Coupling of Carbomethoxy and Vinylidene Ligand in Molybdenum Complexes

Article abstract of DOI:10.1021/om9907167

Treatment of [Cp(dppe)(CO)Mo=C=C(Ph)CH₂CH=CH₂]I (2) with MeONa caused nucleophilic attack to occur at the terminal CO ligand. This is followed by a coupling reaction of the resulting carbomethoxy group with Cα of the vinylidene ligand accompanied with coordination of the terminal olefin to afford Cp(dppe)MoC(COOMe)=-C(Ph)CH₂CH==CH₂ (5). Similar coupling was observed when [Cp(dppe)(CO)Mo=C=C(Ph)CH₂Ph]I (3) was treated with MeONa, but the reaction afforded the neutral allylic complex Cp(dppe)Mo[CH-(COOMe)C(Ph)CHPh] (6). The structures of complexes 5 and 6 have been determined by X-ray diffraction analysis.

Full text of DOI:10.1021/om9907167

Organometallics 2000, 19, 269-274
269
Cou p lin g of Ca r bom eth oxy a n d Vin ylid en e Liga n d in
Molybd en u m Com p lexes
J ung-Yen Yang, Shou-Ling Huang, Ying-Chih Lin,* Yi-Hong Liu, and Yu Wang
Department of Chemistry, National Taiwan University, Taipei, Taiwan, 106 Republic of China
Received September 13, 1999
Treatment of [Cp(dppe)(CO)ModCdC(Ph)CH2CHdCH2]I (2) with MeONa caused nucleo-
philic attack to occur at the terminal CO ligand. This is followed by a coupling reaction of
the resulting carbomethoxy group with CR of the vinylidene ligand accompanied with
coordination of the terminal olefin to afford Cp(dppe)MoC(COOMe)dC(Ph)CH2CHdCH2 (5).
Similar coupling was observed when [Cp(dppe)(CO)ModCdC(Ph)CH2Ph]I (3) was treated
with MeONa, but the reaction afforded the neutral allylic complex Cp(dppe)Mo[CH-
(COOMe)C(Ph)CHPh] (6). The structures of complexes 5 and 6 have been determined by
X-ray diffraction analysis.
In tr od u ction
involving CR of a vinylidene ligand on the metal complex
are limited in the literature. Herein we report prepara-
tion of a number of cationic molybdenum vinylidene
complexes Cp(Ph2PCH2CH2PPh2)(CO)ModCdC(Ph)-
CH2R and nucleophilic addition of methoxide to the CO
ligand followed by a coupling reaction leading to carbon-
carbon formation at CR of the vinylidene ligand.
We previously described a new type of deprotonation
reaction of several cationic vinylidene complexes leading
to a rare class of metal complexes containing various
cyclic ligands.1 Using this synthetic strategy, we suc-
cessfully prepared several ruthenium cyclopropenyl
complexes containing various substituents as well as
ruthenium furanyl complexes. For the cyclopropenyl
complex, the cyclization reaction also results in forma-
tion of a chiral carbon center in the three-membered
ring. These features render this cyclization process
potentially useful for organic synthesis.2 Therefore, we
set out to study the chemical reactivity of a molybdenum
vinylidene system of Cp(Ph2PCH2CH2PPh2)(CO)Mo.3
Such a system was chosen because the presence of donor
phosphine ligands is known to assist the preparation
of cationic metal vinylidene complexes,4 and the pres-
ence of a CO ligand could be utilized to study carbon-
carbon bond formation. Surprisingly, treatment of these
vinylidene complexes containing a terminal CO ligand
with sodium methoxide affords unexpected products via
an unprecedented coupling of a carbomethoxy group
with CR of the vinylidene ligand.5 Coupling reactions
Resu lts a n d Discu ssion
P r ep a r a tion of th e Acetylid e Com p lex 1. The
acetylide complex [Mo](CO)CtCPh (1, [Mo] ) (η5-
C5H5)(dppe)Mo, dppe ) Ph2PCH2CH2PPh2) was pre-
pared by two different methods. The reaction of [Mo]-
(CO)Cl with LiCCPh in THF, which gave 1 in reasonable
yield, required handling of an air-sensitive lithium
reagent. We therefore pursued an alternative synthesis,
namely, the reaction of [Mo](CO)Cl with HCtCPh. This
reaction gave {[Mo](CO)dCdCHPh}Cl, which under-
went thermal decarbonylation to afford {[Mo](η2-HCt
CPh)}Cl. Then the η2-phenylacetylene complex was
treated with CO in the presence of MeONa to give 1.
The tautomerization of alkyne to vinylidene on the
bisdimethylphenylphosphine molybdenum analogue has
been reported before.3c Our scheme involves more steps
but gives higher overall yield.
(1) (a) Ting, P. C.; Lin, Y. C.; Cheng, M. C.; Wang, Y. Organome-
tallics 1994, 13, 2150. (b) Ting, P. C.; Lin, Y. C.; Lee, G. H.; Cheng, M.
C.; Wang, Y. J . Am. Chem. Soc. 1996, 118, 6443. (c) Chang, C. W.;
Ting, P. C.; Lin, Y. C.; Lee, G. H.; Wang, Y. J . Organomet. Chem. 1998,
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Asymmetry 1998, 9, 4419. (c) Plemenkov, V. V.; Rul, S. V.; Gubaidullin,
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Chem. 1998, 34, 971.
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A. G.; Williams, I. D. J . Chem. Soc., Dalton Trans. 1985, 435. (b)
Beevor, R. G.; Green, M.; Orpen, A. G.; Williams, I. D. J . Chem. Soc.,
Dalton Trans. 1987, 1319. (c) Nickias, P. N.; Seleague, J . P.; Young,
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Commun. 1998, 1441.
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4585. (c) Faure, M.; Maurette, L., Donnadieu, B.; Lavigne, G. Angew.
Chem., Int. Ed. Engl. 1999, 34, 518.
The 31P NMR spectrum of 1 exhibits two sets of
doublet resonances at δ 90.4 and 78.7 with J P-P ) 37.2
1
Hz. In the H NMR spectrum, the resonance for the Cp
ligand is a doublet at δ 4.49 with J H-P ) 1.6 Hz,
indicating coupling with only one of the phosphorus
atoms of the dppe. In the 13C NMR spectrum, the signal
for the terminal CO ligand is also a doublet at δ 245.0
with J C-P ) 22.2 Hz, indicating the same coupling
pattern. By the use of selective heteronuclear decoupling
techniques, i.e., 1H{31P} and 13C{31P} NMR spectra, we
1
are able to determine that both H-31P coupling of the
Cp ligand and 13C-31P coupling of the CO ligand
originate from the same phosphorus atom displaying the
downfield resonance (at δ 90.4) in the 31P NMR spec-
trum. Coupling between carbon and phosphorus nuclei
of the complex with a piano-stool coordination geometry
10.1021/om9907167 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 12/31/1999

270 Organometallics, Vol. 19, No. 3, 2000
Yang et al.
Sch em e 1
1
depends on the orientation.6 In the H NMR spectrum
of {[Mo](η2-HCtCPh)}Cl, the characteristic triplet reso-
nance at δ 10.02 with J H-P ) 13.8 Hz is assigned to the
terminal CH. The corresponding 1H signal of the vi-
nylidene proton of {[Mo](CO)dCdCHPh}Cl appears as
a singlet at δ 4.78.
Hz for 3 and δ 66.8 and 63.7 with J P-P ) 30.7 Hz for 4).
Other spectroscopic features are consistent with their
formulations.
Rea ction s of 2 a n d 3 w ith MeONa . Having estab-
lished the cyclopropenation reaction of several cationic
vinylidene complexes of ruthenium, we examined the
deprotonation reaction of the molybdenum complex 2
using various bases with an expectation to see similar
results. However, much to our surprise, treatment of 2
with n-Bu4NOH, DBU, and n-Bu4NF gave no reaction.
In the reaction of 2 with MeONa the coupling product
[Mo](η3-C(COOMe)dC(Ph)CH2CHdCH2) (5) (Scheme 1)
was obtained in high yield. Formation of 5 is rational-
ized by nucleophilic addition of MeO- to the terminal
CO ligand7 giving the carbomethoxy group followed by
a coupling reaction8 of the carboxymethoxy group with
CR of the vinylidene ligand to afford 5 (Scheme 1) in
high yield. The terminal olefin group, acting as a two-
electron donor, fills the vacant site left from the coupling
reaction. It is interesting to note the difference in
spectral characteristics of 2 and 5. Signals of the
terminal vinyl group in the 1H NMR spectrum of 2
appear at δ 5.62 (dCH) and 5.00, 4.96 (dCH2), while
those of 5 occur at δ 1.78 (dCH) and 2.58, 3.66 (dCH2).
These assignments are determined by the use of 2D
COSY and HSQC experiments. While most of H-H
P r ep a r a tion of Vin ylid en e Com p lexes. Treatment
of 1 with BrCH2R (R ) CHdCH2, C6H5, and CN)
afforded cationic brown-red vinylidene complexes {[Mo]-
(CO)dCdC(Ph)CH2R}Br (2, R ) CHdCH2; 3, R ) C6H5;
4, R ) CN). All reactions gave the desired products in
70-80% yields. Use of organic iodides gave lower yields.
All these vinylidene complexes are soluble in CHCl3,
CH2Cl2, and CH3OH but are insoluble in hexane.
Complex 2 is air- and moisture-sensitive but is stable
under nitrogen. The 1H NMR spectrum of 2 displays
multiplet resonances centered at δ 5.00, 4.96 and 2.87,
2.78 assignable to the olefinic and saturated diaste-
reotopic CH2 units, respectively, and the multiplet
resonance at δ 5.62 to the allylic CH unit. The geminal
coupling constant of the diastereotopic methylene pro-
tons is 15.6 Hz, and interestingly, the long-range P-H
coupling with one of the phosphorus atoms (5J P-H ) 2.8
1
and 2.0 Hz) is also observed for these protons. The H
NMR spectra of complexes 3 and 4 display the same
features. In the 13C NMR spectrum, the characteristic
doublet of doublet resonance centered at δ 358.4 with
2J P-C ) 36.0 and 6.5 Hz is assigned to the vinylidene
CR. In the 31P NMR spectrum, two doublet resonances
at δ 71.5 and 67.0 with J P-P ) 37.5 Hz are assigned to
the dppe ligand. In the 31P NMR spectra of 3 and 4, the
31P resonances fall in a similar region with comparable
coupling constants (δ 69.0 and 66.2 with J P-P ) 36.3
(7) (a) Nakazawa, H.; Kadoi, Y.; Mizuta, T.; Miyoshi, K.; Yoneda,
H. J Organomet. Chem. 1989, 366, 333. (b) Gibson, D. H.; Ong, T. S.;
Ye, M.; Franco, J . O.; Owens, K. Organometallics 1988, 7, 2569. (c)
Busetto, L. L.; Zanotti, V.; Norfo, L.; Palazzi, A.; Albano, V. G.; Braga,
D. Organometallics 1993, 12, 190. (d) Nakazawa, H.; Yamaguchi, M.;
Kubo, K.; Miyoshi, K. J Organomet. Chem. 1992, 428, 145. (e) Werner,
H.; Hofmann, L.; Zolk, R. Chem. Ber. 1987, 120, 379. (f) Kiel, W. A.;
Buhro, W. E.; Gladysz, J . A. Organometallics 1984, 3, 879. (g) Carlos,
F.; Barrientos-Penna, A.; Hugo, K. O.; Derek, S. Organometallics 1985,
4, 367. (h) Bao, Q. B.; Rheingold, A. L.; Brill, T. B. Organometallics
1986, 5, 2259.
(6) (a) Bainbridge, A.; Craig, P. J .; Green, M. J . Chem. Soc. (A) 1968,
2713. (b) Faller, J . W.; Anderson, A. S. J . Am. Chem. Soc. 1970, 92,
5852. (c) Beach, D. L.; Barnett, K. W. J . Organomet. Chem. 1975, 97,
C27. (d) Sakaba, H.; Ishida, K.; Horino, H. Chem. Lett. 1995, 1145.
(8) (a) Wiedemann, R.; Steinert, P.; Gevert, O.; Werner, H. J . Am.
Chem. Soc. 1996, 118, 2495. (b) Braun, T.; Meuer, P.; Werner, H.
Organometallics 1996, 15, 4075.

Coupling of Carbomethoxy and Vinylidene Ligand
Organometallics, Vol. 19, No. 3, 2000 271
F igu r e 1. ORTEP drawing of 5 with thermal ellipsoids
shown at the 30% probability level. For the dppe phenyl
groups, only the ipso carbons are shown.
F igu r e 2. ORTEP drawing of 6 with thermal ellipsoids
shown at the 30% probability level. For the dppe phenyl
groups, only the ipso carbons are shown.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) of
Cp (d p p e)MoC(COOMe)dC(P h )CH2CHdCH2 (5)
MeO- to the terminal CO ligand is bound to CR. And it
is clear that the internal olefin C4-C5 is in an E
configuration with the phenyl group and the Mo frag-
ment in a trans disposition. The terminal olefin is
oriented such that the CdC bond is contained in the
plane defined by the metal, the center of the Cp ring,
and the trans phosphorus atom. The olefinic ligand
coordinates to the metal center with Mo-C1 ) 2.216-
(3) Å and Mo-C2 ) 2.295(3) Å. The Mo-C5 bond length
of 2.248(3) Å is typical of a Mo-C single bond, and the
C4-C5 bond length of 1.338(5) Å typical of a CdC
double bond. The C1-C2 bond length of 1.406(5) Å,
resulting from coordination to the metal center, is
slightly longer that that of the C4-C5 double bond. The
CdC double bond of 1.437(9) Å in the cationic olefin
complex Cp[P2(Me)4C2H4](CO)Mo(C2H3Ph)10 is slightly
longer possibly due to stronger back-bonding to the
antibonding orbital of the olefin.
Treatment of 3 with MeONa similarly causes nucleo-
philic addition of MeO- to the terminal CO ligand
followed by an analogous coupling reaction and affords
the neutral allylic product [Mo][η3-CH(COOMe)C(Ph)-
CHPh] (6) in high yield. Due to the lack of a terminal
olefin donor group, the vinylidene ligand in 3 transforms
to the η3-allylic ligand of 6 possibly by coupling followed
by a 1,3-hydrogen shift. The 13C resonance attributed
to the ester carbon appears at δ 183.2, and C-P
coupling constants of three multiplet resonances, ap-
Mo-P1
Mo-P2
Mo-C1
Mo-C2
Mo-C5
P1-C14
P1-C16
P1-C22
P2-C15
P2-C28
P2-C34
O1-C6
O2-C6
O2-C7
C1-C2
C2-C3
2.4844(11)
2.4794(11)
2.216(3)
2.295(3)
2.248(3)
1.855(4)
1.842(4)
1.841(4)
1.829(4)
1.824(4)
1.844(4)
1.199(5)
1.355(4)
1.433(5)
1.406(5)
1.503(5)
C3-C4
1.494(5)
1.338(5)
1.493(5)
1.473(5)
1.383(5)
1.380(5)
1.382(6)
1.367(7)
1.345(7)
1.383(6)
1.521(5)
1.400(6)
1.413(6)
1.380(6)
1.401(6)
1.395(6)
C4-C5
C4-C8
C5-C6
C8-C9
C8-C13
C9-C10
C10-C11
C11-C12
C12-C13
C14-C15
C40-C41
C40-C44
C41-C42
C42-C43
C43-C44
P1-Mo-P2
P1-Mo-C1
P1-Mo-C2
P1-Mo-C5
P2-Mo-C1
P2-Mo-C2
P2-Mo-C5
C1-Mo-C2
C1-Mo-C5
C2-Mo-C5
C6-O2-C7
Mo-C1-C2
Mo-C2-C1
77.36(4)
126.81(11)
90.56(10)
83.71(9)
86.08(10)
74.37(9)
140.73(10)
36.28(14)
78.22(12)
71.72(12)
115.6(3)
Mo-C2-C3
C1-C2-C3
C2-C3-C4
C3-C4-C5
C3-C4-C8
C5-C4-C8
Mo-C5-C4
Mo-C5-C6
C4-C5-C6
O1-C6-O2
O1-C6-C5
O2-C6-C5
114.54(22)
119.9(3)
110.2(3)
116.7(3)
116.1(3)
127.1(3)
121.01(25)
121.51(24)
117.4(3)
121.1(3)
126.7(3)
112.2(3)
74.89(20)
68.84(20)
coupling constants in the allylic group are measurable
for 2, only the coupling constant of 17.2 Hz between
mutually trans-protons in the coordinated olefin is
attainable for 5. However, significant upfield shifts
indicate π-coordination of the terminal double bond in
5. Surprisingly, in the 31P NMR spectrum of 5, two
singlet resonances at δ 90.5 and 71.2 with equal
intensity are observed possibly because of a particular
orientation of the dppe ligand.9 In the 13C NMR spec-
trum of 5, resonances of π-coordinated olefinic carbon
pearing at δ 48.7 (d), 90.3 (t), and 49.2 (d) with J C-P
)
4.5, 3.1, and 2.7 Hz, respectively, clearly indicate the
η3-allylic bonding mode. Two 31P resonances at δ 71.3
and 72.2 with J P-P ) 36.8 Hz are assigned to the dppe
ligand.
The structure of 6 has also been confirmed by an
X-ray diffraction analysis. An ORTEP drawing is shown
in Figure 2, and selected bond distances and angles are
listed in Table 2. The carbomethoxy group is again
bound to the allylic terminal carbon. The trisubstituted
allylic ligand is in an endo conformation with a syn-
phenyl group and an anti-carbomethoxy group at two
terminal carbon atoms. The two allylic C-C bond
lengths are about equal (C1-C4 ) 1.463(4) Å, C4-C5
) 1.446(4) Å), with the Mo-C1 bond slightly shorter
atoms appeared at δ 60.3 (dd) and 47.6 (d) with J C-P
)
5.4, 4.0, and 5.9 Hz, respectively. To fully characterize
this product, single crystals of 5 were grown from a
hexane/CH2Cl2 solution, and the molecular structure
was determined by X-ray diffraction analysis. An ORTEP
drawing is shown in Figure 1, and selected bond
distances and angles are listed in Table 1. The environ-
ment about the metal center corresponds to a structure
of distorted four-legged piano-stool geometry. The car-
bomethoxy group resulting from nucleophilic attack of
(10) (a) Kegley, S. E.; Bergstrom, D. T.; Crocker, L. S.; Weiss, E. P.;
Berndt, W. G.; Rheingold, A. L. Organometallics 1991, 10, 573. (b)
Abugideiri, F.; Kelland, M. A.; Poli, R. Organometallics 1992, 11, 1311.
(c) Kegley, S. E.; Walter, K. A.; Bergstrom, D. T.; MacFarland, D. K.;
Young, B. G.; Rheingold, A. L. Organometallics 1993, 12, 2339.
(9) Morton, M. S.; Lachicotte, R. J .; Vicic, D. A.; J ones, W. D.
Organometallics 1999, 18, 227.

272 Organometallics, Vol. 19, No. 3, 2000
Yang et al.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) of Cp (d p p e)MoCH(COOMe)C(P h )CHP h (6)
of the two groups on the ruthenium metal center. For
the analogous CN-substituted vinylidene complex 4, the
same reaction yielded an unstable cyclopropenyl com-
plex through deprotonation.
Mo-P1
Mo-P2
Mo-C1
Mo-C4
Mo-C5
P1-C19
P1-C20
P1-C26
P2-C18
P2-C32
2.4992(8)
2.4951(8)
2.259(3)
2.328(3)
2.324(3)
1.851(4)
1.858(3)
1.858(3)
1.857(3)
1.846(3)
P2-C38
O1-C2
O2-C2
O2-C3
C1-C2
C1-C4
C4-C5
C4-C6
C5-C12
1.839(3)
1.210(4)
1.376(4)
1.435(4)
1.462(4)
1.463(4)
1.446(4)
1.510(4)
1.483(4)
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were performed
under nitrogen using vacuum-line, drybox, and standard
Schlenk techniques. CH2Cl2 was distilled from CaH2 and
diethyl ether and THF from Na/diphenylketyl. All other
solvents and reagents were of reagent grade and were used
as received. NMR spectra were recorded on Bruker AM-300WB
and DMX-500 FT-NMR spectrometers at room temperature
(unless states otherwise) and are reported in units of δ with
residual protons in the solvents as a standard (CDCl3, δ 7.24;
C2D6O, δ 2.04). FAB mass spectra were recorded on a J EOL
SX-102A spectrometer. Complex [Mo](CO)Cl ([Mo] ) (η5-
C5H5)(dppe)Mo, dppe ) Ph2PCH2CH2PPh2) was prepared
according to the methods reported in the literature.11 Elemen-
tal analyses and X-ray diffraction studies were carried out at
the Regional Center of Analytical Instrumentation located at
the National Taiwan University.
P1-Mo-P2
P1-Mo-C1
P1-Mo-C4
P1-Mo-C5
P2-Mo-C1
P2-Mo-C4
P2-Mo-C5
C2-C1-C4
77.63(3)
87.27(8)
100.36(8)
134.73(8)
132.36(8)
101.46(7)
96.09(8)
124.2(3)
C1-C2-O1
C1-C2-O2
O1-C2-O2
C2-O2-C3
C1-C4-C5
C1-C4-C6
C5-C4-C6
C4-C5-C12
130.3(3)
109.0(3)
120.7(3)
115.3(3)
113.1(3)
117.7(3)
126.5(3)
129.5(3)
than the other two Mo-C(allylic) bonds (Mo-C1 )
2.259(3) Å, Mo-C4 ) 2.328(3) Å, and Mo-C5 ) 2.324-
(3) Å). The different configuration of the carbomethoxy
group relative to the neighboring phenyl group (cis in 5
and trans in 6) could possibly be attributed to the
additional hydrogen shift process in the formation of 6.
Treatment of 4 with MeONa in MeOH gave, in
moderate yield, an unstable green complex, which
decomposed at room temperature in 2 h in CDCl3. This
solid product was isolated by precipitation from the CH2-
Cl2 solution of the product via addition of ether. The
FAB mass spectrum of this complex displays peaks that
could be attributed to the cyclopropenyl complex [Mo]-
P r ep a r a tion of [Mo](CO)CtCP h (1). To a sample of [Mo]-
(CO)Cl (0.22 g, 0.35 mmol) dissolved in 30 mL of THF at room
temperature was added a THF solution of lithium phenyl-
acetylide (1.0 M, 0.40 mL) via a syringe. The resulting mixture
was heated under reflux for 1 h. After removal of all volatile
substances in vacuo, 20 mL of Et2O was added to the residue
under nitrogen, and the extract was filtered. The solvent of
the filtrate was removed under vacuum to afford the yellow
product 1, which was further recrystallized from a 1:1 mixture
of hexane/CH2Cl2 to afford crystals of 1 (0.14 g, 61% yield).
Spectroscopic data for 1: IR (cm-1, CH2Cl2) 2074 (s, νCtC), 1850
1
(s, νCO); H NMR (CDCl3) δ 7.95-6.64 (m, 25H, Ph), 4.49 (d,
J H-P ) 1.6 Hz, 5H, Cp), 2.40, 1.78 (m, 4H, CH2CH2); 13C NMR
(CDCl3) δ 245.0 (d, J C-P ) 22.2 Hz, CO), 141.9-119.2 (Ph),
91.0 (Cp), 31.8 (dd, J C-P ) 28.0 Hz, J C-P ) 18.6 Hz, PCH2),
28.6 (dd, J C-P ) 22.0 Hz, J C-P ) 17.3 Hz, PCH2); 31P NMR
(CDCl3) δ 90.4 (d, J P-P ) 37.2 Hz), 78.7 (d, J P-P ) 37.2 Hz);
MS (FAB, m/z, Mo98) 690 (M+), 662 (M+ - CO). Anal. Calcd
for C40H34OP2Mo: C, 69.77; H, 4.98. Found: C, 70.02; H, 4.79.
Rea ction of [Mo](CO)Cl w ith HCtCP h . To a sample of
[Mo](CO)Cl (0.20 g, 0.32 mmol) dissolved in 50 mL of MeOH
at room temperature was added phenylacetylene (0.21 mL,
1.82 mmol) via a syringe. The resulting mixture was heated
under reflux for 2.5 h to give a green solution. After removal
of all volatile substances in vacuo, 20 mL of CH2Cl2 was added
to the residue, and the extract was filtered. The solvent of the
filtrate was reduced under vacuum to about 5 mL and the
solution added to a stirred solution of Et2O to give green
precipitates. The solid was collected by filtration and washed
with Et2O to give the green product {[Mo](η2-HCtCPh}Cl (0.20
g, 90% yield). Spectroscopic data: 1H NMR (CDCl3) δ 10.02
(t, J H-P ) 13.8 Hz, CH); 7.50-6.82 (m, 25H, Ph), 5.03 (s, 5H,
Cp), 2.70 (m, 4H, PCH2CH2P); 31P NMR (CDCl3) δ 79.3 (s);
MS (FAB, m/z, Mo98) 663 (M+). Anal. Calcd for C39H35P2MoCl:
C, 67.20; H, 5.06. Found: C, 67.21; H, 5.23.
Rea ction of [Mo](CO)Cl w ith HCtCP h in th e P r esen ce
of CO. To a sample of [Mo](CO)Cl (0.10 g, 0.16 mmol) dissolved
in 30 mL of MeOH at room temperature was added phenyl-
acetylene (0.11 mL, 0.92 mmol) via a syringe. The resulting
mixture was heated under reflux for 2.5 h to give a green
solution. After cooling to room temperature the solution was
treated with 1 atm of CO gas and the solution turned yellow.
After removal of all volatile substances in vacuo, 20 mL of CH2-
Cl2 was added to the residue, and the extract was filtered. The
solvent of the filtrate was reduced under vacuum to about 5
mL and the solution added to a stirred solution of hexane to
give yellow precipitates, which were collected by filtration and
washed with hexane to afford {[Mo](CO)(dCdCHPh}Cl, (0.12
(CO)CdC(Ph)CHCN (7). In the IR spectrum of 7, the
absorption at 1846 cm-1 is assigned to the vibrational
stretching of the terminal CO ligand, indicating that
there is no nucleophilic addition. And in the 31P NMR
spectrum, chemical shifts of two singlet resonances at
δ 105.4 and 103.9 differ significantly from the range (δ
90.5 and 71.2) observed for 5 and 6. Unfortunately, we
can obtain spectroscopic data only for this green com-
pound, and there is no established data for a molybde-
num cyclopropenyl complex for comparison. This is
somewhat surprising since in the ruthenium system1
the presence of an electron-withdrawing CN substituent
seemed to stabilize a number of cyclopropenyl com-
plexes. In this Mo vinylidene system with a terminal
CO ligand, the CN group provides no similar effect. In
our attempts to carry out addition reactions of 4 using
nucleophilic reagents other than MeO-, we do not
observe any coupling products as in the reactions of 2
and 3.
In summary, we report high-yield preparation of three
cationic molybednum vinylidene complexes {[Mo](CO)d
CdC(Ph)CH2R}Br (2, R ) CHdCH2; 3, R ) C6H5; 4, R
) CN). In the presence of MeONa, the molybdenum
vinylidene complexes 2 and 3, each containing a termi-
nal carbonyl ligand, undergo nucleophilic addition at the
CO ligand followed by a C-C coupling reaction at CR
of the vinylidene ligand to give addition products. The
site preference of this coupling reaction is possibly due
to the relatively strong bond of RudCR and proximity
(11) (a) Staerker, K.; Curtis, M. D. Inorg. Chem. 1985, 24, 3006. (b)
Lau, Y. Y. Huckabee, W. W.; Gipson, S. L. Inorg. Chim. Acta 1990,
172, 41.

Coupling of Carbomethoxy and Vinylidene Ligand
Organometallics, Vol. 19, No. 3, 2000 273
g, 87% yield). Spectroscopic data: IR (cm-1, CH2Cl2) 1909 (s,
under nitrogen, and the extract was filtered. The solvent of
the filtrate was reduced in volume under vacuum to ca. 5 mL.
The solution was added dropwise to a stirred Et2O solution to
give brown precipitate. The solid was collected by filtration
and washed with Et2O under nitrogen. The solid was dried
under vacuum to afford [[Mo](CO)dCdC(Ph)CH2CN]Br (4)
(0.52 g, 74% yield). Spectroscopic data for 4: IR (cm-1, CH2-
Cl2) 1977 (s, νCO); 1H NMR (CDCl3) δ 7.74-6.77 (m, 25H, Ph),
5.21 (s, 5H, Cp), 3.58, 3.29, 2.52, 2.33 (m, 4H, PCH2CH2P),
2.95 (m, J H-H ) 18.2 Hz, J H-P ) 5.2 Hz, 1H of CH2CN), 2.84
(m, J H-H ) 18.2 Hz, J H-P ) 5.5 Hz, 1H of CH2CN); 31P NMR
(CDCl3) δ 66.8, 63.7 (2d, J P-P ) 30.7 Hz); MS (FAB, m/z) 730
(M+), 702 (M+ - CO). Anal. Calcd for C42H36NOBrP2Mo
(808.5): C, 62.39; H, 4.49; N, 1.73. Found: C, 62.17; H, 4.68;
N, 1.76.
1
νCO); H NMR (CDCl3) δ 7.50-6.82 (m, 25H, Ph), 5.05 (s, 5H,
Cp), 4.78 (s, 1H, dCH), 2.70 (m, 4H, PCH2CH2P); 31P NMR
(CDCl3) δ 58.5 (d, J P-P ) 18.0 Hz), 15.5 (d, J P-P ) 18.0 Hz);
MS (FAB, m/z, Mo98) 691 (M+), 663 (M+ - CO). Anal. Calcd
for C40H35OP2MoCl: C, 66.26; H, 4.87. Found: C, 66.41; H,
4.98. This reaction is reversible. If the MeOH solution of the
product was heated under refluxing, decarbonylation occurred
and the η2-acetylide complex was obtained in quantitative
yield. The carbonylation reaction in the presence of MeONa
(54 mg, 0.10 mmol in 30 mL of MeOH) gave the acetylide
complex 1 in 92% yield.
Rea ction of 1 w ith Allyl Br om id e. To a sample of 1 (0.60
g, 0.87 mmol) dissolved in 50 mL of CHCl3 at room tempera-
ture was added excess BrCH2CHdCH2 (0.10 mL, 1.16 mmol)
via a syringe. The resulting mixture was stirred for 36 h in
the dark. The color of the reaction mixture changed from
yellow to brown within this period. After removal of all volatile
substances in vacuo, 10 mL of CH2Cl2 was added to the residue
under nitrogen, and the extract was filtered. The solvent of
the filtrate was removed under vacuum to afford a brown
residue. The residue was redissolved in 5 mL of CH2Cl2 and
was then added dropwise to a stirred Et2O solution to cause
precipitation of brown solid, which was collected by filtration
and washed with Et2O under nitrogen and dried under vacuum
to afford [[Mo](CO)dCdC(Ph)CH2CHdCH2]Br (2) (0.57 g, 81%
yield). Spectroscopic data for 2: IR (cm-1, CH2Cl2) 1931 (s, νCO);
Rea ction of 2 w ith Na OMe in Meth a n ol. To a sample of
2 (0.33 g, 0.41 mmol) dissolved in 10 mL of methanol at room
temperature was added a methanol solution of sodium meth-
oxide (0.15 g, 2.78 mmol) via a cannula. An orange powder
precipitated after 1 h, and the resulting solution was stirred
for 4 h as the color of the reaction mixture changed from red
to yellow. The product was collected by filtration and washed
with 20 mL of methanol under nitrogen. The powder was dried
under vacuum to afford the product [Mo][η3-C(CO2Me)dC(Ph)-
CH2CHdCH2] (5) (0.25 g, 80% yield). The powder was further
recrystallized from a mixture of hexane/CH2Cl2 to afford yellow
crystals of 5 for X-ray diffraction analysis. Spectroscopic data
for 5: IR (cm-1, CH2Cl2) 1673 (s, νCO); 1H NMR (C6D6) δ 8.25-
6.71 (m, 25H, Ph), 4.71 (s, 5H, Cp), 3.66 (d, J H-H ) 17.2 Hz,
1H, dCH2), 3.41 (s, 3H, OCH3), 2.82 (br, 1H, PCH2), 2.58 (br,
1H, dCH2), 2.52 (br, 1H, PCH2), 2.35 (br, 1H, PCH2), 2.02 (br,
1H, PCH2), 1.97 (br, 1H, CH2), 1.78 (br, 1H, dCH), 1.70 (br,
1H, CH2); 13C NMR (C6D6) δ 180.6 (CO2), 144.4-124.7 (Ph),
87.6 (Cp), 60.3 (dd, J C-P ) 5.4, 4.0 Hz, dCH), 49.4 (OCH3),
1H NMR (CDCl3) δ 7.72-6.82 (m, 25H, Ph), 5.62 (m, J H-H
)
17.1, 10.1, 6.3, 6.0 Hz, 1H, dCH); 5.20 (s, 5H, Cp), 5.00 (m,
J H-H ) 17.1, 1.5 Hz, 1H, dCH), 4.96 (m, J H-H ) 10.1, 1.5 Hz,
1H, dCH), 3.44, 3.22 (m, 2H, PCH2), 2.87 (ddd, J H-H ) 15.6,
6.3 Hz, J H-P ) 2.0 Hz, 1H of CH2), 2.78 (ddd, J H-H ) 15.6, 6.0
Hz, J P-H ) 2.8 Hz, 1H of CH2), 2.42 (m, 2H, PCH2); 13C NMR
(CDCl3) δ 358.4 (dd, J C-P ) 36.0, 6.5 Hz, CR), 227.4 (d, J C-P
)
21.8 Hz, CO), 135.0 (CH), 134.3-126.5 (Ph), 116.8 (dCH2), 95.7
(Cp), 33.9 (CH2), 30.1 (dd, J C-P ) 27.1, 13.1 Hz, PCH2), 28.9
(dd, J C-P ) 28.5, 12.3 Hz, PCH2); 31P NMR (CDCl3) δ 71.5 (d,
J P-P ) 37.5 Hz), 67.0 (d, J P-P ) 37.5 Hz); MS (FAB, m/z, Mo98)
731 (M+), 703 (M+ - CO). Anal. Calcd for C43H39OP2MoBr: C,
63.79; H, 4.86. Found: C, 64.01; H, 4.97.
47.6 (d, J C-P ) 5.9 Hz, dCH2), 34.6 (CH2), 29.1 (dd, J C-P )
29.9 Hz, J C-P ) 15.0 Hz, PCH2), 27.9 (dd, J C-P ) 25.8, 14.4
Hz, PCH2); 31P NMR (C6D6) δ 90.5 (s), 71.2 (s); MS (FAB, m/z,
Mo98) 762 (M+). Anal. Calcd for C44H42O2P2Mo: C, 69.47; H,
5.57. Found: C, 69.32; H, 5.79.
Rea ction of 3 w ith Na OMe in Meth a n ol. A mixture of 3
(0.40 g, 0.46 mmol) and sodium methoxide (0.20 g, 3.70 mmol)
was dissolved in 30 mL of methanol at room temperature. The
solution was stirred for 1 h, and a red product precipitated.
The product was collected by filtration, washed with methanol
under nitrogen, and dried under vacuum to afford the red
compound [Mo](η3-CH(CO2CH3)C(Ph)CHPh) (6) (0.31 g, 83%
yield). The solid was further recrystallized from a mixture of
Et2O/CH2Cl2 to afford red crystals for diffraction analysis.
Rea ction of 1 w ith Ben zyl Br om id e. A mixture of 1 (0.30
g, 0.43 mmol) and BrCH2C6H5 (0.11 mL, 0.84 mmol) was
dissolved in 40 mL of CHCl3 at room temperature, and the
resulting mixture was stirred for 36 h in the dark. The color
of the reaction mixture changed from yellow to red. After
removal of the solvent in vacuo, 10 mL of CH2Cl2 was added
to the residue under nitrogen, and the extract was filtered.
The solvent of the filtrate was reduced in volume to ca. 5 mL.
The solution was added dropwise to a stirred Et2O solution to
give a brown precipitate. The solid was collected by filtration
and washed with 5 mL of Et2O under nitrogen. The solid was
dried under vacuum to afford the brown product [[Mo](CO)d
CdC(Ph)CH2Ph]Br (3) (0.27 g, 73% yield). Spectroscopic data
for 3: IR (cm-1, CH2Cl2) 1931 (s, νCO); 1H NMR (CDCl3) δ 7.98-
6.73 (m, 30H, Ph), 5.09 (s, 5H, Cp), 3.42 (dd, J H-H ) 14.5 Hz,
J H-P ) 2.0 Hz, 1 H on CH2Ph), 3.27 (dd, J H-H ) 14.5 Hz, J H-P
) 3.7 Hz, 1 H on CH2Ph), 3.20 (m, 2H, CH2), 2.38 (m, 2H, CH2);
13C NMR (CDCl3) δ 356.7 (dd, J C-P ) 37.8 Hz, 5.6 Hz, CR),
227.8 (d, J C-P ) 20.6 Hz, CO), 134.1-126.8 (Ph), 95.9 (Cp),
36.0 (CH2Ph), 30.3 (dd, J C-P ) 28.3, 13.6 Hz, PCH2), 28.5 (dd,
J C-P ) 28.7, 11.4 Hz, PCH2); 31P NMR (CDCl3) δ 69.0 (d, J P-P
) 36.3 Hz), 66.2 (d, J P-P ) 36.3 Hz); MS (FAB, m/z, Mo98) 781
(M+), 753 (M+ - CO). Anal. Calcd for C47H41OP2MoBr: C,
65.67; H, 4.81. Found: C, 65.60; H, 4.99.
1
Spectroscopic data for 6: IR (cm-1, CH2Cl2) 1674 (s, νCO); H
NMR (CD2Cl2) δ 7.98-6.14 (m, 30H, Ph), 4.62 (s, 1H, syn H),
3.88 (d, J H-P ) 11.4 Hz, 1H, anti H), 3.73 (s, 5H, Cp), 3.71 (s,
3H, OCH3), 2.68 (m, 1H, PCH2), 2.53 (m, 1H, PCH2), 2.47 (m,
1H, PCH2), 1.90 (m, 1H, PCH2); 13C NMR (CD2Cl2) δ 183.2 (d,
J C-P ) 3.5 Hz, CO2), 149.0-125.0 (Ph), 92.4 (Cp), 90.3 (t, J C-P
) 3.1 Hz, C(Ph)), 50.2 (OCH3), 49.2 (d, J C-P ) 2.7 Hz, CHPh),
48.7 (d, J C-P ) 4.5 Hz, CHCO2CH3), 33.7 (dd, J C-P ) 28.1, 14.3
Hz, PCH2), 24.2 (dd, J C-P ) 23.1, 12.9 Hz, PCH2); 31P NMR
(CD2Cl2) δ 71.3 (d, J P-P ) 36.8 Hz), 72.2 (d, J P-P ) 36.8 Hz);
MS (FAB, m/z, Mo98) 812 (M+). Anal. Calcd for C48H44O2P2-
Mo: C, 71.11; H, 5.47. Found: C, 71.06; H, 5.59.
Dep r oton a tion of [Cp (d p p e)(CO)ModCdC(P h )CH2CN]-
Br by Na OMe. To a sample of 4 (0.11 g, 0.14 mmol) dissolved
in 15 mL of MeOH at room temperature was added 5 mL of a
MeOH solution of sodium methoxide (0.05 g, 1.9 mmol) via
cannula. The color of the solution changed from red to green
immediately. After removal of the solvent in vacuo, 2 mL of
CH2Cl2 and 20 mL of hexane were added to the residue under
nitrogen, and the extract was filtered. The solvent of the
filtrate was removed under vacuum to afford a green residue.
The residue was redissolved in 2 mL of CH2Cl2. The solution
was added dropwise to a stirred Et2O solution to give green
Rea ction of 1 w ith Br om oa ceton itr ile. To a sample of 1
(0.61 g, 0.87 mmol) dissolved in 40 mL of CHCl3 at room
temperature was added excess BrCH2CN (0.1 mL, 1.44 mmol)
via a syringe. The resulting mixture was stirred for 24 h in
the dark. The color of the reaction mixture changed from
yellow to brown within 12 h. After removal of all volatile
substances in vacuo, 10 mL of CH2Cl2 was added to the residue

274 Organometallics, Vol. 19, No. 3, 2000
Yang et al.
package.12 The structure was solved using direct methods13
and was refined on intensities of 4949 reflections to give R )
0.034, Rw ) 0.037 (I > 2σ(I)). For 6, a single crystal of
dimensions 0.20 × 0.25 × 0.35 mm3 was mounted on a glass
fiber with epoxy. Data were collected at room temperature on
a Siemens SMART CCD area detector system employing a 3
kW sealed tube X-ray source operating at 1.5 kW. The total
data collection was approximately 6 h, yielding 7071 indepen-
dent data after integration using SAINT.14 Unit cell param-
eters were determined from the least-squares refinement of
three-dimensional centroids of unique reflections. Data were
corrected for absorption with the SADABS program.15 The
space group was assigned as P1h, and the structure was solved
and refined using direct methods included in the SHELXTL
package.16 In the final model, non-hydrogen atoms were refined
anisotropically, with hydrogen atoms included in idealized
locations. The structure was refined to R1 ) 0.0411 and wR2
) 0.1386 for I > 2σ(I) and to R1 ) 0.0451 and wR2 ) 0.1434
for all data.17 Crystal and intensity collection data for 5 and 6
are given in Table 3, and fractional coordinates and thermal
parameters are given in the Supporting Information.
Ta ble 3. Cr ysta l a n d In ten sity Collection Da ta for
Cp (d p p e)MoC(COOMe)dC(P h )CH2CdCH2 (5) a n d
Cp (d p p e)MoCH(COOMe)C(P h )CHP h (6)
5
6
mol formula
C45H44O2P2Cl2Mo C48H44O2P2Mo
mol wt
845.63
810.71
space group
a, Å
b, Å
c, Å
P21/c
P1h
17.998(5)
8.647(3)
26.080(5)
9.6178(1)
10.8305(2)
21.3254(3)
96.911(1)
94.388(1)
113.258(1)
2007.22(5)
2
R, deg
â, deg
100.30(2)
γ, deg
V, Å3
3993.6(19)
4
0.30 × 0.35 × 0.40 0.20 × 0.25 × 0.35
Z
cryst dimens, mm3
Mo KR radiation: γ, Å
θ range for data
collection
0.71073
0.97-25.0
0.55-25.0
limiting indices (h, k, l) -21, 21; 0, 10;
-12, 12; -14, 14;
-28, 28
0, 30
no. of reflns collected
no. of ind reflns
7015
4949
16793
7071
max. and min. transmn 0.868 and 0.819
0.492/0.408
full-matrix least-squares on F2
Ack n ow led gm en t. Financial support from the Na-
tional Science Council, Taiwan, is gratefully acknowl-
edged.
refinement method
no. of data/restraints/
params
4949/0/470
7071/0/479
1.196
GOF
1.55
final R indices
[I > 2σ(I)]
Su p p or tin g In for m a tion Ava ila ble: Details of the struc-
tural determination for complexes 5 and 6, including crystal
and intensity collection data, positional and anisotropic ther-
mal parameters, and all of the bond distances and angles. This
material is available free of charge via the Internet at
http://pubs.acs.org.
0.034/0.037
-0.470, +0.490
0.0411/0.1386
0.0451/0.1434
-0.846, +0.507
all data
∆F (in final map), e/Å
precipitates. The solid was collected by filtration, washed with
Et2O under nitrogen, and dried under vacuum to afford a green
OM9907167
solid, Cp(dppe)(CO)Mo-CdC(Ph)CHCN (7) (0.052 g, 53%
yield). Spectroscopic data for 7: IR (cm-1, CH2Cl2) 1846 (s, νCO);
1H NMR (CDCl3) δ 7.81-6.91 (m, 25H, Ph), 4.78 (s, 5H, Cp),
3.73, 3.06 (2m, 4H, PCH2CH2P), 2.51 (s, 1H, CHCN); 31P NMR
(CDCl3) δ 105.4 (s), 103.9 (s); MS (FAB, m/z) 729 (M+), 701
(M+ - CO). Anal. Calcd for C42H35NOP2Mo: C, 69.33; H, 4.85;
N, 1.93. Found: C, 69.97; H, 5.35, N, 2.64.
X-r a y Str u ctu r e Deter m in a tion of 5 a n d 6. Yellow
crystals of 5 suitable for X-ray diffraction study were grown
directly from a mixture of hexane/CH2Cl2. A single crystal of
dimensions 0.30 × 0.35 × 0.40 mm3 was glued to a glass fiber
and mounted on an Nonius CAD-4 diffractometer. Data were
collected and processed, and crystallographic computations
were carried out using the NRCC structure determination
(12) Gabe, E. J .; Lee, F. L.; Lepage, Y. In Crystallographic Comput-
ing 3; Sheldrick, G. M., Kruger, C., Goddard, R., Eds.; Clarendon
Press: Oxford, England, 1985; p 167.
(13) Sheldrick, G. M. SHELXS-86, Program for Crystal Structure
Solution; University of Gottingen: Gottingen, Germany, 1986
(14) SAINT (Siemens Area Detector Integration) program; Siemens
Analytical X-ray: Madison, WI, 1995.
(15) The SADABS program is based on the method of Blessing;
see: Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33.
(16) SHELXTL: Structure Analysis Program, version 5.04; Siemens
Industrial Automation Inc.: Madison, WI, 1995.
(17) GOF ) [∑[w(F2 - F2c)2]/(n - p)]1/2, where n and p denote the
o
number of data and parameters. R1 ) (∑||Fo| - |Fc||)/∑|Fo|, wR2 ) [∑-
[w(F2o - F2c)2]/∑[w(F2o)2]]1/2, where w ) 1/[σ2(F2o) + (aP)2 + bP] and P
) [(max; 0, F2o) + 2F2c]/3.