Thermal decomposition of n-alkyl[bis(triphenylphosphine)](carbonyl)iridium(I) complex

The decomposition of L₂Ir(CO)R, R = n-alkyl) prepared in situ by the reacton of n-alkyllithium or -magnesium reagents with L₂Ir(CO)Cl(2) produces a mixture of n-alkane and isomerized alkene, the ratio of which is strongly dependent on the concentration L] of triphenylphosphine as well as certain other additives. When L] = 0, positional isomerism and isotope scrabling are extensive as is the isomerism of added olefin, suggesting that β-hydride elimination is rapid and reversible and that any olefins participating in an iridium hydride addition-elimination sequence are also capable of exchange with free olefin in solution. When Ph₃P]/2] >/ 1, the principal product (>90%) is the 1-alkene. No positional isomerism or isotope scrambling is observed only a minor amount of alkane is produced. A mechanistic scheme consistent these observations is proposed.