(1–3-η-Allyl)tris(trifluorophosphine)rhodium(I) complexes: syntheses, phosphine-ligand exchange, and an unusual η-allyl isomerisation process

Abstract

Different synthetic routes to a series of volatile (1–3-η-allyl)tris(trifluorophosphine)rhodium(I) complexes [RhL(PF₃)₃] are described [I; L = 1–3-η-allyl, -(2-methylallyl), -(1-methylallyl)(syn- and anti-), -(1,2-dimethylallyl)(syn- and anti-), -(1,1-dimethylallyl), -(1,3-dimethylallyl)(syn- and anti-), -(1-ethyl-3-methylallyl)(syn- and anti-), and cyclohexenyl]. A novel thermal isomerisation of the 1–3-η-(1,1-dimethylallyl) complex to the 1,2-form is reported and a possible mechanism discussed. Variable-temperature ¹⁹F and ¹H n.m.r. spectra are presented and establish that ready inter- and intra-molecular phosphine-exchange processes are both occurring in all these complexes.