Addition of Carbon Nucleophiles to the Allenylidene Ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PiPr3)]BF4: Synthesis of New Organic Ligands by Formal C−C Coupling between Mutually Inert Fragments

EHT-MO Calculations on the model cation [Ru(η 5 -C 5 H 5 )(C C CH 2 )(CO)(PH 3 )] + ( 1a ) suggest that 23% and 31% of the LUMO and 26% of the HOMO of [Ru(η 5 -C 5 H 5 )(C C CPh 2 )(CO)(P i Pr 3 )]BF 4 ( 1 ) are located on C α, C γ, and C β of the allenylidene ligand, respectively. On the basis of these results, we report a new synthetic strategy for the preparation of compounds resulting from the formal addition of phenylacetylene, acetone, and methane to the allenylidene of 1 . Treatment of 1 with LiC⋮CPh leads to the allenyl complex Ru(η 5 -C 5 H 5 ){C(C⋮CPh) C CPh 2 }(CO)(P i Pr 3 ) ( 2 ) and the alkynyl derivative Ru(η 5 -C 5 H 5 ){C⋮C−C(Ph) 2 C⋮CPh}(CO)(P i Pr 3 ) ( 3 ). The reaction of 2 with HBF 4 affords the substituted carbene compound [Ru(η 5 -C 5 H 5 ){C(C⋮CPh)CH CPh 2 }(CO)(P i Pr 3 )]BF 4 ( 4 ), which is a result from the formal addition of phenylacetylene to the C α −C β double bond of the allenylidene of 1 . The molecular structure of 4 has been determined by X-ray crystallography. The geometry around the ruthenium center is close to octahedral with the cyclopentadienyl ligand occupying three sites of a face. The Ru C bond length is 2.004(5) Å. In the presence of KOH, complex 1 reacts with acetone to give Ru(η 5 -C 5 H 5 ){C⋮C−C(Ph) 2 CH 2 C(O)CH 3 }(CO)(P i Pr 3 ) ( 5 ). The reaction of 5 with HBF 4 leads to the unsaturated cyclic carbene Complex 5 also reacts with 2 equiv of CF 3 CO 2 D to and CF 3 CO 2 H, and the reaction of Ru(η 5 -C 5 H 5 ){C⋮C−C(Ph) 2 CD 2 C(O)CD 3 }(CO)(P i Pr 3 ) ( 5- d 5 ) with 2 equiv of HBF 4 and DBF 4 . On the basis of these isotope labeling experiments, the mechanism for the addition of acetone to the allenylidene ligand of 1 is discussed. Complex 1 also reacts with Na(acac) and CH 3 Li. The reaction with Na(acac) leads to Ru(η 5 -C 5 H 5 ){C⋮C−C(Ph) 2 CH[C(O)CH 3 ] 2 }(CO)(P i Pr 3 ) ( 7 ), while the treatment of 1 with CH 3 Li gives a mixture of Ru(η 5 -C 5 H 5 ){C(CH 3 ) C CPh 2 }(CO)(P i Pr 3 ) ( 8 ) and Ru(η 5 -C 5 H 5 ){C⋮C−C(Ph) 2 CH 3 }(CO)(P i Pr 3 ) ( 9 ). Complex 9 reacts with HBF 4 to afford [Ru(η 5 -C 5 H 5 ){C CHC(Ph) 2 CH 3 }(CO)(P i Pr 3 )]BF 4 ( 10 ), which is a result of the formal addition of a C−H bond of methane to the C β −C γ double bond of the allenylidene of 1 .