Effect of the nature of carbene fragments in the tungsten complexes PhMe2E-CH=W(NAr)(OR')2 and Me3E-CH=W(NAr)(OR') 2 (E = C, Si) on their catalytic properties in olefin metathesis reactions

Article abstract of DOI:10.1007/s11172-008-0253-y

Catalytic properties of the silicon-containing carbene complexes of tungsten Me₃Si-CH=W(NAr)(OR')₂(1) and PhMe ₂Si-CH=W(NAr)(OR')₂ (2) and their hydrocarbon analogs Me₃C-CH=W(NAr)(OR')₂ (3) and PhMe₂C-CH=W(NAr) (OR')₂ (4) (Ar = 2,6-Prⁱ ₂C₆H ₃, R' = CMe₂CF₃) were studied in homometathesis of hex-1-ene, metathesis polycondensation of deca-1,9-diene, and ring opening metathesis polymerization of cyclooctene. The nature of the carbene fragment in the tungsten catalysts substantially affects their catalytic activity. Silicon-containing catalysts 1 and 2 were found to be 3-5 times less active than their hydrocarbon analogs 3 and 4. Metathesis polymerization of cyclooctene in the bulk with initiators 1-4 completed within a few minutes to form a block. Stereoregularity of the formed polyoctenamers depends to a considerable extent on the nature of the carbene fragments in the starting initiators. Initiators 1-2 lead to polyoctenamers mainly containing the cis-units, whereas the use of complexes 3 and 4 affords polyoctenamers mainly containing the trans-units. The structures of novel compound 2 and known complexes 1, 3, and 4 were determined by X-ray diffraction analysis.

Full text of DOI:10.1007/s11172-008-0253-y

1
874
Russian Chemical Bulletin, International Edition, Vol. 57, No. 9, pp. 1874—1879, September, 2008
Effect of the nature of carbene fragments in the tungsten complexes
PhMe E—CH=W(NAr)(OR´) and Me E—CH=W(NAr)(OR´)2
3
2
2
3
(
E = C, Si) on their catalytic properties in olefin metathesis reactions
A. L. Bochkarev, Yu. E. Begantsova, E. O. Platonova, G. V. Basova, I. K. Grigor´eva, N. E. Stolyarova,
I. P. Malysheva, G. K. Fukin, E. V. Baranov, Yu. A. Kurskii, L. N. Bochkarev, and G. A. Abakumov
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
4
9 ul. Tropinina, 603950 Nizhnii Novgorod, Russian Federation.
Fax: +7 (831) 462 1497. Eꢀmail: lnb@iomc.ras.ru
Catalytic properties of the siliconꢀcontaining carbene complexes of tungsten
Me Si—CH=W(NAr)(OR´) (1) and PhMe Si—CH=W(NAr)(OR´) (2) and their hydroꢀ
3
2
2
2
carbon analogs Me C—CH=W(NAr)(OR´) (3) and PhMe C—CH=W(NAr)(OR´)2 (4)
3
2
2
i
(
Ar = 2,6ꢀPr C H , R´ = CMe CF ) were studied in homometathesis of hexꢀ1ꢀene, metathesis
2 6 3 2 3
polycondensation of decaꢀ1,9ꢀdiene, and ring opening metathesis polymerization of cyꢀ
clooctene. The nature of the carbene fragment in the tungsten catalysts substantially affects their
catalytic activity. Siliconꢀcontaining catalysts 1 and 2 were found to be 3—5 times less active
than their hydrocarbon analogs 3 and 4. Metathesis polymerization of cyclooctene in the bulk
with initiators 1—4 completed within a few minutes to form a block. Stereoregularity of
the formed polyoctenamers depends to a considerable extent on the nature of the carbene
fragments in the starting initiators. Initiators 1—2 lead to polyoctenamers mainly containing
the cisꢀunits, whereas the use of complexes 3 and 4 affords polyoctenamers mainly containing
the transꢀunits. The structures of novel compound 2 and known complexes 1, 3, and 4 were
determined by Xꢀray diffraction analysis.
Key words: carbene complexes, tungsten, silicon, synthesis, Xꢀray diffraction analysis, metꢀ
athesis, polymerization.
Carbene complexes of tungsten of the type
R—CH=W(NAr)(OR´)2 (R
But, PhMe C,
of tungsten Me Si—CH=W(NAr)(OR´) (1) and
3 2
=
PhMe Si—CH=W(NAr)(OR´) (2) and their hydrocarꢀ
2
2
2
i
t
Ar = 2,6ꢀPr C H , R´ = Alk, Aryl), along with analogous
bon analogs Bu —CH=W(NAr)(OR´)
2
(3) and
2
6
3
i
molybdenum compounds, are widely used as catalysts for
the metathesis of olefins and their numerous functional
derivatives.1 The catalytic activity of the tungsten and
molybdenum catalysts is determined, to a considerꢀ
able extent, by the nature of the alkoxide groups and imiꢀ
PhMe C—CH=W(NAr)(OR´) (4) (Ar = 2,6ꢀPr C H ,
2 2 2 6 3
R´ = CMe CF ) in the homometathesis of hexꢀ1ꢀene,
2
3
—4
metathesis polycondensation of decaꢀ1,9ꢀdiene, and ring
opening metathesis polymerization of cyclooctene chosen
as test reactions.
4
de ligands. The influence of the nature of the carbene
Schrock catalysts 1, 3, and 4 were synthesized as deꢀ
7
,8
fragments in the tungsten and molybdenum complexes
on their catalytic properties in olefin metathesis reacꢀ
tions remain poorly studied. We have recently5
found that the composition and structure of the organoeleꢀ
ment substituent at the carbene carbon atom in the
scribed earlier. New tungsten derivative 2 containing
the dimethylphenylsilyl substituent at the carbenic carꢀ
bon atom was synthesized by the reaction of neoꢀ
pentylidene complex 3 with vinyldimethylphenylsilane
(Scheme 1).
,6
R E—CH=Mo(NAr)(OR´)2 molybdenum complexes
3
i
(
E = Si, Ge; R = Alk, Aryl; Ar = 2,6ꢀPr C H ,
Scheme 1
2
6
3
R´ = CMe CF ) exert a substantial effect on their catalytic
2
3
activity and determine, to a great extent, stereoregularity
of polyoctenamers obtained by the ring opening metatheꢀ
sis polymerization of cyclooctene involving these comꢀ
plexes. Therefore, it seemed reasonable to elucidate
the effect of the carbene fragments on the catalytic proꢀ
perties of the siliconꢀcontaining carbene complexes
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1840—1845, September, 2008.
066ꢀ5285/08/5709ꢀ1874 © 2008 Springer Science+Business Media, Inc.
1

Carbene fragments in tungsten complexes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1875
1
According to the data of H NMR spectroscopy,
C(21)
C(22)
the reaction between the reactants is accomplished within
.5 h to form complex 2 in nearly quantitative yield. Afꢀ
C(20)
C(29)
3
C(23)
C(27)
ter removal of the solvent and volatile products, comꢀ
pound 2 is isolated as a viscous oily substance unstable
in air and highly soluble in usual organic solvents. In
the crystalline state complex 2 was isolated in 33% yield
after crystallization from a minimum amount of ether
at –20 °C.
The structures of complexes 1—4 were determined by
Xꢀray diffraction analysis (Figs 1—4, Table 1). Complex 2
is isostructural to the earlier6 described complex
PhMe Si—CH=Mo(NAr)(OR´) (Ar = 2,6ꢀPr C H ,
R´ = CMe CF ), and complex 1 is isostructural to
Me Е—CH=Mо(NAr)(OR´)2 (E
Me Ge—CH=W(NAr)(OR´) (Ar = 2,6ꢀPr C H ,
C(19)
C(26)
C(4)
C(3) C(8)
C(2)
C(28) C(28)
C(24)
C(5)
C(6)
C(25)
N(1)
W(1)
O(2)
Si(1)
C(1)
C(9)
C(16)
С(13)
F(1)
C(7)
i
O(1)
C(10)
C(17)
C(14)
2
2
2
6
3
6
C(11)
F(3)
2
3
C(15)
= Si, Ge) and
3
i
C(12)
3
2
2
6
3
F(6)
F(2)
6
,9,10
F(4)
R´ = CMe CF ).
The tungsten atoms in structures
—4 have a distorted tetrahedral coordination. The
W(1)—C(1) distances are 1.877(4) (1), 1.888(3) (2),
.891(3) (3), and 1.880(1) Å (4), which is comparable
2
3
F(5)
1
Fig. 1. Molecular structure of complex 2 (thermal ellipsoids are
presented with the 30% probability).
1
with similar distances of 1.877(1)—1.889(2) Å in
PhMe Е—CH=Mo(NAr)(OR´) (Е = Si (2a), C (2b)),
The catalytic properties of synthesized carbene comꢀ
plex 2 and known catalysts 1, 3, and 4 were studied in test
reactions of hexꢀ1ꢀene homometathesis, metathesis polyꢀ
condensation of decaꢀ1,9ꢀdiene, and ring opening metꢀ
athesis polymerization of cyclooctene.
A comparison of the reaction rate constants suggests
that in hexꢀ1ꢀene homometathesis (Table 2) siliconꢀconꢀ
taining catalysts 1 and 2 exhibit almost equal catalytic
activity and although they are about 3 times less active
than their hydrocarbon analogs 3 and 4. According to the
2
2
Me Е—CH=Mо(NAr)(OR´) (E = Si (1a), Ge (1b)), and
3
2
Me Ge—CH=W(NAr)(OR´) (1c). The Si(1)—C(1) disꢀ
3
2
tances in molecules 1 and 2 are 1.828(4) and 1.852(3) Å,
respectively, which is insignificantly shorter than similar
distances in compounds 1a (1.862(2) Å) and 2a (1.856(2) Å).
Note that the Si(1)—C(1) distances in structures 1 and 2
lie in the interval typical of ordinary bonds Si(1)—C(Me,
Ph): 1.840(4)—1.881(4) Å. The R C—C(H) distances in
3
complexes 3 and 4 are 1.522(4) and 1.530(1) Å, respecꢀ
tively, which is close to the value for the ordinary
bond Csp3—Csp2 (1.507 Å).11 It is most likely that
this indicates the absence of electron density delocalizaꢀ
tion in the W=C(H)—Si(Me Ph), W=C(H)—Si(Me ),
C(2)
C(3)
Si(1)
2
3
W=C(H)—С(Me ), and W=C(H)—С(Me Ph) fragments.
3
2
Similar situation is observed for complexes 1a—c and 2a,b.
The values of the W(1)—C(1)—Si(1) angles in compounds
F(3)
H(1)
C(1)
F(2)
C(7)
C(5)
C(11)
1
and 2 are 139.1(2) and 138.9(2)°, which are close to the
values of analogous angles in structures 1a—с and 2a.
In the complex Ph Si—CH=Mo(NAr)(OR´) (Ar =
C(10)
C(8)
C(4)
F(1)
3
2
C(9)
i
5
=
2,6ꢀPr C H , R´ = CMe CF ), the angle Mo—C(H)—Si
F(4)
W(1)
2
6
3
2
3
C(20)
is equal to 144.8(2)°, which characterizes the large steric
C(12)
O(1)
C(6)
C(21)
O(2)
F(6)
size of the SiPh group compared to the groups SiMe Ph
3
2
С(19)
N(1)
and SiMe . However, in complexes 3, 4, and 2b containing
3
F(5)
the neopentyl (3) and neophenyl (4, 2b) ligands the
M—C(H)—С angles (M = W (3, 4), Mo (2b)) are
C(24)
C(13)
C(18)
C(14)
1
44.3(2)—144.79(8)°. Evidently, since the С(Н)—СR3
(
1.514(4)—1.530(1) Å) distances in structures 3, 4, and 2b
C(15)
are shorter than С(Н)—Si(Me Ph) in compounds 2
2
C(22)
C(23)
and 2a and С(Н)—Si(Me ) in complexes 1 and 1a
3
(
1.828(4)—1.862(2) Å), the nonvalent interactions beꢀ
C(17)
C(16)
tween the C(H)—СR fragment and the ligands OR´ and
3
NAr are stronger, which increases the M—C(H)—С angle
Fig. 2. Molecular structure of complex 1 (thermal ellipsoids are
in structures 3, 4, and 2b.
presented with the 30% probability).

1
876
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Bochkarev et al.
F(5)
F(4)
Table 1. Selected bond lengths (d) and bond angles (ω) in comꢀ
plexes 1—4
C(12)
C(11)
C(19)
C(18)
C(10) F(6)
C(6)
Parameter
Bond
1
2
3
4
C(17)
C(20)
C(5)
d/Å
C(24)
O(2)
N(1)
W(1)—N(1)
W(1)—O(1)
W(1)—O(2)
W(1)—C(1)
W(1)—C(21)
Si(1)—C(1)
C(21)—C(22)
1.730(3) 1.731(3) 1.739(2) 1.712(1)
1.889(3) 1.886(2) 1.889(2) 1.903(1)
1.897(2) 1.889(2) 1.908(2) 1.904(1)
C(23)
W(1)
C(4)
C(1)
C(22)
1.877(4) 1.888(3)
—
—
C(21)
C(14)
—
—
1.891(3) 1.880(1)
C(3) C(2)
1.828(4) 1.852(3)
—
—
O(1)
C(9)
C(13)
C(25)
F(2)
—
—
1.522(4) 1.530(1)
C(7)
F(3)
Angle
ω/deg
W(1)—C(1)—Si(1)
W(1)—C(21)—C(22)
139.1(2) 138.9(2)
—
—
C(8)
—
—
144.6(2) 144.79(8)
C(15)
C(16)
F(1)
Fig. 3. Molecular structure of complex 3 (thermal ellipsoids are
presented with the 30% probability).
siliconꢀcontaining complexes 1 and 2 are about 3—5 times
less active than their hydrocarbon analogs 3 and 4. Under
the accepted conditions (room temperature, reaction duꢀ
ration 60 min), the reaction products are mixture of oligoꢀ
mers (see Table 3). The ratio of transꢀ and cisꢀunits in the
formed oligomers is the same in all cases: 62 : 38.
Tungsten carbene complexes 1—4 are active initiators
of the ring opening metathesis polymerization of cyꢀ
clooctene. Before block formation, the polymerization proꢀ
cess is complished within several minutes, and a nearly
complete conversion of the monomer occurs according to
the NMR spectroscopy data. The study of the polymer
samples showed that the ratio of the transꢀ to cisꢀunits in
the polyoctenamers formed depends substantially on the
nature of the carbene fragment in the starting initiators
data of 13C NMR spectroscopy, in all cases, decꢀ5ꢀene
formed during the reactions is a mixture of the transꢀ
and cisꢀisomers in a ratio of ~2 : 1. The earlier studꢀ
ied analogous siliconꢀcontaining carbene complexꢀ
es of molybdenum Me Si—CH=Mo(NAr)(OR´)
3
2
and PhMe Si—CH=Mo(NAr)(OR´) are also less acꢀ
2
2
tive in hexꢀ1ꢀene metathesis than their hydrocarꢀ
t
bon
analogs
Bu —HC=Mo(NAr)(OR´)2
and
PhMe C—CH=Mo(NAr)(OR´) . As a whole, the molybꢀ
2
2
denum catalysts are an order of magnitude more active
than analogous tungsten catalysts.5
,6
In the metathesis polycondensation of decaꢀ1,9ꢀdiene
(
Table 3), as well as in the homometathesis of hexꢀ1ꢀene,
(
Table 4). Siliconꢀcontaining initiators 1 and 2 lead to the
formation of polymers mainly containing the cisꢀunits. On
the contrary, in the case of hydrocarbon analogs 3 and 4,
the polymers formed mainly contain the transꢀunits. We
C(20)
C(8)
F(6)
6
have recently found that, when the molybdenum carbene
C(9)
C(17)
O(2)
C(18)
C(19)
complexes are used as the initiators of the ring opening
metathesis polymerization of cyclooctene, stereoregularity
of the polyoctenamers formed also depends considerably
on the nature of the carbene fragment in the initial molybꢀ
denum complexes. According to the commonly accepted
C(3)
F(4)
F(2)
C(2)
C(7)
C(1)
F(5)
N(1)
W(1)
C(4)
F(1)
C(5)
C(12)
C(10)
C(22)
C(6)
C(14)
O(1)
Table 2. Kinetic data for hexꢀ1ꢀene metathesis using the tungꢀ
sten catalysts*
F(3)
C(16)
C(21)
C(13)
C(15)
C(23)
C(30)
C(11)
C(24)
C(25)
k•106
/L mol–1 s–1
Cataꢀ
lyst
Т
/°С
Conversion
(%)
C(26)
1
2
3
4
20
19
19
19
2.8
2.6
8.2
7.3
0.8±0.1
0.7±0.1
2.8±0.2
2.6±0.2
C(29)
C(27)
C(28)
Fig. 4. Molecular structure of complex 4 (thermal ellipsoids are
presented with the 30% probability).
* Conditions: [hexꢀ1ꢀene]/[catalyst] = 300; in the absence of
solvent; the reaction duration was 60 min.

Carbene fragments in tungsten complexes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1877
Table 3. Kinetic data for decaꢀ1,9ꢀdiene metathesis polycondenstion using the tungsten catalysts* and the
molecular mass characteristics of the formed oligomers**
6
¯
¯
¯
¯
n
Cataꢀ
lyst
Т/°С
Conversion
(%)
k•10
M
M
M /M
w
n
w
/L mol– s–1
1
1
2
3
4
21
18
19
19
4.1
2.2
9.2
1.1±0.1
0.6±0.1
2.7±0.2
3.2±0.2
600
450
760
750
460
320
300
430
1.30
1.30
2.53
1.74
11.1
*
*
Conditions: [decaꢀ1,9ꢀdiene]/[catalyst] = 100; in the absence of solvent; the reaction duration was 60 min.
* The molecular mass characteristics are given for oligomers with the 10% conversion.
mechanism of cycloolefin metathesis polymerization inꢀ
The nature of the carbene fragment in the tungsten catalysts
was shown to noticeably affect their catalytic activity. The
siliconꢀcontaining complexes are 3—5 times less active
than their hydrocarbon analogs. It was found that the steꢀ
reoregularity of the polyoctenamers formed in the ring
opening metathesis polymerization of cyclooctene dependꢀ
ed substantially on the nature of the carbene fragment in
the starting tungsten initiators. When the siliconꢀcontainꢀ
ing carbene complexes are used, the polyoctenamers
with the predominant content of the cisꢀunits are
formed, whereas the polyoctenamers mainly containing
the transꢀunits are formed using the tungsten complexes
with the hydrocarbon carbene fragment.
3
,12
volving the carbene complexes of transition metals,
the
substituent at the carbenic carbon atom of the starting
initiators is transformed in the terminal group of the growꢀ
ing macromolecules. The studied ring opening metathesis
polymerization of cyclooctene on the tungsten carbene
complexes and the earlier studied polymerization of cyꢀ
6
clooctene involving the molybdenum catalysts were carꢀ
ried out under the same conditions, and the catalysts difꢀ
fered only by the substituent at the carbenic carbon atom.
Therefore, stereoregularity of the macromolecular chain
was determined by the nature of the terminal group of the
growing macromolecules. As far as we know, no similar
effect has previously been described in the literature. One
of the possible explanations for this fact is as follows. At the
stages of growth, the terminal group of the formed macroꢀ
molecule is arranged in space, most likely, fairly close to
the catalytic center, coordinates to the central metal atom,
and, depending on the structure, determines the most faꢀ
vorable coordination of the next monomer molecule,
which finally results in the predominant formation of the
transꢀ or cisꢀunit in the growing macromolecule.
Experimental
Experiments with compounds unstable in air were carried
out in evacuated systems using the standard Schlenk technique.
Thoroughly dried and degassed solvents were applied. Comꢀ
7
7
pounds 1, 3, and 4 (Ref. 8) and PhMe SiCH=CH (see Ref. 13)
2
2
were synthesized as described earlier.
The H and 13C NMR spectra were recorded on a Bruker
1
DPXꢀ200 spectrometer using C D and СDCl3 as solvents and
6
6
Thus, the new siliconꢀcontaining carbene complex of
tungsten was synthesized. The catalytic properties of the
compound synthesized and a series of the known tungsten
catalysts were studied in the homometathesis of hexꢀ1ꢀ
ene, metathesis polymerization of decaꢀ1,9ꢀdiene, and
ringꢀopening metathesis polymerization of cyclooctene.
Me Si as the internal standard.
4
The experimental sets of intensities were measured on
a Smart APEX automated diffractometer (graphite monochromaꢀ
tor, МоꢀКα radiation, ϕ—ω scan mode, λ = 0.71073 Å). Strucꢀ
tures 1—4 were solved by a direct method and refined by the
leastꢀsquares method for F2 in the anisotropic approximation
hkl
for all nonꢀhydrogen atoms using the SHELXTL program packꢀ
1
4
age. The SADABS program was used to apply an absorption
1
5
correction. The H atoms were placed in the geometrically calꢀ
culated positions and refined in the riding model. The main crysꢀ
tallographic data for compound 1 (C24H39F NO SiW) at 100 K
Table 4. Characteristics of polyoctenamers obtained in the bulk
using the tungsten catalysts*
6
2
are the following:
a = 10.2453(4) Å, b = 30.6476(11) Å, c = 10.5719(4) Å,
M = 699.50, space group P2(1)/c,
¯
¯
¯
¯
Cataꢀ
lyst
Ratio
trans : cis
M
M
M /M
w
n
w
n
3
–3
β = 118.179(1)°, V = 2926.07(19) Å , Z = 4, d = 1.588 g cm
,
calc
μ = 4.047 mm– , Tmax/Tmin = 0.7648/0.3486, F(000)= 1392,
1
1
2
3
4
13 : 87
14 : 86
91 : 9
528300
532800
105500
554700
238200
283700
64700
2.22
1.88
1.63
1.90
1
6
.33° < θ < 27.5°; 27 690 reflections were collected, of which
685 reflections (Rint = 0.0307) were independent, R = 0.0418
1
and wR = 0.0846 (I > 2σ(I)), R = 0.0510, wR = 0.0874 (by all
83 : 17
291800
2
1
2
2
data), GOF(F ) = 1.047, residual electron density ρmax/ρmin
= 3.007/–1.127 e•Å–3. The main crystallographic parameꢀ
ters for structure 2 (C29H41F NO SiW) at 100 K are the followꢀ
=
*
Conditions: [cyclooctene]/[catalyst] = 100; the reaction duraꢀ
tion until the formation of a solid block in the case of cataꢀ
6
2
lysts 1, 2, and 3 was 20, 25, and 5 min, respectively.
ing: M = 761.57, space group P2(1)/c, a = 16.3724(4) Å,

1
878
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
Bochkarev et al.
b = 17.9479(5) Å, c = 11.3163(3) Å, β = 91.334(1)°,
1.29 (both s, 6 Н each, OСМе СF ); 3.66 (sept, 2 Н, СНМе );
6.98—7.24 (m, 3 Н, 2,6ꢀPr C H + 3 Н, H(2), H(4), H(6),
2 6 3
2
3
2
V = 3324.40(15) Å , Z = 4, d = 1.522 g cm–3, μ = 3.569 mm
3
–1
,
i
calc
Tmax/Tmin = 0.7167/0.2684, F(000) = 1520, 2.44° < θ < 26.0°;
695 collected reflections of which 6480 reflections
Rint = 0.0277) were independent, R = 0.0344 and wR = 0.0857
CHSiMe Ph); 7.48—7.53 (m, 2 Н, Н(3), Н(5), CHSiMe Ph);
2 2
9.49 (s, 1 Н, W=CHSiMe Ph). C NMR (C D ), δ: 0.9
2 6 6
1
3
9
(
(W=CHSiMe Ph); 23.8 (CHMe ), 24.3, 24.4 (OCMe CF ); 28.3
2 2 2 3
1
2
2
2
(
=
I > 2σ(I)), R = 0.0485, wR = 0.0910 (by all data), GOF(F ) =
(CHMe ); 80.2 (q, OCMe CF , JC,F= 29.0 Hz); 122.9 (С(3),
2 2 3
1
2
1.047, residual electron density ρmax/ρmin = 1.684/–0.493 e•Å–3
.
2,6ꢀPr C H ); 126.9 (С(4), 2,6ꢀPr C H ); 127.0 (q, OCMe CF ,
2 6 3 2 6 3 2 3
i
i
1
The main crystallographic parameters for structure
3
JC,F = 285 Hz); 128.4 (С(3), CHSiMe Ph); 129.1 (С(4),
2
(
C25H39F NO W) at 100 K are the following: M = 683.42, space
SiMe Ph); 133.8 (С(2), SiMe Ph); 141.8 (С(1), SiMe Ph);
2 2 2
144.9 (С(2), 2,6ꢀPr C H ); 152.1 (С(1), 2,6ꢀPr C H ); 227.1
2 6 3 2 6 3
(W=CHSi).
6
2
i
i
group P2(1)/c, a = 10.2190(4) Å, b = 30.4509(14) Å,
c = 10.3468(4) Å, β = 117.2910(10)°, V = 2861.3(2) Å , Z = 4,
dcalc = 1.586 g cm , μ = 4.097 mm , Tmax/Tmin = 0.7352/0.4274,
F(000) = 1360, 1.34° < θ < 25.99°; 24 182 collected reflections of
which 5593 reflections were independent (Rint = 0.0250),
R1 = 0.0283 and wR2 = 0.0561 (I > 2σ(I)), R1 = 0.0326,
wR = 0.0574 (by all data), GOF(F ) = 1.070, residual electron
density ρmax/ρmin = 1.472/–0.754 e•Å–3. The main crystalloꢀ
graphic parameters for structure 4 (C30H41F NO W) at 100 K
3
–3
–1
Since no detailed quantitative characteristics were published
for compound 4, we present the NMR and elemental analysis
data. Found (%): С, 48.15; Н, 5.40. C30H41F WNO . Calculated
6
2
1
(%): С, 48.34; H, 5.55. H NMR (C D ), δ: 1.18, 1.23 (both s,
6
6
2
6 H each, OCMe CF ); 1.24 (d, 12 H, CHMe , J = 7.0 Hz); 1.60
2 3 2
2
3
(s, 6 H, CMe Ph); 3.73 (sept, 2 H, CHMe , JH,H = 6.8 Hz);
2
2
i
6.96—7.22 (m, 3 H, 2,6ꢀPr C H + 3 H, H(2), H(4), H(6),
6
2
2
6
3
are the following: M = 745.49, space group C2, a = 18.6868(8) Å,
b = 11.5698(5) Å, c = 15.8320(7) Å, β = 114.0320(10)°,
CMe Ph); 7.31—7.39 (m, 2 H, H(3), H(5), CMe Ph); 8.53 (s, 1 H,
2 2
2
13
W=CH, J
= 13.6 Hz). C NMR (C D ), δ: 23.8 (OCMe CF );
6 6 2 3
W,H
3
–3
–1
V = 3126.2(2) Å , Z = 4, d
= 1.584 g cm , μ = 3.757 mm
,
24.2 (CHMe ); 28.2 (CHMe ); 32.8 (CMe Ph); 51.4 (CMe Ph);
2 2 2 2
calc
2
i
Tmax/Tmin = 0.5512/0.4535, F(000) = 1488, 2.39° < θ < 25.00°;
2 059 collected reflections of which 5386 reflections were indeꢀ
pendent (Rint = 0.0255), R1 = 0.0452 and wR2 = 0.1137
79.9 (q, OCMe CF , J = 29.0 Hz); 123.1 (С(3), 2,6ꢀPr C H );
2 3 C,F 2 6 3
i
1
126.08 (С(3), CMe Ph); 126.11 (С(4), 2,6ꢀPr C H ); 127.2
2 2 6 3
1
(q, OCMe CF , J = 285 Hz); 127.2, 128.4 (С arom.); 145.9
2
3
C,F
2
i
(
I > 2σ(I)), R = 0.0547, wR = 0.1222 (by all data), GOF(F ) =
(С(2), CMe Ph); 151.6 (С(2), 2,6ꢀPr C H ); 151.9 (С(1),
2 2 6 3
CMe Ph); 243.2 (W=CH, J
1
2
1
1
.106, absolute structural parameter 0.508(10), residual electron
= 202.8 Hz).
W,C
2
density ρmax/ρmin = 2.460/–0.949 e•Å–3
.
Metathesis of hexꢀ1ꢀene. The reactions were carried out withꢀ
out solvent at ~20 °C. Hexꢀ1ꢀene (0.9091 g, 10.820 mmol) was
added under an argon atmosphere to an ampule connected with
a gas burette and containing catalyst 2 (27.2 mg, 0.036 mmol),
and the mixture was stirred. The amount of evolved ethylene was
determined volumetrically at an interval of 1 min during 1 h. The
Hexꢀ1ꢀene, decaꢀ1,9ꢀdiene, and cyclooctene (Aldrich) were
degassed before use and kept above the sodium mirror. Necesꢀ
sary amounts were sampled by condensation in vacuo. Kinetic
experiments and the determination of the secondꢀorder reaction
rate constants for hexꢀ1ꢀene homometathesis and decaꢀ1,9ꢀdiꢀ
ene metathesis polycondensation were conducted according to
reaction was stopped by the addition of Al O3 to the reaction
2
earlier described procedures.1
6,17
Polymerization was carried out
in the absence of solvent. The molecular weight distribution of
the polymers was determined by gel permeation chromatography
mixture. Unconverted hexꢀ1ꢀene was removed by evaporation
13
in vacuo, and according to the C NMR spectroscopy data, the
remaining liquid products were a mixture of transꢀ and cisꢀdecꢀ
1
9
(
GPC) on a Knauer chromatograph with a Smartline RID 2300
5ꢀenes in a ratio of 66 : 34. The reactions of hexꢀ1ꢀene metꢀ
athesis using other catalysts were carried out similarly. At least
five kinetic experiments were conducted for each catalyst.
Metathesis polycondensation of decaꢀ1,9ꢀdiene. The reactions
were carried out without solvent at ~20 °C. Decaꢀ1,9ꢀdiene
(1.406 g, 10.170 mmol) was added under an argon atmosphere to
an ampule connected with a gas burette and containing catalyst 1
(68.6 mg, 0.098 mmol), and the mixture was stirred. The amount
of evolved ethylene was determined volumetrically at an interval
of 1 min during 1 h. The reaction was stopped by the addition of
one droplet of benzaldehyde to the reaction mixture. The decaꢀ
1,9ꢀdiene that did not react was removed by evaporation in vacuo
at 70 °C, and the remaining oligomers were analyzed by GPC to
determine the molecular weight characteristics. The ratio of the
differential refractometer as a detector with a set of two Pheꢀ
4
5
nomenex columns (sorbent Phenogel, pore size 10 and 10 Å).
The eluent was THF (2 mL min–1, 40 °C). The columns were
calibrated by 13 polystyrene standards. Oligomers were analyzed
on a Shimadzu chromatograph with a RIDꢀ10A differential reꢀ
fractometer as a detector using a Phenomenex column (sorbent
Phenogel, pore size 500 Å). The eluent was THF (1 mL min–
1
,
4
0 °C). The columns were calibrated by seven polystyrene stanꢀ
dards. The ratio of the transꢀ to cisꢀunits in the polymers was
1
3
determined by C NMR spectroscopy using a known proꢀ
cedure.18
2
,6ꢀDiisopropylphenylimidoꢀbis(1,1ꢀdimethylꢀ2,2,2ꢀtrifluoroꢀ
ethanolato)(dimethylphenylsilylmethylidene)tungsten (2). A soluꢀ
13
tion of PhMe SiCH=CH2 (0.094 g, 0.58 mmol) in benzene
transꢀ and cisꢀunits was determined by C NMR spectroscopy
2
1
8
(
3 mL) was added at ~20 °C to a dark yellow solution of
using a known procedure. The decaꢀ1,9ꢀdiene metathesis polyꢀ
condensation reactions were carried out similarly. At least five
kinetic experiments were carried out for each catalyst.
t
Bu HC=W(NAr)(OCMe CF ) (0.40 g, 0.59 mmol) in benzene
2
3 2
(
5 mL). The reaction mixture was stored for 3.5 h at ~20 °C. The
solvent and volatile products were removed by evaporation
in vacuo. After the residue was recrystallized from a minimum
amount of ether at –20 °C, compound 2 was obtained in a yield
of 0.13 g (33%) as unstable in air light yellowꢀgreen crystals.
Found (%): С, 45.95; Н, 5.47. C29H41F NO SiW. Calculated
Ringꢀopening metathesis polymerization of cyclooctene. Cyꢀ
clooctene (0.6352 g, 5.764 mmol) was added to an ampule filled
with argon and containing catalyst 2 (43.8 mg, 0.058 mmol), and
the mixture was stirred at ~20 °C. The solid transparent block
was formed within 25 min. The reaction mixture was additionally
kept for 1 h at ~20 °C. A polymer sample was dissolved under an
6
2
(
%): С, 45.74; H, 5.42. 1H NMR (C D ), δ: 0.41 (s, 6 H,
6 6
CHSiMe Ph); 1.22 (d, 12 H, CHMe , J
= 7.0 Hz); 1.22 and
argon atmosphere in CDCl with an addition of a small amount
2
2
H,H
3

Carbene fragments in tungsten complexes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 9, September, 2008
1879
of benzaldehyde to decompose the catalyst. 1H and 13C NMR
spectroscopy was used for analysis. It was found that the polyꢀ
octenamer formed contained no starting cyclooctene. Thus, the
yield of the polymer was nearly quantitative. To perform the
GPC analysis, a polymer sample was dissolved under an argon
atmosphere in THF with an addition of benzaldehyde. The moꢀ
lecular weight characteristics are given in Table 4. It was shown
in special experiments that the molecular weight characteristics
remained unchanged after reprecipitation from methanol. The
reactions of ringꢀopening metathesis polymerization of cyꢀ
clooctene using other catalysts and analyses of the polymer prodꢀ
ucts were carried out similarly.
7. R. R. Schrock, R. T. DePue, J. Feldman, C. J. Schaverien,
J. C. Dewan, A. H. Lui, J. Am. Chem. Soc., 1988, 110, 1423.
8. R. R. Schrock, R. T. Depue, J. Feldman, K. B. Yap, D. C.
Yang, W. M. Davis, L. Park, M. DiMare, M. Schofield,
J. Anhaus, E. Walborsky, E. Evitt, C. Krüger, P. Betz, Orgaꢀ
nometallics, 1990, 9, 2262.
9. L. N. Bochkarev, A. V. Nikitinskii, Yu. E. Begantsova, V. I.
Shcherbakov, N. E. Stolyarova, I. K. Grigorieva, I. P. Malyꢀ
sheva, G. V. Basova, G. K. Fukin, E. V. Baranov, Yu. A.
Kurskii, G. A. Abakumov, J. Organomet. Chem., 2005,
690, 3212.
10. L. N. Bochkarev, Yu. E. Begantsova, A. L. Bochkarev, N. E.
Stolyarova, I. K. Grigorieva, I. P. Malysheva, G. V. Basova,
E. O. Platonova, G. K. Fukin, E. V. Baranov, Yu. A. Kurskii,
G. A. Abakumov, J. Organomet. Chem., 2006, 691, 5240.
11. F. H. Allen, O. Kennard, D. G. Watson, J. Chem. Soc., Perꢀ
kin Trans. 2, 1987, S1.
The authors are grateful to V. D. Myakushev and S. A.
Ponomarenko (N. S. Enikolopov Institute of Synthetic
Materials, Russian Academy of Sciences) for help in the
GPC analysis of oligomers.
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos 05ꢀ03ꢀ32694,
1
2. C. W. Bielawski, R. H. Grubbs. Progr. Polym. Sci., 2007,
2, 1.
3
1
1
3. M. Kanazashi, Bull. Chem. Soc. Jpn, 1953, 26, 493.
4. G. M. Sheldrick, SHELXTL v. 6.12, Structure Determination
Software Suite, Bruker AXS, Madison, Wisconsin, USA, 2000.
5. G. M. Sheldrick, SADABS v.2.01, Bruker/Siemens Area Deꢀ
tector Absorption Correction Program, Bruker AXS, Madison,
Wisconsin, USA, 1998.
0
6ꢀ03ꢀ32728, 07ꢀ03ꢀ90822ꢀmob_st, and 08ꢀ03ꢀ00436).
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Received November 14, 2007;
in revised form April 16, 2008