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Coupling of Carbomethoxy and Vinylidene Ligand in

Molybdenum Complexes

Jung-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)CH

CHdCH

]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)CH

CHdCH

(5).

Similar coupling was observed when [Cp(dppe)(CO)ModCdC(Ph)CH

Ph]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.

Introduction

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.

_{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.

_{Therefore, we}

set out to study the chemical reactivity of a molybdenum

vinylidene system of Cp(Ph

PCH

CH

PPh

)(CO)Mo.

Such a system was chosen because the presence of donor

phosphine ligands is known to assist the preparation

of cationic metal vinylidene complexes,

_{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.

_{Coupling reactions}

involving CR of a vinylidene ligand on the metal complex

are limited in the literature. Herein we report

prepara-tion of a number of caprepara-tionic molybdenum vinylidene

complexes Cp(Ph

PCH

CH

PPh

)(CO)ModCdC(Ph)-CH

R 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.

Results and Discussion

Preparation of the Acetylide Complex 1. The

acetylide complex [Mo](CO)CtCPh (1, [Mo] ) (η

-C

H

)(dppe)Mo, dppe ) Ph

PCH

CH

PPh

) 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](η

_-HCt

CPh)

}

Cl. Then the η

_{-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.

_{Our scheme involves more steps}

but gives higher overall yield.

The

_{P NMR spectrum of 1 exhibits two sets of}

doublet resonances at δ 90.4 and 78.7 with J

) 37.2

Hz. In the

_{H NMR spectrum, the resonance for the Cp}

ligand is a doublet at δ 4.49 with J

) 1.6 Hz,

indicating coupling with only one of the phosphorus

atoms of the dppe. In the

_{C NMR spectrum, the signal}

for the terminal CO ligand is also a doublet at δ 245.0

with J

) 22.2 Hz, indicating the same coupling

pattern. By the use of selective heteronuclear decoupling

techniques, i.e.,

_H

{

_P

}

_and

_C

{

_P

}

_{NMR spectra, we}

are able to determine that both

_H-

_{P coupling of the}

Cp ligand and

_C-

_{P coupling of the CO ligand}

originate from the same phosphorus atom displaying the

downfield resonance (at δ 90.4) in the

_{P NMR}

spec-trum. Coupling between carbon and phosphorus nuclei

of the complex with a piano-stool coordination geometry

(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,

553, 417. (d) Lo, Y. H.; Lin, Y. C.; Lee, G. H.; Wang, Y. Organometallics 1999, 18, 982.

(2) (a) Kubota, K.; Mori, S.; Nakamura, M.; Nakamura, E. J. Am.

Chem. Soc. 1998, 120, 13334. (b) Muller, P.; Imogai, H. Tetrahedron: Asymmetry 1998, 9, 4419. (c) Plemenkov, V. V.; Rul, S. V.; Gubaidullin,

A. T.; Litvinov, I. A.; Karaseva, I. P.; Nuretdinov, I. A. Russ. J. Org.

Chem. 1998, 34, 971.

(3) (a) Allen, S. R.; Beevor, R. G.; Green, M.; Norman, N. C.; Orpen, 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,

B. A. Organometallics 1988, 7, 2248. (d) Chang, K. H.; Lin, Y. C. Chem.

Commun. 1998, 1441.

(4) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) Bruce, M. I.; Swincer, A. G. Adv. Organomet. Chem. 1982, 20, 159.

(5) (a) Buil, M. L.; Esteruelas, M. A.; Lo`pez, A. M.; On˜ate, E.

Organometallics 1997, 16, 3169. (b) Bianchini, C.; Casares, J. A.;

Peruzzini, M.; Romerosa, A.; Zanobini, F. J. Am. Chem. Soc. 1996, 118, 4585. (c) Faure, M.; Maurette, L., Donnadieu, B.; Lavigne, G. Angew.

Chem., Int. Ed. Engl. 1999, 34, 518.

10.1021/om9907167 CCC: $19.00 © 2000 American Chemical Society Publication on Web 12/31/1999

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depends on the orientation.

_{In the}

_{H NMR spectrum}

of

{

[Mo](η

_-HCtCPh)

}

_{Cl, the characteristic triplet}

reso-nance at δ 10.02 with J

) 13.8 Hz is assigned to the

terminal CH. The corresponding

_{H signal of the}

vi-nylidene proton of

{

[Mo](CO)dCdCHPh

}

Cl appears as

a singlet at δ 4.78.

Preparation of Vinylidene Complexes. Treatment

of 1 with BrCH

R (R ) CHdCH

, C

H

, and CN)

afforded cationic brown-red vinylidene complexes

{

[Mo]-(CO)dCdC(Ph)CH

R

}

Br (2, R ) CHdCH

; 3, R ) C

H

;

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 CHCl

,

CH

Cl

, and CH

OH but are insoluble in hexane.

Complex 2 is air- and moisture-sensitive but is stable

under nitrogen. The

_{H 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 CH

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 (

_J

P-H

) 2.8

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

_{C NMR spectrum, the characteristic}

doublet of doublet resonance centered at δ 358.4 with

_J

P-C

) 36.0 and 6.5 Hz is assigned to the vinylidene

CR. In the

_{P NMR spectrum, two doublet resonances}

at δ 71.5 and 67.0 with J

) 37.5 Hz are assigned to

the dppe ligand. In the

_{P NMR spectra of 3 and 4, the}

_{P resonances fall in a similar region with comparable}

coupling constants (δ 69.0 and 66.2 with J

) 36.3

Hz for 3 and δ 66.8 and 63.7 with J

) 30.7 Hz for 4).

Other spectroscopic features are consistent with their

formulations.

Reactions of 2 and 3 with 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-Bu

NOH, DBU, and n-Bu

NF gave no reaction.

In the reaction of 2 with MeONa the coupling product

[Mo](η

_{-C(COOMe)dC(Ph)CH}

2

CHdCH

) (5) (Scheme 1)

was obtained in high yield. Formation of 5 is

rational-ized by nucleophilic addition of MeO

to the terminal

CO ligand

_{giving the carbomethoxy group followed by}

a coupling reaction

_{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

_{H NMR spectrum of 2}

appear at δ 5.62 (dCH) and 5.00, 4.96 (dCH

), while

those of 5 occur at δ 1.78 (dCH) and 2.58, 3.66 (dCH

).

These assignments are determined by the use of 2D

COSY and HSQC experiments. While most of H-H

(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.

(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.

(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.

Scheme 1

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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

_{P 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.

_{In the}

_{C NMR}

spec-trum of 5, resonances of π-coordinated olefinic carbon

atoms appeared at δ 60.3 (dd) and 47.6 (d) with J

)

5.4, 4.0, and 5.9 Hz, respectively. To fully characterize

this product, single crystals of 5 were grown from a

hexane/CH

Cl

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

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 ) 2.2952.216-(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[P

(Me)

C

H

](CO)Mo(C

H

Ph)

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][η

-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 η

_{-allylic ligand of 6 possibly by coupling followed}

by a 1,3-hydrogen shift. The

_{C resonance attributed}

to the ester carbon appears at δ 183.2, and C-P

coupling constants of three multiplet resonances,

ap-pearing at δ 48.7 (d), 90.3 (t), and 49.2 (d) with J

)

4.5, 3.1, and 2.7 Hz, respectively, clearly indicate the

η

_{-allylic bonding mode. Two}

_{P resonances at δ 71.3}

and 72.2 with J

) 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

(9) Morton, M. S.; Lachicotte, R. J.; Vicic, D. A.; Jones, W. D.

Organometallics 1999, 18, 227.

(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.

Figure 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.

Table 1. Selected Bond Distances (Å) and Angles (deg) of Cp(dppe)MoC(COOMe)dC(Ph)CH2CHdCH2(5) Mo-P1 2.4844(11) C3-C4 1.494(5) Mo-P2 2.4794(11) C4-C5 1.338(5) Mo-C1 2.216(3) C4-C8 1.493(5) Mo-C2 2.295(3) C5-C6 1.473(5) Mo-C5 2.248(3) C8-C9 1.383(5) P1-C14 1.855(4) C8-C13 1.380(5) P1-C16 1.842(4) C9-C10 1.382(6) P1-C22 1.841(4) C10-C11 1.367(7) P2-C15 1.829(4) C11-C12 1.345(7) P2-C28 1.824(4) C12-C13 1.383(6) P2-C34 1.844(4) C14-C15 1.521(5) O1-C6 1.199(5) C40-C41 1.400(6) O2-C6 1.355(4) C40-C44 1.413(6) O2-C7 1.433(5) C41-C42 1.380(6) C1-C2 1.406(5) C42-C43 1.401(6) C2-C3 1.503(5) C43-C44 1.395(6) P1-Mo-P2 77.36(4) Mo-C2-C3 114.54(22) P1-Mo-C1 126.81(11) C1-C2-C3 119.9(3) P1-Mo-C2 90.56(10) C2-C3-C4 110.2(3) P1-Mo-C5 83.71(9) C3-C4-C5 116.7(3) P2-Mo-C1 86.08(10) C3-C4-C8 116.1(3) P2-Mo-C2 74.37(9) C5-C4-C8 127.1(3) P2-Mo-C5 140.73(10) Mo-C5-C4 121.01(25) C1-Mo-C2 36.28(14) Mo-C5-C6 121.51(24) C1-Mo-C5 78.22(12) C4-C5-C6 117.4(3) C2-Mo-C5 71.72(12) O1-C6-O2 121.1(3) C6-O2-C7 115.6(3) O1-C6-C5 126.7(3) Mo-C1-C2 74.89(20) O2-C6-C5 112.2(3) Mo-C2-C1 68.84(20)

Figure 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.

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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 CDCl

. This

solid product was isolated by precipitation from the CH

-Cl

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]-(CO)CdC(Ph)CHCN (7). In the IR spectrum of 7, the

absorption at 1846 cm

is assigned to the vibrational

stretching of the terminal CO ligand, indicating that

there is no nucleophilic addition. And in the

_{P 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 system

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)CH

R

}

Br (2, R ) CHdCH

; 3, R ) C

H

; 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

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.

Experimental Section

General Procedures. 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 JEOL 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.

Preparation of [Mo](CO)CtCPh (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/CH2Cl2to afford crystals of 1 (0.14 g, 61% yield). Spectroscopic data for 1: IR (cm-1, CH2Cl2) 2074 (s, νCtC), 1850 (s, νCO);1H NMR (CDCl3) δ 7.95-6.64 (m, 25H, Ph), 4.49 (d, JH-P) 1.6 Hz, 5H, Cp), 2.40, 1.78 (m, 4H, CH2CH2);13C NMR (CDCl3) δ 245.0 (d, JC-P) 22.2 Hz, CO), 141.9-119.2 (Ph), 91.0 (Cp), 31.8 (dd, JC-P) 28.0 Hz, JC-P) 18.6 Hz, PCH2), 28.6 (dd, JC-P) 22.0 Hz, JC-P) 17.3 Hz, PCH2);31P NMR (CDCl3) δ 90.4 (d, JP-P) 37.2 Hz), 78.7 (d, JP-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. Reaction of [Mo](CO)Cl with HCtCPh. 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 CH2Cl2was 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: 1_{H NMR (CDCl}

3) δ 10.02 (t, JH-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 C}

39H35P2MoCl: C, 67.20; H, 5.06. Found: C, 67.21; H, 5.23.

Reaction of [Mo](CO)Cl with HCtCPh in the Presence 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 -Cl2was 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

(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.

Table 2. Selected Bond Distances (Å) and Angles (deg) of Cp(dppe)MoCH(COOMe)C(Ph)CHPh (6) Mo-P1 2.4992(8) P2-C38 1.839(3) Mo-P2 2.4951(8) O1-C2 1.210(4) Mo-C1 2.259(3) O2-C2 1.376(4) Mo-C4 2.328(3) O2-C3 1.435(4) Mo-C5 2.324(3) C1-C2 1.462(4) P1-C19 1.851(4) C1-C4 1.463(4) P1-C20 1.858(3) C4-C5 1.446(4) P1-C26 1.858(3) C4-C6 1.510(4) P2-C18 1.857(3) C5-C12 1.483(4) P2-C32 1.846(3) P1-Mo-P2 77.63(3) C1-C2-O1 130.3(3) P1-Mo-C1 87.27(8) C1-C2-O2 109.0(3) P1-Mo-C4 100.36(8) O1-C2-O2 120.7(3) P1-Mo-C5 134.73(8) C2-O2-C3 115.3(3) P2-Mo-C1 132.36(8) C1-C4-C5 113.1(3) P2-Mo-C4 101.46(7) C1-C4-C6 117.7(3) P2-Mo-C5 96.09(8) C5-C4-C6 126.5(3) C2-C1-C4 124.2(3) C4-C5-C12 129.5(3)

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g, 87% yield). Spectroscopic data: IR (cm-1_{, CH}

2Cl2) 1909 (s, νCO);1H 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, JP-P) 18.0 Hz), 15.5 (d, JP-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.

Reaction of 1 with Allyl Bromide. To a sample of 1 (0.60 g, 0.87 mmol) dissolved in 50 mL of CHCl3at 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 CH2Cl2was 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 CH2Cl2and 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); 1_{H NMR (CDCl} 3) δ 7.72-6.82 (m, 25H, Ph), 5.62 (m, JH-H) 17.1, 10.1, 6.3, 6.0 Hz, 1H, dCH); 5.20 (s, 5H, Cp), 5.00 (m, JH-H) 17.1, 1.5 Hz, 1H, dCH), 4.96 (m, JH-H) 10.1, 1.5 Hz, 1H, dCH), 3.44, 3.22 (m, 2H, PCH2), 2.87 (ddd, JH-H) 15.6, 6.3 Hz, JH-P) 2.0 Hz, 1H of CH2), 2.78 (ddd, JH-H) 15.6, 6.0 Hz, JP-H) 2.8 Hz, 1H of CH2), 2.42 (m, 2H, PCH2);13C NMR (CDCl3) δ 358.4 (dd, JC-P) 36.0, 6.5 Hz, CR), 227.4 (d, JC-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, JC-P) 27.1, 13.1 Hz, PCH2), 28.9 (dd, JC-P) 28.5, 12.3 Hz, PCH2);31P NMR (CDCl3) δ 71.5 (d, JP-P) 37.5 Hz), 67.0 (d, JP-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.

Reaction of 1 with Benzyl Bromide. A mixture of 1 (0.30 g, 0.43 mmol) and BrCH2C6H5 (0.11 mL, 0.84 mmol) was dissolved in 40 mL of CHCl3at 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 CH2Cl2was 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, JH-H) 14.5 Hz, JH-P) 2.0 Hz, 1 H on CH2Ph), 3.27 (dd, JH-H) 14.5 Hz, JH-P ) 3.7 Hz, 1 H on CH2Ph), 3.20 (m, 2H, CH2), 2.38 (m, 2H, CH2); 13_{C NMR (CDCl} 3) δ 356.7 (dd, JC-P) 37.8 Hz, 5.6 Hz, CR), 227.8 (d, JC-P) 20.6 Hz, CO), 134.1-126.8 (Ph), 95.9 (Cp), 36.0 (CH2Ph), 30.3 (dd, JC-P) 28.3, 13.6 Hz, PCH2), 28.5 (dd, JC-P) 28.7, 11.4 Hz, PCH2);31P NMR (CDCl3) δ 69.0 (d, JP-P ) 36.3 Hz), 66.2 (d, JP-P) 36.3 Hz); MS (FAB, m/z, Mo98) 781 (M+_{), 753 (M}+ _{- CO). Anal. Calcd for C}

47H41OP2MoBr: C, 65.67; H, 4.81. Found: C, 65.60; H, 4.99.

Reaction of 1 with Bromoacetonitrile. 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 CH2Cl2was added to the residue

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, JH-H) 18.2 Hz, JH-P) 5.2 Hz, 1H of CH2CN), 2.84 (m, JH-H) 18.2 Hz, JH-P) 5.5 Hz, 1H of CH2CN);31P NMR (CDCl3) δ 66.8, 63.7 (2d, JP-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.

Reaction of 2 with NaOMe in Methanol. 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(CO

2 Me)dC(Ph)-CH2CHdCH2] (5) (0.25 g, 80% yield). The powder was further recrystallized from a mixture of hexane/CH2Cl2to 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, JH-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, JC-P) 5.4, 4.0 Hz, dCH), 49.4 (OCH3), 47.6 (d, JC-P) 5.9 Hz, dCH2), 34.6 (CH2), 29.1 (dd, JC-P) 29.9 Hz, JC-P) 15.0 Hz, PCH2), 27.9 (dd, JC-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.

Reaction of 3 with NaOMe in Methanol. 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(CO

2CH3)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. Spectroscopic data for 6: IR (cm-1, CH2Cl2) 1674 (s, νCO);1H NMR (CD2Cl2) δ 7.98-6.14 (m, 30H, Ph), 4.62 (s, 1H, syn H), 3.88 (d, JH-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, JC-P) 3.5 Hz, CO2), 149.0-125.0 (Ph), 92.4 (Cp), 90.3 (t, JC-P ) 3.1 Hz, C(Ph)), 50.2 (OCH3), 49.2 (d, JC-P) 2.7 Hz, CHPh), 48.7 (d, JC-P) 4.5 Hz, CHCO2CH3), 33.7 (dd, JC-P) 28.1, 14.3 Hz, PCH2), 24.2 (dd, JC-P) 23.1, 12.9 Hz, PCH2);31P NMR (CD2Cl2) δ 71.3 (d, JP-P) 36.8 Hz), 72.2 (d, JP-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.

Deprotonation of [Cp(dppe)(CO)ModCdC(Ph)CH2 CN]-Br by NaOMe. 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 CH2Cl2and 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

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precipitates. The solid was collected by filtration, washed with Et2O under nitrogen, and dried under vacuum to afford a green solid, Cp(dppe)(CO)Mo-CdC(Ph)CHCN (7) (0.052 g, 53% yield). Spectroscopic data for 7: IR (cm-1_{, CH}

2Cl2) 1846 (s, νCO); 1_{H NMR (CDCl}

3) 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 C}

42H35NOP2Mo: C, 69.33; H, 4.85; N, 1.93. Found: C, 69.97; H, 5.35, N, 2.64.

X-ray Structure Determination of 5 and 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

package.12 _{The structure was solved using direct methods}13 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.

Acknowledgment. Financial support from the

Na-tional Science Council, Taiwan, is gratefully

acknowl-edged.

Supporting Information Available: 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.

OM9907167

(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

o- F2c)2]/(n - p)]1/2, where n and p denote the number of data and parameters. R1 ) (∑||Fo| - |Fc||)/∑|Fo|, wR2 ) [∑-[w(F2

o- F2c)2]/∑[w(F2o)2]]1/2, where w ) 1/[σ2(F2o) + (aP)2+ bP] and P ) [(max; 0, F2_{o) + 2F}2_c]/3.

Table 3. Crystal and Intensity Collection Data for Cp(dppe)MoC(COOMe)dC(Ph)CH2CdCH2(5) and Cp(dppe)MoCH(COOMe)C(Ph)CHPh (6) 5 6 mol formula C45H44O2P2Cl2Mo C48H44O2P2Mo mol wt 845.63 810.71 space group P21/c P1h a, Å 17.998(5) 9.6178(1) b, Å 8.647(3) 10.8305(2) c, Å 26.080(5) 21.3254(3) R, deg 96.911(1) β, deg 100.30(2) 94.388(1) γ, deg 113.258(1) V, Å3 _{3993.6(19) 2007.22(5)} Z 4 2 cryst dimens, mm3 _{0.30× 0.35 × 0.40 0.20 × 0.25 × 0.35} Mo KR radiation: γ, Å 0.71073

θ range for data

collection 0.55-25.0 0.97-25.0 limiting indices (h, k, l) -21, 21; 0, 10; 0, 30 -12, 12; -14, 14; -28, 28

no. of reflns collected 7015 16793

no. of ind reflns 4949 7071

max. and min. transmn 0.868 and 0.819 0.492/0.408 refinement method full-matrix least-squares on F2

no. of data/restraints/ params 4949/0/470 7071/0/479 GOF 1.55 1.196 final R indices [I > 2σ(I)] 0.034/0.037 0.0411/0.1386 all data 0.0451/0.1434

∆F (in final map), e/Å -0.470, +0.490 -0.846, +0.507

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