Ligand Rearrangement and Hemilability in Rhodium(I) and Iridium(I) Complexes Bearing Terphenyl Phosphanes

Abstract

The synthesis of a series of cationic rhodium(I) and iridium(I) compounds stabilized by sterically demanding phosphanes that contain a terphenyl substituent PMeAr′ (Ar′ = 2,6-diarylphenyl) is described. Salt metathesis of metal precursors [MCl(COD)(PMeAr′)] (M = Rh, Ir; COD = cyclooctadiene) with NaBAr {BAr = B[3,5-CH(CF)]} resulted in a series of cationic complexes in which the loss of the chlorido ligand is compensated by the appearance of relatively weak π interactions with one of the flanking aryl rings of the terphenyl substituent. The same experiments carried out with carbonyl complexes [MCl(CO)(PMeAr′)] led to the corresponding cationic carbonyl complexes, the CO-induced rearrangement reactivity of which was investigated, both experimentally and computationally. The differences in reactivity between rhodium and iridium complexes and as a result of varying the sterics of terphenyl phosphanes are discussed.