Chemical ligand non-innocence in pyridine diimine Rh complexes

The formation and reactivity of pyridine diimine rhodium(I) alkyl complexes without β-hydrogens (Me, Bz, CH2SiMe3) is described. In contrast to the corresponding cobalt complexes, the rhodium complexes could not be activated to polymerise ethene. Rh ethyl complexes could not be prepared. Examples of hydrogen transfer to and from the ligand were observed, illustrating the active role the pyridine diimine ligand can play in the reactions of its complexes. Decomposition via loss of free ligand was observed in many cases, indicating that the pyridine diimine ligand is not a very suitable one for RhI.