Iridium complexes phosphorus donors

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphorus, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

Iridium(IV), d, salts of halides, hydroxide, sulfide, se-lenide, and telluride have been reported. The commercial product H2[IrCl6] 6H2O is water soluble and acts as a catalyst. Ir02 is prepared from the hexahydroxo complex. Iridium(IV) does not form many complexes, but the six-coordinate halides (excluding the iodo species), and some amine and pyridine complexes are known. Compounds with phosphorus, arsenic, and sulfur donor atoms are not stable these ligands reduce iridium(IV) to the iridium(in) state. 

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