Bis(imidodithiodiphosphinato) titanium and zirconium complexes: Synthesis, characterization, and their catalytic activity in the polymerization of α-Olefins

Article abstract of DOI:10.1021/om801176a

synthesis, characterization, and low-temperature crystal structures of a family of group 4 complexes containing different numbers of imidodithiodiphosphinate ligands and different metal oxidation states is presented. Their catalytic activity in the polyme

Full text of DOI:10.1021/om801176a

Organometallics 2009, 28, 2391–2400
2391
Bis(imidodithiodiphosphinato) Titanium and Zirconium Complexes:
Synthesis, Characterization, and Their Catalytic Activity in the
Polymerization of r-Olefins
Fapu Chen,† Moshe Kapon,† J. Derek Woollins,‡ and Moris S. Eisen*,†
Schulich Faculty of Chemistry and Institute of Catalysis, Science and Technology, Technion-Israel
Institute of Technology, Haifa, 32000, Israel, and Department of Chemistry, UniVersity of St Andrews,
St Andrews, Fife KY16 9ST, Scotland, U.K.
ReceiVed December 11, 2008
The synthesis, characterization, and low-temperature crystal structures of a family of group 4 complexes
containing different numbers of imidodithiodiphosphinate ligands and different metal oxidation states is
presented. Their catalytic activity in the polymerization of ethylene and propylene was studied. For ethylene,
when these complexes are activated with methylalumoxane (MAO), they are active catalysts in the
polymerization producing extremely high molecular weight, high-density polyethylene with very narrow
polydispersities. However, for propylene, the activity of these complexes is low, producing only atactic
polypropylene. The bis(imidodithiodiphosphinate)titanium(bis(amido)) complex 6e has a singular reactivity,
which upon heating forms the corresponding imido complex with the concomitant elimination of Et3N
and the formation of the homoleptic complex tris(imidodithiodiphosphinate)titanium(III) (6h).
During the last decade, we have been interested in the
synthesis of group 4 complexes containing the heteroallylic
N-C-N moieties, as part of the ancillary ligation motif, such
as in benzamidinate (1a, 1b)5 and amidopyridines (2).6
Introduction
The polymerization of olefins by single-site catalysts has
experienced a phenomenal growth in the last two decades, from
academic to industrial research groups engaging in the design
of new coordinative unsaturated complexes for the controlled
polymerization.1 Since the discovery of ansa-metallocene
complexes as active precatalysts for the stereoregular poly-
merization of propylene (isotactic or syndiotactic), it has been
established that clever designs of the organometallic complex2
are able to induce specific changes in the skeleton of the
obtained polymers, providing access to unusual materials, such
as hemi-isotactic polypropylene and stereoblock (isotactic-
atactic) materials, some of them with elastic properties.1-3 It is
remarkable that the chemical nature of the active organometallic
complexes can produce distinctive polymeric materials, exhibit-
ing sometimes spectacular insights.2-4
When activated with the cocatalyst, methylalumoxane (MAO),
the corresponding complexes containing these ancillary ligands
were found to be active catalytic precursors for the polymeri-
zation of R-olefins. 7 Recently, also we have shown that titanium
and zirconium heteroallylic complexes containing the P-N-X
(X ) Ph (3a), PPh2 (3b)) ligand functionalities8 or the expanded
heteroallylic acetylacetonate moiety 4a-4e9 are also active
catalysts for the polymerization of propylene, forming a unique
* Corresponding author. E-mail: chmoris@tx.technion.ac.il.
† Technion-Israel Institute of Technology.
‡ University of St Andrews.
(1) For recent reviews of single-site olefin polymerization, see: (a) Li,
H.; Marks, T. J. Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 15295, and
references therein. (b) Severn, J. R.; Chadwick, J. C.; Duchateau, R.;
Friederichs, N. Chem. ReV. 2005, 105, 4073, and references therein. (c)
Kaminsky, W. J. Polym. Sci., Part A: Polym. Chem. 2004, 42, 3911. (d)
Gladysz, J. A. Chem. ReV. 2000, 100 (special issue on Frontiers in Metal-
Catalyzed Polymerization), and references therein. (e) Nayak, P. L. Popular
Plastics Packaging 2003, 48, 86.
(2) (a) Guo, N.; Stern, C. L.; Marks, T. J. J. Am. Chem. Soc. 2008, 130,
2246, and references therein. (b) Motta, A.; Fragala, I. L.; Marks, T. J.
J. Am. Chem. Soc. 2007, 129, 7327, and references therein. (c) Naga, N. J.
Polym. Sci., Part A: Polym. Chem. 2005, 43, 1285. (d) Li, H.; Li, L.;
Schwartz, D. J.; Metz, M. V.; Marks, T. J.; Liable-Sands, L.; Rheingold,
A. L. J. Am. Chem. Soc. 2005, 127, 14756, and references therein. (e) Li,
H.; Stern, C. L.; Marks, T. J. Macromolecules 2005, 38, 9015, and references
therein. (f) Lee, S.-G.; Hong, S.-D.; Park, Y.-W.; Jeong, B.-G.; Nam, D.-
W.; Jung, H. Y.; Lee, H.; Song, K. H. J. Organomet. Chem. 2004, 689,
2586. (g) Kim, I.; Ha, C.-S. Polym. Bull. 2004, 52, 133. (h) Nomura, K.;
Fujita, K.; Fujiki, M. J. Mol. Catal. A: Chem. 2004, 220, 133. (i) Iedema,
P. D.; Hoefsloot, H. C. J. Macromolecules 2003, 36, 6632. (j) Klosin, J.;
Kruper, W. J., Jr.; Nickias, P. N.; Roof, G. R.; De Waele, P.; Abboud,
K. A. Organometallics 2001, 20, 2663. (k) McKnight, A. L.; Waymouth,
R. M. Chem. ReV. 1998, 98, 2587.
(3) (a) Tritto, I.; Boggioni, L.; Ferro, D. R. Coord. Chem. ReV. 2006,
250, 212, and references therein. (b) Hotta, A.; Cochran, E.; Ruokolainen,
J.; Khanna, V.; Fredrickson, G. H.; Kramer, E. J.; Shin, Y.-W.; Shimizu,
F.; Cherian, A. E.; Hustad, P. D.; Rose, J. M.; Coates, G. W. Proc. Natl.
Acad. Sci. U.S.A. 2006, 103, 15327, and references therein. (c) Kaminsky,
W.; Tran, P.-D.; Werner, R. Macromol. Symp. 2004, 213, 101. (d) Kim,
E.-G.; Klein, M. L. Organometallics 2004, 23, 3319. (e) Lavoie, A. R.;
Ho, M. H.; Waymouth, R. M. Chem. Commun. 2003, 7, 864. (f) Coates, G.
W. Chem. ReV. 2000, 100, 1223. (g) Ewen, J. A.; Jones, R. L.; Elder, M. J.;
Camurati, I.; Pritzkow, H. Macromol. Chem. Phys. 2004, 205, 302. (h) De
Rosa, C.; Auriemma, F.; Circelli, T.; Longo, P.; Boccia, A. C. Macromol-
ecules 2003, 36, 3465.
(4) Resconi, L.; Cavallo, L.; Fait, L.; Fait, A.; Piemontesi, F. Chem.
ReV. 2000, 100, 1253, and references therein. (b) Rodriguez-Delgado, A.;
Hannant, M. D.; Lancaster, S. J.; Bochmann, M. Macromol. Chem. Phys.
2004, 205, 334, and references therein.
10.1021/om801176a CCC: $40.75
2009 American Chemical Society
Publication on Web 03/25/2009

2392 Organometallics, Vol. 28, No. 8, 2009
Chen et al.
type of elastomeric materials; for the latter complexes, remark-
able activity in the polymerization of cyclic esters was observed.
complexes in the polymerization of R-olefins.11 An intriguing
conceptual question that we wished to consider regards the
synthetic approach toward the general family of complexes
containing the imidodithiodiphosphinate ancillary ligand as in
complex A.
The rationale behind the synthetic approach of these inorganic
ligands regards their isolobal identity to the ligand motif
presented in complexes 4 and 5. It was interesting to compare
their chemical reactivity with group 4 metal salts and the
molecular structure of the new inorganic compounds (σ vs π;
planar vs chair-like). In addition, it was important to evaluate
the activity of the latter complexes in the polymerization of
R-olefins. In this article, we report the synthesis, characterization,
and low-temperature crystal structures of a family of group 4
complexes containing different numbers of the imidodithio-
diphosphinate ligands and different metal oxidation states.
Furthermore, we present their catalytic activities in the polym-
erization of ethylene and propylene. We show that when these
complexes are activated with methylalumoxane (MAO), they
are active for the polymerization of ethylene, producing
extremely high molecular weight, high-density polyethylene with
very narrow polydispersities. However, for propylene, unexpect-
edly, the activity of these complexes is low, nonetheless
producing a medium molecular weight atactic polypropylene.
Interestingly, Novak et al.,10a and later Kim et al.,10b have
found that the ꢀ-diketiminate complexes of zirconium (5a) are
highly active catalysts in the polymerization of ethylene. In
parallel, we have shown that the corresponding bis(ꢀ-diketimi-
nate) titanium dichloride complexes (5b) are also very active
(5) (a) Volkis, V.; Lisovskii, A.; Eisen, M S. Stud. Surf. Sci. Catal. 2006,
161, 105, and references therein. (b) Aharonovich, S.; Volkis, V.; Eisen,
M. S. Macromol. Symp. 2007, 260, 165. (c) Smolensky, E.; Eisen, M. S.
Dalton Trans. 2007, 5623, and references therein. (d) Volkis, V.; Averbuj,
C.; Eisen, M. S. J. Organomet. Chem. 2007, 692, 1940, references therein.
(e) Bambirra, S.; Otten, E.; van Leusen, D.; Meetsma, A.; Hessen, B. Zeit.
Anorg. Allg. Chem. 2006, 632, 1950. (f) Volkis, V.; Rodensky, M.; Lisovskii,
A.; Balazs, Y.; Eisen, M. S. Organometallics 2006, 25, 4934. (g) Lisovskii,
A.; Eisen, M. S. In LiVing and Controlled Polymerization: Synthesis,
Characterization and Properties of the RespectiVe Polymers and Copoly-
mers; Jagur-GrodzinskiJ., Ed.; Nova Science Publishers, Inc., 2006; Chapter
10, p 343. (h) Volkis, V.; Lisovskii, A.; Tumanskii, B.; Shuster, M.; Eisen,
M. S. Organometallics 2006, 25, 2656. (i) Volkis, V.; Nelkenbaum, E.;
Lisovskii, A.; Hasson, G.; Semiat, S.; Kapon, M.; Botoshansky, M.; Eishen,
Y.; Eisen, M. S. J. Am. Chem. Soc. 2003, 125, 2179. (j) Volkis, V.;
Schmulinson, M.; Shaviv, E.; Lisovskii, A.; Plat, D.; Kuhl, O.; Koch, T.;
Hey-Hawkins, E.; Eisen, M. S. In Beyond Metallocenes; Next Generation
Polymerization Catalysts; Patiland, A. O., Hlatky,G. G., Eds.; American
Chemical Society Symposium Series 857; 2003; p 46.
Results and Discussion
Syntheses and Characterization of Bis(imidodithiodiphos-
phinate) Complexes. The synthesis of titanium and zirconium
imidodithiodiphosphinate complexes was performed following
two different synthetic pathways. The first route uses the metal
chloride salts (MCl4, M ) Ti, Zr) with the corresponding lithium
salt of the imidodithiodiphosphinate ancillary ligand, whereas
the second route utilizes the homoleptic diethylamido complexes
(MNEt2)4 (M ) Ti, Zr) with the corresponding neutral amin-
odithiodiphosphinate ligand. The deprotonation of the neutral
ligand (Ph2PS)2NH (6a) in THF with a slight excess of n-BuLi
(6) Smolensky, E.; Kapon, M.; Woollins, J. D.; Eisen, M. S. Organo-
metallics 2005, 24, 3255.
(7) (a) Richter, J.; Edelmann, F. T.; Noltemeyer, M.; Schmidt, H. G.;
Shmulinson, M.; Eisen, M. S. J. Mol. Catal. Part A: Chem. 1998, 130,
149. (b) Herskovics-Korine, D.; Eisen, M. S. J. Organomet. Chem. 1995,
503, 307. (c) Lee, C. H.; La, Y.-H.; Park, J. W. Organometallics 2000, 19,
344. (d) Mack, H.; Eisen, M. S. J. Organomet. Chem. 1996, 525, 81. (e)
Mack, H.; Eisen, M. S. J. Chem. Soc., Dalton Trans. 1998, 917. (f) Averbuj,
C.; Tith, E.; Eisen, M. S. J. Am. Chem. Soc. 1998, 120, 8640. (g) Michael,
M.; Roesky, H. W.; Stalke, D.; Pauer, F.; Henkel, T.; Sheldrick, G. M.
J. Chem. Soc., Dalton Trans. 1989, 2173.
(10) (a) Jin, X.; Novak, B. M. Macromolecules 2000, 33, 6205. (b) Kim,
J.; Hwang, J.-W.; Kim, Y.; Lee, M. H.; Han, Y.; Do, Y. J. Organomet.
Chem. 2001, 620, 1.
(8) Kuhl, O.; Koch, T.; Somoza, F. B.; Junk, P. C.; Hey-Hawkins, E.;
Plat, D.; Eisen, M. S. J. Organomet. Chem. 2000, 604, 116.
(9) Shmulinson, M.; Galan-Fereres, M.; Lisovskii, A.; Nelkenbaum, E.;
Semiat, Rafi.; Eisen, M. S. Organometallics 2000, 19, 1208.
(11) Shaviv, E.; Botoshanski, M.; Eisen, M. S. J. Organomet. Chem.
2003, 683, 165–180.

Bis(imidodithiodiphosphinato) Ti and Zr Complexes
Organometallics, Vol. 28, No. 8, 2009 2393
Scheme 1. Synthetic Approach for the Synthesis of Complexes 6b-6h
gives quantitatively the corresponding lithium salt of the
imidodithiodiphosphinate ligand solvated with two THF mol-
ecules, producing (Ph2PS)2NLi · 2THF (6b) (isolated yield 94%)
(Scheme 1). Similar literature reactions, which have been utilized
to prepare the same complex 6b, using lithium metal as the
deprotonation reagent proceed in lower yields (78%).12 Slow
recrystallization of complex 6b in THF at -35 °C for 24 h yields
single crystals, suitable for X-ray diffraction studies. The crystal
structure of complex 6b is presented in Figure 1. The low-
temperature X-ray analysis of complex 6b shows the lithium
metal as a part of a six-membered ring in an almost C2V
symmetry about the N-Li vector. The deprotonation of 6a
surprisingly induces a small expansion of the PNP angle
(133.9(2)°) as compared to either the free ligand (132.6(1)°)13
or the analogous potassium salt, K[SPPh2NPPh2S] (128.6(2)°).14
In addition, there is an expected shortening of the P-N bonds
(1.578(3) and 1.591(3) Å) as compared to 6a (1.671(2) and
1.684(2) Å) and identical bond lengths to those exhibited by
the corresponding potassium salt (1.592(2) Å). Furthermore, also
an increase in the length of the PdS bonds (1.9839(14) and
1.9851(14) Å) in complex 6b is observed as compared to those
of 6a (1.950(1) and 1.936(1) Å) and almost identical to those
of the potassium salt (1.978(1) Å). The increase of the N-P-S
bond angles in complex 6b (119.61(13)° and 120.22(12)°) and
in the corresponding potassium salt (120.7(1)°) as compared to
the free ligand (114.7(1)° and 115.3(1)°) indicates the increased
delocalization of the charge in the metal complexes within the
S-P-N-P-S core unit. The metal exhibits a tetrahedral
geometry environment coordinating to two sulfur atoms and two
oxygen atoms of the THF solvent molecules with bond lengths
falling within the normal range (Li-O ) 1.894(8) and 1.917(8)
Å; Li-S ) 2.473(8) and 2.474(8) Å). Interestingly, when
comparing the lithium and the potassium complexes, in the
(12) (a) Schmidbaur, H.; Lauteschlager, S.; Kohler, F. H. J. Organomet.
Chem. 1984, 271, 173. (b) Schmidpeter, A.; Groeger, H. Z. Anorg. Allgem.
Chem. 1966, 345, 106.
(13) X-ray structure of the free ligand has been reported, and the
dimensional comparisons were made to the reference aquiring the best R
factors. (a) Noth, H. Z. Naturforsch., Teil B 1982, 37, 1491. (b) Husebye,
S.; Maartmann-Moe, K. Acta Chem. Scand., Ser. A 1983, 37, 439. (c) Nixon,
J. F.; Hitchcock, P. B. Inorg. Chim. Acta 1985, 96, 77.
Figure 1. ORTEP plot of the molecular structure of the lithium
complex 6. All hydrogens were removed for clarity and thermal
ellipsoids are given at 50% probability. Selected bond lengths (Å)
and angles (deg): Li-S(1) ) 2.474(8), Li-S(2) ) 2.473(8),
P(1)-N(1) ) 1.591(3), P(2)-N(1) ) 1.578(3), O(1)-Li-O(2) )
109.3(4), O(2)-Li-S(2) ) 112.5(4), O(1)-Li-N(1) ) 89.59(8),
S(2)-Li-S(1) ) 109.5(3).
(14) Slawin, A. M. Z.; Ward, J.; Williams, D. J.; Woollins, J. D. J. Chem.
Soc., Chem. Commum. 1994, 421.

2394 Organometallics, Vol. 28, No. 8, 2009
Chen et al.
formation of the corresponding [(Ph2PS)2N]2Ti[N(CH2CH3)2]2
(6e) and [(Ph2PS)2N]2Zr[N(CH2CH3)2]2 (6f) in 73% and 89%
isolated yields, respectively. Both diethylamido complexes were
characterized spectroscopically and by elemental analysis, and
for the latter zirconium complex, 6f, single-crystal X-ray
diffraction studies were also performed. Both diethylamido
complexes were found to be soluble in toluene or more polar
solvents, in contrast to their related chloride complexes. In
addition, the melting points of the diethylamido complexes were
found to be much lower than those of the corresponding chloride
complexes (6e ) 79 °C; 6f ) 91-93 °C; 6c ) 173-175 °C;
6d ) 229 °C (dec)). The high melting temperatures of the
chloride complexes may be indicative, again, of the large
chlorine-metal intermolecular interactions, inducing their low
solubility. In solution, the 31P NMR of 6e and 6f also exhibits
only one narrow singlet line for each complex at 39.9 and 41.8
ppm, respectively, indicating also a rapid equilibrium among
the disposition of the ligands around the metal center, induc-
ing the magnetic equivalence of the phosphorus atoms. Interest-
ingly, the diethylamido groups of both complexes are also
magnetically equivalent, as revealed by NMR showing only one
triplet and one quartet for all four methylene and methyl groups,
Figure 2. Possible dynamic processes in complexes 6c and 6d.
former the S-Li-S bond angle (109.5(3)°) is much larger than
in the latter complex (S-K-S ) 80.5(1)°).14 Presumably, this
contracted angle is an outcome of the K-S ladder-like polymeric
structure of the latter as compared to a solvated lithium complex.
In solution, however, the 31P NMR spectrum of the lithium
complex exhibits only one singlet, suggesting that the two
phosphine atoms are magnetically equivalent in solution at room
temperature.
The reaction of lithium salt (6b) with 0.5 equiv of either the
titanium or the zirconium tetrachloride salt afforded the corre-
sponding disubstituted titanium or zirconium dichlorides com-
plexes, 6c and 6d, in high yields, respectively (isolated yields:
Ti ) 91%; Zr ) 89%) (Scheme 1). Complexes 6c and 6d were
characterized spectroscopically and by elemental analysis. These
two complexes were found to be insoluble in nonpolar solvents,
neither in CH2Cl2 or in diethyl ether, and showed only ∼10%
solubility in THF solutions at either room or reflux temperatures.
Our attempts to obtain single crystals suitable for X-ray dif-
fraction studies were unsuccessful due to the constant presence
of microcrystalline material.
The THF-d8 solutions of complexes 6c and 6d showed narrow
singlet signals in the 31P NMR, at 41.5 and 43.9 ppm,
respectively, indicating the magnetic equivalence of the four
phosphorus atoms in each complex at room temperature. The
dynamic behavior of the complexes may be due to one of the
following possibilities: (i) a Bailar twist15 that proceeds via a
nondissociative mechanism resulting in the opposite enantiomer
(Figure 2a) or (ii) a disconnection and recoordination of the
chelating ligands through the weaker Ti-S bond, resulting in
the formation of different stereoisomers/oligomers in solution
(Figure 2b).
1
respectively, in the H NMR, and one singlet line for all four
methylenes and one singlet line for the methyl groups in the
13C NMR.17 The dynamic behavior of these complexes was
studied by 1H and 31P NMR low-temperature experiments,
indicating a ∆Sq > 0, implying that a rapid disconnection and
recoordination of the chelating ligands through the weaker Ti-S
bond is the main operative mechanism, resulting in the rapid
formation of the different stereoisomers in solution
We have found that complex 6f is thermally stable even when
refluxing for long periods of time in toluene. Complex 6f was
recrystallized from a solution of toluene/hexane at room
temperature for 24 h, yielding yellow crystals suitable for X-ray
diffraction studies. The crystal structure of complex 6f is
presented in Figure 3. The X-ray analysis of complex 6f shows
that the zirconium atom is arranged in a slightly distorted
octahedral environment with two diethylamido ligands disposed
in the cis stereochemistry. The equatorial plane is formed by
the N(58)-N(63)-S(1)-S(68) atoms with a sum of angles of
360.2°, and the apical positions are occupied by the S(29) and
S(30) atoms, forming an angle of 174.13°. The metal nitrogen
bond lengths are alike and are within the normal range for other
zirconium amido bond lengths.18
Different metal-sulfur bond lengths are exhibited in complex
6f: two short distances between Zr-S(2) (2.6487(14) Å) and
Zr-S(3) (2.6658(14) Å) and two longer distances in Zr-S(1)
(2.7666(14) Å) and Zr-S(4) (2.7723(14) Å). The longer
distances are the result of the larger trans effect between the
sulfur and the nitrogen atom of the amido groups. Regarding
the imidodithiodiphosphinate moiety, the bond lengths within
the ligand (besides the metal-sulfur distance and the trans
effect) are very alike (S(2)-P(2) ) 2.0150(18) Å, S(1)-P(1)
) 2.0026(18) Å, P(2)-N(1) ) 1.591(4) Å, P(1)-N(1) )
1.586(4) Å). This disposition of atoms indicates a high delo-
calization effect of the electronic charge, although the geometry
of the ligand is not planar. Therefore, the delocalization must
be operative through the d-orbitals of the phosphorus and sulfur
atoms.
In order to establish which dynamic process takes place, low-
1
temperature H and 31P NMR experiments were performed in
an attempt to calculate ∆Sq for the processes. The rapid
precipitation of the complexes prevented us from obtaining good
line broadening data; however the formation of precipitate
oligomeric structures implies a dissociative mechanism and
excludes the possibility of a Bailar twist as the main operative
pathway for the dynamic process.16
Taking into consideration the low solubility of complexes
6c and 6d, we decided to follow a different synthetic methodol-
ogy for the preparation of similar soluble complexes. Hence,
the reaction of the neutral ligand 6a with a half equivalent of
the homoleptic complexes M(NEt2)4 (M ) Ti, Zr) allowed the
(17) Diethylamido complexes of Zr and Ti do not show normal
methylene equivalence, and when observed, they are exhibited only at high
temperatures. See for example ref 6.
(18) Blake, A. J.; Collier, P. E.; Dunn, S. C.; Li, W.-S.; Mountford, P.;
Shishkin, O. V. J. Chem. Soc., Dalton Trans. 1997, 1549.
(15) Bailar, J. C. J. Inorg. Nucl. Chem. 1958, 8, 165.
(16) Long, R. J.; Gibson, V. C.; White, A. J. P.; Williams, D. J. Inorg.
Chem. 2006, 45, 511.

Bis(imidodithiodiphosphinato) Ti and Zr Complexes
Organometallics, Vol. 28, No. 8, 2009 2395
Figure 3. ORTEP plot of the molecular structure of the zirconium complex 6f. All hydrogens were removed for clarity, and thermal
ellipsoids are given at 50% probability. Selected bond lengths (Å) and angles (deg): S(1)-P(1) ) 2.0026(18), S(4)-P(4) ) 2.0067(18),
N(1)-P(2) ) 1.591(4), N(2)-P(3) ) 1.589(4), N(1)-P(1) ) 1.586(4), Zr-S(1) ) 2.7666(14), Zr-S(2) ) 2.6487(14), Zr-S(3) ) 2.6658(14),
Zr-S(4) ) 2.7723(14), N(4)-Zr-N(3) ) 102.34(16), N(4)-Zr-S(2) ) 97.73(12), N(3)-Zr-S(2) ) 83.60(16), N(4)-Zr-S(3) ) 84.56(12),
S(2)-Zr-S(3) ) 174.13(15), S(2)-Zr-S(4) ) 86.86(4), S(3)-Zr-S(4) ) 89.48(4), S(2)-Zr-S(1) ) 89.04(4), S(3)-Zr-S(1) ) 85.53(4),
S(4)-Zr-S(1) ) 73.80(4), N(3)-Zr-S(1) ) 165.97(12).
Figure 4. ORTEP plot of the molecular structure of the zirconium complex 6g. All hydrogens were removed for clarity, and thermal
ellipsoids are given at 50% probability. Selected bond lengths (Å) and angles (deg): Ti-N(3) ) 1.667(7), Ti-S(4) ) 2.514(2), Ti-S(2)
) 2.522(3), Ti-S(3) ) 2.573(2), Ti-S(1) ) 2.525(3), N(3)-C(49) ) 1.450(10), N(3)-Ti-S(4) ) 98.0(2), N(3)-Ti-S(2) ) 101.9(2),
N(3)-Ti-S(1) ) 104.9(2), N(3)-Ti-S(3) ) 101.0(2), S(4)-Ti-S(1) ) 86.97(8), S(4)-Ti-S(2) ) 160.05(10), S(2)-Ti-S(1) ) 89.20(8),
S(4)-Ti-S(3) ) 90.14(8), S(1)-Ti-S(3) ) 154.17(10), S(2)-Ti-S(3) ) 84.82(8).
When the reaction of the neutral ligand 6a with 0.5 equiv of
Ti[(NEt2)4] was performed in toluene at 110 °C, two unexpected
products were produced: the bis(imidodithiodiphosphinate)ti-
tanium(IV) ethylimido complex (6g) as the major product
(isolated in 70% yield) and the tris(imidothiophosphonate)tita-
nium(III) (isolated in 5% yield) (6h) complex (Scheme 1). These
compounds are easily separated by fractional precipitation from
toluene/hexane (6g) and then from hexane only (6h) solutions
at low temperatures. Single crystals for both complexes were
obtained by their recrystallization at -45 °C for 72 h.
Spectroscopically, complex 6g shows only one singlet in the
31P NMR at 39.8 ppm, similar to those found for complexes 6c
and 6e, indicating again the magnetic equivalence of the ligands.
The crystal structure of complex 6g is presented in Figure 4.
The X-ray analysis of complex 6g shows the presence of a
distorted square-planar pyramid of a five-coordinated imidoti-
tanium complex, in which the central titanium is connected to
one nitrogen atom (N3) at the apical position. The TidN bond
length (1.667(7) Å) is close to the typical range found for other
crystallographically characterized imidotitanium complexes
19
(1.672(7)-1.723(4) Å),
as well as the angle of the imido
moiety with the metal, C(49)-N(3)-Ti ) 172.8(6)°. The

2396 Organometallics, Vol. 28, No. 8, 2009
Chen et al.
Figure 5. ORTEP plot of the molecular structure of the zirconium complex 6h. All hydrogen atoms were removed for clarity, and thermal
ellipsoids are given at 50% probability. Selected bond lengths (Å) and angles (deg): Ti-S(4) ) 2.486(2), Ti-S(5) ) 2.487(2), Ti-S(3) )
2.497(2), Ti-S(6) ) 2.501(2), Ti-S(2) ) 2.553(2), Ti-S(1) ) 2.573(2), S(4)-Ti-S(5) ) 97.89(8), S(4)-Ti-S(3) ) 96.28(8), S(5)-Ti-S(3)
) 87.96(8), S(4)-Ti-S(6) ) 85.89(8), S(5)-Ti-S(6) ) 95.00(8), S(3)-Ti-S(6) ) 176.07(9), S(4)-Ti-S(2) ) 87.85(8), S(5)-Ti-S(2)
) 171.94(9), S(4)-Ti-S(1) ) 177.15(9).
Scheme 2. Proposed Mechanism for the Formation of Complex 6g
imidodithiodiphosphinate ligands in 6g have essentially the same
geometry as each other and those in 6f (Vide infra). Remarkable
is again the delocalization of the charge through the ligand. Both
ligands are η2 and nonplanar in the solid state: one ligand has
a chair conformation, whereas the second ligand maintains a
boat conformation.20 Hence if delocalization is operative, it is
plausibly being performed through the d-orbitals of the P and
S atoms of the ligands in the solid state, and in solution, by
their rapid rotation.
Normally the formation of monomeric imido complexes
proceeds either via the corresponding bisamido complex, in
which the amido groups contain at least one hydrogen atom
(descendent from a primary amine), or by heating an alkyl amido
complex (also containing a hydrogen attached to the nitrogen),
eliminating an alkane moiety. 21 The formation of complex 6g
is presumably via the metathesis elimination of an ethyl moiety
of the corresponding bisamido complex, eliminating Et3N
(Scheme 2). To corroborate the proposed mechanism, we have
to investigate the thermal stability of complex 6e. Hence, by
refluxing complex 6e in a toluene solution for 1 h, Et3N and
complex 6g were formed. This result supports the remarkable
ability of this titanium complex to induce the ethyl migration
toward the formation of the imido complex. Interestingly,
heating of the zirconium complex 6f for long periods of time
did not induce any amine elimination, indicating the higher
thermal stability of the complex as compared to that of the
isolobal titanium complex.
The formation of the small amounts of complex 6h is very
surprising and totally unexpected. The complex is paramagnetic
and is NMR silent. The crystal structure of complex 6h is
presented in Figure 5. The X-ray analysis of the complex shows
a slightly distorted octahedral environment around the metal
(19) Dunn, S. C.; Batsanov, A. S.; Mountford, P. J. Chem. Soc., Chem.
Commun. 1994, 2007.
(20) For late transition complexes, the boat/chair conformation has been
observed; see: (a) Phillips, J. R.; Slawin, A. M. Z.; White, A. J. P.; Williams,
D. J.; Woollins, J. D. J. Chem. Soc., Dalton Trans. 1995, 2467. (b)
Bhattacharyya, P.; Slawin, A. M. Z.; Woollins, J. D. Polyhedron 2001, 20,
1831.
(21) Straub, T.; Haskel, A.; Neyroud, T. G.; Kapon, M.; Botoshansky,
M.; Eisen, M. S. Organometallics 2001, 20, 5017.

Bis(imidodithiodiphosphinato) Ti and Zr Complexes
Organometallics, Vol. 28, No. 8, 2009 2397
Scheme 3. Plausible Mechanism for the Formation of Complex 6h
center. We have chosen the apical atoms to be S(2) and S(5)
due to the better angles of the formed square-planar geometry
around the metal utilizing the other four sulfur atoms (sum of
angles ) 360.0°).
dodithiodiphosphinate complex as found for amines with
isolobal metal complexes.26 Our attempts to fully characterize
this latter complex were unproductive, most likely due to the
formation of oligomeric structures. The synthesis of complex
6h was performed following an independent route in good yield
(69%) from the reaction of Ti(III)Cl3(THF)3 with 3 equiv of
the ligand 6b in THF at reflux temperatures. The complex is
highly oxygen sensitive and decomposes rapidly in air at room
temperature. Crystalline and analytically pure material can be
obtained from its recrystallization in hexane at low temperatures
(-45 °C) for 72 h, and the collection of the crystals was via a
swivel frit under argon.
Two of the three η2-chelating ligands are in a chair conforma-
tion, whereas the remaining ligand is in a distorted boat
conformation with normal distances and geometrical dispositions
similar to those found for the other titanium and zirconium
imidodithiodiphosphinate complexes presented above. As re-
gards the metal-ligand environment bond length distances, two
ligands exhibit similar Ti-S distances and one ligand presents
a slightly longer Ti-S bond distance. When comparing the
Ti(IV)-S and Ti(III)-S bond length distances, it has been
recognized that Ti(IV)-S bond lengths (2.378-2.397 Å)22 are
somewhat shorter than Ti(III)-S (2.487-2.584 Å)23 bond
lengths by ca. 0.14 Å, which may be compared with the
difference of the ionic radii for Ti(III)+ (0.81 Å) and Ti(IV)+
(0.75 Å).24 However, in complexes 6g (Ti(IV)-S: 2.514-2.573
Å) and 6h (Ti(III)-S: 2.486-2.573 Å) similar bond distances
(Ti-S) are appreciably in contrast to the expectations, probably
due to the steric repulsions among the congener phenyl groups
of the ligands.
Catalytic Polymerizations. The catalytic polymerization of
ethylene and propylene was studied with the catalytic precursors
6c, 6d, 6e, 6f, 6g, and 6h. Cationic catalysts were generated in
solution by the reaction of the corresponding precursor with an
excess of MAO. To shed some light on the structure of the
active cationic complexes, we have followed the reactions of
complexes 6c and 6d with an excess of MAO by 13C NMR in
BrC6D5. Hence, for complex 6c, a Ti-CH3+ cationic signal was
observed at 102 ppm, whereas for the isolobal complex 6d, the
+
Zr-CH3 is obtained at 60.3 ppm. It is important to point out
+
that for octahedral benzamidinate complexes, similar M-CH3
Recently, we and others have reported the formation and solid
state characterization of some Ti(III) complexes, when TiCl4
was reacted with either an allylic or a heteroallylic ligand in
which a carbon-carbon bond was formed as the corresponding
oxidation step.10,25 Hence, the formation of complex 6h presum-
ably proceeds in two steps. In the first step a redistribution of
ancillary ligands must be operational at high temperature,
whereas in the second step, the metal may undergo a reduction
to form complex 6h and probably the oxidation of the amine
(Scheme 3). We were able to trap only trace amounts (GC-
MS) of the tetraethylhydrazine (Et2NNEt2) presumably since it
is mainly bound to the coordinatively unsaturated monoimi-
chemical shifts have been observed for the corresponding
cationic complexes.27
The polymerizations were carried out under strictly anaerobic/
anhydrous conditions. The reactions were quenched after
measured time intervals with methanol/HCl solution prior to
polymer collection, washing, and drying. In the case of ethylene,
high-density polyethylene (mp 133-136 °C) was always
obtained. However, at 1 atm of ethylene, all complexes showed
low catalytic activities (ca. ∼3000 g PE/mol · cat · h atm) with
almost no differences for the various complexes. Under pressure
(30 atm), the activities of the complexes were much higher and
the results are summarized in Table 1.
The polymerization of ethylene with complex 6c was the most
active, and the produced polymer was obtained with a very high
(22) (a) White, G. S.; Stephan, D. W. Inorg. Chem. 1985, 24, 1499. (b)
White, G. S.; Stephan, D. W. Organometallics 1987, 6, 2169. (c) White,
G. S.; Stephan, D. W. Organometallics 1988, 7, 903.
(23) Matsuzaki, K.; Kawaguchi, H.; Voth, P.; Noda, K.; Itoh, S.; Takagi,
H. D.; Kashiwabara, K.; Tatsumi, K. Inorg. Chem. 2003, 42, 5320–5329.
(24) Shannon, R. D. Acta Crystallogr. 1976, A32, 751–767.
(25) Ray, B.; Nuyrun, T. G.; Kapon, M.; Eichen, Y.; Eisen, M. S.
Organometallics 2001, 20, 3044.
(26) Haskel, A.; Wang, J. Q.; Straub, T.; Gueta-Neyroud, T.; Eisen, M. S.
J. Am. Chem. Soc. 1999, 121, 3025.
(27) Volkis, V.; Nelkenbaum, E.; Lisovskii, A.; Hasson, G.; Semiat,
Rafi.; Kapon, M.; Botoshansky, M.; Eishen, Y.; Eisen, M. S. J. Am. Chem.
Soc. 2003, 125, 2179.

2398 Organometallics, Vol. 28, No. 8, 2009
Chen et al.
Table 1. Activity, Molecular Weight, and Melting Point Data for the Polymerization of Ethylenea
b
entry
complex
time (h)
activityA × 10-4
Mw × 10-3
Mn × 10-3
MWDd
mp (°C)
1
2
3
4
5
6
7
8
6c
6d
6e
6f
6g
6h
6h
6h
3
3
3
3
3
3
6
20
10.0
4.0
4.1
3.0
3.2
4.3
4.9
5.5
HMWPEc
2567
HMWPE
1955
HMWPE
1.31
1.18
1.40
1.29
1.13
1.25
1.19
136.6
136.3
132.5
135.9
133.2
134.4
135.1
135.3
1973
2166
2060
1576
2005
2195
1676
1540
1588
1395
1604
1845
a Al:complex ratio ) 1600; the methylaluminoxane solvent was removed from a 20% solution in toluene at 25 °C/10-6 Torr, toluene, RT, 5 mmol of
catalyst, 30 atm of olefin (kept constant via a solenoid). b Activity in g PE/mol cat · h · atm. c Molecular weight too high to be measured by regular GPC
(out of the measurement limit) and low solubility at 165 °C in 1,2,4-trichlorobenzene. d Mw/Mn.
Table 2. Activity, Molecular Weight, and Melting Point Data for the Polymerization of Propylenea
b
entry
complex
MAO:M
solvent
A × 10-3
Mw
Mn
MWDc
1
2
3
4
6c
6c
6h
6h
400
1600
400
toluene
toluene
toluene
toluene
2.4
3.3
513 000
91 200
424 000
324 000
315 000
21 700
286 000
79 600
1.6
4.2
1.5
4.1
42.5
86.4
1600
a The methylaluminoxane solvent was removed from a 20% solution in toluene at 25 °C/10-6 Torr, toluene, RT, 4 h, 5 mmol of catalyst, 10 atm of
olefin (kept constant having liquid propylene in excess). b Activity in g PP/mol cat · h · atm. c Mw/Mn.
Mw, beyond our measurements limits, >7 × 106 g/mol. All the
other complexes were active in a similar way, producing in all
cases high Mw polymers (>106 g/mol) with unexpectedly very
narrow polydispersities (MWD ) 1.18-1.31). Although we
have shown that bisamido group IV complexes can be used
instead of similar dichloride complexes as the precursor for the
catalytic polymerization of olefins,28 in these systems the
dichloride complexes are more active than the corresponding
bisamido complexes. Moreover, the titanium complexes show
better catalytic activities than the corresponding zirconium
complexes regardless of the ligands. A very interesting result
regards the polymerization with complex 6h. In the absence of
MAO, no catalytic activity was observed. When reacted with
MAO and a small amount of ethylene, the ESR signal for the
Ti(III) disappears and polymer is obtained. We have recently
disclosed that for some octahedral heteroallylic complexes in
the presence of two cocatalysts in the polymerization of
R-olefins, the first activation step is the reduction of the metal
to the oxidation state M(III) by MAO (M ) Ti, Zr). The addition
of the olefin induced the oxidation of the metal and the formation
of the active hydride species (for ethylene) after ꢀ-H elimina-
tion.29 Hence, it is not strange that the activation of complex
6h will be somewhat lower than that of complex 6c; however
the polymer formation will be expected to be comparable.
Monitoring the polymerization over time for complex 6h (entries
6, 7, and 8, Table 1) reveals a linear increase of Mn with
increasing polymerization time. In a polymerization that pro-
ceeds in a living manner an increase of both the polymer weight
and Mn is observed, whereas in a nonliving polymerization only
an increase of the polymer weight is expected. Therefore, an
increase of Mn over time in this case suggests that a certain
percentage of the polymerization proceeds in a living manner.
The percentage of living polymerization was calculated accord-
ing to the formula presented in eq 1 (nl is the moles of living
species and ncat is the moles of catalyst).
insertion, and Mn is the number-average molecular weight; t )
20 h was taken for t f ∞). These calculations showed that at
25 °C about 70% of the polymerization is living.30
Mn ) MWmonomertRi/(n1 + (MWmonomertRi)/Mn(tf∞)) (2)
When the complexes were used for the polymerization of
propylene, an elastomeric polypropylene was obtained (Table
2). Complexes 6d, 6e, and 6f produced only trace amounts of
the polymer, low activities were obtained by complex 6c, and
the best catalytic activities were observed for complex 6h.
13C NMR spectra of polypropylene prepared with complex
6c or 6h were determined in 1,2,4-trichlorobenzene/DMSO-d6
at 135 °C, exhibiting signals at 15.0, 17.1, 30.8, and 35.1 ppm,
characteristic of isolated 2,1 mis-insertion units. Since no
1
vinylidene or vinyl chain end groups were observed in the H
or 13C NMR, presumably due to the higher molecular weight,
we decided to study the effect of MAO.31 Hence, for both
complexes 6c and 6h, when the polymerization was carried with
a larger amount of MAO (MAO:complex ) 1600, instead of
400), a faster reaction was achieved and the polymers obtained
were characterized to have a lower molecular weight and a much
higher polydispersity. For the polymer obtained with complexes
6c and 6h (entries 2 and 4, Table 2), no chain end besides an
isobutyl group was observed in the NMR, indicating that with
this catalyst chain transfer to MAO seems to be the main
operative termination mechanism, and the presence of larger
amounts of MAO not only reduces the polymer molecular
weights but induces the formation of various types of active
sites, resulting in large molecular weight distributions.
Conclusions
Nowadays there is a major effort in the search for non-
metallocene complexes that can be active for the polymerization
(28) (a) Smolensky, E.; Kapon, K.; Woollins, D. J.; Eisen, M. S.
Organometallics 2005, 24, 3255. (b) Gueta-Neyroud, T.; Tumanskii, B.;
Botoshansky, M.; Eisen, M. S. J. Organomet. Chem. 2007, 692, 927. (c)
Gornshtein, F.; Kapon, M.; Botoshansky, M.; Eisen, M. S. Organometallics
2007, 26, 497.
(29) Volkis, V.; Tumanskii, B.; Eisen, M. S. Organometallics 2006, 25,
2722.
% of living polymerization ) (n1100)/ncat
(1)
(30) See Supporting Information.
(31) (a) Resconi, L.; Cavallo, L.; Fait, A.; Piemontesi, F. Chem. ReV.
2000, 100, 1253. (b) Resconi, L.; Piemontesi, F.; Franciscono, G.; Abis,
L.; Fiorani, T. J. Am. Chem. Soc. 1992, 114, 1025.
Number of moles of living species, nl, was isolated from eq
2 (where t is the polymerization time, Ri is the rate of monomer

Bis(imidodithiodiphosphinato) Ti and Zr Complexes
Organometallics, Vol. 28, No. 8, 2009 2399
and used without further purification unless otherwise stated.
of olefins. The synthetic approach to the general family of
complexes containing the imidodithiodiphosphinate ancillary
ligands was introduced. These complexes are isolobal with the
ꢀ-diketiminate or the acetylacetonate complexes and hence
expected to show remarkable properties as to their reactivities.
We have shown that the imidodithiodiphosphinate ligand can
be incorporated with group 4 metal complexes. The chloride
complexes were difficult to work with since low solubility/
oligomeric species are formed. However the corresponding
bis(amido) complexes were monomeric in solution. Moreover,
the reactivity of the titanium complex 6e is unique since upon
heating it forms the corresponding imido complex. The use of
such complexes for the hydroamination of secondary amines is
under investigation. The formation of the homoleptic complex
Ti(III) (6h) via the disproportionation of complex 6e is
fascinating, describing the high reactivity of these complexes
due to the induced coordinative unsaturation acquired by
opening the Ti-S bonds. The catalytic ability of these com-
plexes, upon their activation with MAO, in the polymerization
of ethylene and propylene is described. For ethylene, high
molecular weight and monodisperse polymers were attained,
whereas for propylene, the larger the amount of MAO used,
the larger the polydispersity and the lower the molecular weight
of the polymers obtained. In addition, the X-ray solid state
diffraction study of four different complexes was presented.
(Ph2PS)2NH,32 Ti[N(CH2CH3)2]4,33 and Zr[N(CH2CH3)2]4 were
34
prepared by literature procedures.
(Ph2PS)2NLi · 2THF (6b). n-BuLi (1.6 M) in hexane (9.5 mL,
15.2 mmol) was added dropwise via a gastight syringe during 5
min to a stirred solution of (Ph2PS)2NH (6.25 g, 13.9 mmol) in
THF (50 mL) under an argon flow at 0 °C. The mixture was allowed
to warm slowly to room temperature and stirred overnight under
inert conditions. The solvent was then removed under vacuum, and
the obtained solid was washed three times with hexane, affording
a white powder. Yield: 7.85 g (94%). Mp: 158 °C (dec, 167 °C).35
1H NMR was identical to that reported in the literature.31 Recrys-
tallization of 6b from THF (-35 °C) gave crystals suitable for
X-ray.
[(Ph2PS)2N]2TiCl2 (6c). TiCl4 (102 µL, 0.93 mmol) was added
via a gastight syringe to a 15 mL toluene suspension of 6b (1.11
g, 1.85 mmol) under argon at -50 °C. After the addition, the color
of the reaction mixture changed to brown-red and all ligand 6b
dissolved immediately. The reaction mixture was allowed to warm
slowly to room temperature and stirred overnight under argon. The
volume of the mixture was reduced to half via a vacuum pump,
inducing the precipitation of a brown-red material. Filtering the
solids via a swivel frit followed by washing with 3 × 20 mL of
toluene afforded 0.93 g (91%) of complex 6c. Mp: 173-175 °C.
Anal. Calc for C48H40N2Cl2P4S4Ti · 2LiCl: C, 52.69; H, 3.96; N,
1
2.54; Cl, 12.89. Found: C, 52.93; H, 4.38; N, 2.35; Cl, 12.59. H
NMR (THF-d8, 25 °C, 400 MHz) δ: 7.3 (m, 24H, o-, p-H), 8.0 (m,
16H, m-H). 31P{H} NMR (THF-d8, 25 °C, 160 MHz) δ: 41.5. EI-
MS (THF): 965, 964, 963, 961 (M+ -2Cl + OH), 955, 954, 912,
898, 851, 819, 695, 681, 680, 663, 649, 648, 512, 511, 510, 449
(free ligand, (Ph2PS)2NH, base peak), 416 ((Ph2PS)2NH - HS).
[(Ph2PS)2N]2ZrCl2 (6d). 6b (1.19 g, 2.0 mmol) was added via
a solid addition tube to a stirred solution of 0.224 g (1.0 mmol) of
ZrCl4 in 15 mL of THF under argon at room temperature. Stirring
was continued for 24 h. THF was removed under vacuum. Washing
the residue three times with hexane afforded a white powder, mp
229 °C (dec). Yield: 1.15 g (89%). Anal. Calc for C64H72N2Cl2-
O4P4S4Zr · 2LiCl · 4THF: C, 53.67; H, 5.07; N, 1.95; Cl, 9.90.
Experimental Section
All manipulations of air-sensitive materials were performed with
the rigorous exclusion of oxygen and moisture in flamed Schlenk-
type glassware on a dual-manifold Schlenk line, or interfaced to a
high-vacuum (10-5 Torr) line, or in a nitrogen-filled Vacuum
Atmospheres glovebox with a medium-capacity recirculator (1-5
ppm O2). Argon, ethylene, propylene, and nitrogen gases were
purified by passage through a MnO oxygen-removal column and a
Davison 4 Å activated molecular sieve column. Ether solvents were
distilled over argon from sodium benzophenone ketyl. Hydrocarbon
solvents (toluene, C6D6, hexane, THF-d8) were distilled over Na/K
alloy. All solvents for vacuum line manipulation were stored under
vacuum over Na/K alloy in resealable bulbs. NMR spectra were
recorded on Bruker AM 200 and AM 400 spectrometers. Chemical
shifts for 1H, 13C, and 31P NMR were referenced to internal solvent
resonances and are reported relative to TMS and 85% H3PO4. NMR
experiments were conducted on Teflon valve-sealed tubes (J-Young)
after vacuum transfer of the solvent in a high-vacuum line. The
polypropylene NMR experiments were conducted in 1,2,4-trichlo-
robenzene at 135 °C with DMSO-d6 as external standard and when
possible in CDCl3 at room temperature. ESR spectra were recorded
on a Bruker EMX-10/12 X-band (ν ) 9.4 GHz) digital ESR
spectrometer equipped with Bruker N2-temperature controller. All
spectra were recorded at microwave power 10-1 mW, with 100
kHz magnetic field modulation of 1.0-0.5 G amplitude. Digital
field resolution was 2048 points per spectrum, allowing all hyperfine
splitting to be measured directly with accuracy better than 0.2 G.
EI mass spectra were recorded on a Finnigan TSQ-70B mass
spectrometer using fresh distilled dry THF as solvent. Melting points
of complexes were measured in nitrogen-sealed capillaries and are
uncorrected. Melting points of the polymers were measured by DSC
(Polymer Laboratories, UK) from the second heating thermogram
(heating rate ) 5 °C/min). Molecular weights of polymers were
determined by the GPC method on the Waters-Alliance 2000
instrument using 1,2,4-trichlorobenzene as a mobile phase at 160
°C. Polystyrene standards were used for the standard calibration
curve of the GPC. Elemental analysis was performed by the
microanalytical laboratory at the Hebrew University of Jerusalem.
ZrCl4 (Aldrich) was sublimed twice (150 °C, 10-5 Torr) before
use. All other reagents were purchased from Aldrich and Fluka
1
Found: C, 53.63; H, 5.48; N, 2.09; Cl, 9.76. H NMR (C6D6, 25
°C, 400 MHz) δ: 6.9 (m, 24H, o-, p-H), 8.4 (m, 16H, m-H); THF
signals 3.54 (t, 16H), 1.31 (t, 16H). 31P{H} NMR (THF-d8, 25 °C,
160 MHz) δ: 43.9.
[(Ph2PS)2N]2Ti[N(CH2CH3)2]2 (6e). Ti[N(CH2CH3)2]4 (0.88 g,
2.62 mmol) was added via a gastight syringe to 20 mL of a toluene
suspension containing 2.35 g (5.23 mmol) of 6a under argon at 0
°C (water/ice bath). The color of the reaction mixture changed to
brown immediately, and 6a was dissolved. The mixture was allowed
to warm to room temperature and stirring was continued overnight.
The toluene was removed under vacuum, and the solids were
washed 3 × 30 mL with hexane, affording a brown-red powder,
mp 79 °C (dec). Yield: 2.08 g (73%). Anal. Calc for C56H60N4-
P4S4Ti: C, 61.76; H, 5.55; N, 5.14. Found: C, 61.39; H, 5.60; N,
4.94. 1H NMR (THF-d8, 25 °C, 400 MHz) δ: 0.79 (t, 12H, CH3, J
) 6.8 Hz), 3.83 (q, 8H, CH2, J ) 6.8 Hz), 7.2 (m, 24H, o-, p-H),
7.8 (m, 16H, m-H). 13C{H} NMR (THF-d8, 25 °C, 100.576 MHz)
δ: 142.36, 140.18, 133.87, 133.14, 131.80, 131.55, 129.25, 129.13
(aromatic C), 13.86 (CH3), 49.55 (CH2). 31P{H} NMR (THF-d8,
25 °C, 160 MHz) δ: 39.9. EI-MS: 962, 960, 955, 954, 912, 898,
851, 819, 695, 681, 680, 663, 649, 648, 512, 511, 510, 449 (free
ligand, (Ph2PS)2NH, base peak), 416 ((Ph2PS)2NH - HS).
[(Ph2PS)2N]2Zr[N(CH2CH3)2]2 (6f). Zr[N(CH2CH3)2]4 (1.1 g,
2.9 mmol) was added via a gastight syringe to 12 mL of a toluene
(32) Woolins, J. D. Inorganic Experiments; VCH: Weinheim, 1994; p
145.
(33) Bradley, D. C.; Thomas, I. M. J. Chem. Soc. 1960, 3857.
(34) Diamond, G. M.; Jordan, R. F. Organometallics 1996, 15, 4030.
(35) Ghesner, I.; Palotas, C.; Silvestru, A.; Silvestru, C.; Drake, J. E.
Polyhedron 2001, 20, 1101.

2400 Organometallics, Vol. 28, No. 8, 2009
Chen et al.
suspension of 6a (2.37 g, 5.3 mmol) under argon at room
temperature (water bath). The color of the reaction mixture changed
to orange immediately and 6a was fully dissolved. The reaction
mixture was heated to reflux and stirred for 12 h. After cooling the
reaction mixture to room temperature, 10 mL of hexane was added.
Yellowish crystals suitable for X-ray were obtained after a day when
the solution stood at room temperature. The solvents were filtered
and the resulting crystals were washed three times × 20 mL of
hexane. The crystalline material was dried under vacuum to afford
2.65 g (89%) of yellow plate crystals. Mp: 91-93 °C. Anal. Calc
for C56H60N4P4S4Zr: C, 59.39; H, 5.34; N, 4.95. Found: C, 59.18;
resulting in an appropriate pressure of the mixture. During the
polymerization the decreased pressure showed in a manometer and
a solenoid valve inserts ethylene to maintain the starting pressure
(∆P ) 2 atm). After a measured amount of time the reaction reactor
is released of the excess of ethylene in a well-ventilated hood, and
the reaction mixture is quenched adding a methanol/HCl mixture
(9:1). The polymer product was collected by filtration and washed
with methanol, water, and acetone. The polymer was dried under
vacuum (10-5 Torr) at 65 °C for 24 h or until constant weight was
obtained.
Propylene Polymerization. A 100 mL heavy wall glass reactor
with a magnetic stirring bar was charged with 5 mg of the
corresponding catalyst and a specific amount of MAO in the
glovebox. The reactor was connected to a Schlenk line, and 5 mL
of dry solvent was quickly added via a gastight syringe in an argon
flow. After stirring the mixture for 1 h at room temperature, it was
inserted into a liquid nitrogen bath and propylene was condensed
into the reactor after been condensed in a measured container kept
at liquid nitrogen temperature. The temperature of the reactor was
rapidly raised and equilibrated through a thermostatted bath. The
reaction was stirred vigorously, and after a measured amount of
time the reactor was opened in a well-ventilated hood to exhaust
any excess of propylene gas followed by the addition of a methanol/
HCl mixture. The polymer was then washed with methanol, water,
and acetone. The resulting polymer was dried under vacuum (10-5
Torr) at 65 °C for 24 h or until constant weight.
1
H, 5.64; N, 4.55. H NMR (THF-d8, 25 °C, 400 MHz) δ: 0.79 (t,
12H, CH3, J ) 6.9 Hz), 3.38 (q, 8H, CH2, J ) 6.9 Hz), 7.2 (m,
24H, o-, p-H), 7.8 (m, 16H, m-H). 13C{H} NMR (THF-d8, 25 °C,
100.576 MHz) δ: 13.93 (CH3), 44.39 (CH2), 129.19, 129.46, 131.77,
132.97, 133.19, 139.71, 141.90 (aromatic C). 31P{H} NMR (THF-
d8, 25 °C, 160 MHz) δ: 41.8. EI-MS (toluene): 982, 981
([(Ph2PS)2N]2ZrN(CH2CH3)2 -Ph), 953, 952 ([(Ph2PS)2N]2ZrNCH2-
CH3 -Ph), 449 (free ligand, (Ph2PS)2NH, base peak). 416
((Ph2PS)2NH - HS).
[(Ph2PS)2N]2TidN(CH2CH3)2 (6g) and [(Ph2PS)2N]3Ti (6h).
Ti[N(CH2CH3)2]4 (0.88 g, 2.62 mmol) was added via a gastight
syringe to 20 mL of a toluene suspension containing 2.35 g (5.23
mmol) of the ligand 6a, under argon at room temperature. The
mixture was heated to reflux under argon and stirred for 19 h.
Toluene was removed under vacuum, and the solids were washed
three times with 20 mL of hexane in a swivel frit to afford 1.8 g
(70%) of brown powder of 6g. Mp: 127 °C (dec). Anal. Calc for
C50H45N3P4S4Ti: C, 60.79; H, 4.59; N, 4.25. Found: C, 60.45; H,
5.35; N, 4.00. 1H NMR (THF-d8, 25 °C, 400 MHz) δ: 0.81 (t, 3H,
CH3, J ) 6.9 Hz), 3.85 (q, 2H, CH2, J ) 6.9 Hz), 7.25 (m, 24H,
o-, p-H), 7.84 (m, 16H, m-H). 13C{H} NMR (THF-d8, 25 °C,
100.576 MHz) δ: 16.11 (CH3), 57.60 (CH2), 142.15, 140.01, 133.84,
133.20, 131.78, 131.67, 129.22, 129.10 (aromatic C). 31P{H} NMR
(THF-d8, 25 °C, 160 MHz) δ: 39.8. EI-MS (toluene): 1296 (M+-
3S), 963, 962, 961 (M+ - CH2CH3), 955, 954, 912, 898, 897, 851,
819, 695, 681, 680, 663, 649, 648, 512, 511, 510, 449 (free ligand,
(Ph2PS)2NH, base peak), 416 ((Ph2PS)2NH - HS). Recrystallization
of the powder from 20 mL of a 1:1 toluene/hexane mixture (-38
°C) gave fine red needle crystals of 6g suitable for X-ray studies.
After the crystallization of complex 6g was completed, the
crystallization of the remaining solid with hexane at -45 °C yielded
dark green crystals in small amounts, 0.03 g, of complex 6h.
[(Ph2PS)2N]3Ti (6h). Ti(Cl3)(THF)3 (0.6 g, 1.61 mmol) in 20
mL of THF was added via a gastight syringe to 20 mL of a THF
solution containing 3.40 g (5.56 mmol) of the ligand 6b, under
argon at -45 °C. The reaction was heated to reflux for 72 h and
the solvent evacuated through a high-vacuum line. The reaction
mixture was dissolved in toluene, filtered, and dried to separate
the insoluble LiCl. Crystallization of complex 6h in hexane at -45
°C yielded dark green crystals, 1.6 g (67%).
Characterization of the Polymers. NMR spectra of the
polymers were conducted in deuterated tetrachlorethane at 85 °C
and recorded on a Bruker Avance 500 MHz spectrometer. Chemical
1
shifts for H and 13C NMR were referenced to internal solvent
resonances and reported relative to SiMe4.
X-ray Crystallographic Measurements. The single-crystalline
material was immersed in Paratone-N oil and was quickly fished
with a capillary tube and mounted on the Kappa CCD diffractometer
under a cold stream of nitrogen at 200 K. Data collection was
performed using monochromatized Mo KR radiation using omega
and phi scans to cover the Ewald sphere.36 Accurate cell parameters
were obtained with the number of indicated reflections.30,37 The
structure was solved by SHELXS97 direct methods38 and refined
by the SHELXL97 program package.39 The atoms were refined
anisotropically. Hydrogens were included using the riding mode.
Software used for molecular graphics: ORTEP, TEXRAY Structure
Analysis package.40
Acknowledgment. This research was supported by the
USA-Israel Binational Science Foundation under contract
2004075. We thank Dr. Mark Botoshanskii for DSC mea-
surements, Dr. Victoria Volkis for GPC high-temperature
measurements, and Dr. Dorit Plat for helpful discussions.
Supporting Information Available: Derivation of eq 2. Crystal-
lographic data and structure refinement details for complexes 6b,
6f, 6g, and 6h. Cif files for the characterization of compounds 6b,
6f, 6g, and 6h. This material is available free of charge via the
Internet at http://pubs.acs.org.
Mp: 154 °C (dec). Anal. Calc for C72H60N3P6S6Ti: C, 62.06; H,
4.34; N, 3.02. Found: C, 61.75; H, 3.99; N, 3.32. EI-MS (toluene):
1392 (M+), 976, 559, 449 (free ligand, (Ph2PS)2NH, base peak),
416 ((Ph2PS)2NH - HS). ESR measurements show a single line
centered at g )1.976 at 298 K.
OM801176A
Ethylene Polymerization. Ethylene polymerization was carried
out in a 35 mL stainless steel autoclave equipped inside with a 26
mL glass container and a magnetic stirring bar. In the glovebox,
the reactor was charged with a catalyst (typically, 5 mg) and a
specific amount of MAO. The reactor was connected to a Schlenk
line, and 8 mL of dry toluene was quickly added via syringe in an
argon flow. After stirring for 1 h at room temperature (preactiva-
tion), a certain amount of ethylene was inserted into the reactor,
(36) Nonius. Kappa CCD Server Software; Nonius BV: Delft, The
Netherlands, 1997.
(37) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.
(38) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(39) Sheldrick, G. M. SHELXL97. Program for the Refinement of Crystal
Structures; University of Gottingen: Germany, 1997.
(40) Molecular Structure Corporation. ORTEP. TEXRAY Structure
Analysis Package; MSC: The Woodlands, TX, 1999.