Mechanism of the addition of fluoro-olefins to iridium(I) and platinum(0) complexes

Abstract

Addition of trans-(Ph₃P)₂ Ir(CO)Cl to trans-CF₃(CN)CC(CF₃)CN affords (Ia)(Ph₃P)₂Ir(CO)Cl[CF₃(CN)C₂(CF₃)CN] where the phosphine ligands and CF₃ groups have respectively a relative cis- and trans-configuration. trans-(Ph₂PMe)₂Ir(CO)Cl reacts with the same olefin to form and isostructural complex (II). Stilbene(bistriphenylphosphine)platinum adds to trans-CF₃(CN)CC(CF₃)CN to form a vinyl complex (III)(Ph₃P)₂PtCN-[C(CF₃)^tC(CN)CF₃]. The kinetics of the reaction with trans-(Ph₃P)₂Ir(CO)Cl to form (Ia) have been studied in different solvents and activation parameters obtained. Reaction of cis-/trans-CF₃(CN)CC(CF₃)CN with trans-(Ph₃P)₂Ir(CO)Cl gives only (Ia), and this is interpreted in terms of an ionic-intermediate. The formation of (Ph₃P)₂Pt[CF(Cl)C(F)Cl](IVa)(trans) and (Ph₃P)₂Pt[CF(Cl)C(Cl)F](IVb)(cis), which differ only in the stereochemistry of the olefin, in the ratio of trans : cis= 2·3 : 1 from, stilbenebis(triphenylphosphine)platinum and 1,2-dichloro-1,2-difluoroethylene (cis : trans= 1 : 1), is also interpreted in terms of a similar ionic-intermediate.