Structural studies of some chromium, molybdenum and tungsten complexes of N-salicylidene-2-hydroxyaniline

Interaction of the Schiff base N-salicylidene-2-hydroxyaniline (shaH(2)) with M(CO)(6) (M=Cr and W) in THF under reduced pressure resulted in the formation of CrO2(CO)(2)(shaH(2)) (1) and W(CO)(2)(shaH)(2) (4). The two complexes MoO(sha) (2) and Mo2O4(sha)(2) (3) were isolated from the reaction of Mo(CO)(6) with shaH(2) in air, depending on the reaction period. All complexes were characterised by elemental analysis, IR, mass and H-1 NMR spectroscopy. The structural studies of the complexes revealed that the ligand shaH(2) bonds to the metal through the oxygen atoms of the hydroxyl groups and the nitrogen atom of the imine group. Magnetic studies of 1 showed it to be paramagnetic with mu(eff) = 2.8 BM, suggesting that Cr is in a high-spin (d(2)) electronic configuration. The other complexes 2-4 showed diamagnetic behaviour. Electronic spectra of the complexes in different donor solvents displayed weak visible bands due to ligand-to-metal charge transfer. The thermal Properties of the complexes were investigated by thermogravimetry techniques.