The interaction of [Cp*RuCl(dippe)] and [CpRuCl(dippe)] with alkynols: Hydroxyvinylidene, allenylidene and related derivatives (dippe equals 1,2-bis(diisopropylphosphino)ethane)

The reactions of [Cp*RuCl(dippe)] and [CpRuCl(dippe)] (dippe = 1,2-bis(diisopropylphosphino)ethane) with several alkynols HC=CC(OH)RR' (R = R' = H, Me; R = Me, R' = Ph) have been studied. These reactions leads to the formation of the corresponding allenylidene derivatives, although in some cases hydroxyvinylidene complexes were isolated as intermediates in such process. The X-ray crystal structure of [CpRu=C=C=CMePh(dippe)][BPh4] was determined. In the course of the reaction of [CpRuCl(dippe)] with HC=CC(OH)Me-2, there is evidence for the formation of a deep blue dimeric alkynyl-carbene (or alkenyl-allenylidene) complex [{CpRu(dippe)}(2)(mu-C10H11)][BPh4] resulting formally from the coupling of two allenylidene moieties followed by the loss of one proton. The reaction of [Cp*Ru=C=C=CMePh(dippe)][BPh4] with KOBut leads to the ene-yne derivative [Cp*Ru(C=CC(Ph)=CH2)(dippe)] as result of the deprotonation of the allenylidene ligand at the delta-position. This compound was structurally characterized by single crystal X-ray crystallography. In an attempt to obtain the primary allenylidene complex [Cp*Ru=C=C=CH2(dippe)][BPh4] by dehydration of the hydroxyvinylidene [Cp*Ru=C=CHCH2OH(dippe)][BPh4] using P2O5, the previously reported carbonyl complex [Cp*Ru(CO)(dippe)][BPh4] was obtained and its crystal structure determined. This is also accessible by aerial oxidation of the hydroxy-vinylidene derivative. (C) 1997 Elsevier Science S.A.