Facile deprotonation of a number of cationic ruthenium vinylidene complexes, followed by cyclopropenation, is accomplished in acetone. The deprotonation of [Ru]dCd(Ph)CH 2 R + , ([Ru] ) (η 5 -C 5 H 5 )(PPh 3 ) 2 Ru) by n-Bu 4 -NOH induces a novel cyclization reaction and yields the neutral cyclopropenyl complexes [Ru]-CdC(Ph)CHR (3b, R ) CN; 3c, R ) Ph; 3d, R ) CHdCH 2 ; 3e, R ) CHdCMe 2 ). Complex [Ru]-CdC(C 6 H 9 )CHCN + (3k) is similarly prepared. Protonation of 3b-3e regenerates the corresponding vinylidene complexes. Deprotonation of [Ru]dCdC(Ph)CH 2 COOMe + (2h) by n-Bu 4 NOH induces a different type of cyclization and yields the neutral furan complex [Ru]-CdC(Ph)CHdC(O)OMe (4h). The cyclopropenyl complex containing a methoxy substituent cannot be prepared from [Ru]dCdC(Ph)CH 2 OCH 3 + (2i), but Fof n-Bu 4 NF attacks the CR of 2i to produce the unstable vinyl complex [Ru]C(F)dC(Ph)CH 2 OCH 3 (5). Complex [Ru]-CdC(Ph)C(CN)OCH 3 (9b) was indirectly prepared from the addition of TCNQ to 3b, giving [Ru]dCdC(Ph)CH(CN)TCNQ (6b) followed by methanolysis. Unlike 3, complex 9b is not converted to vinylidene complex, instead, removal of the methoxy substituent by acid gives theis similarly prepared from 4h via a TCNQ complex 6h followed by a methoxy-substituted complex 9h. In the presence of allyl iodide, opening of the three-membered ring of 3b, followed by a subsequent oxidative coupling reaction, gives a dimeric dicationic product {[Ru]dCdC(Ph)-CHCN} 2 2+ (11). Proton abstraction of 11 by n-Bu 4 -NF gives the biscyclopropenyl complex {[Ru]-CdC(Ph)CCN} 2 (12). Molecular structures of complexes 3b, 3f, 4h, 6b, 9b, and 11 have been confirmed by X-ray diffraction analysis.

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Deprotonation of the cationic vinylidene complex [Cp(PPh3)2Ru=C=C(Ph) CH2CNII (2a) by (n -Bu)flF yields the neutral cyclopropenyl complex Cp-(PPh3)2Ru-C=C(Ph) CHCN (3a). For Cp(PPh&Ru= C=C(Ph)CH2OCHJl (2b) the fluoride attacks C, to produce the vinyl complex Cp(PPh3)2Ru-C(F)=C(Ph)-CH2OCH3 (4). Electrophilic attack at the methyne carbon of 3a by H+ or Ph&+ opens the three-membered ring and gives back the vinylidene complexes.

Protonation at one of the phenylacetylide substituents of the allylic complexes [W(cp) (CO),{q3-H,CC[C(C=CPh),] CH,R}] (cp = q-C5H5), including the first cationic tungsten-ruthenium allylic vinylidene complex, R = C( Ph)=C=Ru (cp) (PPh,), (crystal structure), gave q4-vinylallene complexes.

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