Cationic transition-metal complexes. Part I. Synthesis and reactions of bis(diene)-rhodium and -iridium tetrafluoroborates

Reaction of [M(dien)(acac)](M = Rh or Ir; diene = 1,5-C8H12 or bicyclo[2,2,1]heptadiene) with Ph3C+BF4– in the presence of an excess of diene affords [M(diene)2]+BF4–, from which diene is readily displaced by acetonitrile to form [M(diene)(CH3CN)2]+BF4–. Reaction of [M(diene)(CH3CN)2]+BF4– with phosphines and bipyridyl are described; complexes of the type [M(diene)L2]+BF4– and [ML4]+BF4– being formed depending on the nucleophilicity of the ligand L. Reaction of [M(1,5-C8H12)2]+BF4– with sodium iodide in acetone affords [M(1,5-C8H12)I]2. Methanol reacts with [Ir(1,5-C8H12)2]+BF4– in the presence of sodium carbonate to give [Ir(1,5-C8H12)OMe]2; a mixture of syn- and anti-isomers.