Some diolefin complexes of iridium(I) and a trans-influence series for the complexes [IrCl(cod)L]

A high-yield synthesis of IrCl(cod)]₂ (cod = 1,5-cyclooctadiene) is described. The ¹H and ¹³C NMR spectra of a number of complexes IrCl(cod)L] are interpreted in terms of a trans-effect series Cl^? < sym-collidine < 2-picoline < PCy₃ < P-i-Pr₃ < Pet₃ ～ AsPh₃ < PMe₂Ph < PMePh₂ < PPh₂ <P(MeO)Ph₂ < PClPh₂ < P(OPh)₃ < PCl₂Ph. Some ligand exchange reactions of IrCl(cod)L] are discussed. A number of complexes of the type Ir(cod)L_n]PF₆ (L = a variety of amines (n = 2) and phosphines (n = 2 or 3)) are described. Exchange reactions of the sort: Ir(cod)(PR₃)₂]PF₆ + Ir(cod)(py)₂]PF₆ ? Ir(cod)(PR₃)Py]PF₆ are reported in which, surprisingly, the isolable mixed ligand complexes are the only detectable species at equilibrium (py = pyridine).