Selective protonation of the styryl ligand of RuMe{(E)-CH:CHPh}(CO)2(PiPr3)2 and migratory CO insertion in the methyl group of [RuMe(CO)2(PiPr3)2]BF4

Complex RuCl{(E)-CH=CHPh}(CO)2(PiPr3)2 (1) reacts with CH3Li in toluene at room temperature to give Ru(CH3){(E)-CH=CHPh}(CO)2(PiPr 3)2 (2). The structure of 2 was determined by an X-ray investigation. The coordination geometry around the ruthenium atom is octahedral with the phosphine ligands occupying trans positions. The perpendicular plane is formed by the methyl and styryl ligands mutually cis disposed and by two additional carbonyl groups. The reaction of 2 with HBF4•OEt2 leads to styrene and the cationic five-coordinate complex [Ru(CH3)(CO)2(PiPr3) 2]BF4 (3), which adds carbon monoxide to give the corresponding derivative [Ru(CH3)(CO)3(PiPr3) 2]BF4 (5). The related styryl complex [Ru-{(E)-CH=CHPh}(CO)3(PiPr3) 2]BF4 (6) can be prepared by reaction of 1 with AgBF4 under a carbon monoxide atmosphere. Complex 3 also reacts with NaCl, NaI, LiOPh, and LiC≡CPh. The reaction with NaCl leads to the η1-acyl carbonyl Ru{C(O)CH3}Cl(CO)(PiPr3)2 (7). The structure of 7 was also determined by an X ray investigation. The geometry of 7 can be rationalized as a square pyramid with the acyl ligand located at the apex. The reaction of 3 with NaI gives a mixture of the methyl dicarbonyl Ru(CH3)I(CO)2(PiPr3)2 (8) and the η1-acyl-carbonyl Ru{C(O)CH3}I(CO)(PiPr3)2 (9). Similarly, the treatment of 3 with LiOPh results in a rapidly established equilibrium mixture of the methyl dicarbonyl Ru(CH3)(OPh)(CO)2(Pi-Pr3) 2 (12) and the η1-acyl carbonyl Ru{C(O)CH3}(OPh)(CO)(PiPr3)2 (13), while the reaction of 3 with LiC≡CPh affords Ru(CH3)(C≡CPh)(CO)2(PiPr 3)2 (14). Under a CO atmosphere 14 is quantitatively converted into Ru{C(O)CH3}(C≡CPh)(CO)2(PiPr 3)2 (15). Under a CO atmosphere, 2 is in equilibrium with Ru{C(O)CH3}{(E)-CH=CHPh}(CO)2(PiPr 3)2 (17). © 1995 American Chemical Society.We thank the DGICYT (Project PB 92-0092, Programa de Promoción General del Conocimiento) and EU (Project: Selective Processes and Catalysis Involving Small Molecules) for financial support. E.O. thanks the Diputación General de Aragón (DGA) for a grant.Peer Reviewe