A. L.; Berg, D. J. Can. J. Chem. 2000,
78, 255-264.
(21) Note that -CPh2O- is a poorer donor as compared to -CMe2O-,
which is anticipated to facilitate N coordination.
Ph] (140.4(1)°, 145.2(1)°),4 Zr(CH2Ph)2(2,6-bis{menth-
oxo}pyridyl) (128.66°, 130.49°),5 and MX2[{-CH2N-
(Me)CH2C(CF3)2O}2] (Ti-O-C: 129.8(1)°, 129.4(1)°;
Zr-O-C: 127.58(7)°, 130.75(7)°).18 The alkoxide ligands
in those species are incorporated into six- and five-
membered rings, which may constrain the M-O-C
angle more than flexible eight-membered rings in 11
and 13. Overall, 11 and 13 are best described as 16-
(22) Note that a Zr‚‚‚S bonding interaction with a distance of 2.7657-
(8) Å has been established in the bis(sulfur-bridged binaphtholate)
zirconium complex Zr[1,1′-S(2-OC10H4-tBu2-3,6)2]2(THF), despite the
presence of an additional coordinated THF molecule and a much more
severe constraint within the five-membered Zr-O-aryl-S rings; see
ref 9e.
(23) (a) Jung, D.; Evain, M.; Novoa, J. J.; Whangbo, M.-H.; Beno,
M. A.; Kini, A. M.; Schultz, A. J.; Williams, J. M.; Nigrey, P. J. Inorg.
Chem. 1989, 28, 4516-4522. (b) Rovira, C.; Novoa, J. Chem. Phys. Lett.
1997, 279, 140-150, and references therein.

5610 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
Figure 7. Intermolecular S‚‚‚H interactions in Ti{OSOMe}2 (7). All hydrogen atoms except those involved in the interactions
have been omitted for clarity.
Figure 9. ORTEP drawing of the molecule b of complex
Figure 8. ORTEP drawing of the molecule a of complex
4. Ellipsoids are drawn at the 50% probability level; all
4. Ellipsoids are drawn at the 50% probability level; all
hydrogen atoms have been omitted for clarity.
hydrogen atoms have been omitted for clarity.
1
The low-temperature (230 K) H NMR spectrum of
ligands (4a, Figure 8; 4b, Figure 9). In 4a, two
Zr(CH2Ph)2{OSOMe} (8) in toluene-d8 features sharp
Zr(OtBu)2units are linked by a µ,µ-OSOMe ligand
signals (Figure 10). Key resonances include two sing-
(O7a-O3a), which bridges Zr1a and Zr2a by both
lets for the ZrCHHPh groups, two AB doublets for the
oxygens and is also S-bonded to Zr1a, and by a µ-OSOMe
SCHH groups, and two (partially overlapping) sing-
ligand (O30a-O40a), which bridges Zr1a and Zr2a by
lets for the CMe2 groups. The 220 K 13C NMR spec-
one oxygen and is terminal to Zr2a through the other.
Molecule 4b differs from 4a by exchange of the bridging
trum of 8 contains two sets of benzyl resonances, one
SCH2 resonance, and two methyl resonances. These
arm of the µ-OSOMe ligand by a OtBu ligand. The
data are consistent with overall Cs symmetry. The
coordination environment at Zr(1) is thus similar in both
molecules and is best described as strongly distorted
observation of two benzylic CH2 13C signals with well-
differentiated JC-H coupling constants (δ 54.9, JC-H
)
octahedral. Also, the second Zr atom (Zr(2)) is coordi-
nated by six oxygen atoms in a strongly distorted
octahedral environment in both 4a and 4b. The Zr-O
distances (1.935(3)-1.957(3) Å) involving nonbridging
oxygen atoms of the dialkoxide ligand are somewhat
longer than those found in 11 and unexceptional (2.054-
(3)-2.371(3) Å) for those involving bridging oxygen
atoms.9e,24 The Zr-S distances (4a, 2.7401(13); 4b,
2.768(1) Å) are similar to that (2.7657(8) Å) in the
sulfur-bridged binaphtholate zirconium complex Zr[1,1′-
S(2-OC10H4-tBu2-3,6)2]2(THF).9e
Solution Structure and Dynamics of Neutral
Complexes. The solution structures of 8, 12, and 4 have
been investigated in detail by NMR techniques.25 NMR
studies were performed in toluene or benzene solvents
to avoid the formation of solvent adducts.
139.3 Hz; δ 53.6, JC-H ) 128.5 Hz) and two Cipso signals,
with one at high-field (δ 147.6 and 136.5), is diagnostic
for the presence of one η2-benzyl group and one normal
η1-benzyl group.5,26 Coordination of the S atom to Zr in
8 is likely, but the NMR data give no definitive evidence
for it.27
As shown in Figure 10, raising the temperature
results in broadening and coalescence of the ZrCH2Ph
(25) The NMR spectra of the six-coordinated bis(THF) complexes
11 and 13 are consistent with the structures observed in the solid state.
The solution structure and dynamics of 9 could not be investigated in
a noncoordinating solvent, since this complex is only soluble in THF
(suggesting it exists as strongly agglomerated species in noncoordi-
nating solvents).
(26) (a) Latesky, S. L.; McMullen, A. K.; Nicollai, G. P.; Rothwell, I.
P. 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.; Abdul Malik, K. M. Organometallics 1994, 13, 2235-2243.
(27) No clear trend was observed in the 1H and 13C chemical shifts
of SCH2 units in complexes prepared in this study that could be related
to coordination of S to the metal center. However, coordination of N to
Zr has been observed in the solid-state structure of the parent complex
Zr(CH2Ph)2{ONOMe}; see ref 7.
(24) (a) Heyn, R. H.; Stephan, D. W. Inorg. Chem. 1995, 34,
2804-2812. (b) Boyle, T. J.; Schwartz, R. W.; Doedens, R. J.; Ziller,
J. W. Inorg. Chem. 1995, 34, 1110-1120. (c) Swamy, K. C. K.; Veith,
M.; Huch, V.; Mathur, S. Inorg. Chem. 2003, 42, 5837-5843. (d)
Evans, W. J.; Ansari, M. A.; Ziller, J. W. Polyhedron 1998, 17, 869-
878.

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5611
Figure 12. Plausible C1-symmetric dimeric structures for
TiCl2{OSOMe} (12).
cal‚mol-1‚K-1),21 which occurs unambiguously via a
dissociative mechanism.7,30
Figure 10. Experimental (left) and simulated (right)
variable-temperature 1H NMR spectra of Zr(CH2Ph)2-
{OSOMe} (8) (toluene-d8, 300 MHz) showing the ZrCH2Ph
(δ 1.40 and 2.55) and SCH2 (δ 1.55 and 2.75) resonances.
The vertical expansion is different in each case for clarity.
Best-fit first-order rate constants (k) are shown with the
simulated spectra (* and Σ denote resonances for PhCH3
and PhCHD2, respectively).
1
The room-temperature H NMR spectrum of TiCl2-
{OSOMe} (12) in toluene-d8 consists of only two sharp
singlets for the CMe2 and SCH2 groups. Upon lowering
the temperature, these resonances broaden and split
and, at 218 K, one major series of resonances is present
(accounting for ca. 90% of the product), which comprises
eight doublets for the SCHH groups and eight singlets
for the CH3 groups. Also, four SCH2CMe2O groups were
distinguished by 2D NMR experiments (HMBC, HMQC,
and COSY) and each group integrated equally. From
these NMR data, and the X-ray structures of related
sulfur-bridged bis(phenoxide) titanium complexes,10c,12a
we propose that 12 exists in toluene solution as a single
C1-symmetric dimer. Dimerization of 12 is plausible
since stabilization of the electron-deficient metal center
cannot proceed intramolecularly as in benzyl complex
8. The observation of two low-field (δ 96.1 and 96.0) and
two high-field (δ 92.6 and 91.1) C-O resonances in the
13C NMR spectrum of 12 suggests that dimerization of
12 occurs by double bridging from the oxygen atoms of
the dialkoxide ligand10c rather than µ-Cl bridging12a
(Figure 12).
1
Similarly, the room-temperature H NMR spectrum
of Zr(OtBu)2{OSOMe} (4) consists of sharp singlets for
the CMe2, SCH2 groups, and tert-butoxide groups of
Figure 11. Eyring plot for Zr(CH2Ph)2{OSOMe} (8) (toluene-
d8 solvent) (R2 ) 0.977).
1
appropriate relative intensity. The 233 K H spectrum
resonances and of the SCH2 resonances, and at 333 K
sharp singlets are observed for those groups. A single
set of resonances for equivalent SCH2, CMe2, and
benzylic groups is also observed in the room-tempera-
ture 13C NMR spectrum of 8. These data establish that
8 undergoes exchange of the η2/η1-benzyl ligands, as
shown in eq 6.5 Line-shape analysis demonstrated that
both the ZrCH2Ph hydrogens and the SCH2 hydrogens
exchange at the same (or at least quite similar) rates
(Figure 10), as expected for the fluxional process in eq
6.28 The activation parameters for this fluxional behav-
ior (∆Hq ) 10.6 ( 1 kcal‚mol-1; ∆Sq ) -2.7 ( 2
cal‚mol-1‚K-1) were derived from an Eyring analysis
(Figure 11).29 The activation parameters for 8 differ
from those for benzyl exchange in Zr(CH2Ph)2-
{ONOMe} (∆Hq ) 20.0 ( 1 kcal‚mol-1; ∆Sq ) 13.1 ( 2
is quite complicated, contains three series of resonances
(accounting for >90% of the product) of comparable
intensity. Most of the CMe2 and OtBu resonances
(28) Simulation of the OCMe2 resonances was not attempted because
of the minute difference in the chemical shifts.
(29) (a) These values correspond well with the free energy of
activation determined experimentally from the coalescence tempera-
q
ture (Tc ) ca. 270 K) for both the ZrCH2Ph and SCH2 hydrogens (∆Gcoal
) 11.3(3) kcal‚mol-1, ∆Gcalc ) 11.3 kcal‚mol-1). Exchange barriers ∆Gq
q
were determined from the coalesence of the SCHH AB patterns using
the following equations for an equally populated, two-site exchange:
∆Gq ) 4.576Tc[10.319 + log(Tc/kc)], where Tc is the coalesence tem-
perature and kc is the exchange rate constant at coalesence, which is
given by kc ) π[(∆νAB + 6JAB ] . The errors on ∆Gcoal were
1/2/21/2 b-d
2
2
q
estimated assuming (2% uncertainty in the chemical shifts and
coalescence temperature. (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. Tetrahedron Lett. 1974,
4533-4536.

5612 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
overlap at 233 K, which hampers valuable analysis. In
contrast, the SCHH hydrogens were well resolved. Two
of the three series of resonances are composed of eight
doublets for the SCHH groups, while the third series
contains only four doublets for the SCHH groups. In the
233 K HMQC spectrum, the three series of hydro-
gens correlate respectively with two series of four
SCH2 carbons and one series of two SCH2 carbons. It
is reasonable to assume that the first two series of
resonances can be assigned to the dimeric C1-sym-
metric molecules 4a and 4b observed in the solid-state
structure of 4, which differ in the nature of the µ-bridg-
ing ligands. The third series may correspond to a C2/
Cs-symmetric dimer or a C1-symmetric mononuclear
species.
Although the nuclearity of all [MX2{OSOMe}]n spe-
cies could not be unambiguously established, mono-
nuclear and dinuclear structures appear as the most
plausible hypotheses. For both 4 and 12, fast sym-
metrization of the putative dinuclear structures on the
NMR time scale occurs at high temperature. This is
likely to proceed via intramolecular ligand exchange,
and there is no evidence for the formation of mono-
nuclear species in apolar solvents. It seems therefore
Figure 13. 1H NMR spectra (400 MHz, 240 K) of
[Zr(CH2Ph){OSOMe}][B(C6F5)4] (15) (CD2Cl2, bottom) and
[Zr(CH2Ph){OSOMe}][B(CH2Ph)(C6F5)3] (16) (toluene-d8,
top). The markers R, δ, and γ denote resonances for PhCH3,
PhCHD2, and CHDCl2, respectively; the marker τ denotes
the resonances for the neutral complex Zr(CH2Ph)2{OSOMe
}
(8); the markers π and ø denote resonances for pentane
and organic impurities, respectively.
that the nuclearity of electron-deficient MX2{OSOMe
}
NMR spectrum of 15 (240 K) contains four singlets for
the Me groups, four doublets for the SCHH groups, and
two doublets for the PhCHH hydrogens (Figure 13). A
complete set of 13C resonances is observed, which are
particularly well differentiated for the methylene groups
adjacent to the sulfur atom (δ 59.9 and 51.3). The
Zr-benzyl ipso-carbon 13C resonance appears at high-
field (δ 132.4, assigned by the HMBC correlation with
PhCHH), consistent with η2-benzyl coordination,26 as in
the parent neutral complex 8. Also, the 1H NMR
spectrum of 15 exhibits a 1:2:2 pattern of downfield
resonances (δ 8.30, p-H; 7.91, m-H; 7.69, o-H) for the
benzyl group that indicates a very strong interaction of
the phenyl ring with the metal center.34 Additionally,
complex 15 may be further stabilized by solvent coor-
dination.
Generation of Zr(CH2Ph){OSOMe}+ species by reaction
of 8 with B(C6F5)3 was also investigated.31f,33 Addition
of cold toluene to a mixture of 8 and B(C6F5)3 at 243 K
resulted in the virtually instantaneous generation of an
intense yellow color, indicating rapid alkyl abstraction.
The product exhibited high solubility in toluene and has
been characterized by 1H, 11B, 13C, and 19F NMR
spectroscopy as the zwitterion Zr(CH2Ph){OSOMe}+(µ-
η6,η1-PhCH2B(C6F5)3]- (16, eq 7). Anion coordination to
zirconium via a η6 π-benzene interaction was clearly
indicated by the characteristic downfield location of the
species is controlled by the nature of the X ligands (X
) CH2Ph, Cl, OR). Among those investigated in this
work, only the benzyl ligands enable stabilizing mono-
nuclear species in solution, possibly thanks to their
intramolecular η2-coordination mode, while chloro and
alkoxide ligands induce bridging modes and formation
of dinuclear species.
Generation of Cationic Benzyl-Zirconium Com-
plexes. The reaction of Zr(CH2Ph)2{OSOMe} (8) with
[Ph3C][B(C6F5)4]31 at 240 K resulted in the almost
instantaneous formation of 1 equiv of Ph3CCH2Ph32
and a yellow-orange complex characterized by 1H,
11B, 13C, and 19F NMR spectroscopy as the cationic
complex [Zr(CH2Ph){OSOMe}][B(C6F5)4] (15, eq 6). Com-
plex 15 separates from toluene solution as an orange
oil, which is soluble and relatively stable at 240 K in
CD2Cl2 solution (in the absence of excess trityl re-
agent). Significant decomposition of 15 and/or reaction
with the solvent to produce mixtures of unidentified
products was observed, however, after 2 h at 240 K in
CD2Cl2 and was complete within 20 min at room
temperature.
(31) For use of [Ph3C][B(C6F5)4] in the generation of LnM(R)+ species,
see: (a) Chien, J. C. W.; Tsai, W.; Rausch, M. D. J. Am. Chem. Soc.
1991, 113, 8570-8571. (b) Ewen, J. A.; Elder, M. J. Makromol. Chem.,
Macromol. Symp. 1993, 66, 179-190. (c) Bochmann, M.; Lancaster,
S. Organometallics 1993, 12, 633-640. (d) Razavi, A.; Thewalt, U. J.
Organomet. Chem. 1993, 445, 111-114. (e) Straus, D. A.; Zhang, C.;
Tilley, T. D. J. Organomet. Chem. 1989, 369, C13-C17. (f) Chen, E.
Y.-X.; Marks, T. J. Chem. Rev. 2000, 100, 1391-1434.
As expected, no evidence was found for coordination
of the [B(C6F5)4]- counteranion in 15: 19F NMR reso-
nances were unperturbed from the free anion values.
The 1H and 13C NMR spectra show that 15 has a
nonfluxional C1-symmetric structure up to 273 K, at
which temperature fast decomposition proceeds. The 1H
(32) Stoebenau, E. J.; Jordan, R. F. J. Am. Chem. Soc. 2003, 125,
3222-3223.
+
(30) 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.
(33) For use of B(C6F5)3 in the generation of M(R)Ln species, see:
(a) Jordan, R. F. Adv. Organomet. Chem. 1991, 32, 325-387. (b) Yang,
X.; Stern, C. L.; Marks, T. J. J. Am. Chem. Soc. 1994, 116, 10015-
10031, and references therein.
(34) Horton, A. D.; de With, J. Organometallics 1997, 16, 5424-
5436.

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5613
B-benzyl ipso-C 13C NMR resonance at δ 159.2 in 16
(compared to δ 148.5 for the free anion),34,35 downfield
shift of the meta- and para-fluorine 19F resonances
relative to those of the free anion, and the difference in
the chemical shifts of the meta- and para-fluorine 19F
resonances (∆δ(m,p-F) ) 3.7).34 The high solubility of
16 in toluene solution is also consistent with benzylbo-
rate anion coordination to the metal center, rather than
a solvent-separated ionic structure. The 1H NMR spec-
trum of 16 in the temperature range 230-250 K con-
tains two singlets for the methyl groups, two doublets
for the SCHH hydrogens, and a broadened singlet for
the Zr-CHHPh hydrogens, consistent with a Cs-sym-
metric structure.36
Figure 14. 1H NMR spectrum (toluene-d8, 400 MHz, 296
K) of the decomposition product from 16 ([Zr(C6F5)-
{OSOMe}]+[η6-(PhCH2)B(CH2Ph)(C6F5)2]-, 17). The mark-
ers 4 and 0 denote resonances for PhCH3 and PhCHD2,
respectively; the markers Σ and ] denote resonances for
pentane and unidentified impurities, respectively.
experiments, product 17 has been formulated as [Zr-
(C6F5){OSOMe}]+[η6-(PhCH2)B(CH2Ph)(C6F5)2]- (eq 8).
However, despite the anion coordination, 16 is ther-
mally sensitive and converts cleanly to a second species
(17) over several hours at 296 K and much faster at
higher temperatures. The conversion was monitored by
1H, 11B, 13C, and 19F NMR spectroscopy. 11B NMR
monitoring (see Supporting Information) indicated that
16 (δ -11.4) is selectively transformed into another ionic
species, 17, which also has a four-coordinate anionic
boron center slightly shifted upfield (δ -11.7). The 19F
NMR spectrum of 17 contains three ortho-fluorine
resonances: two at δ -114.9 and -128.2 that integrate
respectively for 1 o-F and are characteristic of a C6F5
group (unsymmetrically) coordinated onto Zr,37,39 and
Room-temperature 1H NMR data indicate an overall
Cs-symmetry for 17 on the NMR time scale. As judged
1
by H NMR spectroscopy, complex 17 does not exhibit
fluxionality in toluene in the temperature range 243-
303 K. This was unexpected considering the possible
exchange process between the coordinated arene and
the phenyl ring of the other benzyl ring.38 Reasons for
this stability are not clear at the moment. Decomposi-
tion pathways of zirconium cationic species associated
with the alkylborate [RB(C6F5)3]- anion usually involve
transfer of C6F5 fragments from boron to the metal
center, to end up with neutral zirconium species.5,34,39
The selective transformation of 16 to 17 suggests that
the cationic center of 17 is not electrophilic enough, for
-
a third one at δ -130.5 for 4 o-F of a (PhCH2)2B(C6F5)2
group.38 In the aromatic region of the 1H NMR spectrum
(Figure 14), in addition to a normal pattern of reso-
nances for a typical benzyl group, three separate
resonances were observed for the phenyl hydrogens of
the other benzyl moiety. The upfield shift of some of
these resonances from their usual positions is indicative
of coordination of the phenyl ring to the metal center.38
Similar features were evident in the 13C{1H} NMR
spectrum. Also, the 1H and 13C{1H} NMR spectra
contain respectively two singlets at δ 3.45 and 2.88, and
two broad resonances at δ 38.2 and 35.2 for the two
BCH2 groups, consistent with previous assignments on
closely related species.38 Moreover, no resonances at-
tributable to a Zr-CH2Ph moiety were observed in the
1H and 13C NMR spectra of 17. On the basis of these
data, corroborated by 2D HMQC, HMBC, and COSY
-
electronic and/or steric reasons, to pull off a C6F5
substituent of the coordinated borate anions and gener-
ate in turn a neutral bis(pentafluorophenyl)zirconium
complex.
Ethylene Polymerization. The prepared complexes
were briefly investigated in ethylene polymerization.
Neutral MCl2{OSOR}(THF)n complexes 9-14 were ac-
tivated with MAO or a combination of [Ph3C][B(C6F5)4]
with Al(iBu)3,40 while molecular Lewis acidic activators
were used to generate the cationic benzyl-zirconium
species 15 and 16 from 8 in situ. The results are
summarized in Table 5.
(35) (a) Pellecchia, C.; Grassi, A.; Immirzi, A. J. Am. Chem. Soc.
1993, 115, 1160-1162. (b) Pellecchia, C.; Immirzi, A.; Grassi, A.;
Zambelli, A. Organometallics 1993, 12, 4473-4478. (c) Pellecchia, C.,
Grassi, A.; Zambelli, A. J. Mol. Catal. 1993, 82, 57-65.
(36) The SCHH and Zr-CHHPh resonances broaden on raising the
temperature, and coalescence of the methyl singlets is observed at 250
K, yielding a sharp singlet at room temperature. However, due to rapid
decomposition above 250 K, the fluxional behavior of 16 could not be
investigated in detail.
(39) Gauvin, R.; Mazet, C.; Kress, J. J. Organomet. Chem. 2002,
658, 1-8, and references therein.
(37) (a) Bochmann, M.; Sarsfield, M. J. Organometallics 1998, 17,
5908-5912. (b) Indado, G. J.; Lancaster, S. J.; Thornton-Pett, M.;
Bochmann, M. J. Am. Chem. Soc. 1998, 120, 6816-6817. (c) Kraft, B.
M.; Jones, W. D. J. Organomet. Chem. 2002, 658, 132-140. (d)
Stoebenau, E. J.; Jordan, R. F. J. Am. Chem. Soc. 2004, 126, 11170-
11171.
(40) (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.
(38) Spence, R. E. v. H.; Piers, W. E. Organometallics 1995, 14,
4617-4624.

5614 Organometallics, Vol. 24, No. 23, 2005
Table 5. Ethylene Polymerization Dataa
Lavanant et al.
c
d
temp
(°C)
time
(min)
yield
(g)
activityb
Mw
(10-3
Tm
c
entry
catalyst precursor
activator (equiv)
(kg PE‚mol-1‚h-1
)
)
Mw/Mn
(°C)
1
2
3
TiCl2{OSOMe} (12)
TiCl2{OSOMe} (12)
TiCl2{OSOMe} (12)
MAO (500)
25
60
25
40
30
30
1.382
0.803
0.152
14
10
7
513
274
138
110
52
137.3
137.7
136.7
MAO (500)
[Ph3C][B(C6F5)4] (3)/
Al(iBu)3 (10)
MAO (500)
13.6
4
TiCl2{OSOMe}(THF)2 (13)
TiCl2{OSOtol} (14)
ZrCl2{OSOMe} (9)
ZrCl2{OSOMe} (9)
ZrCl2{OSOMe} (9)
25
25
25
35
25
30
65
0.08
0.08
0.08
0.040
0.520
0.041
0.295
0.120
1
10
470
7190
1130
419
nd
nd
1110
480
14.4
nd
nd
10.8
2.5
135.7
135.1
138.6
136.1
141.9
5e
6
MAO (700)
MAO (500)
7
8
MAO (500)
[Ph3C][B(C6F5)4] (3)/
Al(iBu)3 (10)
MAO (500)
9
ZrCl2{OSOMe}(THF) (10)
Zr(CH2Ph)2{OSOMe} (8)
Zr(CH2Ph)2{OSOMe} (8)
25
25
25
0.08
0.08
30
0.040
0.075
0
590
146
0
nd
458
nd
4.8
138.1
141.5
10f
11f,g
B(C6F5)3 (1)
[Ph3C][B(C6F5)4] (1)
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 under 1 atm of ethylene. f Conducted in the presence of
100 equiv of Al(iBu)3 as scavenger. g No activity was observed in the absence of Al(iBu)3.
Titanium complexes 12-14 activated by MAO in
toluene solution are poorly active for ethylene polym-
erization (entries 1-5).41 No discoloration of the pale
orange-yellow reaction mixture was observed over 60
min and ethylene consumption continued over this
period,42 suggesting that the active species are quite
stable under these conditions. However, the high mo-
lecular weights of the PEs recovered indicate poor
initiation efficiencies. Increase of the temperature to 60
°C had a minor impact on the results (entries 1 and 2).
In contrast, catalysts based on zirconium complexes
9 and 10 are much more active but deactivate very fast.
Under the conditions investigated (entries 6-10), all of
the polyethylene is formed within 5 s, and no more
ethylene is consumed after this time. The activity is
significantly enhanced up to 7 tons PE‚mol-1‚h-1by
raising the polymerization temperature to 35 °C instead
of 25 °C (entries 6 and 7). The apparent activity is
higher than those reported for related catalysts based
on discrete zirconium precursors having amino-alkoxide
or amino-dialkoxide ligands,43 although direct compari-
sons are difficult due to differences in polymerization
time and conditions. The activity observed from THF-
free precursor 9 (entry 6) is comparable to that for the
bis-THF complex 10 (entry 9), most likely because
excess MAO traps THF. On the other hand, low or no
activity was observed with discrete in situ-generated
ionic complex 16 (entries 10, 11). Berg4 and Kress5
observed similar insignificant or no ethylene polymer-
ization activity with Zr(CH2Ph)2[RN{CH2CH2C(O)R′2}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 polymers produced under these conditions have
a quite high molecular weight and melting temperatures
in the range 135-141 °C, indicative of essentially linear
long chain microstructures. The molecular weight dis-
tributions were generally broad,43 especially for Ti
systems, although most of them feature monomodal
shapes with long tailing on low42 and high molecular
weights (see Supporting Information). The polyethylene
produced with the 9/[Ph3C][B(C6F5)4]/Al(iBu)3 (1:3:10)
activating combination (entry 8) had a relatively narrow
monomodal molecular weight distribution, characteris-
tic of a single-site catalyst.
Conclusions
The aim of this study was to investigate the co-
ordination properties of the tridentate ligand sys-
tems {OCR2CH2SCH2CR2O}2- in simple neutral group
4 MX2{OSOR} complexes and cationic M(R){OSOR}+
alkyl species. Effective routes for the preparation of a
variety of chloro, isopropoxo, amido, and benzyl Zr and
Ti complexes, as well as bis-ligand complexes, have been
identified with the methyl-substituted ligand system.
Those compounds have been characterized in the solid
state and in solution. Difficulties have been encountered
in the synthesis of complexes derived from the ligand
system having p-tolyl substituents; further studies are
required to evaluate the relative influence of steric and
electronic factors in this case. Remarkably, most of the
MX2{OSOMe} complexes studied adopt mononuclear
structures in the solid state and in solution, despite the
modest steric crowding and electron-donating capability
of the ligand. Discrete cationic species [Zr(CH2Ph)-
{OSOMe}]+ have also been prepared and found to be
moderately stable. Although plausible, the interaction
of the sulfur atom with metal centers in MX2{OSOR}
and M(R){OSOR}+ species could not be established
unambiguously.
(41) Eisen and co-workers have reported that the TiCl2[Py{CPh2O)2]/
MAO combination exhibits modest ethylene polymerization activity (20
°C, 1 atm); see ref 6b.
(42) In these experiments, polyethylene was recovered in virtually
the same amount as that of ethylene consumed; oligomers (if any) are
therefore negligible.
(43) (a) Zr(CH2Ph)2[RN{CH2CH2C(O)R′2}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 4. (b) Zr(CH2Ph)2{PyC(CF3)2O}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(CH2Ph)2{PyC(CF3)2O}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 5.
The high ethylene polymerization activity observed
with some ZrCl2{OSOR}/MAO combinations is in line
with predictive computations carried out several years
ago,11 which forecasted the promising catalytic perfor-
mances of sulfur-bridged dialkoxide complexes. How-
ever, reasons for the high activity but also high insta-
bility of these catalytic systems are still unclear. Current
investigations are directed toward understanding these

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5615
4H, CH2), 1.18 (s, 12H, CH3). 1H NMR (C6D6, 200 MHz): δ
3.40 (s, 2H, OH), 2.56 (s, 4H, CH2), 1.17 (s, 12H, CH3). 1H NMR
(THF-d8, 200 MHz): δ 3.94 (s, 2H, OH), 2.65 (s, 4H, CH2), 1.18
(s, 12H, CH3). 1H NMR (pyridine-d5, 200 MHz): δ 6.01 (s, 2H,
phenomena, assessing in particular possible transfer of
{OSOR}2- ligands between group 4 metal and Al cen-
ters. The promising results obtained in this study in
terms of coordination/organometallic chemistry and
polymerization catalysis suggest possibilities for sig-
nificant improvement by ligand tuning.
1
OH), 3.00 (s, 4H, CH2), 1.25 (s, 12H, CH3). H NMR (CD3CN,
200 MHz): δ 3.12 (s, 2H, OH), 2.68 (s, 4H, CH2), 1.20 (s, 12H,
CH3). 13C{1H} NMR (CDCl3 and THF-d8, 50 MHz): δ 71.3 (C),
49.3 (CH2), 29.1 (CH3). Anal. Calcd for C8H18O2S: C, 53.89;
H, 10.18; S, 17.98. Found: C, 54.05; H, 10.24; S, 17.85. HRMS:
calcd for [M - Me - H2O] 145.0687, found 145.0666; calcd for
[M - Me - 2 H2O] 127.05815, found 127.0583.
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. CD2Cl2 was distilled from calcium hydride.
CD3CN was dried over 3 and 4 Å molecular sieves. 1-Chloro-
2,2-di(4-methylphenyl)-2-ethanol was prepared by reaction of
(4-MeC6H4)MgBr with ethyl chloroacetate in THF. Zirconium
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.44
[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.
Bis(2,2-di(4-methylphenyl)-2-ethanol)sulfide Hydrate
({OSOtol}H2‚H2O, 1b). This product was prepared as described
above for 1a, starting from Na2S‚9H2O (2.25 g, 9.40 mmol) and
(4-MeC6H4)2C(OH)CH2Cl (4.90 g, 18.8 mmol). Addition of
pentane (20 mL) to the final red-orange oily residue precipi-
tated 1b as a colorless powder, which was collected by filtra-
tion and dried in a vacuum (34%). Evaporation of the
former pentane solution and chromatography of the crude
product (silica, heptane/ethyl acetate 100:6 v/v, Rf ) 0.17)
afforded an additional crop of diol (total yield 2.68 g, 57%).
3
1H NMR (C6D6, 200 MHz): δ 7.38 (d, JH-H ) 8.2 Hz, 8H,
3
o-C6H4), 6.96 (d, JH-H ) 8.2 Hz, 8H, m-C6H4), 5.11 (s, 2H,
H2O), 3.86 (s, 2H, OH), 3.34 (s, 4H, CH2), 2.08 (s, 12H, CH3).
13C{1H} NMR (C6D6, 50.3 MHz): δ 21.1 (CH3), 48.4 (CH2), 78.5
1
(Cq), 126.8 (m-C), 129.3 (o-C), 136.8 (p-C), 143.8 (ipso-C). H
3
NMR (DMSO-d6, 200 MHz): δ 7.38 (d, JH-H ) 8.0 Hz, 8H,
3
o-C6H4), 7.09 (d, JH-H ) 8.0 Hz, 8H, m-C6H4), 5.70 (s, 2H,
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
H2O), 3.47 (s, 4H, CH2), 2.53 (s, 2H, OH), 2.27 (s, 12H, CH3).
MS(EI): Calcd for [M - 2 H2O]+ 446.2068, found 446.2093;
calcd for [M - H2O]+ 264.21739, found 264.2113. Anal. Calcd
for C32H36O3S: C, 76.78; H, 7.25; S, 6.40. Found: C, 77.25; H,
7.13; S, 6.50.
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,
K2{OSOMe} (2a). Under argon, a solution of 1a (0.54 g, 3.00
mmol) in THF (20 mL) was added to potassium chunks (0.24
g, 6.2 mmol) in THF (30 mL). The mixture was stirred 4 days
at room temperature, resulting in the disappearance of potas-
sium and the formation of a white precipitate. An extra
amount of potassium chunks (0.024 g, 0.615 mmol) was added,
and the mixture was stirred for two more days. Residual
potassium was removed from the mixture, and volatiles were
removed under vacuum. The white powder obtained was
washed several times with pentane and dried under vacuum
(0.73 g, 94%). Anal. Calcd for C8H16O2SK2: C, 37.67; H, 6.34;
1H-13C HMQC, and HMBC NMR experiments. 19F NMR
spectra are referenced to external neat CFCl3. 11B NMR
spectra are referenced to external neat BF3‚OEt2. NMR probe
temperatures were calibrated by a MeOH thermometer.45 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. 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 poly-
styrene standards and are reported relative to polyethylene
standards, as calculated 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).46 DSC measure-
ments were performed on a TA Instruments DSC 2920
differential scanning 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.
1
S, 12.60. Found: C, 37.17; H, 6.52; S, 14.02. H NMR (THF-
d8, 200 MHz): δ 2.59 (s, 4H, CH2), 1.12 (s, 12H, CH3).
K2{OSOtol} (2b). To a solution of 1b (0.50 g, 1.00 mmol) in
diethyl ether (50 mL) was added KOtBu (0.18 g, 1.60 mmol)
at room temperature. The mixture turned red immediately and
a precipitate formed. The mixture was stirred for 3 days at
room temperature. Filtration of the solution gave 2b as a
colorless precipitate, which was washed with pentane and
dried under vacuum (0.146 g, 35%). 1H NMR (DMSO, 200
3
3
MHz): δ 7.22 (d, JH-H ) 8.2 Hz, 8H, o-C6H4), 7.00 (d, JH-H
) 8.2 Hz, 8H, m-C6H4), 3.30 (s, 4H, CH2), 2.21 (s, 12H, CH3).
13C{1H} NMR (DMSO, 50.3 MHz): 20.5 (CH3), 45.9 (CH2), 77.0
Bis(2-hydroxy-2-methylpropyl)sulfide ({OSOMe}H2, 1a).
In a 250 mL round-bottom flask, 1-chloro-2-methyl-2-propanol
(5.42 g, 50.0 mmol) and Na2S‚9H2O (6.00 g, 25.0 mmol) were
refluxed in ethanol (50 mL) for 30 min. The mixture was cooled
to room temperature and filtered, and the filtrate was con-
centrated under vacuum, leaving a white pasty solid. The
latter was dissolved in toluene (5 mL) and dried over MgSO4
for 12 h. Filtration, removal of toluene, and drying for 40 h
under vacuum gave 1a as a white crystalline powder (3.20 g,
72%). 1H NMR (CDCl3, 200 MHz): δ 3.37 (s, 2H, OH), 2.64 (s,
1
(Cq), 126.0 (m-C), 128.1 (o-C), 135.1 (p-C), 144.7 (ipso-C). H
NMR (C6D6, 200 MHz, low solubility): δ 7.44 (d, JH-H ) 8.2
3
Hz, 8H, o-C6H4), 6.97 (d, 3JH-H ) 8.2 Hz, 8H, m-C6H4), 3.52 (s,
4H, CH2), 2.11 (s, 12H, CH3). Anal. Calcd for C32H32O2SK2:
C, 68.77; H, 5.77; S, 5.74. Found: C, 69.2; H, 5.9; S, 5.6.
{OSOMe}(SiMe3)2 (3a). To a solution of 1a (0.500 g, 2.80
mmol) in toluene (70 mL) were added triethylamine (1.60 mL,
11.8 mmol), DMPA (0.068 g, 0.56 mmol), and ClSiMe3 (1.50
mL, 11.8 mmol). The mixture was stirred for 3 days at room
temperature. A heavy precipitate formed, which was removed
by filtration. The filtrate was concentrated under vacuum,
leaving a white powder, which was washed with pentane
(44) Zucchini, U.; Albizzati, E.; Giannini, U. J. Organomet. Chem.
1971, 26, 357-372.
(45) Van Geet, A. L. Anal. Chem. 1970, 42, 679-680.
(46) Scholte, Th. G.; Meijerink, N. L. J.; Schofelleers, H. M.; Brands,
A. M. G. J. Appl. Polym. Sci. 1984, 29, 3763-3782.
1
(2 × 10 mL) and dried under vacuum (0.78 g, 95%). H NMR
(THF-d8, 200 MHz): δ 2.67 (s, 4H, CH2), 1.30 (s, 12H, CH3),
1
0.12 (s,18H, Si(CH3)3). H NMR (C6D6, 200 MHz): δ 2.66 (s,

5616 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
4H, CH2), 1.27 (s, 12H, CH3), 0.16 (s, 18H, Si(CH3)3). 13C{1H}
NMR (THF-d8, 50 MHz): δ 75.3 (C), 49.1 (CH2), 29.3 (CH3),
2.8 (Si(CH3)3). Anal. Calcd for C14H34O2SSi2: C, 52.11; H, 10.62;
S, 9.94. Found: C, 52.24; H, 10.86; S, 9.73.
filtration of the mixture and concentration of the filtrate under
vacuum, a yellow powder was obtained, which was recrystal-
lized from toluene/pentane to give 7 as a white microcrystalline
powder (0.287 g, 53%).
[OSOtol](SiMe3)2 (3b). To a stirred solution of 1b (0.53 g,
1.06 mmol) in a 1:1 mixture of toluene and Et2O (70 mL) was
added DBU (0.50 mL, 3.30 mmol) and Me3SiCl (0.50 mL, 3.90
mmol) at room temperature. A white precipitate formed, and
the reaction mixture was stirred for 24 h at 70 °C. The
precipitate was filtered off, and volatiles were removed under
vacuum. Recrystallization of the residue from pentane at -35
°C gave 3b as a crystalline beige product (0.41 g, 68%). Anal.
Calcd for C36H44O2SSi: C, 76.01; H, 7.80; S, 5.64. Found: C,
Synthesis by Alcohol Elimination. Compound 7 was
prepared as described above for 6 starting from a solution of
1a (0.100 g, 0.56 mmol) in toluene (2 mL) and a solution of
Ti(OiPr)4
(0.080 g, 0.28 mmol) in toluene (2 mL) at -30 °C.
Workup and recrystallization from pentane at -30 °C gave 7
as a white powder (0.110 g, 81%). Anal. Calcd for C16H32O4S2-
Ti: C, 47.99; H, 8.06; S, 16.02. Found: C, 47.78; H, 8.23; S,
15.92. 1H NMR (C6D6, 200 MHz): δ 2.59 (s, 4H, CH2), 1.23 (s,
12H, CH3). 13C{1H} NMR (C6D6, 75.5 MHz): δ 84.1 (OC), 54.0
1
1
(CH2), 29.4 (CH3). H NMR (THF, 300 MHz): δ 2.75 (s, 4H,
76.26; H, 7.94; S, 5.58. H NMR (C6D6, 200 MHz): δ 7.30 (d,
CH2), 1.23 (s, 12H, CH3). 13C{1H} NMR (THF, 75.5 MHz): δ
82.6 (OC), 52.4 (CH2), 27.7 (CH3).
3
3JH-H ) 8.0 Hz, 8H, o-C6H4), 6.98 (d, JH-H ) 8.0 Hz, 8H,
m-C6H4), 2.90 (s, 4H, CH2), 2.12 (s, 12H, CH3), 0.01 (s, 18H,
Si(CH3)3). 13C{1H} NMR (C6D6, 50.33 MHz): δ 2.3 (Si(CH3)3),
21.2 (CH3), 46.7 (CH2), 81.2 (Cq), 128.2 (m-C), 128.7 (o-C), 136.7
(p-C), 144.7 (ipso-C).
Reaction of Ti(OiPr)4 with 1a (1:2 reaction). A solution
of Ti(OiPr)4 (0.191 g, 0.67 mmol) in toluene (3 mL) cooled at
-30 °C was added dropwise to a cold (-30 °C) solution of
ligand 1a (0.120 g, 0.67 mmol) in toluene. The mixture was
warmed to room temperature and stirred for 12 h. Volatiles
Zr(OtBu)2{OSOMe} (4). A solution of 1a (0.100 g, 0.56
mmol) in toluene (3 mL), cooled at -30 °C, was added dropwise
over 5 min to a solution of Zr(OtBu)4 (0.215 g, 0.56 mmol) in
toluene (2 mL) at -30 °C. The mixture was stirred for 6 h,
over which time the temperature was gradually raised to room
temperature. Volatiles were removed under vacuum, and the
white solid was washed with pentane and dried under vacuum
(0.190 g, 91%). Anal. Calcd for C16H34O2SZr: C, 46.45; H, 8.28;
1
were removed under vacuum to give a white powder. The H
NMR spectrum of this powder in benzene-d6 displayed two sets
of resonances consistent with the presence of both complexes
Ti(OiPr)2{OSOMe} (5, 79%) and Ti{OSOMe}2 (7, 21%). Data
for Ti(OiPr)2{OSOMe}: 1H NMR (C6D6, 500 MHz): δ 4.62 (m,
2H, OCHMe2), 2.55 (s, 4H, CH2), 1.30 (d, 3JH-H ) 6.2 Hz, 12H,
CH(CH3)2), 1.21 (s, 12H, CH3).
1
S, 7.75. Found: C, 45.95; H, 8.52; S, 6.67. H NMR (THF-d8,
Zr(CH2Ph)2{OSOMe} (8). Synthesis by Alkane Elimina-
tion. A solution of 1a (0.117 g, 0.658 mmol) in toluene (10
mL) was added at -20 °C to a solution of Zr(CH2Ph)4 (0.300
g, 0.658 mmol) in toluene (10 mL). The solution was stirred
for 2 h at room temperature, and volatiles were removed under
vacuum. The brown oily residue was triturated with pentane,
and the solid was separated by filtration and dried under
vacuum to leave 8 as pale beige powder (0.180 g, 60%). Anal.
Calcd for C22H30O2SZr: C, 58.75; H, 6.72; S, 7.13. Found: C,
58.71; H, 6.66; S, 7.06.
300 MHz): δ 2.76 (s, 4H, CH2), 1.26 (s, 18H, tBu), 1.23 (s, 12H,
CH3). 13C{1H} NMR (THF-d8, 75.5 MHz): δ 78.1 (OC(CH3)2),
73.8 (C(CH3)3), 53.9 (CH2), 32.9 (C(CH3)3), 30.5 (OC(CH3)2). 1H
NMR (toluene-d8, 300 MHz, 360 K): δ 2.63 (br s, 4H, CH2),
1
1.39 (s, br, 18H, tBu), 1.29 (s, 12H, CH3). H NMR (toluene-
d8, 300 MHz, -40 °C, assignment made from a COSY experi-
ment): 20 methylene resonances were detected (denoted a-j),
2
2
δ 4.02 (d, J ) 14.5 Hz, 1H, CH2(a1)), 3.44 (d, J ) 12.0 Hz,
2
2
1H, CH2(b1)), 3.31 (d, J ) 11.0 Hz, 1H, CH2(c1)), 3.29 (d, J
) 14.5 Hz, 1H, CH2(a2)), 3.15 (d, 2J ) 14.2 Hz, 1H, CH2(d1)),
3.13 (d, 2J ) 12.0 Hz, 1H, CH2(b2)), 3.12 (d, 2J ) 12.8 Hz, 1H,
CH2(e1)), 3.05 (d, 2J ) 14.3 Hz, 1H, CH2(f1)), 3.02 (d, 2J )
13.8 Hz, 1H, CH2(g1)), 2.91 (d, 2J ) 13.0 Hz, 1H, CH2(h1)),
2.78 (d, 2J ) 11.0 Hz, 1H, CH2(c2)), 2.62 (d, 2J ) 12.2 Hz, 1H,
CH2(i1)), 2.60 (d, 2J ) 13.0 Hz, 1H, CH2(h2)), 2.49 (d, 2J )
13.8 Hz, 1H, CH2(j1)), 2.41 (d, 2J ) 13.8 Hz, 1H, CH2(g2)),
Synthesis by Comproportionation. A Teflon-valved NMR
tube was charged with Zr(CH2Ph)4 (0.040 g, 0.088 mmol) and
6 (0.039 g, 0.088 mmol), 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. 1H NMR (toluene-
2
1
2
3
2.41 (d, J ) 13.8 Hz, H, CH2(j2)), 2.37 (d, J ) 12.8 Hz, 1H,
CH2(e2)), 2.33 (d, 2J ) 12.2 Hz, 1H, CH2(i2)), 2.25 (d, 2J )
14.3 Hz, 1H, CH2(f2)), 2.24 (d, 2J ) 14.2 Hz, 1H, CH2(d2)).
13H{1H} NMR (toluene-d8, 125 MHz, -40 °C, selected reso-
nances, assignments made from an HMQC experiment): 10
methylene resonances were detected (denoted a-j), δ 55.3
(CH2(d)), 54.6 (CH2(e)), 54.1 (CH2(f)), 53.1 (CH2(g)), 47.4
(CH2(c)), 47.2 (CH2(b)), 47.1 (CH2(h)), 47.0 (CH2(i)), 44.2
(CH2(j)), 43.2 (CH2(a)).
d8, 300 MHz, 200 K): δ 7.26 (d, J ) 7.5 Hz, 2H, o-H(b)), 7.17
(m, 2H, m-H(b)), 7.09 (m, 2H, m-H(a)), 6.93 (m, 2H, p-H(a,b)),
6.73 (d, 3J ) 7.5, 2H, o-H(a)), 2.67 (d, 2J ) 11.3 Hz, 2H, SCH2),
2.53 (s, 2H, CH2Ar(a)), 1.82 (d, 2J ) 11.3 Hz, 2H, SCH2), 1.75
(s, 2H, CH2Ar(b)), 1.17 (s, 12H, CH3). 1H NMR (toluene-d8, 300
MHz, 333 K): δ 7.08-6.80 (m, 10H, Ph), 2.34 (s, 4H, CH2), 2.05
(s, 4H, CH2), 1.06 (s, 12H, CH3). 13C NMR (toluene-d8, 75.5
MHz, 200 K): δ 147.6 (ipso-C(b)), 136.5 (ipso-C(a)), 131.6
(m-C(a)), 129.0 (o-C(b)), 128.1 (m-C(b)), 127.3 (o-C(a)), 128.1
(m-C(b)), 122.7 (p-C(a)), 119.7 (p-C(b)), 84.2 (s, OC), 54.9 (t,
JC-H ) 139.3 Hz, SCH2), 54.9 (t, JC-H ) 139.3 Hz, CH2Ar(a)),
53.6 (t, JC-H ) 128.5 Hz, CH2Ar(b)), 30.1 (q, JC-H ) 123.7 Hz,
CH3), 29.4 (q, JC-H ) 126.3, CH3). 13C{1H} NMR (toluene-d8,
75.5 MHz, 293 K): δ 137.5 (Ph), 130.3 (Ph), 122.2 (Ph), 84.3
(OC), 55.8 (CH2), 55.4 (CH2), 29.9 (CH3).
Zr{OSOMe}2 (6). This compound was prepared as described
above for 4 starting from a solution of 1a (0.300 g, 1.68 mmol)
in toluene (6 mL) and a solution of Zr(OtBu)4 (0.322 g, 0.84
mmol) in toluene (4 mL). Workup gave 6 as a white powder
(0.350 g, 92%). Anal. Calcd for C17H36O4S2Zr: C, 44.41; H, 7.89;
S, 13.95. Found: C, 44.81; H, 7.79; S, 14.15. 1H NMR (thf-d8,
300 MHz): δ 2.74 (s, 4H, CH2), 1.20 (s, 12H, CH3). 13C{1H}
NMR (THF-d8, 75.5 MHz): δ 77.1 (OC), 53.8 (CH2), 29.8 (CH3).
1H NMR (toluene-d8, 300 MHz, 360 K): δ 2.70 (s, 4H, CH2),
1.29 (s, 12H, CH3).
Ti{OSOMe}2 (7). Synthesis by Salt Elimination. A
yellow suspension of TiCl4(Et2O) was prepared by stirring TiCl4
(0.258 g, 1.35 mmol) in diethyl ether (20 mL) at -30 °C for 1
h. Et3N (1.20 mL, 8.6 mmol) was added by syringe, resulting
in the immediate formation of a dark red solution. A solution
of 1a in diethyl ether (10 mL) was then added dropwise at
-30 °C, giving an immediate precipitate. The mixture was
warmed to room temperature and stirred for 18 h. After
ZrCl2{OSOMe} (9). Synthesis by Alkane Elimination.
To a vigorously stirred solution of ZrCl4 (0.500 g, 2.15 mmol)
in toluene (15 mL) cooled at -78 °C was added dropwise nBuLi
(2.7 mL of a 1.6 M solution in hexanes, 4.30 mmol) over 1 h.
The mixture was gently warmed to room temperature and
stirred for 8 h, resulting in the formation of a dark brown
suspension of “ZrBu2Cl2 + 2 LiCl”. The mixture was cooled to
-40 °C, and a solution of 1a (0.383 g, 2.15 mmol) in toluene
(5 mL) was added dropwise over 30 min. The reaction mixture
was stirred for 2 h at -40 °C and an additional 8 h period at
room temperature. Gas evolution (butane) was noticed without
significant change of the color. The precipitate (LiCl) was

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5617
removed by filtration and washed with toluene, and the filtrate
was concentrated under vacuum to leave 9 as a white pow-
der (0.350 g, 47%). Anal. Calcd for C8H16Cl2O2SZr: C, 28.39;
(d, 2J ) 12.3 Hz, 1H, CH2(a1)), 4.05 (d, 2J ) 10.5 Hz, 1H,
CH2(b1)), 3.92 (d, 2J ) 13.8 Hz, 1H, CH2(c1)), 3.77 (d, 2J )
12.3 Hz, 1H, CH2(a2)), 3.50 (d, 2J ) 13.8 Hz, 1H, CH2(c2)),
3.46 (d, 2J ) 15.9 Hz, 1H, CH2(d1)), 1.92 (d, 2J ) 15.9 Hz, 1H,
1
H, 4.77; S, 9.48. Found: C, 28.74; H, 5.12; S, 9.26. H NMR
CH2 d2)), 1.74 (d, 2J ) 10.5 Hz, 1H, CH2(b2)), 1.84 (s, 3H,
(
(THF-d8) showed resonances only for 11a-d16
.
CH3(a3)), 1.64 (s, 3H, CH3(a4)), 1.53 (s, 3H, CH3(b3)), 1.47 (s,
3H, CH3(c3)), 1.26 (s, 3H, CH3(b4)), 1.21 (s, 3H, CH3(d3)), 1.11
(s, 3H, CH3(c4)), 1.08 (s, 3H, CH3(d4)). 13C{1H} NMR (toluene-
d8, 125 MHz): δ 96.1 (C(c)), 96.0 (C(d)), 92.6 (C(a)), 91.1 (C(b)),
53.7 (CH2(c)), 51.8 (CH2(a)), 49.5 (CH2(b)), 48.7 (CH2(d)), 29.6
(CH3(d3)), 28.9 (CH3(a3), CH3(b3), CH3(c4), CH3(d4)), 27.4
(CH3(a4)), 26.9 (CH3(c3)), 26.3 (CH3(b4)).
Synthesis by Comproportionation of 6 and ZrCl4. A
solution of 6 (0.068 g, 0.135 mmol) in toluene (5 mL), cooled
at -30 °C, was added to a suspension of ZrCl4 (0.036 g, 0.135
mmol) in toluene (5 mL) placed at -30 °C. The mixture was
stirred for 12 h with slow warming to room temperature.
Removal of volatiles under vacuum left 9 as a white powder
(0.091 g, 100%). 1H NMR (THF-d8) showed resonances for 11a
(95%) and 11b (5%).
TiCl2{OSOMe}(THF)2 (13). Synthesis by Salt Elimina-
tion. n-Butyllithium (12.4 mL of a 1.6 M solution in n-hexane,
20.0 mmol) was added dropwise at -20 °C to a solution of 1a
(1.61 g, 9.0 mmol) in THF (25 mL). The mixture was stirred
at room temperature for 2 h, then cooled to -35 °C, and slowly
transferred over 30 min into a solution of TiCl4 (1.72 g, 9.0
mmol) in THF (20 mL) at -35 °C (prepared 5 h before). The
solution, which turned orange upon adding the dialkoxide, was
stirred for 30 h at room temperature and then concentrated
under vacuum until obtaining an oily residue. The residue was
washed with pentane (2 × 10 mL) and extracted with toluene
(2 × 10 mL). Toluene was evaporated under vacuum to give
an orange oily residue, which was triturated with pentane for
12 h. The white precipitate was removed by filtration, and
the filtrate was concentrated under vacuum to give 13 as a
white solid (1.22 g, 45%). Complex 13 was also obtained by
recrystallization of 12 in THF at -30 °C. Anal. Calcd for
C16H32Cl2O4STi: C, 43.75; H, 7.34; S, 7.30. Found: C, 44.14;
ZrCl2{OSOMe}(THF) (10). (a) One-Pot Synthesis from
1a. To a solution of 1a (1.00 g, 5.6 mmol) in THF (25 mL)
cooled at -78 °C was added dropwise nBuLi (7.0 mL of a 1.6
M solution in hexanes, 11.0 mmol). The reaction mixture was
gently warmed to room temperature and stirred for 2 h. The
clear solution was then cooled to -40 °C and transferred via
cannula over 30 min onto a suspension of ZrCl4 (1.31 g, 5.6
mmol) in THF (25 mL) at -40 °C. The solution, which
progressively turned yellow upon addition of the dialkoxide,
was stirred for 20 h at room temperature, and THF was
removed under vacuum. The residue was extracted with
toluene (4 × 25 mL), and the solution was filtered through a
Celite pad and concentrated under vacuum to leave 10 as a
white powder (1.65 g, 61%).
(b) Synthesis from Dipotassium Salt 2a. A suspension
of ZrCl4 (0.210 g, 0.90 mmol) in THF (10 mL) cooled at -35
°C (prepared 1 h before use) was added under stirring to
K2{OSOMe} (2a) (0.229 g, 0.90 mmol) placed in a Schlenk flask.
The mixture was warmed to room temperature and stirred for
24 h. The solution was filtered to remove the precipitate (KCl)
and concentrated under vacuum. The beige residue was
extracted with toluene (3 × 10 mL), and the solution was
filtered through a Celite pad and concentrated under vacuum.
The residue was washed with pentane (2 × 3 mL) and dried
under vacuum to leave 10 as a white powder (0.170 g, 55%).
Anal. Calcd for C12H24O3SCl2Zr: C, 35.11; H, 5.89; S, 7.81.
Found: C, 35.08; H, 6.08; S, 7.60. 1H NMR (CD3CN, 200
MHz): δ 3.80 (m, 4H, THF), 2.66 (s, 4H, CH2), 1.25 (m, 4H,
THF), 1.17 (s, 12H, CH3). The 13C NMR spectrum in THF-d8
was as described below for 11.
1
H, 7.42; S, 7.15. H NMR (THF-d8, 200 MHz): δ 2.94 (s, 4H,
CH2), 1.29 (s, 12H, CH3). 13C{1H} NMR (THF-d8, 75.5 MHz):
δ 83.1 (OC), 50.8 (CH2), 31.4 (CH3).
Reaction of TiCl4 and 1b. Generation of “TiCl2-
{OSOtol}” (14). A solution of 1b (0.441 g, 0.88 mmol) in toluene
(20 mL) was added dropwise at 0 °C to a stirred solution of
TiCl4 (0.258 g, 1.35 mmol) in pentane (20 mL). A yellow-
green precipitate rapidly formed. The mixture was stirred
for 20 h at room temperature. The solid was collected by
filtration, washed with pentane (3 × 5 mL), and dried un-
der vacuum, leaving a yellow powder (0.358 g, 66%). This
product was insoluble in C6D6. 1H NMR (THF-d8, 200
MHz): δ 6.5-7.2 (16H, H aro), 3.36 (s, 4H, CH2), 2.28 (s,
12H, CH3). 13C{1H} NMR (THF-d8, 50 MHz): δ 125.0-143.0
(Caro), 45.0 (CH2), 18.8 and 18.6 (CH3) (Cq not observed). Anal.
Calcd for C32H32O2Cl2STi: C, 64.12; H, 5.38; S, 5.35. Found:
C, 60.45; H, 5.28; S, 4.73. Repeated elemental analyses on
materials from different batches gave systematically poor
results, indicating contamination of 14 with unidentified
impurities.
ZrCl2{OSOMe}(THF)2 (11). Complex 11 was obtained by
recrystallization of 10 in THF at -30 °C. The crystals were
separated from the solution, washed with pentane, and dried
under partial vacuum. Anal. Calcd for C16H32Cl2O4SZr: C,
1
39.82; H, 6.68; S, 6.64. Found: C, 40.13; H, 6.78; S, 6.59. H
NMR (CD3CN, 200 MHz): δ 3.80 (m, 8H, THF), 2.66 (s, 4H,
CH2), 1.25 (m, 8H, THF), 1.17 (s, 12H, Me). Two series of
resonances are observed in THF, assigned to two isomers, 11a
(89-91%) and 11b (9-11%). 11a 1H NMR (THF-d8, 200 MHz):
δ 2.78 (s, 4H, CH2), 1.23 (s, 12H, Me). 13C{1H} NMR (THF-d8,
50 MHz): δ 81.1 (OC), 53.1 (s, CH2), 29.1 (CH3). 11b 1H NMR
(THF-d8, 200 MHz): δ 2.65 (s, 4H, CH2), 1.18 (s, 12H, CH3).
13C{1H} NMR (THF-d8, 50 MHz): δ 70.8 (OC), 49.2 (CH2), 29.1
(CH3).
Reaction of Zr(CH2Ph)2{OSOMe
[B(C6F5)4]. Generation of
[Zr(CH2Ph){OSOMe}]-
} (8) with [Ph3C]-
[B(C6F5)4] (15). A Teflon-valved NMR tube was charged with
Zr(CH2Ph)2{OSOMe} (8, 0.012 g, 0.026 mmol) and [Ph3C]-
[B(C6F5)4] (0.024 g, 0.026 mmol), and CD2Cl2 (0.6 mL) was a
vacuum transferred at -180 °C. The tube was sealed and kept
at -80 °C. A yellow solution formed within 5 min. The 1H NMR
spectrum was recorded at -33 °C and indicated that 15 had
formed quantitatively. Compound 15 is not soluble in hydro-
carbons (toluene, pentane, hexanes). NMR assignments were
made from 2D HMBC, HMQC, and COSY experiments. 1H
TiCl2{OSOMe} (12). TiCl4 (0.090 g, 0.48 mmol) was added
dropwise to a solution of Ti(OiPr)4 (0.136 g, 0.48 mmol) in
toluene (2 mL) at room temperature. The mixture was stirred
for 1 h. A solution of 1a (0.170 g, 0.96 mmol) in toluene (3
mL), cooled at -30 °C, was added to the previous mixture over
2 min, and the mixture was stirred for 12 h. Removal of
volatiles under vacuum, washing of the solid residue with
pentane, and drying at room temperature gave 12 as a white
powder (0.230 g, 82%). Anal. Calcd for C8H16O2STiCl2: C,
32.57; H, 5.47; S, 10.87. Found: C, 32.31; H, 5.65; S, 9.65. 1H
NMR (C6D6, 200 MHz): δ 2.37 (s, 4H, CH2), 1.00 (s, 12H, CH3).
13C{1H} NMR (C6D6, 50 MHz): δ 95.9 (OC), 53.9 (CH2), 28.8
3
NMR (CD2Cl2, 500 MHz, 240 K): δ 8.30 (t, J ) 7.7 Hz, 1H,
3
3
p-H(ZrBz), 7.91 (t, J ) 7.8 Hz, 2H, m-H(ZrBz), 7.69 (d, J )
7.6 Hz, 2H, o-H(ZrBz), 3.70 (d, 2J ) 13.2 Hz, 1H, SCH2), 3.45
(d, 2J ) 13.2 Hz, 1H, SCH2), 3.32 (d, 2J ) 13.7 Hz, 1H, SCH2),
3.24 (d, 2J ) 9.4 Hz, 1H, ZrCH2), 3.05 (d, 2J ) 9.4 Hz, 1H,
ZrCH2), 2.95 (d, 2J ) 13.7 Hz, 1H, SCH2), 1.74 (s, Me), 1.42 (s,
Me), 1.33 (s, Me), 1.22 (s, Me). 13C{1H} NMR (CD2Cl2, 100
MHz, 240 K): δ 148.1 (dm, JC-F ) 240 Hz, o-C6F5), 142.9
1
(CH3). H NMR (toluene-d8, 500 MHz, -55 °C) (assignments
(p-C(ZrBz)), 142.0 (o-C(ZrBz)), 138.0 (dm, JC-F
Hz, p-C6F5), 136.2 (dm, JC-F ) 248 Hz, m-C6F5), 132.4 (ipso-
) 244
made from HMBC, HMQC, and COSY experiments): δ 4.27

5618 Organometallics, Vol. 24, No. 23, 2005
Lavanant et al.
C(ZrBz)), 131.1 (m-C(ZrBz)), 92.4 (SCH2CMe2), 91.9
(SCH2CMe2), 74.5 (ZrCH2Ph), 59.9 (SCH2), 51.3 (SCH2), 31.4
(CH3), 29.8 (CH3), 29.2 (CH3), 28.1 (CH3). 11B NMR (CD2Cl2,
128 MHz, 240 K): δ -15.8 (br s, B(C6F5)4-). 19F{1H} NMR
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; remaining atoms were located
from difference Fourier synthesis, followed by full-matrix least-
squares refinement based on F2 (programs SHELXS-97 and
SHELXL-97).47 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 locations 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 crystal structure of 3b be-
longs to the non-centrosymmetric space group C2 (centro-
symmetric space groups such as C2/c were found inappropri-
ate), due to the presence in the elementary cell of two
molecules that slightly differ in the conformation of the p-tolyl
groups. The crystal structure of molecule 4b is characterized
by a complicated disorder model, which involves the simulta-
neous presence of tert-butoxide and chelating thioether ligands
at the same position of the ligand sphere. Crystal data and
details of data collection and structure refinement for the
different compounds are given in Table 1. Crystallographic
data are also available as cif files (see Supporting Information
Available).
3
(CD2Cl2, 376 MHz, 240 K): δ -132.1 (d, JF-F ) 19.3 Hz, 8F,
o-F B(C6F5)4-), -162.3 (t, 3JF-F ) 19.3 Hz, 4F, p-F B(C6F5)4-),
-166.2 (t, 3JF-F ) 19.3 Hz, 8F, m-F B(C6F5)4-). 1H resonances
for Ph3CCH2Ph:32 δ 7.30 (m, 12H, o-H and m-H(CPh3)), 7.27
(m, 3H, p-H(CPh3)), 7.12 (t, 3J ) 7.7 Hz, 1H, p-H(Bz)), 7.03 (t,
3J ) 7.5 Hz, 2H, m-H(Bz)), 6.68 (d, 3J ) 7.5 Hz, 2H, o-H(Bz)),
3.92 (s, 2H, CH2(Bz)). 13C NMR: δ 146.6 (ipso-C(CPh3)),
138.4 (ipso-(Bz), 131.1 (o-C(Bz)), 129.6 (o-C(CPh3)), 127.5
(m-C(CPh3)), 127.8 (m-C(Bz)), 126.0 (p-C(Bz and CPh3)), 58.5
(CPh3CH2Ph), 45.6 (CPh3CH2Ph).
Reaction of Zr(CH2Ph)2{OSOMe} (8) with B(C6F5)3.
Generation of [Zr(CH2Ph){OSOMe}][PhCH2B(C6F5)3] (16).
A Teflon-valved NMR tube was charged with Zr(CH2Ph)2-
{OSOMe} (8, 0.015 g, 0.033 mmol) and B(C6F5)3 (0.017 g, 0.033
mmol), and toluene-d8 (0.6 mL) was vacuum transferred in at
-180 °C. The tube was sealed and kept at -80 °C. A yellow
solution formed within 5 min. The 1H NMR spectrum was
recorded at -33 °C and indicated that 16 was formed in 90%
yield. 1H NMR (toluene-d8, 400 MHz, 240 K): δ 7.24-6.78 (br
2
m, 8H), 6.15 (br m, 2H), 3.47 (s, br, 2H, BCH2Ph), 2.38 (d, J
) 11.8 Hz, 2H, SCH2), 2.25 (s, 2H, ZrCH2Ph), 1.25 (d, 2J )
1
11.8 Hz, 2H, SCH2), 0.82 (s, 6H, CH3), 0.76 (s, 6H, CH3). H
NMR (toluene-d8, 400 MHz, 298 K): δ 7.01 (m, 2H, m-H BBz),
Line-Shape Analysis and NMR Simulations. NMR
spectral simulations for 8 were performed using “gNMR”
(Cherwell Scientific). Simulations of the NCHHCMe2 and
ZrCHHPh hydrogens were performed in a two-step pro-
cedure. First, the chemical shifts observed in the slow limit
exchange (below 215 K) were used to set up the spin sys-
tems. The relative population ratio was fixed at 1:1:1:1 (mole
fraction of each site ) 0.25). The natural line-width in the
absence of exchange W0 ) 0.8 Hz was measured for the Me
hydrogens at 210 K. The chemical shifts of the NCHHCMe2
and ZrCHHPh hydrogens vary slightly in the slow limit
exchange, and a linear extrapolation was used to estimate the
chemical shifts at higher temperatures. We checked that the
observed and calculated chemical shifts for the collapsed
resonances are identical. Then, for nine temperatures in the
range 213 to 333 K, the exchange rate was varied to get
the best fit between the simulated and the experimental
spectra. 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.48
Ethylene Polymerization. Polymerization experiments
(Table 5) 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,
6.95 (d, 3J ) 8.5 Hz, 2H, o-H BBz), 6.79 (m, 1H, p-H BBz),
3
6.74 (d, J ) 7.4 Hz, 2H, o-H ZrBz), 6.20 (m,2H, m-H ZrBz),
6.11 (m, 1H, p-H ZrBz), 3.38 (br s, 2H, BCH2Ph), 2.34 (br m,
2H, SCH2), 2.17 (s, 2H, ZrCH2Ph), 1.58 (br m, 2H, SCH2), 0.82
(s, 12H, CH3). 13C{1H} NMR (toluene-d8, 100 MHz, 240K): δ
159.2 (ipso-BBz), 149.6 (br d, JC-F ) 242 Hz, o-C6F5), 140.0
(ipso-ZrBz), 139.6 (br d, JC-F ) 243 Hz, p-C6F5), 138.2
(br d, JC-F ) 245 Hz, m-C6F5), 130.8-126.1 (o-BBz, m-BBz,
o-ZrBz, m-ZrBz), 126.0-123.3 (p-ZrBz, p-BBz), 87.6 (C), 65.3
(ZrCH2Ph), 54.3 (2C, SCH2), 29.2 (2C, CH3), 28.3 (2C, CH3).
11B NMR (toluene-d8, 128 MHz, 240 K): δ -11.4 (br s,
{B(C6F5)3Bz}-). 19F{1H} NMR (toluene-d8, 376 MHz, 240 K):
δ -130.0 (br m, 6F, o-F {B(C6F5)3Bz}-), -159.8 (t, 3JF-F ) 19.8
Hz, 3F, p-F {B(C6F5)3Bz}-), -163.5 (t, 3JF-F ) 19.8 Hz, 6F,
m-F {B(C6F5)3Bz}-).
Compound 16 slowly decomposes at room temperature
within 24 h to form 17, formulated [Zr(C6F5){OSOMe}]-
[B(CH2Ph)2(C6F5)3] (assignments made from 2D-HMBC, HMQC,
and COSY NMR experiments). 1H NMR (toluene-d8, 400
2
2
MHz): δ 7.15 (d, J ) 7.6 Hz, 2H, o-H η6-BzB), 7.01 (t, J )
2
7.1 Hz, 2H, m-H BzB) and 6.98 (t, J ) 7.5 Hz, 1H, p-H BzB)
2
(overlap with toluene resonances), 6.77 (d, J ) 7.1 Hz, 2H,
o-H BzB), 6.25 (t, 2J ) 7.6 Hz, 2H, m-H η6-BzB), 6.08 (t, 2J )
7.1 Hz, 1H, p-H η6-BzB), 3.45 (br m, 2H, CH2 η6-BBz), 2.88 (s,
2H, CH2 BBz), 2.27 (s, 4H, SCH2), 1.01 (s, 6H, CH3), 0.84 (s,
6H, CH3). 13C{1H} NMR (toluene-d8, 100 MHz): δ 161.5 (ipso-
2
2
η6-BzB), 149.6 (d, J ) 244 Hz, o-BC6F5), 139.8 (d, J ) 245
Hz, p-BC6F5), 139.1 (d, 2J ) 248 Hz, m-BC6F5), 137.1 (ipso-
BzB), 132.6 (o-η6-BzB), 131.5 (p-η6-BzB), 129.1 (o-BzB), 128.5
(m-BzB), 126.0 (p-BzB), 125.3 (p-η6-BzB), 90.1 (CMe2), 50.9
(SCH2), 38.2 (CH2 BBz), 35.9 (br, CH2 η6-BBz), 31.2 (CH3), 31.3
(CH3); resonances for Zr-C6F5 were not observed. 11B NMR
(toluene-d8, 128 MHz): δ -11.7 (br s, {B(C6F5)2Bz2}-). 19F NMR
3
(toluene-d8, 376 MHz): -114.9 (dm, J ) 34 Hz, o-F ZrC6F5),
3
3
-130.4 (d, J ) 24 Hz, o-F BC6F5), -131.9 (dm, J ) 25 Hz,
3
o-F ZrC6F5)), -158.0 (m, p-F ZrC6F5), -160.0 (t, J ) 20 Hz,
p-F BC6F5), -160.3 (m, m-F ZrC6F5), -161.0 (m, m-F ZrC6F5),
3
-164.1 (t, J ) 20 Hz, m-F BC6F5).
(47) (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.
(48) (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.
Crystal Structure Determination of Ligand Deriva-
tives 1b and 3b and Complexes 4, 7, 11, and 13. Suitable
single crystals were mounted onto glass fibers using the “oil-
drop” method. Diffraction data were collected at 100-120 K
or 279-293 K using a NONIUS Kappa CCD diffractometer
with graphite-monochromatized Mo KR radiation (λ ) 0.71073

Sulfur-Bridged Dialkoxide Ligands
Organometallics, Vol. 24, No. 23, 2005 5619
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.
Melting temperatures of PE samples were determined on a
Perkin-Elmer Pyris 1 differential scanning calorimeter (10
°C/min, nitrogen flow, second pass). Gel permeation chroma-
tography (GPC) analyses were performed on a Polymer
Laboratories PL-GPC 220 instrument using 1,2,4-trichloroben-
zene as 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 and filtered through
2 or 5 µm stainless steel frits prior to injection. Molecular
weights were determined vs polystyrene standards and are
reported relative to polyethylene standards, as calculated by
the universal calibration method using Mark-Houwink pa-
rameters (K ) 17.5 × 10-5, R ) 0.670 for polystyrene; K )
40.6 × 10-5, R ) 0.725 for polyethylene).
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 (post-doc fellowship to A.S.,
ATIPE fellowship to J.F.C.). Work at the University of
Chicago was supported by the U.S. Department of
Energy (DE-FG02-00ER15036). We thank Dr. Christian
W. Lehmann (Max Planck Institut, Mu¨lheim an der
Ruhr, Germany) for the X-ray crystal diffraction analy-
sis of 4.
Supporting Information Available: Crystallographic
data for 1b, 3b, 4, 7, 11, and 13 as CIF files; additional NMR
data (HMQC/HMBC/COSY; VT 1H NMR) for complexes 8, 15,
16, and 17 (11B monitoring); representative GPC traces and
DSC profiles of PEs prepared. This material is available free
of charge via the Internet at http://pubs.acs.org
OM050560C