Steric isomerization of alkyne-dialkyltungsten complexes with a chelating diaryloxo ligand: Crystal structures of Cs- and (CH2SiMe3)2

Article abstract of DOI:10.1016/S0022-328X(02)02016-8

Dichlorotungsten complexes, W(η²-EtC≡CEt) (Me₂tbp)Cl₂ (Me₂tbp = 2,2′-thiobis(4,6-dimethylphenoxo)) and W(η²-EtC≡CEt) (^tBu₂ tbp)Cl₂ (^tBu2tbp = 2,2′-thiobis(4-methyl-6-tert-butylphenoxo)) were reacted with Mg(CH₂SiMe₃)₂ to give the corresponding C_s -dialkyl complexes, C_s-W (η²-EtC≡CEt)(Me₂tbp)(CH ₂SiMe₃)₂(1-C_s) and C_s-W(η²-EtC≡CEt)(^t Bu₂tbp)(CH₂SiMe₃)₂ (2-C_s ). These C_s symmetric dialkyltungsten complexes 1-C_s and 2-C_s were found to undergo steric isomerization to C₁ symmetric isomers, 1-C₁ and 2-C₁, at 30 °C. The thermodynamic parameters for isomerization from 1-C_s to 1-C₁ were estimated. The structures of both the C_s - and C₁-isomers of 1 were determined by X-ray crystallography, indicating that the alkyne ligands in the C_s symmetric complexes could be regarded as four-electron donor ligands and that those in the C₁ symmetric complexes are donating two electrons. The C₁ symmetric dialkyltungsten complexes were heated to 30-60 °C to generate alkylidene species. The substituent effects of the ligands on the catalytic behavior for the ring-opening metathesis polymerization of norbornene derivatives were studied. cis-Contents of the poly(norbornene)s were controlled by the steric effect of alkyne and aryloxo ligands in these dialkyl complexes. The polymerization of 7-methylnorbornene catalyzed by 2, W(η ²-PhC≡CPh)(^tBu₂tbp) (CH₂Ph)₂(3-C₁) and Mo(η ²-PhC≡CPh)(^tBu₂tbp)Cl ₂ (5)-Mg(CH₂SiMe₃)₂ gave the polymers with a cis -atactic structure.

Full text of DOI:10.1016/S0022-328X(02)02016-8

Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
www.elsevier.com/locate/jorganchem
Steric isomerization of alkyneꢀ
chelating diaryloxo ligand: crystal structures of Cs- and C1-W(h2-
CR)[2,2?-S(4-Me-6-R?C6H2O)2](CH2SiMe3)2
/
dialkyltungsten complexes with a
RCÅ
/
Yoshinori Takashima a, Yuushou Nakayama b, Hajime Yasuda b, Akira Nakamura c,
Akira Harada a,ꢁ
a Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyamachou Toyonaka, Osaka 560-0043, Japan
b Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
c OM Research, 7-2-1308, Minami-ohgimachi, Kita-ku, Osaka 530-0052, Japan
Received 23 July 2002; received in revised form 31 August 2002; accepted 3 October 2002
Abstract
Dichlorotungsten complexes, W(h2-EtCÅ
CEt)(tBu2tbp)Cl2 (t Bu2tbpꢂ
2,2?-thiobis(4-methyl-6-tert-butylphenoxo)) were reacted with Mg(CH2SiMe3)2 to give the corre-
sponding Cs-dialkyl complexes, Cs-W(h2-EtCÅCEt)(Me2tbp)(CH2SiMe3)2 (1-Cs) and Cs -W(h2-EtCÅCEt)(tBu2tbp)(CH2SiMe3)2
/
CEt)(Me2tbp)Cl2 (Me2tbpꢂ
/
2,2?-thiobis(4,6-dimethylphenoxo)) and W(h2-EtCÅ
/
/
/
/
(2-Cs ). These Cs symmetric dialkyltungsten complexes 1-Cs and 2-Cs were found to undergo steric isomerization to C1 symmetric
isomers, 1-C1 and 2-C1, at 30 8C. The thermodynamic parameters for isomerization from 1-Cs to 1-C1 were estimated. The
structures of both the Cs- and C1-isomers of 1 were determined by X-ray crystallography, indicating that the alkyne ligands in the Cs
symmetric complexes could be regarded as four-electron donor ligands and that those in the C1 symmetric complexes are donating
two electrons. The C1 symmetric dialkyltungsten complexes were heated to 30ꢀ60 8C to generate alkylidene species. The substituent
/
effects of the ligands on the catalytic behavior for the ring-opening metathesis polymerization of norbornene derivatives were
studied. cis-Contents of the poly(norbornene)s were controlled by the steric effect of alkyne and aryloxo ligands in these dialkyl
complexes. The polymerization of 7-methylnorbornene catalyzed by 2, W(h2-PhCÅCPh)(t Bu2tbp)(CH2Ph)2 (3-C1) and Mo(h2-
/
PhCÅ
/
CPh)(tBu2tbp)Cl2 (5)ꢀ
Mg(CH2SiMe3)2 gave the polymers with a cis-atactic structure.
/
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Steric isomerization; Alkyne/dialkyltungsten complexes; Crystal structures; Ring-opening metathesis polymerization
1. Introduction
CH2O)4CH2CH2PPh2-P,P?}, isomerizes in solution to
yield its trans isomer, after photolysis of the THF
solution of the cis isomer under a nitrogen atmosphere
[5]. Complexes, mer-{MeN(C2H4PPh2)2}M(CO)3 (M:
Mo, W), are thermodynamically unstable and isomerize
to the fac isomers when they are refluxed in 1,2-
dichloroethane or when a trace of acid is present in
their solutions [6]. However, to the best of our knowl-
edge, structurally characterized pairs of the isomers
having the same composition have not been reported in
these studies.
Isomerization of complexes around the metal center is
one of the fundamental elements in coordination
chemistry and essential for understanding the mechan-
isms of metal-catalyzed or mediated reactions. Several
isomerization reactions of octahedral molybdenum and
tungsten complexes have been reported, for example, the
rotational isomerization of the complexes having carbon
dioxide [1], diene [2], alkyne ligands [3], and the E/Z
isomerization of ketone complexes [3,4] are known. A
We have reported that cis-dialkyltungsten complexes
t
metalla
crown
ether,
cis-Mo(CO)4{Ph2P(CH2-
bearing diphenylacetylene and Bu2tbp ligands, W(h2-
PhCÅ
/
CPh)(tBu2tbp)R2 (Rꢂ
CH2SiMe3, CH2Ph, CH3),
/
isomerized from Cs to C1 structure prior to a-H
elimination to generate alkylidene species [7a]. In that
ꢁ Corresponding author. Fax: ꢃ
E-mail address: harada@chem.sci.osaka-u.ac.jp (A. Harada).
/
81-6-6850-5446
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 2 0 1 6 - 8

Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ
/244
235
study, only the C1 isomers were structurally character-
ized. In order to get the crystal structures of the both
isomers, we investigated the similar dialkyltungsten
complexes having alkyne and sulfur-bridged bis(aryl-
oxide) ligands with a variety of substituents. Here we
synthesized a series of dialkyltungsten complexes co-
ordinated with various chelating aryloxo and alkyne
observed at around 249 ppm (1-Cs: 249.8 ppm, 2-Cs:
249.0 ppm), which is approximate to that observed
in Cs-W(h2-PhCÅ
(244.1 ppm) [7a].
/
CPh)(tBu2tbp)(CH2SiMe3)2 (4-Cs)
ligands, and got the structures of Cs ꢀC1 isomerizations
/
with the same composition.
ð2Þ
2. Results and discussion
2.1. Preparation of dialkyl complexes
2.2. Isomerization of the dialkyl complexes
A Cs dialkyltungsten complex, Cs-W(h2-EtCÅ
(Me2tbp)(CH2SiMe3)2 (1-Cs: Me2tbpꢂ2,2?-thiobis(4,6-
dimethylphenoxo)), was prepared by the reaction of Cs-
W(h2-EtCÅ
CEt)(Me2tbp)Cl2 with Mg(CH2SiMe3)2 (Eq.
(1)). Unexpectedly, the reaction of a C1 dichloro
complex, C1-W(h2-EtCÅCEt)(tBu2tbp)Cl2, with Mg-
CEt)-
/
CEt)-
These Cs symmetric complexes 1-Cs, 2-Cs and 3-Cs
were found to isomerize to C1 symmetric complexes 1-
C1, 2-C1 and 3-C1 in C6D6 at 30 8C as observed for 4-Cs
[7a] (Eq. (3)). The rate of the isomerization of 1-Cs, 2-Cs
and 3-Cs were faster than that of 4-Cs, the conversions
of 1-Cs and 3-Cs were 100% after 3 h. Figs. 1 and 2 show
1H-NMR spectra of complexes 1 and 3 having Cs- and
C1-structure. The 3-hexyne complexes 1-C1 and 2-C1
showed the signals for the methylene protons of one of
the two trimethylsilylmethyl groups as AX-type signals
/
/
/
(CH2SiMe3)2 gave a Cs complex, Cs-W(h2-EtCÅ
/
(tBu2tbp)(CH2SiMe3)2 (2-Cs), at first (Eq. (1)). The
corresponding Cs type dibenzyl complex, Cs-W(h2-
PhCÅ
/
CPh)(tBu2tbp)(CH2Ph)2 (3-Cs), was also synthe-
sized by using Mg(CH2Ph)2 instead of Mg(CH2SiMe3)2
(Eq. (2)), which had not been isolated in our previous
at low fields (1-C1: 3.77 and 2.78 ppm, 2JHH
ꢂ5.7 Hz; 2-
ꢂ6.5 Hz) and those of the
/
2
C1: 3.06 and 2.68 ppm, JHH
1
work [7a]. The H-NMR spectra of these complexes 1-
/
other trimethylsilylmethyl group were observed as AB-
type signals at high fields (1-C1: 1.81 and 1.53 ppm,
Cs ꢀ3-Cs showed one singlet for the protons of the two
/
tert-butyl or methyl substituents at 6-position, one
singlet for the protons of the two methyl substituents
at 4-position, and two doublets for the aromatic protons
2
2JHH
ꢂ
/
11.9 Hz; 2-C1: 0.75 and 0.58 ppm, JHH
ꢂ12.1
/
Hz). The large upfield shift of one methylene group
suggests an a-H agostic interaction with the tungsten
metal center in these complexes. In the 13C-NMR
spectrum of 1-C1, a resonance of alkyne carbons was
t
at 3- and 5-positions of the Me2tbp or Bu2tbp ligand,
indicating that these complexes have a Cs symmetric
structure. The AB-type signals at relatively low fields (1-
2
Cs: 2.48 and 1.30 ppm, JHH
observed as a single peak at 212.2 ppm due to WÃ
/
alkyne
ꢂ12.5 Hz; 2-Cs: 1.42 and
/
2
free rotation. On the other hand, the diastereotopic
methylene protons of one of the two alkyl groups in the
diphenylacetylene complexes 3-C1 and 4-C1 were ob-
0.99 ppm, JHH
2JHH
12.0 Hz; 4-Cs: 2.68 and 1.80 ppm, JHH
Hz) of these complexes are assignable to the a-methyl-
ene protons of W-CH2R (Rꢂ
SiMe3, Ph). In their 13C-
ꢂ12.3 Hz, 3-Cs: 3.97 and 3.26 ppm,
/
2
ꢂ
/
ꢂ12.6
/
served as AB-type signals at low fields (3-C1: 5.00 and
2
4.72 ppm, JHH
/
ꢂ11.1 Hz; 4-C1: 3.56 and 3.48 ppm,
/
NMR spectra, the alkyne carbon resonances were
2JHH
methyl group were observed as AX-type signals at
ꢂ
/
7.7 Hz) and those of the other trimethylsilyl-
2
higher fields (3-C1: 4.11 and 1.52 ppm, JHH
ꢂ/10.0
2
Hz; 4-C1: 2.33 and 0.20 ppm, JHH
ꢂ/11.5 Hz). In the
13C-NMR spectrum, the alkyne carbon resonances were
observed at 208.1 and 205.8 ppm for 3-C1 and at 213.9
and 210.6 ppm for 4-C1.
The rate of the transformation of 1-Cs to 1-C1 in
ð1Þ
C6D6 was measured in the temperature range 30ꢀ50 8C.
/
The decrease of 1-Cs followed the first-order kinetic
behavior as observed for 4-Cs (Table 1), an Arrhenius
plot afforded the thermodynamic data DG%(45 8C)ꢂ
/
26
kcal molꢄ1 and DS%(45 8C)ꢂ 22 cal Kꢄ1 molꢄ1. The
rate of isomerization in 2 could not be determined due
/
ꢄ
/
to the accompanying a-H elimination, and that in 3 was

236
Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
Fig. 1. 1H-NMR spectra of: (a) Cs -W(h2-EtCÅ
/
CEt)(Me2tbp)(CH2SiMe3)2 (1-Cs ); and (b) C1-W(h2-EtCÅ
CEt)(Me2tbp)(CH2SiMe3)2 (1-C1).
/
1
too fast to be monitored by H-NMR.
Figs. 3ꢀ5 displays the ORTEP drawings of 1-Cs, 1-C1,
/
2-Cs and 4-Cs, respectively. The selected bond distances
and angles of these complexes are summarized in Table
2. When the alkyne ligands are regarded to occupy one
coordination site around the metal, these complexes can
be best described as distorted octahedral, in which the
tbp ligands coordinate to tungsten in a facial fashion.
The alkyne ligands in 1-Cs, 2-Cs and 4-Cs are located at
the position trans to the sulfur atom of the tbp ligands,
while that in 1-C1 is trans to the oxygen atom of the
Me2tbp ligand.
ð3Þ
The WÃ
/
C(alkyl) bond distance trans to the phenoxo
˚
moiety in 1-C1 (2.165(5) A) is longer by ca. 0.042 A than
˚
˚
that trans to sulfur (2.123(5) A) due to the trans
influence of the phenoxo group, and is shorter by ca.
˚
0.03 A than those trans to phenoxo moiety in 1-Cs
2.3. Structures of the Cs- and C1-dialkyltungsten
complexes and isomerization mechanism
˚
(2.196(5) A). This might come from the stronger
coordination of the alkyne ligand to the metal center
We have reported about the isomerization of complex
4 and W(dpa)(tBu2tbp)Cl2 [7b], but we only had the
structural data of the C1 isomers. Here we got the
structures of both the Cs and C1 isomers, which enabled
us to discuss the structural comparison between the Cs
and C1 isomers.
in 1-Cs than that in 1-C1 (vide infra). The WÃ
/
O bond
˚
distance trans to alkyne in 1-C1 (2.049(3) A) is longer
than that trans to trimethylsilylmethyl ligand (1.935(3)
˚
A) due to the competitive p donation from the trans 3-

Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ
/244
237
Fig. 2. 1H-NMR spectra of: (a) Cs -W(h2-PhCÅ
/
CPh)(t Bu2tbp)(CH2Ph)2 (3-Cs ); and (b) C1-W(h2-PhCÅ
/
CPh)(t Bu2tbp)(CH2Ph)2 (3-C1).
˚
from 1.997(9) to 2.027(2) A are apparently shorter than
Table 1
Observed rate constants and half-lives at various temperatures for the
isomerization of 1-Cs to give 1-C1
those in the corresponding C1 complexes, and the CÅ
/C
bond lengths of the Cs complexes also tend to be rather
longer than those of the C1 complexes. These data
indicate that the alkyne ligands in the Cs complexes
coordinate to tungsten more strongly than those in the
C1 complexes. In accordance with the structural data,
the resonances of the alkyne carbons of the Cs
Temperature (8C)
104kobs (sꢄ1
)
t1/2 (m)
50
45
40
35
30
10.74
5.28
3.88
2.19
1.33
10.76
21.88
29.76
52.77
86.95
complexes in 13C-NMR spectra appeared at 244.5ꢀ
249.8 ppm, typically for four electron donating alkynes
[8ꢀ
11]. In sharp contrast, the 13C-NMR spectra of the
C1 complexes showed signals of the alkyne carbons at
206.7ꢀ215.4 ppm. Thus, the alkyne ligands in Cs
/
/
hexyne ligand. The distortion of C(alkyl)Ã
/
WÃ/C(alkyl)
/
angle from the octahedral geometry in 1-C1
(103.48(19)8) is significantly larger than that in 1-Cs
complexes can be considered as four electron donor
ligands, while those in C1 complexes can be regarded as
two electron donor ligands. Of course, these tendencies
are clear in the comparison between 1-Cs and 1-C1,
whose compositions are completely the same. In the C1
isomers, p-donation from the trans aryloxo oxygen
could disturb the donation from the alkyne ligand to
the same d orbitals to result in the reduced donation
(87.3(3)8), while the O1Ã
is a little deviated from the octahedral geometry as in 1-
C1 (90.82(14)8). The WÃS bond distance of 1-Cs is
similar to that of 1-C1.
/
WÃO2 angle in 1-Cs (93.0(2)8)
/
/
The most notable difference between Cs and C1
complexes is in the bonding mode of the alkyne ligands.
The bond lengths and 13C-NMR chemical shifts con-
cerning the alkyne ligands in these complexes are
from the alkyne ligand. The WÃ
/
O bond length trans to
˚
the alkyl group in 1-C1 (1.935(3) A) is apparently shorter
summarized in Table 3. The WÃ
/
C(alkyne) bond dis-
tances in the Cs complexes 1-Cs, 2-Cs, and 4-Cs ranging
˚
than that of 1-Cs (1.987(4) A), this implies that the

238
Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
Fig. 3. ORTEP drawing of Cs -W(h2-EtCÅ
scheme.
/
CEt)(Me2tbp)(CH2SiMe3)2 (1-Cs ) and C1-W(h2-EtCÅ
CEt)(Me2tbp)(CH2SiMe3)2 (1-C1) with a numbering
/
Fig. 5. ORTEP drawing of Cs -W(h2-PhCÅ
(4-Cs ) with a numbering scheme.
/
CPh)(t Bu2tbp)(CH2SiMe3)2
Fig. 4. ORTEP drawing of Cs -W(h2-EtCÅ
(2-Cs ) with a numbering scheme.
/
CEt)(t Bu2tbp)(CH2SiMe3)2
the 3-hexyne complexes 1-Cs and 2-Cs are compared
with the diphenylacetylene complex 4-Cs, WÃC(alkyne)
bond distances in the 1-Cs (av. 2.003 A) and 2-Cs (av.
electron density around the metal in 1-C1 is lower than
that in 1-Cs. The decreased electron density in the C1
complexes might be one of the key elements for the
subsequent a-H elimination.
/
˚
˚
2.012 A) were shorter than that of 4-Cs (av. 2.017 A)
˚
˚
S bond distances of 1-Cs (2.694(3) A)
and the WÃ
/
˚
We have assumed that the Cs ꢀC1 isomerization
/
became longer than that of 4-Cs (2.631(2) A). We
suppose that the coordination of the diphenylacetylene
ligand is weaker than that of the 3-hexyne ligand, which
is probably due to the delocalization of p-electrons on
proceeded through a simple rotation of the two alkyl
groups and one alkyne ligands around the axis through
the center of those three ligands and tungsten [7a]. When

Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ
/244
239
Table 2
Selected bond distances (A) and angles (8) of 1-Cs , 1-C1, 2-Cs and 4-Cs
˚
Complex
1-Cs
1-C1
2-Cs
4-Cs
Bond distances
WÃO
1.987(4) (O1)
1.935(3) (O1)
2.049(3) (O2)
2.7036(13)
1.9835(19) (O1)
1.9905(19) (O2)
2.6567(7)
1.995(4) (O1)
1.994(4) (O2)
2.631(2)
ꢀ/
WÃS
2.694(3)
WÃC(alkyne)
1.997(9) (C13)
2.008(9) (C14)
2.196(5) (C9)
2.025(5) (C31)
2.062(5) (C35)
2.123(5) (C41)
2.165(5) (C45)
1.278(7)
2.013(3) (C51)
2.010(3) (C55)
2.191(3) (C41)
2.184(3) (C45)
1.310(4)
2.027(2) (C15)
2.007(6) (C16)
2.178(7) (Cl)
2.176(7) (C5)
1.388(8)
WÃC(alkyl)
CÅC(alkyne)
ꢀ/
1.316(15)
Bond angles
OÃWÃO
93.0(2)
102.1(3)
90.82(14)
101.8(2)
91.39(8)
102.38(13)
86.04(12)
89.2(2)
102.3(3)
88.8(3)
CÃSÃC
CÃWÃC(alkyl)
WÃOÃC
87.3(3)
130.3(3) (O1)
103.48(19) (alkyl)
134.2(3) (O1)
126.6(3) (O2)
105.16(17) (O1)
82.07(17) (O2)
36.4(2)
130.47(18) (O1)
130.77(17) (O2)
85.90(10) (O1)
87.04(10) (O2)
38.03 (12)
129.8(4) (O1)
129.3(4) (O2)
87.3(2) (O1)
84.7(2) (O2)
38.4(2)
ꢀ/
OÃWÃC(alkyl)
85.50(17) (O1)
ꢀ/
CÃWÃC(alkyne)
OÃWÃS
38.4(4)
75.98(13) (O1)
73.87(10) (O1)
75.94(10) (O2)
142.8(6) (C32)
142.9(5) (C36)
116.4(2) (Si1)
119.8(3) (Si2)
76.14(6) (O1)
76.17(6)(O2)
142.3(3) (C52)
142.6(3) (C56)
126.59(16) (Si1)
125.03(16) (Si2)
76.1(1) (O1)
76.9(1) (O2)
139.9(6) (C10)
141.5(6) (C17)
125.3(3)
ꢀ/
CÃCÅC(alkyne)
WÃCÃSi
143.0(12) (C15)
142.3(10) (C17)
119.5(3)
ꢀ/
125.1(4)
the alkyne carbons to the phenyl rings. The distortion of
OÃWÃO angles in 1-Cs (93.0(2)8) and 2-Cs (91.39(8)8)
are larger than that in 4-Cs (89.2(2)8) due to the steric
hindrance of the alkyne ligand. This could be a reason
for the faster isomerization rate of 1-Cs than that of 4-
Cs.
and only the latter signal for the a-proton of alkylidene
species was observed. The a-carbon signal of the
alkylidene species appeared at 283.8 ppm in the 13C-
NMR spectrum. Because anti-isomer is generally more
stable than syn-isomer, the signal at 10.83 ppm can be
assigned to the anti-alkylidene species. Some other
/
/
alkylidene tungsten complexes, such as W(CHÃ
Bu)(NAr)R2(PMe3) (RꢂOCMe(CF3)2, OCMe2(CF3),
OÃt-Bu), W(CHÃt-Bu)(NAr)R2(quin) (RꢂOC-
Me(CF3)2, OCMe2(CF3)) and W(CHÃsec-Bu)(OCH2Ã
/
t-
/
2.4. Generation of alkylidene species from the dialkyl
complexes
/
/
/
/
/
t-Bu)3Br have also been reported to form the alkylidene
rotational isomers or rotamers [12,13]. Our efforts to
isolate the alkylidene complexes have resulted in failure
at present. The complex 2 was proved to be converted to
alkylidene species at 30 8C for 96 h in 56% conversion
by H-NMR. When a C6D6 solution of 1 was heated to
60 8C in an NMR tube, the generation of an alkylidene
species was not observed due to contamination by
Further heating of these C1 dialkyl complexes caused
a-H elimination. The 1H-NMR spectrum of 2-C1 treated
at 60 8C for 24 h in C6D6 showed the absence of the
signals for 2-C1 and a new signal set including the
singals at 10.51 and 10.83 ppm, which could be
assignable to a-H protons of alkylidene species. When
2-C1 was kept at room temperature in C6D6 for 1
month, the resonance at d 10.51 completely disappeared
1
Table 3
13C-NMR and structural data concerning the alkyne ligands of the tungsten complexes
˚
˚
Complex
Symmetry
Chemical shift (ppm)
Distances A (WÃC)
CÅC A
1
Cs
C1
Cs
C1
Cs
C1
249.8
212.2
249.0
1.997(9), 2.008(9)
2.025(5), 2.062(5)
2.013(3), 2.010(3)
2.054(7), 2.053(7)
2.027(2), 2.007(6)
2.060(6), 2.062(7)
1.316(15)
1.278(7)
1.310(4)
1.274(9)
1.388(8)
1.319(8)
1
2
3
208.1, 205.8
244.1
208.5, 206.7
4
W(dpa)(t Bu2tbp)(CH3)2

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Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
paramagnetic byproducts. The resonances of alkyne
carbons of the alkylidene species generated from 2 and
3 appears at 229.5 and 238.1 ppm, respectively, suggest-
ing the increased electron donation from the alkyne
ligands to the metal compared with those in the
corresponding C1-dialkyl complexes.
To determine the tacticity of the polymers produced
by these catalysts, we investigated the polymerization of
7-methylnorbornene catalyzed by 2, 3, and Mo(h2-
PhCÅ
/
CPh)(tBu2tbp)Cl2 (5)ꢀ
Mg(CH2SiMe3)2 (Table 5).
/
The 13C-NMR analysis of the poly(7-methylnorbor-
nene)s yielded a wealth of microstructural information
showing diad tacticity [21]. We obtained the poly(7-
methylnorbornene)s in quantitative yields with 2 and 3
catalytic system, but the yield was low in the 5ꢀ
Mg(CH2SiMe3)2 system. All the polymers had high
cis-contents, however, their tacticities were turned out
/
ð4Þ
to be completely atactic (mꢂ50%) [21]. The higher cis
/
regularity of poly(7-methylnorbornene)s than that of
poly(norbornene)s can be attributed to the larger steric
hindrance between the diphenylacetylene ligand and the
methyl substituent of 7-methylnorbornene.
2.5. Polymerization of norbornene catalyzed by the
dialkyltungsten complexes
Well-defined olefin metathesis catalysts, in particular,
Group 6 alkylidene complexes having strong p-donor
ligands such as imido, oxo and alkoxo have led to a
precise description of the whole mechanism, and have
also achieved living ring-opening metathesis polymer-
3. Conclusion
A series of tungsten complexes coordinated with
various chelating aryloxo ligands and acetylene ligands,
Cs-W(h2-EtCÅ
/
CEt)(Me2tbp)(CH2SiMe3)2 (1-Cs, Me2-
2,2?-thiobis(4,6-dimethylphenoxo)),
Cs-W(h2-
CEt)(tBu2tbp)(CH2SiMe3)2 (2-Cs, Bu2tbpꢂ
2,2?-
thiobis(4-methyl-6-tert-butylphenoxo)) and Cs-W(h2-
PhCÅ
CPh)(tBu2tbp)(CH2Ph)2 (3-Cs), was synthesized.
ization (ROMP) with high selectivity [14ꢀ20]. We have
/
tbpꢂ
/
t
reported that the complexes 3 and 4 initiated the ROMP
of norbornene to give poly(norbornene) with high
molecular weight and high cis-content [7a]. We studied
here the catalytic behavior of 1 and 2 for the ROMP of
norbornene to elucidate the substituent effects of the
ligands on the ROMP.
EtCÅ
/
/
/
The bis(trimethylsilylmethyl)tungsten and dibenzyltung-
sten complexes isomerized from Cs- to C1-symmetric
isomers in solution and the molecular structures of both
The catalytic behavior of these complexes for the
polymerization of norbornene was investigated in tolu-
ene, and the results are summarized in Table 4. These
dialkyltungsten complexes were found to initiate the
polymerization of norbornene without any cocatalysts.
The use of more bulky ligands gave poly(norbornene)s
with higher cis-contents in higher yield at 60 8C. These
results agree with the previously proposed mechanism
[7a] in which the steric effects of the ligands are
Cs and C1 isomers of W(EtCÅ
/
CEt)(Me2tbp)(CH2-
SiMe3)2 (1) were determined by X-ray crystallography,
which indicated that the alkyne ligand changed from
four to two electron donor upon Cs ꢀC1 isomererization.
/
The substituent effects of the ligands on the catalytic
behavior of the complexes for the ROMP of norbornene
derivatives were studied. In the polymerization of
norbornene by these complexes, the use of more bulky
ligands gave poly(norbornene)s with higher cis-con-
tents. Thus the cis-contents of the poly(norbornene)s
controlling the cis ꢀtrans selectivity.
/
Table 4
ROMP of norbornene by bis(trimethylsilylmethyl) complexes W(RCÅCR)(R?2tbp)(CH2SiMe3)2 (1, 2 and 4)
Mn/104 b
Mw/Mn
b
c
cis-Content (%)
Catalyst
Temperature (8C)
Time (h)
Yield (%)
R
R?
1
2
4
4
Et
Et
Ph
t Bu
Me
t Bu
60
60
30
60
12
12
1
24
4
90
15
1.6
2.4
1.7
3.4
68
57
93
83
a
a
1.6
62
ꢀ200
49
1
In toluene, [Monomer]0/[W]ꢂ100.
Ref. [10].
a
b
Determined by GPC analysis in THF calibrated with standard poly(styrene)s. Theoretical Mn value is less than the experimental one [28].
Microstructure of double bonds in polymer as determined by 1H-NMR spectra [21,28,29].
c

Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ
/244
241
Table 5
ROMP of 7-methylnorbornene by using tungsten and molybdenum complexes
Mn/104 a
Mw/Mn
cis-Content (%)
Tacticity m (%)
a
b
b
Catalyst
Yield (%)
W(EtCÅCEt)(t Bu2tbp)(CH2SiMe3)2 (2)
W(PhCÅCPh)(t Bu2tbp)(CH2Ph)2 (3)
100
100
20
9.8
1.6
25
4.3
12
96
93
50
50
50
Mo(PhCÅCPh)(t Bu2tbp)Cl2 (5)ꢀ
/
Mg(CH2SiMe3)2
8.9
100
In toluene, [Monomer]0/[W], 100; timeꢂ12 h.
Determined by GPC analysis in THF calibrated with standard poly(styrene)s. Theoretical Mn value is less than the experimental one [28].
a
b
Microstructure of the polymers as determined by 1H-NMR spectra [21,28,29].
were found to be controlled in the wide range by the
design of the catalyst precursors.
4.2. Preparation of Cs-W(h2-EtCÅ
Me2C6H2O)2](CH2SiMe3)2 (1-Cs)
/CEt)[S(4,6-
A solution of Mg(CH2SiMe3)2 (0.34 mmol, 1.5
equivalents) in Et2O was added to a solution of 2
(0.14 g, 0.23 mmol) in Et2O (30 ml) via syringe at
4. Experimental
ꢄ78 8C. After stirring for 20 min, the reaction mixture
/
was allowed to warm to ambient temperature and
stirred there for 4 h. The color of the solution changed
from red to orange. All volatiles were removed under
reduced pressure, followed by extraction with C6H5CH3
(25 ml) from the resulting residue. After the extract was
dried in vacuo, the crude product was recrystallized
4.1. General procedures
All manipulations of air- and moisture-sensitive
organometallic compounds were carried out by the use
of standard Schlenk techniques under an Ar atmo-
sphere. Hexane, THF, C6H5CH3, and C5H12 were dried
and deoxygenated by distillation over sodium benzo-
phenone ketyl under Ar. Dichloromethane was distilled
under Ar after drying over P2O5. Benzene-d6 and
from THF (1 ml) and n-C5H12 (5 ml) at ꢄ
W(h2-EtCÅ
CEt)[S(4,6-Me2C6H2O)2](CH2SiMe3)2 (1-
Cs) as orange crystals in 19% yield, m.p. 168ꢀ171 8C.
1H-NMR (C6D6, 22.5 8C, 400 MHz): d 7.36 (d, 4JHH
1.61 Hz, 2H, 3-C6H2O), 6.61 (d, 4JHH
1.92 Hz, 2H, 5-
C6H2O), 3.91 (q, 4H, CH2CH3), 2.48 (d, 2H, JH
/
20 8C to give
/
/
ꢂ
/
ꢂ
/
C6H5CH3-d8 were distilled from NaꢀK alloy and
/
2
AHB
ꢂ
thoroughly degassed by trap-to-trap distillation before
use. Dichloromethane-d2 and CHCl3-d1 were distilled
from P2O5. Norbornene(bicyclo[2,2,1]hept-2-ene) pur-
chased from the Aldrich Chemical Co. was refluxed over
Na and distilled prior to use. 7-Methylnorbornene [21]
and dialkylmagnesium [22] were prepared according to
the literature.
12:5 Hz; CHAHBSi), 2.08 (s, 6H, 6-Me), 1.98 (s, 6H, 4-
2
B
Me), 1.64 (t, 6H, CH2CH3), 1.30 (d, 2H, JH H
A
ꢂ
12:5 Hz; CHAHBSi), ꢄ
/
0.11 (s, 18H, CH2SiMe3). 13C-
NMR (THF-d8, 22.5 8C, 67.5 MHz): d 249.8 (EtC),
167.2 (1-C6H2O), 130.8 (6-C6H2O), 127.7 (4-C6H2O),
126.1 (3-C6H2O), 119.9 (5-C6H2O), 65.9 (CH2SiMe3),
31.6 (CH2CH3), 22.3 (6-Me), 20.39 (4-Me), 14.6
(CH2CH3), 1.1 (SiMe3). Anal. Calc. for C30H48O2S1-
Si2W1: C, 50.55; H, 6.79. Found: C, 50.83; H, 6.76%.
1
The H (600, 500, 400 and 270 MHz)-, and 13C (125,
100 and 67.5 MHz)- NMR spectra in C6H6-d6, CH2Cl2-
d2, and CHCl3-d1 were measured on VARIAN-UNITY-
600, JEOL JNM-LA500, JEOL JNM-GSX400 and
JEOL JNM-EX270 spectrometers. Assignments for
1H- and 13C-NMR peaks for some complexes were
4.3. Preparation of W(h2-EtCÅ
6-tBuC6H2O)2](CH2SiMe3)2 (2-Cs)
/
CEt)[S(4-MeÃ
/
1
1
aided by 2D Hꢀ1
/
H NOESY, 2D Hꢀ1
H COSY, 2D,
/
2D HMQC and 2D HMBC spectra. Elemental analyses
were performed at Elemental Analysis Center, Faculty
of Science, Osaka University. All m.p.s of the complexes
were measured in sealed tubes under an Ar atmosphere
and were not corrected. ESI-MS measurements were
The 2-Cs was synthesized and isolated as orange
1
crystals in 26% yield in a similar manner to 1-Cs. H-
4
NMR (THF, 0 8C, 500 MHz): d 7.42 (d, JHH
ꢂ1.65
/
4
Hz, 2H, 3-C6H2O), 6.98 (d, JHH
ꢂ1.96 Hz, 2H, 5-
/
C6H2O), 3.99 (q, 4H, CH2CH3), 2.23 (s, 6H, 4-Me), 1.62
(t, 6H, CH2CH3), 1.42 (d, 2H, 2JH ꢂ12:2 Hz;
AHB
performed on a Perkinꢀ
spectrometer.
W(h2-PhCÅ
O)2]Cl2×
THF [7a], W(h2-EtCÅ
W(h2-EtCÅCEt)(tBu2tbp)Cl2 [7b], W(h2-PhCÅ
(tBu2tbp)(CH2Ph)2 (3-C1) [7a], W(h2-PhCÅCPh)(tBu2-
tbp)(CH2SiMe3)2(THF) (4-Cs and 4-C1) [7a] and
Mo(h2-PhCÅCPh)(tBu2tbp)Cl2(THF) (5) [7a] were pre-
pared according to the literature.
/
Elmer/Sciex API III plus
CPh)[S(4-MeÃ
6-tBuC6H2-
CEt)(Me2tbp)Cl2 [7a],
CPh)-
t
CHAHBSi), 1.23 (s, 18H, 6- Bu), 0.99 (d, 2H, JH H
2
B
A
/
/
ꢂ
/
/
12:4 Hz; CHBHASi), ꢄ
/
0.25 (s, 18H, CH2SiMe3). 13C-
/
/
NMR (THF, 0 8C, 125 MHz): d 249.0 (EtC), 166.8 (1-
C6H2O), 146.1 (6-C6H2O), 131.8 (4-C6H2O), 131.5 (3-
C6H2O), 130.6 (5-C6H2O), 122.3 (2-C6H2O), 56.1
(CH2SiMe3), 35.7 (CMe3), 32.9 (CH2CH3), 30.2
(CMe3), 20.9 (4-Me), 15.2 (CH2CH3), 3.6 (SiMe3).
/
/

242
Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
Anal. Calc. for C36H60O2S1Si2W1: C, 54.26; H, 7.59.
Found: C, 54.31; H, 7.65%. ESI-MS for m/z: 797 [Mꢃ
H]ꢃ.
tempts to isolate 2-C1 have been in failure because it was
highly soluble even in C6H14 at ꢄ78 8C.
/
/
4.6. Kinetic study for isomerization of 1-Cs to 1-C1
4.4. Preparation of W(h2-PhCÅ
/
CPh)[S(4-MeÃ
/
6-tBuC6H2O)2](CH2Ph)2 (3-Cs)
The complex 1-Cs (0.063 g, 0.071 mmol) was dis-
solved in C6D6 (4.00 ml) at r.t., and the solution (0.018
M) was divided equally among five NMR tubes. Each of
This complex was synthesized and isolated in a similar
1
manner to 1-Cs. The yield of 3-Cs was 20%. H-NMR
them was sealed under Ar and kept at ꢄ
used. Reaction temperatures were maintained within
0.1 8C by the JEOL JNM-EX270 temperature con-
/
20 8C until
(C6D6, 22.5 8C, 270 MHz): d 8.03 (d, 4H, o-PhC), 7.35
(t, 4H, m-PhC), 7.20 (t, 2H, p-PhC), 7.20ꢀ7.03 (m, 6H,
/
9
/
3-C6H2O, o-CH2Ph), 7.07 (t, 4H, m-CH2Ph), 6.98ꢀ
/
6.83
ꢂ
troller and progress of isomerization was monitored by
1H-NMR. The value [1-Cs]t, which refers to the
concentration of 1-Cs at the reaction time t, was
determined by the sum of intensities of areas assignable
to 18 protons (SiMe3) in 1-Cs. Treatment of the data is
described in the text.
p-CH2Ph), 3.97 (d, 2H, 2JH
AHB
(m, 4H, 5-C6H2Oꢃ
/
2
B
A
11:8 Hz; CHAHBPh), 3.26 (d, 2H, JH H ꢂ12:2 Hz;
CHBHAPh), 2.02 (s, 6H, 4-Me), 1.16 (s, 18H, 6-tBu).
Anal. Calc. for C50H52O2S1W1: C, 66.66; H, 5.82.
Found: C, 66.60; H, 6.05%.
4.5. Isomerization of Cs-dialkyl complexes to C1-
complexes
4.7. Polymerization of norbornene
4.5.1. Typical procedure
4.7.1. General procedures
The complex 1-Cs was dissolved in C6D6 (0.6 ml) in a
5 mm NMR tube, which was sealed under Ar and placed
for a day at room temperature (r.t.). The color changed
To a solution of 2-Cs (16.0 mg, 0.02 mmol) in
C6H5CH3 (1.0 ml) was added a solution of norbornene
(100 equivalents, 2 mmol) in C6H5CH3 (2 M, 1.0 ml) at
30 8C. After the solution was stirred at 30 or 60 8C for a
prescribed period, MeOH (15 ml) was added to the
resulting reddish viscous solution to precipitate a pale-
yellow polymer. The polymer was washed with MeOH
and then dried in vacuo.
1
from red to pale orange, and the H- and 13C-NMR
1
spectra of the solution were measured. 1-C1: H-NMR
4
(C6D6, 22.5 8C, 400 MHz): d 7.46 (d, JHH
ꢂ2.06 Hz,
/
1H, 3-C6H2O), 7.27 (d, 4JHH
6.89 (d, 4JHH 2.12 Hz, 1H, 5-C6H2O), 6.37 (d, 4JHH
1.84 Hz, 1H, 5?-C6H2O), 3.92 (br, 4H, CH2CH3), 3.77
ꢂ1.92 Hz, 1H, 3?-C6H2O),
/
ꢂ
/
ꢂ
/
The cis-content of double bond of the polymers was
1
determined comparison of H-NMR with that of the
1
2
2
1
2
(d, 1H, JH H ꢂ5:7 Hz; CH H Si), 2.78 (d, 1H,
JH H ꢂ5:7 Hz; CH H Si), 2.69 (s, 3H, 6-Me), 2.14
(s, 3H, 4-Me), 1.89 (s, 3H, 4?-Me), 1.84 (s, 3H, 6?-Me),
2
1
2
literature [21]. Unfortunately, the 13C-NMR spectrum
of poly(norbornene)s displayed no resonances for m/r
splitting. In order to determine the tacticity of the
polymer, we used 7-methylnorbornene as a monomer.
Polymerization of a 1:1 mixture of syn- and anti-7-
methylnorbornene by using 2 as a catalyst afforded
poly(anti-7-methylnorbornene)s, whose tacticities were
determined by comparison of the 13C-NMR spectral
data [21].
2
1
4
3
2
4
3
1.81 (d, 1H, JH H ꢂ11:9 Hz; CH H Si), 1.53 (d, 1H,
3
4
2
4
3
JH H ꢂ11:9 Hz; CH H Si), 1.34 (br, 6H, CH2CH3),
0.57 (s, 9H, SiMe3), ꢄ
/
0.14 (s, 9H, SiMe?): 13C-NMR
3
(CD2Cl2, 30 8C, 150 MHz): d 212.2 (br, EtC), 167.3 (4-
C6H2O), 165.7 (4?-C6H2O), 133.8 (5-C6H2O), 133.6 (5?-
C6H2O), 131.3 (6-C6H2O), 131.2 (6?-C6H2O), 130.9 (3-
C6H2O), 128.8 (3?-C6H2O), 128.3, 126.6, 120.4, 118.9,
86.1 (CH1H2Si, JCH ꢂ116; JCH ꢂ107 Hz); 72.6
1
1
1
2
1
(CH3H4Si, JCH
ꢂ113 Hz), 26.8 (br, CH2CH3), 20.5
/
(4-Me), 20.4 (4?-Me), 17.9 (6-Me), 17.2 (6?-Me), 14.8
(CH2CH3), 2.9 (SiMe3), 1.2 (/
4.8. GPC analysis of the polymers
SiMe?): 2-C1: 1H-NMR
3
4
(C6D6, 22.5 8C, 400 MHz): d 7.58 (d, JHH
ꢂ
/
2.10 Hz,
For the polymers obtained by using 2ꢀ4 as catalysts,
/
1H, 3?-C6H2O), 7.32 (d, 4JHH
7.24 (d, 4JHH 2.11 Hz, 1H, 5?-C6H2O), 6.79 (d, 4JHH
2.06 Hz, 1H, 5-C6H2O), 3.73 (br, 4H, CH2CH3), 3.06 (d,
ꢂ/2.04 Hz, 1H, 3-C6H2O),
Gel permeation chromatographic (GPC) analyses were
carried out at 40 8C using Tosoh TSKgel HXL-H and L
columns connected to a Tosoh RI-8012 detector.
ꢂ
/
ꢂ
/
3
4
2
2
3
4
4
3
1H, JH H ꢂ6:47 Hz; CH H Si), 2.68 (d, 1H, JH H
ꢂ
Samples were prepared in THF (0.1ꢀ0.3% (w/v)) and
/
6:50 Hz; CH4H3Si), 2.20 (s, 3H, 4?-Me), 1.95 (s, 3H, 4-
were filtered through an Advantec DISMIC-25JP filter
in order to remove particulate before injection. GPC
columns were calibrated versus commercially available
polystyrene standards (Polymer Laboratories Ltd.)
Me), 1.79 (s, 9H, 6-tBu), 1.29 (br, 6H, CH2CH3), 1.14
(s, 9H, 6?-tBu), 0.75 (d, 1H, JH H ꢂ12:05 Hz;
2
2
1
2
1
2
1
2
CH H Si), 0.65 (s, 9H, SiMe?); 0.58 (d, 1H, JH H ꢂ
0.12 (s, 9H, SiMe3). All at-
3
12:05 Hz; CH1H2Si), ꢄ
/
whose molecular weight ranged from 500 to 2.15ꢅ
106.
/

Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ
/244
243
4.9. Crystallographic data collections and structure
determination of 1-Cs, 1-C1, 2-Cs and 4-Cs
The agreement indices are defined as Rꢂ
/
a jjFojꢄ
/
jFcjj/a jFoj and Rw ꢂ[a w(F2 ꢄF2)2=a w(F2)2]1=2: The
o
c
o
positions of all non-hydrogen atoms for the complexes
were found from a difference Fourier electron density
The crystals of 1-Cs, 1-C1 and 2-Cs suitable for X-ray
diffraction studies were mounted on a cryoloop. The
measurement of 1-Cs, 1-C1 and 2-Cs was made on a
Rigaku R-AXIS-RAPID Imaging Plate diffractometer
maps and refined anisotoropically. All hydrogen atoms
˚
Hꢂ0.95 A) and
were placed in calculated positions (CÃ
/
/
kept fixed.
A crystal of 4-Cs was sealed in a glass capillary under
Ar. The crystal of 4-Cs mounted on a Rigaku AFC-5R
with graphite monochromated Moꢀ
/
Ka radiation (lꢂ
/
0.71069). Relevant crystal and data statistics are sum-
marized in Table 6. Indexing was performed from one
oscillations which were exposed for 5.0 min. The camera
radius was 127.40 mm. Read-out was performed in the
0.100 mm pixel mode. A symmetry-related absorption
correction using the program ABSCOR [23] was applied.
The data was corrected for Lp effects. The structures of
complex 1-Cs was solved by direct methods (SHELXS-86)
[24] and expanded using Fourier techniques (DIRDIF-94)
[25] and refined by full-matrix least-squares refinement
four-circle diffractometer for data collection using Moꢀ
/
Ka radiation. Relevant crystal and data statistics are
summarized in Table 6. The unit cell parameters and the
orientation matrix at 23 8C were determined by a least-
squares fit to 2u values of 25 strong higher reflections
for complex 4-Cs. Three standard reflections were
chosen and monitored every 150 reflections. Empirical
absorption correction was carried out on the basis of an
azimuthal scan. Complex 4-Cs showed no significant
intensity decay during the data collection. The structure
of complex 4-Cs was solved by direct methods (SHELXS-
(
SHELXL-97) [26]. The structure of complex 1-C1 was
solved by direct methods (SHELXS-97) [26] and expanded
using Fourier techniques (DIRDIF-94) [25] and refined by
full-matrix least-squares refinement (SHELXL-97) [26].
The structure of complex 2-Cs was solved by direct
methods (SIR-92) [27] and expanded using Fourier
techniques (DIRDIF-94) [25] and refined by full-matrix
least-squares refinement (SHELXL-97) [26]. In the sub-
86) [24] and expanded using Fourier techniques (DIRDIF
94) [25] and refined by the full-matrix least-square
method. Measured non-equivalent reflections with I ꢀ
-
/
3.0s(I) were used for the structure determination. In the
jFcj)2 was
subsequent refinement the function a w(jFojꢄ
/
minimized, where jFoj and jFcj are the observed and
calculated structure factors amplitudes, respectively.
sequent refinement the function a v(jFojꢄ
/
jFcj)2 was
minimized, where jFoj and jFcj are the observed and
calculated structure factors amplitudes, respectively.
The agreement indices are defined as Rꢂ
/
a jjFojꢄ
/
jFcjj/a jFoj and Rwꢂ
/
[a v(jFojꢄ
/
jFcj)2/a v(jFoj)2]1/2
Table 6
Crystal data and collection parameters of 1-Cs , 1-C1, 2-Cs and 4-Cs
Complex
1-Cs
1-C1
2-Cs
4-Cs
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C30H48O2SSi2W
712.77
200(2)
C30H48O2SSi2W
712.77
296(2)
C36H60O2SSi2W
796.93
193(1)
C44H60O2SSi2W
893.04
296(1)
Orthorhombic
Pnma (#62)
12.0641(6)
22.1541(11)
12.1829(5)
Monoclinic
C2/c (#15)
35.418(2)
Monoclinic
P21/c (#14)
19.5341(4)
16.8368(3)
19.7103(1)
Triclinic
¯
P1 (#2)
/
˚
a (A)
13.299(5)
14.329(7)
12.344(4)
98.18(4)
110.01(3)
91.78(4)
2179(1)
2
˚
b (A)
10.3063(6)
19.0312(12)
˚
c (A)
a (8)
b (8)
g (8)
V (A )
Z
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
103.892(2)
143.06
ꢀ/
ꢀ/
3
˚
3256.1(3)
4
6743.8(7)
8
3895.51(13)
4
1.359
Dcalc (g cmꢄ3
F(000)
)
1.454
1448.00
37.09
1.404
2896.00
35.82
1.361
1640.00
31.08
916.00
27.89
16.0
m (Moꢀ )
Ka) (cmꢄ1
/
Scan speed (8 minꢄ1
Scan width (8)
2umax (8)
)
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
1.63ꢃ0.35 tan u
55.0
55.0
55.0
54.8
Unique data (Rint
Observations
Variables
R
)
3835
2685
182
7266
5834
337
8840
6669
395
9983
5991
467
0.037
0.0271
0.0728
1.352
0.0366
0.1034
1.092
0.0290
0.0524
0.934
Rw
0.038
1.12
Goodness-of-fit

244
Y. Takashima et al. / Journal of Organometallic Chemistry 664 (2002) 234ꢀ244
/
where vꢄ1 ꢂs2(Fo)ꢂ[sc2(Fo)ꢃp2=4(Fo2)]: The positions
of all non-hydrogen atoms for complex 5-Cs were found
from a difference Fourier electron density map and
refined anisotropically. Hydrogen atoms were refined
(b) J.L. Templeton, B.C. Ward, J. Am. Chem. Soc. 102 (1980)
3288;
(c) J.L. Templeton, B.C. Ward, G.-G.J. Chen, J.W. McDonald,
W.E. Newton, Inorg. Chem. 20 (1981) 1248;
(d) J.L. Templeton, B.C. Ward, J. Am. Chem. Soc. 102 (1980)
3288;
isotropically, and they were placed in calculated posi-
˚
Hꢂ0.95 A) and constrained to ride on their
(e) J.R. Morrow, T.L. Tonker, J.L. Templeton, Organometallics 4
(1985) 745;
tions (CÃ
/
/
respective carbon atoms.
All calculations were performed using the TEXSAN
crystallographic software package, and illustrations
(f) J.R. Morrow, T.L. Tonker, J.L. Templeton, J. Am. Chem. Soc.
107 (1985) 6956;
(g) J.L. Templeton, Adv. Organomet. Chem. 29 (1989) 1.
[9] S. Otsuka, A. Nakamura, Adv. Organomet. Chem. 14 (1976) 245.
[10] A. Mayr, K.S. Lee, M.A. Kjelsberg, D.V. Engen, J. Am. Chem.
Soc. 109 (1986) 6079.
were drawn with ORTEP
.
[11] L. Ricard, R. Weiss, W.E. Newton, G.J.-J. Chen, J.W. McDo-
nald, J. Am. Chem. Soc. 100 (1978) 1318.
5. Supplementary material
[12] (a) R.R. Schrock, L.W. Messerle, C.D. Wood, L.J. Guggenberger,
J. Am. Chem. Soc. 100 (1978) 3793;
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
(b) R.R. Schrock, W.E. Crowe, G.C. Bazan, M. DiMare, M.B.
O’Regan, M.H. Schofield, Organometallics 10 (1991) 1832.
[13] J. Kress, J.A. Osborn, J. Am. Chem. Soc. 109 (1987) 3953.
[14] For comprehensive reviews: (a) K.J. Ivin, J.C. Mol, Olefin
Metathesis and Metathesis Polymerization, Academic Press,
London, 1997;
Data Centre, CCDC Nos. 181587ꢀ181590 for the
/
compounds 1-Cs, 1-C1, 2-Cs and 4-Cs, respectively.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: ꢃ44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
/
(b) F.Z. Dorwald, Metal Carbenes in Organic Synthesis, Wiley-
¨
VCH, Weiheim, 1998;
(c) A. Furstner, Alkene Metathesis in Organic Synthesis,
¨
Springer-Verlag, Berlin, 1998;
(d) R.R. Schrock, Pure Appl. Chem. 66 (1994) 1447.
[15] J. Feldman, R.R. Schrock, Prog. Inorg. Chem. 39 (1991) 1.
[16] R.R. Schrock, Acc. Chem. Res. 12 (1979) 98.
[17] R.H. Grubbs, W. Tumas, Science 243 (1989) 907.
[18] B.M. Novak, W. Risse, R.H. Grubbs, Adv. Polym. Sci. 102 (1990)
47.
Acknowledgements
Y.T. is a research fellow of the Japan Society for the
Promotion of Science, 2000ꢀ2002.
/
[19] N.W. Eilerts, J.A. Heppert, Polyhedron 14 (1995) 3255.
[20] M. Schuster, S. Blechert, Angew. Chem. Int. Ed. Engl. 36 (1997)
2036.
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