Reactions of chromium and molybdenum carbonyls with bis-(salicylaldehyde)-1,3-propylenediimine Schiff base

Interaction of a Schiff base, bis-(salicylaldehyde)-1,3-propylenediimine, salpenH(2), with M(CO)(6) (M = Cr or Mo) in the presence of oxygen gave the oxo-complexes[M(O)(salpen)]. Magnetic studies for the two oxo-complexes showed chromium and molybdenum in the +4 formal oxidation state. In presence of pyridine, reaction of Cr(CO)(6) with salpenH(2) gave the identical product; [Cr(O)(salpen)]. Reaction of Mo(CO)(6) with salpenH(2) in presence of pyridine (py) resulted in formation of the square-pyramidal complex [Mo(py)(salpenH(2))]. Reactions of M(CO)(6) with salpenH(2) in presence of a ligand L (L = bipyridine (bpy) or 3,3-dimethylbipyridine (dmbpy)) gave the octahedral complexes [M(L)(salpenH(2))]. All the complexes were characterized by elemental analyses, IR, mass and H-1 NMR spectroscopy. The spectroscopic studies revealed the proposed structures. UV-Vis spectra of the ligand and its complexes in DMSO exhibited visible bands due to metal-to-ligand or ligand-to-metal charge transfer.