A Cationic Unsaturated Platinum(II) Complex that Promotes the Tautomerization of Acetylene to Vinylidene

Complex [PtMe(PMeAr)] (1), which contains a tethered terphenyl phosphine (Ar =2,6-(2,6-PrCH)CH), reacts with [H(EtO)]BAr (BAr =B[3,5-(CF)CH] ) to give the solvent (S) complex [PtMe(S)(PMeAr)] (2⋅S). Although the solvent molecule is easily displaced by a Lewis base (e.g., CO or CH) to afford the corresponding adducts, treatment of 2⋅S with CH yielded instead the allyl complex [Pt(η-CH)(PMeAr)] (6) via the alkyne intermediate [PtMe(η-CH)(PMeAr )] (5). Deuteration experiments with CD, and kinetic and theoretical investigations demonstrated that the conversion of 5 into 6 involves a Pt-promoted HC≡CH to :C=CH tautomerization in preference over acetylene migratory insertion into the Pt−Me bond.Fondos FEDER, Subprogramas Ramón y Cajal and Juan de la Cierva BES - 2011 - 048035Ministerio de Ciencia e Innovación CTQ2013 - 42501- P, CTQ2014 -51912 - REDC, CTQ - 2014 - 52769 - C3 - 3 - RJunta de Andalucía FQM - 119 and project P09 - FQM - 4832 and FQM - 212