Oxovanadium(IV), Nickel(II) and Palladium(II) Complexes of Tridentate Salicylaldiminates Derived from 2,4-Di-ter-butyl-6-aminophenol

Several new binuclear nickel(II), oxovanadium(IV) and palladium(II) complexes (MLX) of tridentate salicylaldimines (LXH2) obtained from substituted salicylaldehydes and 2,4-di-tert-butyl-6-aminophenol, as well as mononuclear nickel(II) and oxovanadium(IV), MQx nH2O, complexes with hydrogenated LX H2 ligands (QXH2) have been prepared and their spectroscopic, magnetic and catalytic activity (for PdLx) have been investigated. NiLx and VOLx complexes when dissolved in pyridine, take up three or two pyridine molecules to form six coordinated complexes, respectively. The Ni(II) and VO(IV) complexes obtained from QXH2 can be formu­lated as NiQx-3H2O and VOQx H2O. All VO(IV) complexes have been characterized by ESR parameters. It has been found that some PdLx complexes without any preliminary activation, in EtOH, THF and DMF exhibit high catalytic activity in the hydrogenation of nitrobenzene or cyclohexene at room temperature and at 30 -40 °C under 760 torr H2. When this reaction has been carried out in the ESR cavity at room temperature the triplet of 12 line multiplets due to the nitroxyl type coordinated radical (g = 2.013, AN = 10 G, AH = 0.8 G) was detected.