Reactions of bis[tricarbonyl(triphenylphosphine)iridium] with triphenyl phosphite, triphenylphosphine, and sulphur dioxide

The compound [{Ir(CO)3(PPh3)}2](1) reacts with P(OPh)3 to give [{Ir(CO)2[P(OPh)3]2}2] from which [{Ir(CO)3[P(OPh)3]}2] may be obtained. Compound (1) also gives [Ir2(CO)5(PPh3)3] with PPh3, [Ir2(CO)5{PPh2(C6H4Me-p)}2(PPh3)] with PPh2(C6H4Me-p), and [{Ir(CO)2(PPh3)(SO2)}2], having two bridging sulphur dioxide molecules, with SO2. Reaction of the last compound with hydrogen gives [{Ir(CO)2H(PPh3)}2SO2] and reaction with iodine gives [{Ir(CO)2(PPh3)I2}2SO2], having two bridging and two terminal iodine atoms and one bridging sulphur dioxide molecule, but no metal–metal bond. The compounds [{Ir(CO)2[P(OPh)3]2}2] and [{Ir(CO)3[P(OPh)3]}2] and sulphur dioxide gives [{Ir(CO)[P(OPh)3]2(SO2)}2] and [{Ir(CO)2[P(OPh)3](SO2)}2] respectively in each of which a metal–metal bond is postulated.