Tertiary bismuthines complexes

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphoms, 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. 

Due to the low nucleophilicity of the lone pair, tertiary bismuthines have found little use in the construction of onium salts and transition metal complexes. Trimethylbismuthine reacts with methyl triflate in acetonitrile to yield tetramethylbismuthonium triflate, which has so far been the only known example of tetraalkylbismuthonium salts [94AG(E)976]. Some transition metal complexes coordinated by tertiary bismuthine have been reported. They are described in Section 2.4. 

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