Oxovanadium(IV), nickel(II) and palladium(II) complexes of tridentate salicylaldiminates derived from 2,4-di-tert-butyl-6-aminophenol

Several new binuclear nickel(II), oxovanadium(IV) and palladium(II) complex es (MLX) of tridentate salicylaldimines ((LH2)-H-X) obtained from substitut ed salicylaldehydes and 2,4-di-tert-butyl-6-aminophenol, as well as mononuc lear nickel(II) and oxovanadium(IV), MQ(X). nH(2)O, complexes with hydrogen ated (LH2)-H-X ligands (Q(X)H(2)) have been prepared and their spectroscopi c, magnetic and catalytic activity (for PdLX) have been investigated. NiLX and VOLX complexes when dissolved in pyridine, take up three or two pyridin e molecules to form six coordinated complexes, respectively. The Ni(II) and VO(IV) complexes obtained from Q(X)H(2) can be formulated as NiQ(X.). 3H(2 )O and VOQ(X.).H2O. All VO(IV) complexes have been characterized by ESR par ameters. It has been found that some PdLX complexes without any preliminary activation, in EtOH, THF and DMF exhibit high catalytic activity in the hy drogenation of nitrobenzene or cyclohexene at room temperature and at 30-40 degreesC under 760 torr H-2. When this reaction has been carried out in th e ESR cavity at room temperature the triplet of 12 line multiplets due to t he nitroxyl type coordinated radical (g = 2.013, A(N) = 10 G, A(H) = 0.8 G) was detected.