Transition metal complexes with bidentate ligands spanning trans‐positions. IV. Preparation and properties of some rhodium and iridium complexes of 2,11‐bis(diphenylphosphinomethyl)benzo [c]phenanthrene

The bidentate phosphine 2,11‐bis(diphenylphosphinomethyl)benzo [c]phenanthrene (1) has been used to prepare the mononuclear, square planar complexes trans‐[MX(CO)(1)] and trans‐[M(CO)(CH3CN)(1)][BF4] (M = Rh, Ir; X = Cl, Br, I, NCS). It is found that the tendency of these complexes to form adducts with CO, O2 and SO2 is significantly lower than that of the corresponding Ph3P complexes. The oxidative‐addition reactions of complexes trans‐[IrX (CO) (1)] with hydrogen halides give the six‐coordinate species [IrHX2(CO) (1)]. The complexes [IrH2I (CO) (1)] and [IrH2L (CO) (1)] [BF4] (L = CO and CH3CN) have been obtained from hydrogen and the corresponding substrates. The model compounds trans‐[MCl (CO) (Ph2PCH2Ph)2] (M = Rh, Ir), trans‐[Ir (CO) (CH3CN) (Ph2PCH2Ph)2] [BF4], [IrHCl2(CO)(Ph2PCH2Ph)2] and [IrH2(CO)2(Ph2PCH2Ph)2] [BF4] have been prepared and their special parameters are compared with those of the corresponding complexes of ligand 1. The influence of the static requirements of this ligand on the chemistry of its rhodium and iridium complexes is discussed.