Synthesis and reactions of tungsten oxo vinylalkylidene complexes: reactions of WCl2(O)(PX3) (X = OMe, R) precursors with 3,3-diphenylcyclopropene

Article abstract of DOI:10.1021/om950389c

Complexes of the type WCl₂(O)[PX₃]₃ (PX₃ = P(OMe)₃ (1); PMePh₂ (2)) were synthesized according to procedures previously described in the literature. Upon treatment with 3,3-diphenylcyclopropene, complexes 1 and 2 afforded the corresponding η²-cyclopropene complexes. Spectroscopic data of W(η²-diphenylcyclopropene)Cl₂(O)[PX₃] ₂ (PX₃ = P(OMe)₃ (4); PMePh₂ (5)) were consistent with an octahedral geometry in which the two mutually trans PX₃ ligands and the cyclopropene ligand occupy equatorial positions cis to the apical oxo ligand. The thermal rearrangement of the η²-cyclopropene complexes leads to the dimerization product of 3,3-diphenylcyclopropene: 1,1,6,6-tetraphenyl-1,3,5-hexatriene. The presence of carbene species before the dimerization occurs has been demonstrated. Upon treatment with 2 equiv of lithium hexafluoro-tert-butoxide, complexes 4 and 5 give the vinyl alkylidene complexes W(=CHCH=CPh₂)(O)[OC(CH₃)(CF₃)₂] ₂[PX₃] (PX₃ = P(OMe)₃ (10); PMePh₂ (7)). The spectroscopic data of 10 and 7 indicated a distorted trigonal bipyramid, where the oxo and alkylidene ligands are cis to each other and placed in the equatorial plane.

Full text of DOI:10.1021/om950389c

Organometallics 1996, 15, 577-584
577
Syn th esis a n d Rea ction s of Tu n gsten Oxo
Vin yla lk ylid en e Com p lexes: Rea ction s of WCl2(O)(P X3)
(X ) OMe, R) P r ecu r sor s w ith 3,3-Dip h en ylcyclop r op en e†
F. J avier de la Mata and Robert H. Grubbs*
Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry
and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
Received May 25, 1995X
Complexes of the type WCl2(O)[PX3]3 (PX3 ) P(OMe)3 (1); PMePh2 (2)) were synthesized
according to procedures previously described in the literature. Upon treatment with 3,3-
diphenylcyclopropene, complexes 1 and 2 afforded the corresponding η2-cyclopropene
complexes. Spectroscopic data of W(η2-diphenylcyclopropene)Cl2(O)[PX3]2 (PX3 ) P(OMe)3
(4); PMePh2 (5)) were consistent with an octahedral geometry in which the two mutually
trans PX3 ligands and the cyclopropene ligand occupy equatorial positions cis to the apical
oxo ligand. The thermal rearrangement of the η2-cyclopropene complexes leads to the
dimerization product of 3,3-diphenylcyclopropene: 1,1,6,6-tetraphenyl-1,3,5-hexatriene. The
presence of carbene species before the dimerization occurs has been demonstrated. Upon
treatment with 2 equiv of lithium hexafluoro-tert-butoxide, complexes 4 and 5 give the vinyl
alkylidene complexes W(dCHCHdCPh2)(O)[OC(CH3)(CF3)2]2[PX3] (PX3 ) P(OMe)3 (10);
PMePh2 (7)). The spectroscopic data of 10 and 7 indicated a distorted trigonal bipyramid,
where the oxo and alkylidene ligands are cis to each other and placed in the equatorial
plane.
In tr od u ction
The arylimido tungsten and molybdenum alkylidene
complexes are among the most effective early-transition-
metal metathesis catalysts synthesized to date.10-14
Three different types of arylimido tungsten alkylidene
complexes have been reported:
(a) Neopentyl complexes10 such as W(dCHCMe3)-
(NAr)(OR′)2. These four-coordinate monomeric species
are stabilized by the substantial steric bulk of the imido,
alkoxide, and alkylidene ligands.
Transition-metal alkylidene and metallacyclobutane
complexes are important intermediates in acyclic olefin
metathesis,1 ring-opening metathesis polymerization
(ROMP),1 acyclic diene2 and alkyne3 polymerizations,
carbonyl olefinations,4 and ring-closing metathesis5
(RCM). Notable among the isolable complexes6,7 that
catalyze these transformations are titana8- and tanta-
lacyclobutane9 derivatives and certain alkylidene com-
plexes of tungsten,10-13 molybdenum,14 rhenium,15 and
ruthenium.16
(6) For general references on transition-metal alkylidene complexes,
see: (a) Feldman, J .; Schrock, R. R. In Progress in Inorganic Chemistry;
Lippard, S. J ., Ed.; J ohn Willey & Sons: New York, 1991; pp 1-74.
(b) Nugent, W. A.; Mayer, J . M. Metal-Ligand Multiple Bonds; J ohn
Wiley & Sons: New York, 1988. (c) Schrock, R. R. In Reactions of
Coordinated Ligands; Braterman, P. S., Ed.; Plenum: New York, 1986;
Vol. 1, pp 221-283. (d) Collman, J . P.; Hegedus, L. S.; Norton, J . R.;
Finke, R. G. Principles and Applications of Organotransition Metal
Chemistry; University Science Books: Mill Valley, CA, 1987; pp 119-
137. (e) Crabtree, R. H. The Organometallic Chemistry of the Transi-
tion Metals; J ohn Wiley & Sons: New York, 1988; Chapter 11.
(7) For general references on metallacycle complexes, see: (a)
Ingroso, G. In Reactions of Coordinated Ligands; Braterman, P. S.,
Ed.; Plenum: New York, 1986; Vol. 1, pp 639-677. (c) Collman, J . P.;
Hegedus, L. S.; Norton, J . R.; Finke, R. G. Principles and Applications
of Organotransition Metal Chemistry; University Science Books: Mill
Valley, CA, 1987; Chapter 9.
† Contribution No. 9099.
X Abstract published in Advance ACS Abstracts, November 15, 1995.
(1) For general references on the metathesis reaction, see: (a)
Grubbs, R. H.; Tumas, W. Science 1989, 243, 907-915. (b) Ivin, K. J .
Olefin Metathesis; Academic Press: London, 1983. (c) Grubbs, R. H.
In Comprehensive Organometallic Chemistry; Wilkinson, G., Ed.;
Pergamon Press, Ltd.: New York, 1982; Vol. 8, pp 499-551. (d)
Leconte, M.; Basset, J . M.; Quignard, F.; Larroche, C. In Reactions of
Coordinated Ligands; Braterman, P. S., Ed.; Plenum: New York, 1986;
Vol. 1, pp 371-420.
(2) Wagener, K. B.; Boncella, J . M.; Nel, J . G. Macromolecules 1991,
24, 2649-2657.
(3) (a) Schlund, R.; Schrock, R. R.; Crowe, W. E. J . Am. Chem. Soc.
1989, 111, 8004-8006. (b) Park, L. Y.; Schrock, R. R.; Stieglitz, S. G.;
Crowe, W. E. Macromolecules 1991, 24, 3489-3495. (c) Wallace, K.
C.; Liu, A. H.; Davis, W. M.; Schrock, R. R. Organometallics 1989, 8,
644-654.
(8) (a) Gilliom, L. R.; Grubbs, R. H. J . Am. Chem. Soc. 1986, 108,
733-742. (b) Petasis, N. A.; Fu, D. J . Am. Chem. Soc. 1993, 115, 7208-
7214.
(4) (a) Pine, S. H.; Zahler, R.; Evans, D. A.; Grubbs, R. H. J . Am.
Chem. Soc. 1980, 102, 3270-3272. (b) Brown-Wesley, K. A.; Buchwald,
S. L.; Cannizzo, L.; Clawson, L.; Ho, S.; Meinhardt, D.; Stille, J . R.;
Straus, D.; Grubbs, R. H. Pure Appl. Chem. 1983, 55, 1733-1744. (c)
Aguero, A.; Kress, J .; Osborn, J . A. J . Chem. Soc., Chem. Commun.
1986, 531-533. (d) Bazan, G. C.; Schrock, R. R.; O’Regan, M. B.
Organometallics 1991, 10, 1062-1067.
(5) (a) Fu, G. C.; Grubbs, R. H. J . Am. Chem. Soc. 1992, 114, 5426-
5427. (b) Fu, G. C.; Grubbs, R. H. J . Am. Chem. Soc. 1992, 114, 7324-
7325. (c) Fu, G. C.; Grubbs, R. H. J . Am. Chem. Soc. 1993, 115, 3800-
3801. (d) Fujimura, O.; Fu, G. C.; Grubbs, R. H. J . Org. Chem. 1994,
59, 4029-2031. (e) Kim, S. H.; Bowden, N.; Grubbs, R. H. J . Am.
Chem. Soc. 1994, 116, 10801.
(9) (a) Wallace, K. C.; Liu, A. H.; Dewan, J . C.; Schrock, R. R. J .
Am. Chem. Soc. 1988, 110, 4964-4975. (b) Wallace, K. C.; Schrock,
R. R. Macromolecules 1987, 20, 448-450. (c) Wallace, K. C.; Dewan,
J . C.; Schrock, R. R. Organometallics 1986, 5, 2162-2164.
(10) Schrock, R. R.; DePue, R. T.; Feldman, J .; Schaverien, C. J .;
Dewan, J . C.; Liu, A. H. J . Am. Chem. Soc. 1988, 110, 1423-1435.
(11) (a) Kress, J .; Wesolek, M.; Osborn, J . A. J . Chem. Soc., Chem.
Commun. 1982, 514. (b) Aguero, A.; Kress, J .; Osborn, J . A. J . Chem.
Soc., Chem. Commun. 1985, 793. (c) Couturier, J .; Paillet, C.; Leconte,
M.; Basset, J . M.; Weiss, K. Angew. Chem., Int. Ed. Engl. 1992, 31,
628-631.
(12) J ohnson, L. K.; Grubbs, R. H.; Ziller, J . W. J . Am. Chem. Soc.
1993, 115, 8130-8145.
0276-7333/96/2315-0577$12.00/0 © 1996 American Chemical Society

578 Organometallics, Vol. 15, No. 2, 1996
de la Mata and Grubbs
(b) Imido vinylalkylidene complexes12 such as
W(dCHCHdCPh2)(NAr)(OR′)2[P(OMe)]3; in this case,
the smaller size of the alkylidene group requires the
presence of trimethyl phosphite in order to stabilize the
complex.
Sch em e 1
(c) Tungsten imido alkylidene complexes have been
reported by Van Koten and co-workers,13 using biden-
tate phenoxide and alkoxide ligands.
In comparison to the large number of tungsten imido
alkylidene complexes, the synthesis of tungsten oxo
alkylidene complexes that can be used in metathesis
processes was essentially unknown at the outset of this
study.17 Only a couple of tungsten oxo alkylidene
complexes are described in the literature,18,19 but these
complexes require Lewis acid activation to be metath-
esis catalysts.
In this paper we report the synthesis of the first oxo
tungsten vinylalkylidene complexes via the reaction of
appropriate tungsten(IV) oxo precursors and 3,3-diphe-
nylcyclopropene. We also report some details about
their catalytic activity in ROMP and RCM processes.
This reaction of 1 with 3, carried out in benzene,
methylene chloride, or diethyl ether, was complete in
24 h at room temperature, while 2 and 3 required at
least 6 h in benzene at 40 °C. In order to drive the
reactions to completion, a slight excess of 3 was neces-
sary. The resulting products, 4 and 5, are yellow
powders that can be purified by recrystallization from
methylene chloride/pentane.
Resu lts a n d Discu ssion
The tungsten(IV) oxo precursors WCl2(O)(PX3)3 (PX3
) P(OMe)3 (1); PMePh2 (2)) were prepared via known
or modified literature procedures20b (see Experimental
Section) (Scheme 1).
η2-Cyclop r op en e Com p lexes. Syn th esis, Ch a r -
a cter iza tion , a n d Sta bility. Syn th esis. The reac-
tion of 1 and 2 with 3,3-diphenylcyclopropene (3) was
then investigated. In both cases, only one mode of
reactivity was identified, leading to the η2-cyclopropene
complexes W(η2-diphenylcyclopropene)Cl2(O)[PX3]2 (PX3
) P(OMe)3 (4); PMePh2 (5)) (eq 1).
1
Ch a r a cter iza tion . The H-NMR spectrum of 4 in
deuterated benzene presents a triplet at δ ) 5.70 (J H-P
) 6.3 Hz) corresponding to the two olefinic protons of
the diphenylcyclopropene ligand. This indicates the
equivalence of both protons and that they are coupled
to two equivalent phosphite ligands.
This 1H-NMR spectrum also shows another triplet
found at δ ) 3.75 (J H-P ) 5.4 Hz) corresponding to the
two mutually trans phosphite ligands. The 13C-NMR
spectrum of this complex presents a triplet and a singlet
for the three-membered ring carbons of the cyclopropene
ligand and a triplet for the methyl groups of the
phosphite ligand (see Experimental Section for details).
The 31P-NMR spectrum is a singlet at δ ) 116.4, which
shows the equivalence of both phosphite ligands. The
spectroscopic data obtained for 5 are analogous to those
presented by 4.
(13) Van der Schaaf, P. A.; Abbenhuis, R. A.; Van der Noort, W. P.
A.; de Graaf, R.; Grove, D. M.; Smeets, W. J . J .; Spek, A. L.; Van Koten,
G. Organometallics 1994, 13, 1433-1444.
The spectroscopic data obtained for 4 and 5 are very
similar to that of the analogous imido η2-diphenylcy-
clopropene tungsten complexes prepared earlier,12 which
suggests a distorted octahedral structure: The olefin
carbons occupy one position in the equatorial plane, the
oxygen atom occupies one of the axial positions cis to
the 3,3-diphenylcyclopropene ligand, the two mutually
trans PX3 groups occupy the equatorial positions in each
side of the η2-diphenylcyclopropene ligand, and, finally,
the two chloride ligands occupy the remaining equato-
rial and axial positions (Figure 1).
For the tungsten imido phosphite η2-diphenylcyclo-
propene complexes, it has been shown that the chemical
shift of the olefinic proton and carbon resonances shifts
downfield as the steric bulk of the imido ligand in-
creases, corresponding to a weaker binding of the
cyclopropene in the more sterically crowded molecule.12
In the oxo phosphite complex 4, the steric bulk of the
oxo ligand is lower than that of any imido group.
However, the observed chemical shift for the olefinic
(14) (a) Murdzek, J . S.; Schrock, R. R. Organometallics 1987, 6,
1373-1374. (b) Murdzek, J . S.; Schrock, R. R. Macromolecules 1987,
20, 2640-2642. (c) Schrock, R. R.; Murdzek, J . S.; Bazan, G. C.;
Robbins, J .; DiMare, M.; O’Regan, M. J . Am. Chem. Soc. 1990, 112,
3875-3886. (d) Bazan, G. C.; Oskam, J . H.; Cho, H.-N.; Park, L. Y.;
Schrock, R. R. J . Am. Chem. Soc. 1991, 113, 6899-6907.
(15) Toreki, R.; Schrock, R. R. J . Am. Chem. Soc. 1990, 112, 2448-
2449. (b) Schofield, M. H.; Schrock, R. R.; Park, L. Y. Organometallics
1991, 10, 1844-1855.
(16) (a) Nguyen, S. T.; J ohnson, L. K.; Grubbs, R. H.; Ziller, J . W.
J . Am. Chem. Soc. 1992, 114, 3974-3975. (b) Nguyen, S. T.; Grubbs,
R. H.; Ziller, J . W. J . Am. Chem. Soc. 1993, 115, 9858.
(17) These complexes were proposed by Goddard as active, chain-
carrying metathesis catalysts for high-valent Mo, W, and Re complexes.
Rappe´, A. K.; Goddard, W. A. J . Am. Chem. Soc. 1982, 104, 448-456.
(18) (a) Schrock, R. R.; Rocklage, S.; Wengrovious, J .; Rupprecht,
G.; Fellmann, J . J . Mol. Catal. 1980, 8, 73-83. (b) Wengrovious, J .
H.; Schrock, R. R.; Churchill, M. R.; Missert, J . R.; Youngs, W. J . J .
Am. Chem. Soc. 1980, 102, 4515-4516.
(19) (a) Blosch, L. L.; Abboud, K.; Boncella, J . M. J . Am. Chem. Soc.
1991, 113, 7066-7068. (b) Bryan, J . C.; Mayer, J . C. J . Am. Chem.
Soc. 1990, 112, 2298-2308.
(20) (a) Butcher, A. V.; Chatt, J .; Leigh, G. J .; Richards, P. L. J .
Chem. Soc., Dalton Trans. 1972, 1064. (b) Carmona, E.; Sanchez, L.;
Poveda, M. L. Polyhedron 1983, 2, 797-801. (c) Bradley, D. C.;
Hursthouse, M. B.; Malik, K. M. A.; Nielson, A. J .; Short, R. L. J . Chem.
Soc., Dalton Trans. 1983, 2651-2656.

Reactions of WCl2(O)(PX3)3
Ta ble 1. Selected NMR Sp ectr a Da ta for Som e η2-Dip h en ylcyclop r op en e Com p lexesa
1H (t, HCdCH) 13C (t, HCdCH)
Organometallics, Vol. 15, No. 2, 1996 579
31P (PRR′2)
η2-diphenylcyclopropene complex
δ
J HP
δ
J CP
δ
W(η2-cyclopropene)Cl2(O)[P(OMe)3]2
5.70
4.35
5.08
5.29
4.19
6.3
6.0
5.8
6.0
5.7
69.8
76.8
64.8
66.2
72.4
13.5
7
16
15
9
116
13
118
110
5
W(η2-cyclopropene)Cl2(O)[PMePh2]2
W(η2-cyclopropene)Cl2(NPh)[P(OMe)3]2
W(η2-cyclopropene)Cl2(N-2,6-Me2Ph)[P(OMe)3]2
W(η2-cyclopropene)Cl2(NPh)[PMePh2]2
a
b
All spectra were acquired in C6D6. Uncomplexed HCdCHCPh2: 1H(CD2Cl2) δ 7.54 (HCdCH); 13C (CD2Cl2) δ 113.8 (HCdCH).
Sch em e 2
F igu r e 1. Structure proposed for η2-cyclopropene com-
plexes.
tion of 4 and 5, the cis:trans ratio varies from batch to
batch but the cis isomer is always the major isomer in
the mixture. In contrast, decomposition of the ruthe-
nium catalyst gives only the trans isomer.21
The mechanism involved in this dimerization process
is uncertain, but the following evidence suggests the
presence of a carbene complex as an intermediate:
F igu r e 2. Cis and trans isomers for 1,1,6,6-tetraphenyl-
1,3,5-hexatriene.
protons is consistent with a more weakly bound cyclo-
propene (Table 1).
(a) When a solution of 5 is heated to 70 °C for 2 h,
the formation of a small amount of a vinyl alkylidene
species can be observed by NMR spectroscopy. By
comparison to known compounds, it can be infered that
this alkylidene species might be W(dCHCHdCPh2)Cl2-
(O)[PMePh2]2.
Sta bility. The oxo η2-diphenylcyclopropene com-
plexes (4 and 5) can be stored under argon at room
temperature for long time periods without decomposi-
tion; both are soluble in aromatic hydrocarbons, tet-
rahydrofuran, and chlorinated solvents such as meth-
ylene chloride or chloroform.
(b) There are examples in the literature that implicate
carbene species in the transition-metal-catalyzed dimer-
ization of cyclopropene23 (Scheme 2).
Complexes 4 and 5 have different thermal stabilities.
When a benzene solution of 4 is heated at 50 °C over 1
h in the presence of an equivalent of P(OMe)3, regenera-
tion of the starting material 1 and formation of a new
product corresponding to cis- and trans-1,1,6,6-tetraphe-
nyl-1,3,5-hexatriene (6) is observed in the 1H-NMR
spectrum (Figure 2).
Complex 5 is more stable; higher temperatures (70
°C) and longer reactions times (5-6 h) are necessary to
observe decomposition. Thermal decomposition of 5 also
leads to the dimerization of diphenylcyclopropene, but
in this case the presence of a vinyl alkylidene species,
W(dCHCHdCPh2)Cl2(O)(PMePh2)2, is observed in solu-
tion as an intermediate.
(c) When the thermal decomposition of 4 and 5 occurs
in the presence of strained olefins such as norbornene,
the ROMP product of this olefin is obtained. A viscous,
high-molecular-weight polymer is obtained when only
10 equiv of norbornene is added, indicating that initia-
tion is much slower than propagation in this particular
case (PDI ) 1.83, Mn ) 4018) (eq 3).
The compound Ph2CdCHCHdCHCHdCPh2 (6) had
been previously observed by the dimerization of 3 using
a ruthenium alkylidene catalyst.21 The structure of 6
was confirmed by comparison of spectroscopic data with
an independent synthesized sample (eq 2). By employ-
ing TiCl4/Zn coupling conditions, the trans isomer was
obtained in more than 90% yield.22 In the decomposi-
(d) If the thermal decomposition of 4 is carried out in
the presence of an enamide such as CH2dCHCH2C(O)-
(21) Gagne, M. R.; Grubbs, R. H.; Feldman, J .; Ziller, J . W.
Organometallics 1992, 11, 3933-3935.
(22) Mukaiyama, T.; Sato, T.; Hanna, J . Chem. Lett. 1973, 1041.
(23) Techl, H. H. Chem. Ber. 1964, 97, 2681-2688.

580 Organometallics, Vol. 15, No. 2, 1996
de la Mata and Grubbs
NMe2, the carbonyl olefination product is obtained24 (eq
4).
F igu r e 3. Proposed structure for 7.
1
alkylidene complexes.12,25 The H-NMR spectrum pre-
sents two double doublets corresponding to the reso-
nances of the vinyl alkylidene ligand, at δ ) 12.07 (dd,
J H-H ) 14.7 Hz, J H-P ) 5.4 Hz) and δ ) 8.83 (dd, J H-H
) 14.7 Hz, J H-P ) 1.8 Hz) for the anti isomer and δ )
11.48 (dd, J H-H ) 11.4 Hz, J H-P ) 3.3 Hz) and δ ) 8.48
(dd, J H-H ) 11.4 Hz, J H-P ) 1.8 Hz) for the syn isomer.
The spectroscopic data of 7 are very similar to
those observed in an analogous imido complex
W(dCHCHdCPh2)(NPh)(ORf6)2[PMePh2].26 The chemi-
cal shift and coupling constant corresponding to the HR
and Hâ of the vinylalkylidene ligand are practically
identical in both complexes. Accordingly, we proposed
for our complex 7 a structure analogous to that found
by X-ray diffraction for the above-mentioned phenyl
imido vinyl alkylidene complex: a distorted trigonal
bipyramid, where the oxo and vinylalkylidene ligands
are cis to each other in the equatorial plane and the
two apical positions are occupied by an alkoxide ligand
and the phosphite ligand, making both alkoxides in-
equivalent (Figure 3).
The complex described above evolved from the study
of a series of tungsten oxo vinyl alkylidene systems that
started with the reaction of 4 with LiORf6. When this
reaction was done in C6D6, the formation of two new
complexes was observed. After 10 min at room tem-
perature the signals corresponding to a new η2-diphe-
nylcyclopropene complex (8) appear. This complex
presents a triplet at δ ) 5.18 (J H-P ) 5.7 Hz), corre-
sponding to the olefinic protons of the cyclopropene
ligand, another triplet at δ ) 3.49 (J H-P ) 5.4 Hz),
corresponding to two mutually trans phosphite groups,
and a singlet at δ ) 1.57, corresponding to the methyl
protons of the alkoxide group. These spectroscopic data
seem to indicate that 8 is the result of the substitution
of one chloride ligand by one hexafluoro-tert-butoxide
ligand, leading to W(η2-diphenylcyclopropene)(O)Cl-
(ORf6)[P(OMe)3]2. Complex 8 can also be observed when
3 is added to a solution containing W(O)Cl(ORf6)-
[P(OMe)3]3 in THF-d8, confirming the proposed struc-
ture of this new olefin complex. The appearance of
another product can be detected over the course of time,
and in fact after 16 h this new product (9) becomes the
final product of this reaction at room temperature. This
spectrum shows two broad signals at δ ) 4.95 and δ )
4.10, corresponding to the protons of the cyclopropene
ligand, indicating that both protons are inequivalent,
and a broad doublet to δ ) 3.25 ppm, corresponding to
the presence of only one phosphite group in 9.
(e) Thermal decomposition of isolated tungsten oxo
vinyl alkylidene complexes also leads to the formation
of 6 (see the next section in this paper).
Syn th esis, Ch a r a cter iza tion , a n d Ca ta lytic
Activity of New Tu n gsten Oxo Alk oxy
Vin yla lk ylid en e Com p lexes
Syn th esis a n d Ch a r a cter iza tion . The detection of
vinyl alkylidene species as intermediates in the decom-
position reactions of the previous derivatives provided
an impetus for the synthesis of new, potentially stable
oxo vinyl alkylidene complexes. Exchange of chloride
ligands for bulkier ligands such as suitable alkoxides
was proposed to be a way to stabilize the final vinyl
alkylidene complexes.
The reaction of 1 equiv of 5 with 2 equiv of LiOC-
(CH3)(CF3)2 (LiORf6) in benzene or toluene at 55-60 °C
over 12 h leads to the formation of the tungsten oxo
vinyl alkylidene complex W(dCHCHdCPh2)(O)(ORf6)2-
(PMePh2) (7), which can be isolated as a yellow powder
in 70-80% yield (eq 5). Complex 7 can be stored under
argon at -30 °C for long time periods without showing
signs of decomposition. This complex is soluble in
aromatic hydrocarbons, tetrahydrofuran, and chlori-
nated solvents. When solutions of 7 are heated to more
than 80 °C, the complex decomposes and the dimer 6 is
observed.
Complex 7 is isolated as a mixture of two different
(syn and anti) rotamers, the designations of which are
based on comparison of the value of the IHH coupling
constants to those of other analogous imido vinyl
There is not enough data available to unambiguously
assign the structure of 9; however, the inequivalency
and chemical shift of the signals of the cyclopropene
(24) The 1H-NMR data in CD2Cl2 for this product: δ 7.6-7.2 (m,
10, Haromatic), 6.74 (d, 1, J H-H ) 10.8 Hz), 6.42 (m, 1), 5.41 (dd, 1, J )
16.8, 1.5 Hz), 5.13 (dd, 1, J ) 9.90, 1.5 Hz), 3.01 (s, 6, NMe2), 1.43 (d,
2, J ) 17.4 Hz).
(25) Schrock, R. R.; Crowe, W. E.; Bazan, G. C.; DiMare, M.;
O’Regan, M. B.; Schofield, M. H. Organometallics 1991, 10, 1832-1843.
(26) De la Mata, F. J .; Claverie, J . P.; Grubbs, R. H., unpublished
results.

Reactions of WCl2(O)(PX3)3
Sch em e 3
Organometallics, Vol. 15, No. 2, 1996 581
the M-P(OMe)3 bond in the oxo complex relative to the
imido can be explained by the tendency of the oxo ligand
to form a partial triple bond. This makes the oxo ligand
a better π-donor that destabilizes the M-P(OMe)3 bond.
This lack of stability has impeded the isolation of pure
samples of 10 in the solid state, nevertheless 10 can be
obtained cleanly in solution and these solutions can be
used to study its activity in metathesis and polymeri-
zation processes (see the next section).
The reactions of 10 with an excess of THF lead to the
corresponding THF adduct W(dCHCHdCPh2)(O)(ORf6)2-
(THF) (12). This complex can also be prepared by
carrying out the alkoxide addition to 4 in a mixture of
C6D6/THF-d8, CD2Cl2/THF-d8, or THF-d8 using the
same reaction conditions as before. In all cases, no
phosphite-bound alkylidene species are observed at any
time, again demonstrating the weakness of the metal-
phosphite bond (eq 6).
ligand are similar to those observed in the 1H-NMR
spectra of other well-characterized η2-diphenylcyclopro-
pene complexes27 where only one phosphite group is
present. Accordingly, we think that 9 could be W(η2-
diphenylcyclopropene)(O)(ORf6)2[P(OMe)3].
When solutions of 9 are heated to 55-60 °C for 1-2
h, the monophosphite adduct of the corresponding
tungsten oxo vinylalkylidene alkoxide complex,
W(dCHCHdCPh2)(O)(ORf6)2[(P(OMe)3] (10), is obtained
as a mixture of syn and anti rotamers. Again syn and
anti designations are based on comparison with analo-
gous imido vinyl alkylidene complexes12,25 (Scheme 3).
The resonances of the HR and Hâ of the vinylalky-
Complex 12 also appears as a mixture of syn and anti
rotamers, in 1:1 ratio probably due to the low ligand
steric bulk. In this case the 1H-NMR spectrum presents
two doublets for the resonances of the HR and Hâ in each
rotamer, at δ ) 11.86 (d, J H-H ) 12.6 Hz) and δ ) 9.32
(d, J H-H ) 12.6 Hz) for the anti isomer and at δ ) 10.25
(d, J H-H ) 10.8 Hz) and δ ) 9.28 (d, J H-H ) 10.8 Hz)
for the syn isomer (Figure 4).
1
lidene ligand (in 10) appear in the H-NMR spectrum
as two doublet of doublets, at δ ) 12.5 (dd, J H-H ) 14.4
Hz, J H-P ) 6.6 Hz) and δ ) 8.83 (dd, J H-H ) 14.4 Hz,
J H-P ) 2.1 Hz) for the anti isomer and at δ ) 11.75 (dd,
J H-H ) 11.4 Hz, J H-P ) 4.5 Hz) and δ ) 9.03 (dd, J H-H
) 11.4 Hz, J H-P ) 2.1 Hz) for the syn isomer.
The spectroscopic data of 10 are very similar to those
of 7 and also to those reported for the corresponding
2,6-diisopropyl imido complex W(dCHCHdCPh2)(NAr)-
(ORf6)2[P(OMe)3] (11).12 Accordingly we proposed for 10
the same structure that we have discussed for 7.
We have found some differences between the two
phosphite vinylalkylidene complexes 10 and 11. For
example, the syn isomer is the major isomer in the oxo
complex 10, while the anti one is the main isomer in
the imido complex 11. This could be attributed to the
different steric environment presented by the oxo and
imido ligands. Another difference concerns the facility
of ligand exchange with phosphites. In order to remove
P(OMe)3 from 11, it is necessary to use a phosphite
sponge such us CuCl or [RuCp*(OR)]2 in the presence
of a weaker ligand.28 In contrast, ligand exchange in
10 is accomplished by simple addition of suitable
ligands. When solutions of 10 are concentrated under
vacuum, phosphite dissociation occurs, causing the
decomposition of the metal complex. The weakness of
The alkoxide addition to 4 is always accompanied by
a small amount of decomposition, which is more evident
when THF is present during the reaction. Among the
major organic products of these reactions are 6 and
Ph2CdCHCH2CH2CHdCPh2, which have been charac-
teized by NMR and GC-MS analyses.29 Finally, in an
analogous manner to other alkoxylations, hexafluoro-
tert-butyl alcohol is also produced in small amounts.28
In order to make more stable oxo vinylalkylidene
species, two possible approaches were devised. One is
to use bulkier alkoxides to afford a larger stabilization
of the final alkylidene product. This approach has been
successful and will be reported in a separate paper.27b
The other way to stabilize these oxo vinyl alkylidene
complexes is to change the P(OMe)3 ligand to another
ligand which is able to form stronger bonds with the
metal center, as we have shown above with the ex-
change of P(OMe)3 by PMePh2.
(27) (a) de la Mata, F. J .; J ohnson, L. K.; Grubbs, R. H., unpublished
results. (b) de la Mata, F. J .; Fujimura, O.; Grubbs, R. H., unpublished
results.
(28) Claverie, J . P. Ph.D. Thesis, California Institute of Technology,
1995.
(29) 1H-NMR data of Ph2CdCHCH2CH2CHdCPh2 (C6D6): δ 7.3-
7.0 (m, 20, Haromatic), 5.96 (m, 2, CH), 2.21 (m, 4, CH2). GC-MS data:
m/z ) 386.

582 Organometallics, Vol. 15, No. 2, 1996
de la Mata and Grubbs
Ta ble 2. Selected NMR Sp ectr a l Da ta for Som e Vin yl Alk ylid en e Com p lexesa
HR
Hâ
diphenylvinyl alkylidene complex
δ
J HH
11.4
J HP
δ
J HH
11.4
J HP
δ
syn-W(dCHCHdCPh2)(O)(ORf6)2 (10)
[P(OMe)3]
11.75
4.5
9.03
2.1
anti-W(dCHCHdCPh2)(O)(ORf6)2 (10)
[P(OMe)3]
12.47
11.6
14.4
11.0
14.4
10.8
12.9
11.4
14.7
6.6
5.1
8.0
8.83
8.72
8.72
9.32
9.28
8.48
8.83
14.4
11.0
14.4
10.8
12.9
11.4
14.7
2.1
syn-W(dCHCHdCPh2)(NAr)(ORf6)2 (11)b
[P(OMe)3]
256
264
anti-W(dCHCHdCPh2)(NAr)(ORf6)2 (11)b
[P(OMe)3]
syn-W(dCHCHdCPh2)(O)(ORf6)2 (12)
(THF)
anti-W(dCHCHdCPh2)(O)(ORf6)2 (12)
(THF)
syn-W(dCHCHdCPh2)(O)(ORf6)2 (7)
(PMePh2)
12.3
10.25
11.83
11.48
12.07
3.3
5.4
1.8
2.1
263.6
268
anti-W(dCHCHdCPh2)(O)(ORf6)2 (7)
(PMePh2)
a
b
All spectra were acquired in C6D6 unless indicated otherwise. Reference 12.
investigation30 and here we provide a preliminary
account of our results.
Complexes 10 and 12 were found to be very active
catalysts in the ring-opening metathesis polymerization
of norbornene at room temperature. These complexes
can also ROMP cyclic olefins such as cyclooctene, 1,5-
cyclooctadiene, and cyclooctatetraene derivatives. Only
the most active metathesis catalysts will polymerize
cyclooctatetraene. In contrast to the analogous imido
complex 11, there is no need to use a phosphite sponge
to activate the complex. Complex 10 is also active in
the ring-closing metathesis reaction of some dienes such
as diethyl diallyl malonate or diene-yne derivatives.31
Con clu sion . Complexes of the type WCl2(O)[PX3]3
react with 3,3-diphenylcyclopropene to give η2-cyclopro-
pene complexes. The thermal decomposition of these
η2-cyclopropene complexes leads to the dimerization
product of the diphenylcyclopropene ligand as a mixture
of cis and trans isomers. The mechanism of this
dimerization remains unknown, but the presence of
vinyl alkylidene species before the dimerization occurs
has been demonstrated. These η2-cyclopropene com-
plexes react with suitable alkoxides, first at room
temperature and then at higher temperatures (50-60
°C) to give the first tungsten oxo vinylalkylidene com-
plexes which have shown activity as a metathesis
catalysts in ROMP and RCM processes.
The results of this study represent a greatly simplified
entry into tungsten-based alkylidene olefin metathesis
catalysts and demonstrate that oxo alkylidene com-
plexes can serve as single-component, well-defined
metathesis catalysts.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All manipulations were carried
out under argon with standard Schlenck techniques or in a
nitrogen-filled glovebox equipped with a -40 °C freezer. Argon
was purified by passage through columns of Chemalog R3-11
catalyst and Linde 4-Å molecular sieves. NMR spectra were
recorded with either a J EOL FX-90Q (89.60-MHz 1H, 22.53-
1
F igu r e 4. (a) H NMR (alkylidene region) of 7 in C6D6;
(b) 1H NMR (alkylidene region) of 10 in C6D6; (c) 1H NMR
(alkylidene region) of 12 in C6D6.
Ca ta lytic Activity of th e Oxo Vin yla lk ylid en e
Com p lexes
1
MHz 13C, 36.20-MHz 31P) or a QE-300 Plus (300.10-MHz H,
75.49-MHz 13C) spectrometer. All coupling constants are
reported in hertz. For the 1H- and 13C-NMR virtual triplet
resonances of the trans phosphite/phosphine ligands, the
The reactivity of these new tungsten oxo vinylalky-
lidene complexes 7, 10, and 12 was studied with various
substrates. They show a significant activity in processes
such as ROMP and RCM. A complete study about the
activity of these new catalysts is currently under
(30) Claverie, J . P.; de la Mata, F. J .; Grubbs, R. H., unpublished
results.
(31) Zuercher, W.; Kim, S. H.; Grubbs, R. H., unpublished results.

Reactions of WCl2(O)(PX3)3
Organometallics, Vol. 15, No. 2, 1996 583
2
4
coupling constant N ) | J HP + J HP| is given, where N is the
separation of the outer lines of the triplet.32 GC-MS spectra
were recorded at the California Institute of Technology
(Hewlett-Packard 5890) or at the University of California at
Riverside. Elementary analyses were performed at the Cali-
fornia Institute of Technology or by Oneida Research Services,
Inc. All reactions were carried out at room temperature unless
otherwise indicated.
[P(OMe)3]3 (0.26 g, 0.47 mmol) in benzene. After being stirred
for 2 h at 55 °C, the reaction mixture was passed through a
silica gel column. Removal of the solvent in vacuo gave a
yellow crystalline solid (0.16 g, 70%). 1H NMR (C6D6) trans
isomer δ 7.4-7.1 (m, 20, Haryl), 6.67 (m, 4, HCCHdCHCH);
cis isomer δ 7.4-7.1 (m, 20, Haryl), 6.25 (dd, 2, J ) 8.4, 2.1 Hz,
HCCHdCHCH), other doublet of doublets is obscured by the
aromatic signals; 1H NMR (CD2Cl2) trans isomer δ 7.44-7.25
(m, 20, Haryl), 6.75 (dd, 2, J ) 7.7, 3.2 Hz), 6.52 (dd, 2, J ) 7.7,
3.2 Hz); cis isomer δ 7.44-7.25 (m, 20, Haryl), 6.10 (dd, 2, J )
8.4, 2.4 Hz), other doublet of doublets is obscured by the
aromatic signals. Exact MS: calcd for (C30H24) 384.1878; found
384.1884. Meth od B. One Schlenk flask was charged with
cinnamaldehyde (0.50 g, 2.4 mmol), a solution of TiCl4 in CH2-
Cl2 (9.6 mL, 9.6 mmol), and Zn (1.25 g, 19.0 mmol), after which
dioxane (30 mL) was added to the reaction mixture. The
resulting suspension was refluxed for 12 h and then was
allowed to settle before it was filtered, giving a yellow solution.
Dioxane was removed under vacuum and the resulting yellow
residue was washed twice with pentane (5 mL), leading to a
yellow powder characterized as 6 (95% trans).
Ma ter ia ls. Toluene, benzene, diethyl ether, and tetrahy-
drofuran were purified by methods developed in our research
group.33 Pentane was stirred over concentrated H2SO4, dried
over CaH2 and MgSO4, and then transferred onto sodium
benzophenone ketyl. Benzene-d6 and THF-d8 were dried over
sodium benzophenone ketyl and methylene chloride-d2 was
dried over P2O5, vacuum transferred, and then degassed by
repeated freeze-pump-thaw cycles.
3,3-Diphenylcyclopropene,34 WCl4(O),35 WCl2(O)[P(OMe)3]3,20b
20b
and WCl2(O)[PMePh2]3
were synthesized according to lit-
erature methods. P(OMe)3 was vacuum-transferred from Na
and then subjected to several freeze-pump-thaw cycles.
(CF3)2(CH3)COH was purchased, dissolved in Et2O, deproto-
nated with 1 equiv of freshly titrated BuLi,36 and purified by
standard techniques.
W(dCHCH dCP h 2)(O)[OC(CH 3)(CF 3)(CF 3)2]2(P MeP h 2)
(7). A mixture of W(HCdCHCPh2)Cl2(O)[PMePh2]2 (0.85 g,
0.98 mmol) and LiOC(CH3)(CF3)2 (0.39 g, 2.07 mmol) was
suspended in benzene (15 mL). This solution was stirred for
2 h at room temperature, then 2 h at 55-60 °C. The yellow
suspension was filtered into -70 °C pentane, giving a yellow
precipitate that was dried under vacuum (0.61 g, 65%): 1H
P r oced u r es.
W(η2-d ip h en ylcyclop r op en e)Cl2(O)-
[P (OMe)3]2 (4). A 5-mL benzene solution of 3,3-diphenylcy-
clopropene (0.77 g, 4.02 mmol) was added to a purple solution
of WCl2(O)[P(OMe)3]3 (2 g, 3.66 mmol) in 20 mL of benzene.
The original purple solution turned yellow as the reaction
mixture was stirred for 24 h. The solvent was removed under
vacuum, and the resulting yellow oil was left under dynamic
vacuum for an additional 12 h and then washed with two 15-
mL portions of pentane. The yellow solid (2.25 g, 95%) was
dried in vacuo and stored at -30 °C: 1H NMR (C6D6) δ 7.30-
6.90 (m, 10, Haryl), 5.70 (t, 2, J H-P ) 6.30 Hz, HCdCH), 3.57
(t, 18, N ) 10.80, P(OMe)3); 13C NMR (C6D6) δ 151.5 (CPhPh′:
NMR (C6D6) anti rotamer, δ 12.07 (dd, J H-H ) 14.7, J H-P
5.4 Hz, HR); 8.83 (dd, J H-H ) 14.7, J H-P ) 2.1 Hz, Hâ), 7.5-6.8
(m, 20, Haryl), syn rotamer δ 11.48 (dd, J H-H ) 11.4, J H-P
)
)
3.3 Hz, HR); 8.48 (dd, J H-H ) 11.4, J H-P ) 1.8 Hz, Hâ), 7.5-6.8
(m, 20, Haryl). 13C NMR (C6D6), major rotamer, δ 263.6 (d, J C-P
) 12.46 Hz, CR), 142.1 (d, J C-P ) 3.9 Hz, Cγ), 141.1, 138.8,
137.7, 132.6, 132.4 (C aromatic), 123.2 (d, J C-P ) 4.5 Hz, Câ),
18.7 (s, OC(CH3)(CF3)2), 16.9 (s, OC(CH3)(CF3)2), 12.6 (d, J C-P
) 15.02 Hz, PMePh2).
C
ipso), 142.6 (CPhPh′: C′ipso), 132.2, 126.3, 125.9 (CPhPh′), 69.8
(t, J C-P ) 13.51 Hz, HCdCH), 63.0 (s, CPh2), 53.8 (t, N ) 4.0
Hz, P(OMe)3); 13C NMR (CD2Cl2) δ 151.2 (CPhPh′: Cipso), 141.8
(CPhPh′: Cipso), 131.8, 127.9, 127.6, 127.5, 126.3, 126.0 (CPh-
Ph′: Co, C′o, Cm, C′m, Cp, C′p), 69.7 (t, J C-P ) 13.43 Hz,
HCdCH), 62.6 (s, CPh2), 54.5 (t, P(OMe)3); 31P NMR (C6D6) δ
116.4. Anal. Calcd for (C21H30Cl2O7P2W): C, 38.99; H, 4.67.
Found: C, 38.62; H, 4.41.
Obser va tion of W(η2-d ip h en ylcyclop r op en e)Cl(O)[OC-
(CH3)(CF 3)2][P (OMe)3]2 (8): P r oced u r e A. The cyclopropene
complex 4 (20 mg, 0.031 mmol) was dissolved in C6D6 (500
mg) and LiOC(CH3)(CF3)2 (64 mg, 0.034 mmol) was added.
After 5-6 h at room temperature, a new cyclopropene complex
7 is the major product in the reaction mixture as identified by
1H-NMR spectroscopy. 1H NMR (C6D6) δ 7.6-6.9 (m, 10, Haryl),
5.18 (t, 2, J H-P ) 5.7 Hz, HCdCH), 3.49 (t, 18, N ) 10.8 Hz,
P(OMe)3), 1.57 (s, 3, OC(CH3)(CF3)2). P r oced u r e B. The oxo
triphosphite complex 1 (20 mg, 0.036 mmol) was dissolved in
THF-d8 and LiOC(CH3)(CF3)2 (14 mg, 0.072 mmol) was added.
After a week at room temperature, approximately 50% of 1
was converted to another triphosphite complex identified as
WCl(O)(OC(CH3)(CF3)2)[P(OMe)3]3 by NMR spectroscopy. The
reaction of this compound with diphenylcyclopropene results
in the observation of 8.
Obser va tion of W(η2-d ip h en ylcyclop r op en e)(O)[OC-
(CH3)(CF 3)2]2[P (OMe)3] (9). The cyclopropene complex 4 (20
mg, 0.031 mmol) was dissolved in C6D6 and then LiOC(CH3)-
(CF3)2 (12 mg, 0.062 mmol) was added. After 18 h at room
temperature, a new organometallic complex 9 was observed
as the major product in the reaction mixture. 1H NMR (C6D6)
δ 7.45-7.05 (m, 10, Haryl), 5.1 (dd broad, 1, HCdCH), 4.2 (d
broad, 1, HCdCH), 3.25 (d, 9, P(OMe)3), 1.93 (s, 3, OC-
Me(CF3)2), 1.77 (s, 3, OCMe(CF3)2).
W(η2-d ip h en ylcyclop r op en e)Cl2(O)[P MeP h 2]2 (5).
A
10-mL benzene solution of 3,3-diphenylcyclopropene (0.32 g,
1.69 mmol) was added to a purple solution of WCl2(O)-
[PMePh2]3 (1.34 g, 1.54 mmol) in 30 mL of benzene. The
reaction mixture was stirred for 4 h at 45 °C. The solvent
was removed in vacuo to yielded a pale yellow solid, which
was washed with three 15-mL portions of pentane. The
resulting yellow product was dried under vacuum and stored
at -30 °C in the drybox freezer (1.33 g, 90%). 1H NMR (C6D6)
δ 7.7-6.91 (m, 30, Haryl), 4.35 (t, 2, J H-P ) 6.0 Hz, HCdCH),
2.47 (t, 6, N ) 9.6, PMePh2); 13C NMR (C6D6, only some Caryl
chemical shifts are listed) δ 151.4 (CPhPh′: Cipso), 143.1
(CPhPh′: Cipso), 134.7, 132.7, 132.3, 132.0, 130.9, 130.2 (Caro
-
matic), 76.8 (t, J C-P ) 6.5 Hz, HCdCH), 66.1 (s, CPh2), 13.61 (t,
N ) 35.5, PMePh2); 31P NMR (C6D6) δ 13.3. Anal. Calcd for
(C41H38Cl2OP2W): C, 57.03; H, 4.43. Found: C, 56.89; H, 4.26.
P h 2CdCHCHdCHCHdCP h 2 (6): Meth od A. A 15-mL
benzene solution of 3,3-diphenylcyclopropene (0.46 g, 2.37
mmol) was added by cannula to a purple solution of WCl2(O)-
W(dCHCHdCP h 2)(O)[OC(CH3)(CF 3)2]2[P (OMe)3] (10).
A mixture of W(HCdCHCPh2)Cl2(O)[P(OMe)3]2 (25 mg, 0.038
mmol) and LiOC(CH3)(CF3)2 (16 mg, 0.085 mmol) was sus-
pended in deuterated benzene. The solution was stirred for
18 h at room temperature and then 2 h at 60 °C. The resulting
yellow-brown suspension was filtered to remove the LiCl. The
resulting solution contains the vinyl alkylidene 9 and 1 equiv
of free P(OMe)3. 1H NMR (C6D6), anti rotamer, δ 12.5 (dd,
J HH ) 14.4, J HP ) 6.6 Hz, HR), 8.83 (dd, J HH ) 14.4, J HP ) 2.1
Hz, Hâ), 7.5-7.0 (m, 10, Haryl), 3.13 (d, 9, J HP ) 12.0 Hz,
(32) Harris, R. K. Can. J . Chem. 1964, 42, 2275.
(33) Pangborn, A. B.; Giardello, M. H.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J . Organometallics, submitted for publication.
(34) Moore, J . S.; Nguyen, S. T.; Grubbs, R. H., unpublished results.
(35) WOCl4 may be purchased commercially or synthesized from (a)
WO3 and SOCl2 (Nielson, A. J . In Inorganic Syntheses; Kirschner, S.,
Ed.; J ohn Wiley & Sons: New York, 1985; pp 195-199) or (b) WCl6
and (Me3Si)2O (Gibson, V. C.; Kee, T. P.; Shaw, A. Polyhedron 1988,
7, 579-580).
(36) Lipton, M. F.; Sorensen, C. M.; Sadler, A. C.; Shapiro, R. H. J .
Organomet. Chem. 1980, 186, 155-158.

584 Organometallics, Vol. 15, No. 2, 1996
de la Mata and Grubbs
P(OMe)3), 1.86 (s, 3, OCMe(CF3)2), 1.69 (s, 3, OC′Me(CF3)2);
syn rotamer, δ 11.75 (dd, J HH ) 11.4, J HP ) 4.5 Hz, HR), 9.03
(dd, J HH ) 11.4, J HP ) 2.1 Hz, Hâ), 7.5-7.0 (m, 10, Haryl), 3.22
(d, 9, J HP ) 12.0 Hz, P(OMe)3), 1.82 (s, 3, OCMe(CF3)2), 1.73
(s, 3, OC′Me(CF3)2).
50 µmol) under inert atmosphere. After 30 min the reaction
mixture was quenched with a drop of benzaldehyde and poured
into 100 mL of methanol. The precipitated polymer was
collected by filtration, dissolved again in methylene chloride,
and passed through a silica column; the solvent then was
removed under vacuum and the resulting polymer was dried
in vacuo.
F or m a tion of W(dCHCHdCP h 2)(O)[OC(CH3)(CF 3)2]2-
(THF ) (12). Meth od A. A mixture of W(HCdCHCPh2)Cl2-
(O)[P(OMe)3]2 (20 mg, 0.031 mmol) and LiOC(CH3)(CF3)2 (11.6
mg, 0.062 mmol) was suspended in a mixture of C6D6/THF-d8
in a ratio of 10:1. The solution was stirred for 18 h at room
temperature and then 2 h at 60 °C. The resulting yellow-
brown suspension was filtered to remove LiCl. The resulting
solution contains the vinyl alkylidene 12 and free P(OMe)3.
1H NMR (C6D6), anti rotamer, δ 11.83 (d, 1, J HH ) 12.9 Hz,
HR), 9.28 (d, 1, J HH ) 12.9 Hz, Hâ); syn rotamer, δ 10.25 (d, 1,
J HH ) 10.8 Hz, HR), 9.32 (d, 1, J HH ) 10.8 Hz, Hâ). Meth od
B. THF-d8 (75 equiv) was added to a solution of 10 in
deuterated benzene, leading immediately to the formation of
12.
Meta l Com p lex Ca ta lyzed RCM Rea ction s w ith Dif-
fer en t Dien es. In a typical experiment, the corresponding
diene (5.0 mmol) was added to a solution of the corresponding
catalyst in benzene (50 µmol) under inert atmosphere. When
the reaction was complete, the reaction mixture was passed
through a silica column to remove the catalyst; the solvent
was then removed under vacuum and the organic residue was
analyzed by NMR spectroscopy and GC-MS.
Ack n ow led gm en t. We gratefully acknowledge sup-
port from the NSF, and F.J .M. thanks the Ministerio
de Educacion y Ciencia of Spain for a postdoctoral
fellowship. Thanks also to Dr. Scott Miller and J erome
P. Claverie for helpful discussions.
Meta l Com p lex Ca ta lyzed ROMP Rea ction s w ith Dif-
fer en t Str a in ed Olefin s. In a typical experiment, a solution
of the corresponding olefin in benzene (10 mL of a 0.5 M
solution, 5.0 mmol) was added to a stirred solution of the
corresponding catalyst in benzene (1 mL of a 0.05 M solution,
OM950389C