A high-yield synthetic approach to trans-[Ir(ER3)(2)(CO)X] (ER3 = PMe3, PEt3, PPhMe2, PPh2Me, P(OMe)(3), AsMe3, AsEt3, AsPh3, SbPh3; X = Cl, Br)

The complex [Ir(CO)(2)X-2][NBu4] (X=Cl, Br) forms Vaska-type complexes, tra ns-[Ir(ER3)(2)(CO)X], when treated with two equivalents of aryl- or alkyl-p hosphines, arsines, or stibines under a CO atmosphere. The synthesis is gen eral for a wide range of phosphines, arsines, or stibines irrespective of t he cone angle. For small cone-angle ligands, the initial addition of ligand to [Ir(CO)(2)X-2][NBu4] is performed at low temperature. The synthesis and characterisation of three new Vaska-type complexes trans [Ir(P(OMe)(3))(2) (CO)Cl], trans[Ir(AsMe3)(2)(CO)Cl], and trans-[Ir(AsEt3)(2)(CO)Cl] is also reported. (C) 1999 Elsevier Science Ltd. All rights reserved.