Synthesis, structural characterization, and ethylene polymerization behavior of the vanadium(III) complexes bearing salicylaldiminato ligands

Article abstract of DOI:10.1021/om800097b

Vanadium(III) complexes bearing salicylaldiminato ligands (2a-k) [RN=CH(ArO)]VCl₂(THF)₂ (Ar = C₆H₄, R = Ph, 2a; p-CF₃Ph, 2b; p-CH₃Ph, 2c; 2,6-Me₂Ph, 2d; 2,6-iPr₂Ph, 2e

Full text of DOI:10.1021/om800097b

3840
Organometallics 2008, 27, 3840–3848
Synthesis, Structural Characterization, and Ethylene Polymerization
Behavior of the Vanadium(III) Complexes Bearing Salicylaldiminato
Ligands
Ji-Qian Wu,†,‡ Li Pan,† Ning-Hai Hu, and Yue-Sheng Li*,†
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry,
Chinese Academy of Sciences, Changchun 130022, People’s Republic of China, and Changchun Branch of
Graduate School of the Chinese Academy of Sciences, People’s Republic of China
ReceiVed February 3, 2008
Vanadium(III) complexes bearing salicylaldiminato ligands (2a-k) [RNdCH(ArO)]VCl2(THF)2 (Ar
) C6H4, R ) Ph, 2a; p-CF3Ph, 2b; p-CH3Ph, 2c; 2,6-Me2Ph, 2d; 2,6-iPr2Ph, 2e; cyclohexyl, 2f; Ar )
C6H3tBu(2), R ) Ph, 2g; 2,6-iPr2Ph, 2h; Ar ) C6H2tBu2(2,4), R ) Ph, 2i; 2,6-iPr2Ph, 2j; Ar ) C6H2Br2,
R ) Ph, 2k) were prepared from VCl3(THF)3 by treating with 1.0 equiv of (RNdCH)ArOH in
tetrahydrofuran (THF) in the presence of excess triethylamine (TEA). The reaction of VCl3(THF)3 with
2.0 equiv of (RNdCH)ArOH in THF in the presence of excess TEA afforded vanadium(III) complexes
bearing two salicylaldiminato ligands (3a-k), [RNdCH(ArO)]2VCl(THF)x (Ar ) C6H4, x ) 1, R ) Ph,
3a; p-CF3Ph, 3b; p-CH3Ph, 3c; 2,6-Me2Ph, 3d; 2,6-iPr2Ph, 3e; cyclohexyl, 3f; Ar ) C6H3tBu(2), x ) 1,
R ) Ph, 3g; x ) 0, 2,6-iPr2Ph, 3h; Ar ) C6H2tBu2(2,4), x ) 1, R ) Ph, 3i; 2,6-iPr2Ph, x ) 0, 3j; Ar )
C6H2Br2, x ) 1, R ) Ph, 3k). These complexes were characterized by FTIR and mass spectra as well as
elemental analysis. Structures of complexes 2a, 2b, 2g, 2i, 2k, 3b, 3c, 3e, 3j, and 3k were further confirmed
by X-ray crystallographic analysis. The complexes were investigated as catalysts for ethylene
polymerization in the presence of Et2AlCl. Complexes 2a-k exhibited high catalytic activities (up to
22.3 kg PE/mmolV · h · bar) and afforded high molecular weight polymers (Mw > 100 kg/mol) with
unimodal molecular weight distributions at room temperature, while displaying relatively low catalytic
activities, and produced polymers with low molecular weight (Mw < 30 kg/mol) and broad molecular
weight distributions at 70 °C. Complexes 3a-k were also effective catalyst precursors for ethylene
polymerization. Even at 70 °C these complexes produced polyethylenes with unimodal distributions.
These results indicated that the structural model of the salicylaldiminato vanadium(III) complexes greatly
affected the ethylene polymerization behaviors.
especiallyforthesynthesesofhighmolecularweightpolyethylene,2,3
Introduction
syndiotactic polypropylene,5 and poly(ethylene-co-propylene)
and poly(ethylene-co-propylene-co-diene) elastomers.4 There-
fore, the design and synthesis of new vanadium complexes as
olefin polymerization catalysts has attracted considerable at-
tention. Recently, modification of the ligand frameworks of
A significant number of advances in olefin polymerization
catalysis have been reported in the past decade, and the
development of new generation “non-metallocene” catalysts has
attracted great interest recently.1 Among the transition metals,
vanadium catalysts exhibited promising characteristics,2–19
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* To whom correspondence should be addressed. Fax: +86-431-5262124.
E-mail: ysli@ciac.jl.cn.
† State Key Laboratory of Polymer Physics and Chemistry.
‡ Changchun Branch of Graduate School of the Chinese Academy of
Sciences.
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10.1021/om800097b CCC: $40.75
2008 American Chemical Society
Publication on Web 07/09/2008

Vanadium(III) Complexes Bearing Salicylaldiminato Ligands
Organometallics, Vol. 27, No. 15, 2008 3841
Scheme 1. General Synthetic Route of the Vanadium
Complexes Used in This Study
vanadium complexes has led to impressive advances in catalyst
productivity, thermal stability, and comonomer incorporation
capability.6–20 For example, Gambarotta and co-workers found
that bis(imino)pyridine vanadium(III) complexes showed high
catalytic activity toward ethylene polymerization and produced
bimodal molecular weight distribution PEs.10b The bis(benz-
imidazole)amine vanadium catalysts reported by Gibson’s group
displayed high efficiency for ethylene (co)polymerization,
affording high molecular weight polymers with unimodal
distribution.7c Nomura demonstrated that high catalytic activity
and efficient R-olefin or cycloolefin incorporation could be
obtained if the (arylimino)(aryloxo)vanadium complexes were
used as catalyst precursors.17 Redshaw’s group investigated
various aryloxide-based vanadyl complexes, which exhibited
excellent performance in olefin polymerization.19 Recently, our
group reported the synthesis and structural characterization of
a type of vanadium catalyst featuring unsymmetrical bidentate
ꢀ-enaminoketonato ligands, which revealed remarkable catalytic
activity not only for ethylene polymerization but also for
ethylene/R-olefin and ethylene/cycloolefin copolymerizations.21
Salicylaldiminato ligands have been used in transition metal
organometallics and have already been shown to afford highly
active olefin polymerization catalysts for group 4,22 group 6,23
and group 1024 metal systems. For instance, it has been known
that titanium/zirconium complexes containing bis(salicylaldi-
minato) ligands can be used to produce polyethylene or
syndiotactic polypropylene with high molecular weight and
narrow molecular weight distribution, and the catalytic behaviors
were highly affected by the substituents on both the phenoxy
and the imino groups.25 However, the reports on the salicyla-
ldiminato vanadium catalysts for olefin polymerization are
limited so far.19d,20a,b,26 In this paper, we investigated the
synthesis and structural analysis of a series of salicylaldiminato
vanadium complexes [RNdCH(ArO)]VCl2(THF)2 (2a-k) and
bis(salicylaldiminato) vanadium complexes [RNdCH(ArO)]2-
VCl(THF)x (3a-k). We also present our preliminary results
concerning their use as catalysts for ethylene polymerization
in the presence of Et2AlCl.
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Results and Discussion
1. Synthesis and Characterization of Vanadium(III)
Complexes [RNdCH(ArO)]VCl2(THF)2. A general synthetic
route for new vanadium complexes used in this study is shown in
Scheme 1. The reaction of VCl3(THF)3 with 1.0 equiv of
(RNdCH)ArOH (1a-k) in tetrahydrofuran (THF) in the presence
of excess TEA afforded vanadium(III) complexes 2a-k in moder-
ate to high yields (2a, 70%; 2b, 70%; 2c, 60%; 2d, 63%; 2e, 76%;
2f, 69%; 2g, 71%; 2h, 53%; 2i, 76%; 2j, 64%; 2k, 62%). These
reactions took place along with evolution of hydrochloride, and
the pure samples as dark red or brown crystallized solids were
isolated from the chilled concentrated mixture of THF and hexane
solution. These complexes were identified by FTIR and mass
spectra as well as elemental analysis. In the EI/MS spectra of
complexes 2, there were no peaks of complexes 3 or 3:1 or 0:1
ligand-to-V(III) complexes, indicating the complexes display high
purity. The resonances are broadened to such an extent that they
become effectively unobservable in the 1H (or 13C) NMR spectra
for these complexes in CD2Cl2 or C6D6, indicating that they are
paramagnetic species.
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Arbaoui, A.; Elsegood, M.; Dale, S. H.; Yamato, T.; Casas, C. P.; Matsui,
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A.; Williams, D. J. J. Am. Chem. Soc. 2005, 127, 11037.
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R. H.; Bansleben, D. A.; Day, M. W. Organometallics 1998, 17, 3149. (b)
Younkin, T. R.; Conner, E. F.; Henderson, J. I.; Friedrich, S. K.; Grubbs,
R. H.; Bansleben, D. A. Science 2000, 287, 460. (c) Li, X. F.; Li, Y. S. J.
Polym. Sci. Part A: Polym. Chem. 2002, 40, 2680.
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M.; Mohri, J.; Yoshida, Y.; Saito, J.; Ishii, S.; Tsuru, K.; Matsui, S.;
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3842 Organometallics, Vol. 27, No. 15, 2008
Wu et al.
Table 1. Selected Bond Distances (Å) and Angles (deg) for
Complexes 2a, 2b,2g, 2i, and 2k
2a 2b 2g
Bond Distances
2i
2k
V-N(1)
V-O(1)
V-O(2)
V-O(3)
V-Cl(1)
V-Cl(2)
2.1099(18) 2.116(3)
1.8684(16) 1.865(2)
2.1379(16) 2.105(2)
2.1140(16) 2.135(2)
2.3639(7) 2.3638(10) 2.366(2)
2.3509(7) 2.3738(10) 2.352(2)
2.104(6)
1.858(5)
2.105(5)
2.137(5)
2.069(3)
1.853(3)
2.164(3)
2.119(3)
2.3527(14) 2.3581(8)
2.3421(14) 2.3525(8)
2.107(2)
1.8813(19)
2.0931(19)
2.1203(19)
Bond Angles
O(1)-V-O(2) 176.79(6) 175.02(10) 175.5(2)
171.75(12) 174.99(8)
88.54(12) 90.02(8)
88.91(13) 89.18(8)
O(1)-V-O(3) 87.08(7)
O(1)-V-N(1) 89.58(7)
O(1)-V-Cl(1) 92.70(6)
O(1)-V-Cl(2) 87.73(5)
O(2)-V-O(3) 89.71(7)
O(2)-V-Cl(1) 87.21(5)
O(2)-V-Cl(2) 87.73(5)
O(3)-V-Cl(1) 90.23(5)
O(3)-V-Cl(2) 88.33(5)
N(1)-V-O(2) 93.63(7)
89.30(10) 89.9(2)
89.11(10) 89.7(2)
91.11(8)
93.94(8)
86.78(9)
85.98(7)
88.88(7)
92.21(7)
86.32(7)
93.15(16) 94.86(10) 90.82(7)
91.59(16) 94.56(10) 92.00(7)
85.97(19) 83.22(11) 85.00(8)
88.49(15) 85.66(8)
86.62(15) 85.23(8)
87.31(15) 91.99(9)
90.50(15) 89.70(9)
89.56(6)
87.62(6)
88.88(6)
90.96(6)
Figure 1. ORTEP drawing for complex 2b. Thermal ellipsoids are
drawn at the 30% probability level, and H atoms are omitted for
clarity.
94.85(10) 94.4(2)
99.34(12) 95.78(8)
177.41(13) 177.64(8)
N(1)-V-O(3) 174.62(7) 178.19(10) 179.5(2)
N(1)-V-Cl(1) 94.13(5)
N(1)-V-Cl(2) 87.59(5)
88.69(8)
92.92(8)
92.98(17) 87.81(10) 93.35(6)
89.25(17) 90.92(10) 86.84(6)
Cl(1)-V-Cl(2) 174.75(3) 174.72(4) 174.77(10) 170.47(5) 177.18(3)
Crystals suitable for crystallographic analysis were grown
from the THF-hexane mixture solution containing compounds
2a, 2b, 2g, 2i, and 2k, respectively, and their molecular
structures were further confirmed by X-ray crystallographic
analysis as the monomeric species. The molecular structure of
2b is shown in Figure 1, and those of 2a, 2g, 2i, and 2k are
shown in Figure S1-4 in the Supporting Information, respec-
tively. As shown in Figure 1, complex 2b has a six-coordinate
distorted octahedral geometry around the V metal center. The
two chlorine atoms are situated in the trans position, while the
two THF molecules are in cis position to each other, as seen in
the bond angles for Cl(1)-V-Cl(2) (174.7°) and O(2)-V-O(3)
(86.78°). These bond angles are somewhat analogous to those
for vanadium complex [PhNdC(CH3)CHC(CF3)O]VCl2(THF)2
[Cl(1)-V-Cl(2) (175.49°) and O(2)-V-O(3) (86.96°)], re-
ported previously.21 The V-Cl bond distances (2.3639, 2.3509
Å) are also close to values reported previously.8,9,21,27
Table 2. Selected Bond Distances (Å) and Angles (deg) for
Complexes 3b, 3c, 3e, 3j, and 3k
3b
3c
3e
3j
3k
Bond Distances
V-N(1)
V-N(2)
V-O(1)
V-O(2)
V-O(3)
V-Cl
2.122(3)
2.140(3)
1.897(2)
1.910(2)
2.146(2)
2.1290(18) 2.187(2)
2.1336(17) 2.166(3)
1.9038(14) 1.907(2)
1.9079(14) 1.897(2)
2.1366(13) 2.184(2)
2.117(6)
1.890(5)
2.150(2)
1.9289(17)
2.148(3)
2.2826(11)
2.3405(10) 2.3317(6) 2.3303(10) 2.261(4)
Bond Angles
O(1)-V-O(2) 171.53(10) 168.12(6) 93.30(10) 99.9(3)
163.88(11)
81.94(5)
89.00(8)
89.90(8)
O(1)-V-O(3) 87.59(10) 83.83(6)
O(1)-V-N(1) 88.49(10) 88.46(7)
O(1)-V-N(2) 91.29(10) 90.47(6)
81.66(9)
85.73(9)
94.84(9)
86.9(2)
95.8(2)
O(1)-V-Cl
94.06(8)
96.65(5)
84.30(6)
95.20(5)
167.58(8) 130.05(15) 98.06(5)
174.88(10)
97.56(8)
O(2)-V-O(3) 84.27(9)
O(2)-V-Cl
O(3)-V-Cl
94.14(7)
177.92(7) 178.65(5) 87.55(6)
180.0
The molecular structures of complexes 2a and 2g are similar to
that of complex 2b, but there are some differences among
complexes 2a, 2i, and 2k (Table 1). For example, the O(1)-V-O(2)
(171.75°), O(2)-V-O(3) (83.22°), and Cl(1)-V-Cl(2) (170.47°)
bond angles in complex 2i are smaller than those in 2a (176.79°,
89.71°, and 174.75°), and the V-N(1) (2.069 Å) and V-O(1)
(1.853 Å) bond distances in 2i are somewhat shorter than those in
2a (2.110 and 1.868 Å). In complex 2k, the Cl(1)-V-Cl(2)
(177.18°) bond angle is larger than that in complex 2a (174.75°),
while the V-O(1) (1.881 Å) bond distance is slightly longer than
that in complex 2a (1.868 Å). These differences result from the
steric and electronic effects of the substituents in the aryloxy group
(two tBu in 2i and two Br in 2k).
2. Synthesis and Characterization of Vanadium(III)
Complexes [RNdCH(ArO)]2VCl(THF)x. As shown in Scheme
1, reaction of VCl3(THF)3 with 2 equiv of salicyladimine ligands
1a-k in the presence of excess TEA in THF afforded
bis(salicyladiminato) complexes 3a-k in moderate yields (3a,
64%; 3b, 51%; 3c, 69%; 3d, 30%; 3e, 66%; 3f, 62%; 3g, 42%;
3h, 56%; 3i, 65%; 3j, 61%; 3k, 80%). The reaction products
were identified by mass spectra, FTIR, and elemental analysis.
Similar to the case of complexes 2, in the EI/MS spectra of
N(1)-V-O(2) 93.64(10) 91.46(6)
N(1)-V-O(3) 88.76(10) 86.63(6)
83.52(9)
96.95(9)
89.50(7)
86.06(6)
87.86(16) 93.94(6)
N(1)-V-Cl
90.01(8)
94.64(5)
N(1)-V-N(2) 177.91(11) 176.08(6) 171.63(10) 175.7(3)
172.13(11)
88.99(8)
N(2)-V-O(2) 86.88(10) 88.82(6)
N(2)-V-O(3) 93.30(10) 89.51(6)
88.11(10)
91.39(9)
91.54(7)
N(2)-V-Cl
87.94(8)
89.23(5)
complexes 3there were also no peaks of complexes 2 or 3:1 or
0:1 ligand-to-V(III) complexes. 1H NMR spectra indicated that
these complexes are also paramagnetic species, which is similar
to the case of complexes 2a-k.
Dark red crystals of complexes 3b, 3c, 3e, 3j, and 3k suitable
for X-ray crystallographic analysis were grown from the chilled
THF-hexane mixture solution, and their molecular structures were
further confirmed by X-ray crystallographic analysis. The selected
bond angles and distances of complexes 3b, 3c, 3e, 3j, and 3k are
summarized in Table 2. The molecular structures of 3b, 3e, and
3j are shown in Figures 2–4, respectively, and those of 3c and 3k
are shown in Figures S5 and S6 in the Supporting Information,
respectively. Similar to complexes 2a, 2b, 2g, 2i, and 2k, complexes
3b, 3c, 3e, and3k also have a six-coordinate distorted octahedral
geometry around the vanadium metal center.
As shown in Figures 2, S5, and S6, complexes 3b, 3c, and 3k
display similar molecular configurations. They all have a six-
coordinate distorted octahedral geometry around the V metal center,
in which the equatorial positions are occupied by oxygen and
(27) Gambarotta, S.; Mazzanti, M.; Floriani, C.; Chiesi-Villa, A.;
Guastini, C. Inorg. Chem. 1986, 25, 2308.
(28) The THF is liberated while heating in vacuo at 120 °C in the
amidinate vanadium(III) complexes (see ref 9).

Vanadium(III) Complexes Bearing Salicylaldiminato Ligands
Organometallics, Vol. 27, No. 15, 2008 3843
3k, 172.1°). The V-O and V-N bond distances in complex 3k
(1.929 and 2.150 Å) are slightly longer than those in complexes
3b (1.897/1.910 and 2.122/2.140 Å), 3c (1.904/1.908 and 2.129/
2.134 Å), and V(salophen)Cl(THF) (1.894/1.909 and 2.084/2.109
Å) reported by Gambarotta.27 A small but significant lengthening
of the V-O and V-N bond distances in vanadium complexes 3b
and 3k in contrast with those in their analogues 2b (1.865 and
2.116 Å) and 2k (1.881 and 2.107 Å) were observed because the
two coordinated ligands repulsed each other.
Compared with complex 3b, complex 3e displays different
geometry, in which the equatorial positions are occupied by two
oxygen atoms of the salicyladiminato ligand and an additional
oxygen atom of the THF molecule as well as chlorine atoms.
Two nitrogen atoms are coordinated on the axial position. The
DFT calculation indicates that in complex 3e the THF and Cl
prefer to exhibit a cis configuration (27.11 kJ/mol lower than
the corresponding trans configuration), although the trans
configuration of complex 3b showed relatively lower formation
energy (11.77 kJ/mol) than the cis configuration (see Table S1
in the Supporting Information). The V-N (2.187 and 2.166 Å)
and V-O3 (THF) (2.184 Å) bond distances in complex 3e are
longer than those in complexes 3b, 3c, and 3k.
Figure 2. ORTEP drawing for complex 3b. Thermal ellipsoids are
drawn at the 30% probability level, and H atoms are omitted for
clarity.
Interestingly, different from complexes 3b, 3c, 3e, and 3k,
complex 3j has a five-coordinate distorted trigonal-bipyramidal
geometry; no THF molecule is coordinated around the vanadium
metal center due to the steric effects of the ligands, which is
also established by mass spectra and elemental analysis. The
equatorial positions are occupied by two oxygen atoms and a
chlorine atom. The nitrogen atoms are coordinated on the axial
position. These results indicate that the steric effect of the ligand
significantly influenced the structure of the bis(salicylaldiminato)
vanadium complexes. Compared with complex 3e, although
additional obstacles were introduced in the aryloxy group in
complex 3j, the V-N bond distances (2.117 Å) in complex 3j
are somewhat shorter since there is no repulsion from the
coordinated THF. The V-Cl bond distances in 3j (2.261 Å)
and 3k (2.2826 Å) are shorter than those in 3b (2.3405 Å), 3c
(2.3317 Å), and 3e (2.3303 Å).
3. Ethylene Polymerization Screening Results. A great deal
of research has shown that cocatalysts play an important role
in vanadium catalysts. Halogen-containing alkylaluminium
compounds such as Et2AlCl, Et3Al2Cl3, EtAlCl2, and Me2AlCl
were effective cocatalysts for vanadium catalysts in ethylene
homo- and copolymerization.6b,7c,17a,d,e,21 Et2AlCl was proved
to be an efficient cocatalyst in the N,O chelate ꢀ-enaminoke-
tonato vanadium catalytic systems; thus we chose it as the
cocatalyst and optimized reaction conditions with complexes
2a and 3a. We found that the highest activities for ethylene
polymerization appeared when the Al/V (mol/mol) equals
3000-4000 (Figure 5). However, the molecular weights of the
polymer obtained gradually decreased with the increase of
Et2AlCl concentration. This indicates that chain transfer to
aluminum took place during the polymerization.
Figure 3. ORTEP drawing for complex 3e. Thermal ellipsoids are
drawn at the 30% probability level, and H atoms are omitted for
clarity.
Complexes 2a-k and 3a-k have been investigated as
effective catalysts for ethylene polymerization under atmospheric
pressure. As shown in Figures 6–9, ligand structure, complex
model, and reaction temperature considerably influence catalytic
activities and the molecular weights of the polymers obtained.
Figure 4. ORTEP drawing for complex 3j. Thermal ellipsoids are
drawn at the 30% probability level, and H atoms are omitted for
clarity.
Although the structures of complexes 2a-e are rather
different, they display comparable catalytic activities (17-22
× 103 kg PE/molV · h · bar) toward ethylene polymerization at
25 °C. On introducing one para-trifluoromethyl (electron-
withdrawing group) or para-methyl (donating group) into the
N-aryl moiety of the ligand, to form complex 2b or 2c, catalytic
nitrogen atoms of two chelating salicyladiminato ligands. The
chlorine atom is coordinated on the axial position, and the THF
occupies another axial position, as seen in the bond angles for
O(3)-V-Cl (around 179°), O(1)-V-O(2) (3b, 171.5°; 3c, 168.1°;
and 3k, 163.9°), and N(1)-V-N(2) (3b, 177.9°; 3c, 176.1°; and

3844 Organometallics, Vol. 27, No. 15, 2008
Wu et al.
Figure 7. Viscosity-average molecular weight of the polyethylenes
obtained by complexes 2a-k at different temperatures. Reaction
conditions: 0.5 µmol of vanadium complex, Cl3CCO2Et 0.15 mmol,
Et2AlCl 2 mmol, ethylene 1 bar, toluene 50 mL, polymerization
for 5 min.
Figure 5. Plot of catalytic activity of vanadium complexes and
viscosity-average molecular weight of the polymers obtained vs
Al/V (molar ratio). Reaction conditions: 0.5 µmol of vanadium
complex, Cl3CCO2Et 0.15 mmol, ethylene 1 bar, toluene 50 mL,
at 25 °C, polymerization for 5 min.
the aryloxy moiety of the ligand, complex 2k displayed the
lowest catalytic activity (9.12 × 103 kg PE/molV · h · bar) among
11 salicyladiminato vanadium complexes, and the molecular
weight of the polymers obtained under the same conditions are
comparable with those obtained by other complexes. It seems
that both electronic and steric effects play a role toward the
decrease of catalytic activity for ethylene polymerization with
the salicyladiminato vanadium complexes.
All bis(salicyladiminato) vanadium complexes are effective
catalyst precursors for ethylene polymerization, although they show
lower catalytic activities than the corresponding salicyladiminato
complexes at low reaction temperature (Figure 8). Different from
the case of complexes 2a-k, the structures of the ligand in 3a-k
greatly affect catalysis behavior of these bis(salicyladiminato)
vanadium complexes toward ethylene polymerization.
Figure 6. Catalytic activities of complexes 2a-k toward ethylene
polymerization at different temperatures. Reaction conditions: 0.5
µmol of vanadium complex, Cl3CCO2Et 0.15 mmol, Et2AlCl 2
mmol, ethylene 1 bar, toluene 50 mL, polymerization for 5 min.
Compared with complex 3a, complexes 3b and 3k, bearing
CF3-substituted and diBr-substituted salicyladiminato ligands,
respectively, exhibited higher catalytic activities, indicating that
electron-withdrawing effects can improve catalytic performance
of the bis(salicyladiminato) vanadium complexes, which is
different from the case of the corresponding salicyladiminato
vanadium complexes. It is noteworthy that the catalytic activities
of complexes 3d and 3e are much higher than that of complex
3a under the same conditions, which shows that the steric effects
of the N-moiety of the salicyladiminato ligands can improve
vanadium catalyst performance. Furthermore, the catalytic
activities of complexes 3g and 3i are also higher than that of
complex 3a, which shows that the steric effects of the aryloxy
moiety of the ligands also ameliorate vanadium catalyst
performance. However, complexes 3h and 3j display only
extremely low catalytic activities. The molecular structure of
3j (Figure 4) may shed some light on this result. The bulky
substituents on both the N-moiety and aryloxy moiety of the
salicyladiminato ligand, which have excluded the THF molecule
from the vanadium center, probably hinder the ethylene insertion
reaction. Interestingly, complex 2f, with nonconjugated cyclo-
hexyl on the N-moiety of the ligand, exhibited higher catalytic
activity than complex 2a at 50 and 70 °C.
activity did not increase but decreased about 10%, and on
introducing two ortho-isopropyls (bulky group) into the N-aryl
moiety of the ligand, to form complex 2e, catalytic activity
increased about 10%. It is noteworthy that the catalytic activities
of complexes 2b-e rapidly decrease with an increase in
temperature, but complex 2a displays quite high activity at 50
°C, which is comparable with that at room temperature.
Interestingly, with the introduction of a nonconjugated sub-
stituent cyclohexyl into the N-moiety of the ligand, complex
2f exhibited much lower catalytic activity (10.8 × 103 kg PE/
molV · h · bar) than 2a (22.3 × 103 kg PE/molV · h · bar) at 25
°C, but different from complexes 2a-e, complex 2f displayed
the highest catalytic activity toward ethylene polymerization at
70 °C. The molecular weights of the polymers obtained by
complexes 2a-f are comparable, and all decrease with an
increase of reaction temperature.
Compared with complexes 2a and 2e, the complexes 2g-j,
bearing bulky tert-butyl on the aryloxy moiety of the ligand,
showed much lower catalytic activities. This implies that the
steric effect of the aryloxy moiety of the ligand would suppress
a chain propagation reaction to some extent, which is different
from that of the N-aryl moiety of the ligand. In addition,
compared with complexes 2g and 2i, complexes 2h and 2j
produced higher molecular weight polymers under the same
conditions especially at high reaction temperature, indicating
that the steric effect of the N-moiety of the ligand can suppress
chain transfer reaction. On introducing two bromine atoms into
Although the molecular weights of the polymers obtained by
the bis(salicyladiminato) vanadium complexes at high reaction
temperature are also much lower than those obtained at low reaction
temperature (Figure 9), the bis(salicyladiminato) vanadium com-
plexes, except 3h and 3j, all display similar or even higher catalytic
activities at high reaction temperature than at low temperature,
which is completely different from the case of the corresponding
salicyladiminato complexes 2a-k. Moreover, with the increase of

Vanadium(III) Complexes Bearing Salicylaldiminato Ligands
Organometallics, Vol. 27, No. 15, 2008 3845
Figure 8. Catalytic activities of complexes 3a-k toward ethylene polymerization at different temperatures. Reaction conditions: 0.5 µmol
of vanadium complex, Cl3CCO2Et 0.15 mmol, Et2AlCl 2 mmol, ethylene 1 bar, toluene 50 mL, polymerization for 5 min.
on the substituents on the salicyladiminato. Screening of bis(sali-
cyladiminato) vanadium complexes found high activities were
available at high polymerization temperature by introducing an
electron-withdrawing group or alkyl substituents into the N-moiety
of the ligand. Narrow molecular weight distribution polymers were
produced by bis(salicyladiminato) vanadium complexes at high
polymerization temperature, indicating good thermal stability of
the catalysts. These results clearly indicate that the substituents on
both the N-moiety and aryloxy moiety directly affect the polym-
erization behavior of the vanadium complexes, although the exact
active species is still unknown to date.
Experimental Section
General Procedures and Materials. All manipulation of air- and/
Figure 9. Viscosity-average molecular weights of the polyethylenes
or moisture-sensitive compounds was carried out under a dry argon
atmosphere by using standard Schlenk techniques or under a dry argon
obtained by complexes 3a-k at different temperatures. Reaction
conditions: 0.5 µmol of vanadium complex, Cl3CCO2Et 0.15 mmol,
atmosphere in an MBraun glovebox unless otherwise noted. All
Et2AlCl 2 mmol, ethylene 1 bar, toluene 50 mL, polymerization
for 5 min.
1
solvents were purified from an MBraun SPS system. The H NMR
spectra of the vanadium complexes were obtained on a Bruker 300
MHz spectrometer at ambient temperature, with CD2Cl2 as the solvent.
The IR spectra were recorded on a Bio-Rad FTS-135 spectrophotom-
eter. Elemental analyses were recorded on an elemental Vario EL
spectrometer. Mass spectra were obtained using electron impact (EI-
MS) and LDI-1700 (Linear Scientific Inc.). The DSC measurements
were performed on a Perkin-Elmer Pyris 1 differential scanning
calorimeter at a rate of 10 °C/min. The weight-average molecular
weight (Mw) and the polydispersity index (PDI) of polymer samples
were determined at 150 °C by a PL-GPC 220 type high-temperature
chromatograph equipped with three Plgel 10 µm mixed-B LS type
columns. 1,2,4-Trichlorobenzene (TCB) was employed as the solvent
at a flow rate of 1.0 mL/min. The calibration was made by polystyrene
standard EasiCal PS-1 (PL Ltd.). The intrinsic viscosity of the polymer
sample was measured in decalin at 135 °C using an Ubbleohed
viscometer, and the average molecular weight was calculated using
the following equation.29
reaction temperature, the molecular weight distribution of the
polymers produced by the salicyladiminato complexes such as 2a
dramatically broaden (from 2.7 to 12.0, entries 1-3 in Table 3),
while those obtained by the bis(salicyladiminato) complexes such
as 3a only slightly broaden (from 1.9 to 2.6, rntries 9-11 in Table
3). In addition, the catalytic activities of the salicyladiminato
complexes such as 2a sharply decline with prolonged reaction time,
while those of the bis(salicyladiminato) complexes such as 3a only
slightly decrease, as shown in Figure 10. These results indicate
that two salicyladiminato ligands can stabilize active species and
maintain single-site catalytic behaviors of the vanadium catalyst
for ethylene polymerization.
Conclusions
Vanadium(III) complexes bearing one or two salicyladiminato
ligands can be synthesized by controlling the molar ratio of
VCl3(THF)3 and ligand. Molecular structures show that the
substituents on the salicyladiminato have a slight effect on the
configuration of the monosalicyladiminato vanadium complexes,
while the steric obstacles influence the configuration of the
bis(salicyladiminato) vanadium complexes, which has been also
established by DFT calculations. In the presence of Et2AlCl,
salicyladiminato vanadium complexes were highly active catalysts
for ethylene polymerization at 25 °C, and with increasing the
polymerization temperature the catalytic behavior varied depending
0.7
[η] ) 6.2 × 10-4 Mv
(1)
Ethyl trichloroacetate (ETA) was purchased from Aldrich, dried
over calcium hydride at room temperature, and then distilled.
Diethylaluminium chloride (DEAC) was obtained from Albemarle
Corporation. VCl3(THF)3, phenol compounds, and amine com-
pounds were purchased from Aldrich. Literature procedures were
used to synthesize salicylaldiminato ligands.24a
(29) Chiang, R. J. Polym. Sci. 1957, 28, 235.

3846 Organometallics, Vol. 27, No. 15, 2008
Wu et al.
Table 3. Typical Results of Ethylene Polymerization by Complexes [RNdCH(ArO)]VCl2(THF)2 and [RNdCH(ArO)]2VCl(THF)x as well as
a
VCl3(THF)3
c
entry
complex
2a
2a
2a
2b
2e
2f
2g
2k
3a
3a
3a
3b
3b
3e
3f
time (min)
temperature (°C)
polymer(g)
activityb
Mwc( × 104)
Mw/Mn
1
2
3
4
5
6
7
8
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
25
50
70
50
50
50
50
50
25
50
70
50
70
50
50
25
50
70
0.93
0.88
0.53
0.61
0.61
0.50
0.74
0.38
0.35
0.43
0.41
0.70
0.76
0.59
0.80
0.85
0.78
0.40
22.3
21.1
12.7
14.6
14.6
12.0
17.8
9.12
8.40
10.3
9.84
16.8
18.2
14.2
19.2
20.4
18.7
9.60
13.8
5.7
3.8
4.7
7.3
5.4
5.4
5.8
17.1
6.1
1.5
5.7
3.2
7.0
3.9
24.6
15.5
2.7
3.8
12.0
3.7
3.5
3.2
3.4
4.0
1.9
2.2
2.6
2.8
3.0
2.4
2.8
2.6
5.3
9
10
11
12
14
15
16
17
18
19
VCl3(THF)3
VCl3(THF)3
VCl3(THF)3
a Reaction conditions: 1 bar of ethylene pressure, 0.5 µmol of vanadium complex, Cl3CCO2Et/V (molar ratio) ) 300, Al/V (molar ratio) ) 4000,
toluene 50 mL. b kg of PE/mmolV · h · bar. c Weight-average molecular weight and polydispersity index of the resultant polyethylene determined by
high-temperature GPC using polystyrene standard.
637, 611, 585, 549, 527, 496, 472, 445 cm-1. EI-MS (70 eV): m/z
527 [M+]. Anal. Calcd for C22H23F3Cl2NO3V: C, 50.02; H, 4.39;
N, 2.65. Found: C, 50.29; H, 4.44, N, 2.58.
[p-MeC6H4NdCH(C6H4O)]VCl2(THF)2 (2c). Yield: 60%. Mp:
161-163 °C. IR (KBr pellets): ν 3056, 2983, 2956, 2885, 1610,
1599, 1589, 1543, 1507, 1469, 1436, 1387, 1342, 1333, 1294, 1255,
1231,1212, 1189, 1179, 1148, 1123, 1020, 979, 953, 928, 863, 834,
806, 758, 715, 680, 639, 625, 588, 532, 504, 495, 469, 425 cm-1
.
EI-MS (70 eV): m/z 473 [M+]. Anal. Calcd for C22H26Cl2NO3V:
C, 55.71; H, 5.53; N, 2.95. Found: C, 55.79; H, 5.60, N, 2.91.
[2,6-Me2C6H3NdCH(C6H4O)]VCl2(THF)2 (2d). Yield: 63%.
Mp: 155-158 °C. IR (KBr pellets): ν 2975, 2903, 1604, 1585,
1468, 1458, 1436, 1385, 1338, 1298, 1252, 1212, 1173, 1150, 1126,
1095, 1030, 1011, 984, 928, 879, 856, 811, 766, 737, 709, 671,
637, 613, 568, 522, 513, 458, 425 cm-1. EI-MS (70 eV): m/z 487
[M+]. Anal. Calcd for C23H28Cl2NO3V: C, 56.57; H, 5.78; N, 2.87.
Found: C, 55.20; H, 5.91, N, 2.79.
[2,6-iPr2C6H3NdCH(C6H4O)]VCl2(THF)2 (2e). Yield: 76%.
Mp: 157-160 °C. IR (KBr pellets): ν 3049, 3016, 2964, 2927,
2869, 1604, 1584, 1542, 1465, 1442, 1385, 1373, 1359, 1339, 1390,
1330, 1290, 1249, 1210, 1169, 1151, 1126, 1111, 1093, 1058, 1044,
1029, 1014, 991, 941, 929, 911, 894, 854, 796, 762, 757, 701, 674,
617, 550, 533, 525, 460 cm-1. EI-MS (70 eV): m/z 543 [M+].
Anal. Calcd for C27H36Cl2NO3V: C, 59.57; H, 6.66; N, 2.57. Found:
C, 60.10; H, 6.72, N, 2.53.
[C6H11NdCH(C6H4O)]VCl2(THF)2 (2f). Yield: 69%. Mp:
147-148 °C. IR (KBr pellets): ν 3046, 2927, 2853, 1611, 1546,
1471, 1447, 1414, 1357, 1338, 1322, 1291, 1270, 1245, 1208, 1146,
1121, 1076, 1061, 1043, 1022, 995, 969, 916, 872, 844, 820, 772,
740, 688, 631, 584, 544, 504, 490, 455, 426 cm-1. EI-MS (70 eV):
m/z 465 [M+]. Anal. Calcd for C21H30Cl2NO3V: C, 54.09; H, 6.48;
N, 3.00. Found: C, 54.15; H, 6.53, N, 2.96.
[C6H5NdCH(OC6H3tBu-2)]VCl2(THF)2 (2g). Yield: 71%. Mp:
177-179 °C. IR (KBr pellets): ν 3064, 2966, 2896, 1603, 1588,
1549, 1489, 1451, 1421, 1388, 1314, 1286, 1265, 1185, 1146, 1090,
1027, 1016, 975, 921, 874, 854, 766, 750, 705, 692, 653, 561, 470,
408 cm-1. EI-MS (70 eV): m/z 515 [M+]. Anal. Calcd for
C25H32Cl2NO3V: C, 58.15; H, 6.25; N, 2.71. Found: C, 58.30; H,
6.27, N, 2.75.
Figure 10. Lifetime plot of ethylene polymerization for complexes
2a (O) and 3a ([) at 50 °C. Reaction conditions: 0.1 µmol of
vanadium complex, Cl3CCO2Et 0.03 mmol, Et2AlCl 0.4 mmol,
ethylene 1 bar, toluene 50 mL.
Synthesis of Vanadium Complexes. [C6H5NdCH(C6H4O)]-
VCl2(THF)2 (2a). To a stirred solution of VCl3(THF)3 (0.75 g, 2.0
mmol) in dried tetrahydrofuran (20 mL) was added slowly a solution
of 2-(PhNCH)C6H4OH (0.40 g, 2.0 mmol) in tetrahydrofuran (20
mL). The red reaction mixture was stirred for 10 min, and Et3N
(0.3 mL, 216 mg, 2.1 mmol) was added. After stirring for 4 h at
room temperature the solution was concentrated to about 10 mL,
and then the mixture was filtered to remove NH4Cl. Crystallization
by diffusion of n-hexane (20 mL) into the clear solution yielded
red-black crystals of 2a (0.65 g, 70%). Compound 2b-k were
prepared analogously. Mp: 148-150 °C. IR (KBr pellets): ν 3058,
2979, 2895, 1607, 1586, 1544, 1487, 1452, 1441, 1384, 1320, 1295,
1286, 1255, 1227, 1186, 1177, 1150, 1080, 1024, 975, 939, 918,
876, 850, 801, 764, 752, 702, 637, 590, 544, 531, 493, 463, 404
cm-1
.
EI-MS (70 eV): m/z 459 [M+]. Anal. Calcd for
C21H24Cl2NO3V: C, 54.80; H, 5.26; N, 3.04. Found: C, 54.65; H,
5.16, N, 3.09.
[p-CF3C6H4NdCH(C6H4)]VCl2(THF)2 (2b). Yield: 70%. Mp:
165-167 °C. IR (KBr pellets): ν 3060, 2966, 2897, 1602, 1588,
1545, 1510, 1470, 1440, 1417, 1389, 1378, 1325, 1299, 1251, 1227,
1179, 1151, 1109, 1068, 1015, 987, 930, 867, 841, 807, 763, 672,
[2,6-iPr2C6H3NdCH(OC6H3tBu-2)]VCl2(THF)2 (2h). Yield:
53%. Mp: 140-141 °C. IR (KBr pellets): ν 3063, 2959, 2869, 1599,
1588, 1544, 1464, 1438, 1416, 1382, 1362, 1289, 1265, 1197, 1166,
1147, 1088, 1002, 932, 877, 855, 800, 754, 680, 567, 540, 515,

Vanadium(III) Complexes Bearing Salicylaldiminato Ligands
Organometallics, Vol. 27, No. 15, 2008 3847
476 cm-1. EI-MS (70 eV): m/z 599 [M+]. Anal. Calcd for
C31H44Cl2NO3V: C, 62.00; H, 7.38; N, 2.33. Found: C, 61.92; H,
7.33, N, 2.35.
[C6H5NdCH(OC6H2tBu2-2,4)]VCl2(THF)2 (2i). Yield: 76%.
Mp: 201-202 °C. IR (KBr pellets): ν 3054, 2947, 2901, 1608,
1591, 1542, 1488, 1460, 1432, 1388, 1358, 1300, 1273, 1253, 1192,
1173, 1135, 1024, 970, 927, 871, 843, 773, 752, 705, 694, 645,
568, 545, 518, 488, 417 cm-1. EI-MS (70 eV): m/z 541 [M+].
Anal. Calcd for C29H40Cl2NO3V: C, 60.84; H, 7.04; N, 2.45. Found:
C, 60.75; H, 6.49, N, 2.47.
[2,6-iPr2C6H3NdCH(OC6H2tBu2-2,4)]VCl2(THF)2 (2j). Yield:
64%. Mp: 156-158 °C. IR (KBr pellets): ν 3063, 2960, 2869, 1606,
1583, 1538, 1463, 1430, 1383, 1362, 1272, 1251, 1201, 1167, 1097,
1014, 932, 864, 843, 800, 764, 636, 572, 545, 462 cm-1. EI-MS
(70 eV): m/z 655 [M+]. Anal. Calcd for C35H52Cl2NO3V: C, 64.02;
H, 7.98; N, 2.13. Found: C, 64.12; H, 7.89, N, 3.01.
4032, 1022, 955, 926, 867, 854, 812, 793, 758, 702, 649, 629, 613,
532, 516, 457 cm-1. EI-MS (70 eV): m/z 718 [M+]. Anal. Calcd
for C42H52ClN2O3V: C, 70.13; H, 7.29; N, 3.89. Found: C, 70.59;
H, 7.22, N, 3.96.
[C6H11NdCH(C6H4O)]2VCl(THF) (3f). Yield: 62%. Mp:
159-160 °C. IR (KBr pellets): ν 3050, 2921, 2850, 1618, 1598,
1554, 1518, 1473, 1447, 1414, 1357, 1319, 1287, 1264, 1252, 1216,
1207, 1150, 1123, 1074, 1050, 1033, 994, 967, 943, 914, 890, 857,
852, 843, 823, 791, 756, 737, 691, 650, 639, 582, 545, 497, 457,
427 cm-1. EI-MS (70 eV): m/z 562 [M+]. Anal. Calcd for
C30H40ClN2O3V: C, 64.00; H, 716; N, 4.98. Found: C, 64.20; H,
7.02, N, 4.99.
[C6H5NdCH(OC6H3tBu-2)]2VCl(THF) (3g). Yield: 42%. Mp:
191-193 °C. IR (KBr pellets): ν 3065, 2948, 2904, 2868, 1601,
1590, 1544, 1485, 1461, 1451, 1419, 1383, 1355, 1332, 1321, 1297,
1265, 1243, 1183, 1144, 1088, 1029, 979, 911, 874, 854, 809, 770,
763, 751, 701, 687, 646, 621, 614, 605, 548, 462, 404 cm-1. EI-
MS (70 eV): m/z 662 [M+]. Anal. Calcd for C38H44ClN2O3V: C,
68.82; H, 6.69; N, 4.22. Found: C, 68.95; H, 6.57, N, 4.16.
[2,6-iPr2C6H3NdCH(OC6H3tBu-2)]2VCl (3h). Yield: 56%. Mp:
161-164 °C. IR (KBr pellets): ν 3062, 2960, 2868, 1602, 1589,
1546, 1465, 1440, 1410, 1382, 1362, 1317, 1261, 1225, 1197, 1168,
1147, 1094, 1058, 1031, 975, 934, 873, 849, 799, 763, 752, 677,
631, 566, 539, 515, 476 cm-1. EI-MS (70 eV): m/z 758 [M+].
Anal. Calcd for C46H60ClN2O2V: C, 72.76; H, 7.96; N, 3.69. Found:
C, 72.85; H, 8.04, N, 3.66.
[C6H5NdCH(OC6H2tBu2-2,4)]2VCl(THF) (3i). Yield: 65%.
Mp: 217-219 °C. IR (KBr pellets): ν 3057, 2960, 2903, 2867,
1608, 1585, 1548, 1533, 1487, 1460, 1431, 1384, 1361, 1317, 1303,
1273, 1255, 1192, 1169, 1138, 1079, 1026, 998, 978, 920, 905,
866, 835, 810, 784, 764, 745, 707, 695, 637, 557, 542, 531, 495,
474 cm-1. EI-MS (70 eV): m/z 774 [M+]. Anal. Calcd for
C46H60ClN2O3V: C, 71.25; H, 7.80; N, 3.61. Found: C, 71.18; H,
7.83, N, 3.63.
[2,6-iPr2C6H3NdCH(OC6H2tBu2-2,4)]2VCl (3j). Yield: 61%.
Mp: 174-175 °C. IR (KBr pellets): ν 3060, 2962, 2869, 1609,
1586, 1540, 1465, 1427, 1381, 1362, 1327, 1270, 1248, 1201, 1167,
1137, 1098, 1057, 1042, 979, 933, 872, 833, 799, 762, 635, 567,
546, 472 cm-1. EI-MS (70 eV): m/z 870 [M+]. Anal. Calcd for
C54H76ClN2O2V: C, 74.41; H, 8.79; N, 3.21. Found: C, 74.29; H,
8.81, N, 3.19.
[C6H5NdCH(OC6H2Br2-2,4)]2VCl(THF) (3k). Yield: 80%.
Mp: 180-182 °C. IR (KBr pellets): ν 3049, 2953, 2870, 1601,
1585, 1515, 1486, 1438, 1400, 1377, 1297, 1224, 1190, 1165, 1065,
1026, 863, 847, 765, 747, 717, 696, 626, 607, 546, 533, 519, 505,
438 cm-1. EI-MS (70 eV): m/z 861 [M+]. Anal. Calcd for
C30H24Br4ClN2O3V: C, 41.58; H, 2.79; N, 3.23. Found: C, 41.30;
H, 2.75, N, 3.22.
Ethylene Polymerization. Polymerization was carried out under
atmospheric pressure in toluene in a 150 mL glass reactor equipped
with a mechanical stirrer. Toluene (50 mL) was introduced into
the nitrogen-purged reactor and stirred vigorously (600 rpm). The
toluene was kept at a prescribed polymerization temperature, and
then ethylene gas feed was started. After 15 min, a solution of
Et2AlCl in toluene and a solution of ETA in toluene were added
and stirred for 5 min. Then a toluene solution of the vanadium
complexes was added into the reactor with vigorous stirring (900
rpm) to initiate polymerization. After a prescribed time, acidic
alcohol (10 mL) was added to terminate the polymerization reaction,
and the ethylene gas feed was stopped. The resulting mixture was
added to acidic alcohol. The solid polyethylene was isolated by
filtration, washed with alcohol, and dried at 60 °C for 24 h in a
vacuum oven.
[C6H5NdCH(OC6H2Br2-2,4)]VCl2(THF)2 (2k). Yield: 62%.
Mp: 168-169 °C. IR (KBr pellets): ν 3062, 2977, 2897, 1601,
1585, 1516, 1486, 1432, 1401, 1377, 1298, 1224, 1193, 1166, 1077,
1024, 1011, 973, 920, 848, 770, 745, 723, 703, 630, 544, 519, 438
cm-1
.
EI-MS (70 eV): m/z 614 [M+]. Anal. Calcd for
C21H22Cl2NO3V: C, 40.81; H, 3.59; N, 2.27. Found: C, 40.71; H,
3.64, N, 2.32.
[C6H5NdCH(C6H4O)]2VCl(THF) (3a). To a stirred solution of
VCl3(THF)3 (0.36 g, 1.0 mmol) in dried tetrahydrofuran (20 mL)
was added slowly a solution of 2-(PhNCH)C6H4OH (0.40 g, 2.0
mmol) in tetrahydrofuran (20 mL). The red reaction mixture was
stirred for 20 min, and Et3N (0.3 mL, 216 mg, 2.1 mmol) was added.
After stirring overnight at room temperature the solution was
concentrated to about 10 mL and then the mixture was filtered to
remove NH4Cl. Crystallization by diffusion of n-hexane (20 mL)
into the clear solution and chilling the solution (-40 °C) yielded
352 mg of 3a (64%) as red-brown crystals. Compounds 3b-k were
prepared analogously. Mp: 170-172 °C. IR (KBr pellets): ν 3050,
2972, 2898, 1949, 1605, 1589, 1542, 1487, 1470, 1443, 1386, 1336,
1303, 1254, 1227, 1184, 1148, 1122, 1077, 1027, 977, 934, 906,
871, 854, 803, 760, 698, 657, 629, 585, 545, 521, 496, 464 cm-1
.
EI-MS (70 eV): m/z 549 [M+]. Anal. Calcd for C30H28ClN2O3V:
C, 65.40; H, 5.12; N, 5.08. Found: C, 64.89; H, 4.97, N, 5.14.
[p-CF3C6H4NdCH(C6H4O)]2VCl(THF) (3b). Yield: 51%. Mp:
219-220 °C. IR (KBr pellets): ν 3047, 2979, 2902, 1602, 1589,
1544, 1510, 1469, 1442, 1416, 1396, 1378, 1326, 1297, 1257, 1229,
1189, 1177, 1162, 1153, 1147, 1122, 1107, 1067, 1028, 1016, 988,
927, 864, 847, 841, 822, 808, 761, 744, 672, 628, 610, 582, 568,
547, 500, 462, 446 cm-1. EI-MS (70 eV): m/z 686 [M+]. Anal.
Calcd for C32H26ClF6N2O3V: C, 55.95; H, 3.81; N, 4.08. Found:
C, 56.25; H, 3.71, N, 4.01.
[p-MeC6H4NdCH(C6H4O)]2VCl(THF) (3c). Yield: 69%. Mp:
203-205 °C. IR (KBr pellets): ν 3043, 3021, 2977, 2917, 1611,
1598, 1587, 1543, 1505, 1468, 1441, 1391, 1377, 1333, 1296, 1251,
1223, 1185, 1175, 1146, 1122, 1111, 1065, 1031, 1019, 980, 925,
881, 862, 830, 800, 756, 740, 713, 634, 618, 586, 525, 502, 457,
427, 414 cm-1. EI-MS (70 eV): m/z 578 [M+]. Anal. Calcd for
C32H32ClN2O3V: C, 66.38; H, 5.57; N, 4.84. Found: C, 66.68; H,
5.48, N, 4.81.
[2,6-Me2C6H3NdCH(C6H4O)]2VCl(THF) (3d). Yield: 30%.
Mp: 188-189 °C. IR (KBr pellets): ν 2948, 2903, 1611, 1604,
1585, 1542, 1466, 1442, 1390,1383, 1350, 1341, 1318, 1302, 1241,
1221, 1208, 1169, 1149, 1125, 1093, 1059, 1033, 1010, 985, 942,
927, 854, 843, 812, 777, 762, 751, 737, 708, 674, 632, 624, 605,
520, 510, 500, 457, 423 cm-1. EI-MS (70 eV): m/z 606 [M+].
Anal. Calcd for C34H36ClN2O3V: C, 67.27; H, 5.98; N, 4.61. Found:
C, 67.55; H, 5.87, N, 4.60.
[2,6-iPr2C6H3NdCH(C6H4O)]2VCl(THF) (3e). Yield: 66%.
Mp: 212-214 °C. IR (KBr pellets): ν 3060, 2954, 2923, 2863,
1607, 1544, 1470, 1438, 1391, 1382, 1361, 1348, 1339, 1332, 1311,
1297, 1251, 1210, 1168, 1152, 1148, 1124, 1107, 1094, 1058, 1043,
Crystallographic Studies. Crystals for X-ray analysis were
obtained as described in the preparations. The crystallographic data,
collection parameters, and refinement parameters are listed in Tables
4 and 5. The crystals were manipulated in a glovebox. The intensity

3848 Organometallics, Vol. 27, No. 15, 2008
Wu et al.
Table 4. Crystal Data and Structure Refinements of Complexes 2a, 2b, 2g, 2i, and 2k
2a
2b
2g
2i
2k
formula
fw
C21H26Cl2NO3V
462.27
C22H25Cl2F3NO3V
530.27
C25H34Cl2NO3V
518.37
C29H42Cl2NO3V
574.48
C21H24Br2Cl2NO3V
620.07
cryst syst
space group
a (Å)
b (Å)
c (Å)
triclinic
P1
triclinic
P1
monoclinic
P21/c
7.5894(8)
13.7589(14)
24.542(3)
90.00
96.350(2)
90.00
2547.0(5)
4
monoclinic
P2(1)/c
10.7986(13)
21.683(3)
12.8415(15)
90.00
91.601(2)
90.00
3005.6(6)
4
triclinic
P1
j
j
j
7.4606(6)
11.4975(9)
13.9387(11)
109.7700(10)
90.0490(10)
107.6790(10)
1064.85(15)
2
7.6147(9)
12.0671(14)
13.7396(16)
67.631(2)
85.279(2)
86.104(2)
1162.6(2)
2
7.7892(7)
11.9960(11)
13.9022(13)
106.9170(10)
92.6990(10)
103.1800(10)
1201.06(19)
2
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
Dcalcd (Mg/m3)
absorp coeff (mm-1
F(000)
1.442
0.738
480
1.515
0.705
544
1.352
0.625
1088
1.270
0.537
1216
1.715
3.985
616
)
cryst size (mm)
θ range (deg)
no. of reflns collected
no. of indep reflns
no. of data/restraints/params
GOF on F2
0.31 × 0.20 × 0.08
1.56 to 26.02
5863
4078 (Rint ) 0.0128)
4078/0/253
1.040
0.15 × 0.10 × 0.10
1.61 to 25.99
6542
4440 (Rint ) 0.0190)
4440/0/289
1.059
0.22 × 0.12 × 0.03
1.67 to 26.04
14 127
5022 (Rint ) 0.1164)
5022/0/132
0.921
0.25 × 0.09 × 0.04
2.46 to 19.22
15 534
5294 (Rint ) 0.0989)
5294/0/331
0.988
0.46 × 0.26 × 0.16
2.71 to 26.04
6744
4623 (Rint ) 0.0124)
4623/0/271
1.058
R1
0.0398
0.0689
0.1686
0.0649
0.0406
wR2
0.0998
0.1262
0.1016
0.1057
0.0895
Table 5. Crystal Data and Structure Refinements of Complexes 3b, 3c, 3e, 3j, and 3k
3b
3c
3e
3j
3k · 2THF
formula
fw
C32H26ClF6N2O3V
686.94
C32H32ClN2O3V
578.99
C42H52ClN2O3V
719.25
C54H76ClN2O2V
871.59
C38H40Br4ClN2O5V
1010.75
cryst syst
space group
a (Å)
b (Å)
c (Å)
monoclinic
C2/c
26.2027(16)
14.5250(9)
27.0211(17)
90
117.5080(10)
90
9121.4(10)
12
monoclinic
P21/n
12.3342(7)
13.3442(7)
17.9276(10)
90
103.0480(10)
90
2874.5(3)
4
monoclinic
P21/n
11.6439(8)
22.3741(16)
14.8894(11)
90
93.753(2)
90
3870.7(5)
4
monoclinic
C2/c
17.673(3)
27.429(5)
11.8280(19)
90.00
93.019(4)
90.00
5725.8(17)
4
monoclinic
C2/c
23.1831(18)
10.0939(8)
16.7657(13)
90.00
101.7550(10)
90.00
3841.0(5)
4
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
Z
Dcalcd (Mg/m3)
1.501
0.488
4200
1.338
0.473
1208
1.234
0.365
1528
1.094
0.261
2036
1.748
4.534
2008
absorp coeff (mm-1
F(000)
)
cryst size (mm)
θ range (deg)
no. of reflns collected
no. of indep reflns
no. of data/restraints/params
GOF on F2
0.26 × 0.19 × 0.05
1.65 to 25.55
24 215
8529 (Rint ) 0.0498)
8529/0/610
1.009
0.34 × 0.24 × 0.15
1.83 to 25.53
15 120
5331 (Rint ) 0.0201)
5331/0/354
1.101
0.15 × 0.14 × 0.06
1.65 to 25.35
20 510
7073 (Rint ) 0.0717)
7073/0/450
0.990
0.65 × 0.16 × 0.06
2.16 to 17.70
15 902
5650 (Rint ) 0.1547)
5650/0/132
0.995
0.38 × 0.19 × 0.10
1.79 to 26.04
10 555
3809 (Rint ) 0.0242)
5650/0/232
1.033
R1
0.0556
0.0426
0.0584
0.1185
0.0374
wR2
0.1274
0.1330
0.1185
0.3157
0.0754
data were collected with the ω scan mode (186 K) on a Bruker
Smart APEX diffractometer with CCD detector using Mo KR
radiation (λ ) 0.71073Å). Lorentz, polarization factors were made
for the intensity data, and absorption corrections were performed
using the SADABS program. The crystal structures were solved
using the SHELXTL program and refined using full matrix least-
squares. The positions of hydrogen atoms were calculated theoreti-
cally and included in the final cycles of refinement in a riding model
along with attached carbons.
DFT Calculations. All the DFT results were obtained from
calculations based on the Becke-Perdew exchange-correlation
functional, using the Amsterdam Density Functional (ADF)
program.30,31 The standard double-ꢁ STO basis sets with one set
of polarization functions were applied for H, C, N, O, and Cl atoms,
while the standard triple-ꢁ basis sets were employed for the V atom.
The calculations of singlet vanadium species were performed in a
spin-restricted fashion.32 All reported results were calculated in the
gas phase.
Acknowledgment. The authors are grateful for a subsidy
provided by the National Natural Science Foundation of
China (Nos. 20734002 and 50525312) and by the Special
Funds for Major State Basis Research Projects (No.
2005CB623800) from the Ministry of Science and Technol-
ogy of China.
Supporting Information Available: ORTEP drawings for
complexes 2a, 2g, 2i, 2k, 3c, and 3k. X-ray diffraction data for
2a, 2b, 2g, 2i, 2k, 3b, 3c, 3e, 3j, and 3k (as CIF). Cartesian
coordinates and energies of all stationary points discussed in the
text. This material is available free of charge via the Internet at
http://pubs.acs.org.
(30) (a) Baerends, E. J.; Ellis, D. E.; Ros, P. Chem. Phys. 1973, 2, 41.
(b) Baerends, E. J.; Ros, P. Chem. Phys. 1973, 2, 52.
(31) te Velde, G.; Baerends, E. J. J. Comput. Chem. 1992, 99, 84.
(32) Deng, L. Q.; Schmid, R.; Ziegler, T. Organometallics 2000, 19,
3069, and references therein.
OM800097B