Synthesis and Catalytic Activity of Square-Planar Ni(II) Complexes of Bis-N,N'-disubstituted Oxamides and Related Ligands for Epoxidation of Olefins

Four new monomeric square-planar nickel(II) complexes of two bis-N,N'-disubstitute oxamides and related ligands have been prepared and characterized, namely [NMe4]2[Ni(L)]_xH2O, where L = dbopba = 3,5-dibromo-o-phenylenebis-(oxamate) and dbmeopba = 3,5-dibromo-o-phenylenebis-(N_-methyloxamidate), L = meopba = 4-methyl-o-phenylenebis-(oxamate) and memeopba = 4-methyl-o-phenylenebis-(N_- methyloxamidate).NMe4 is thetetramethylammonium cation. Based on elemental analyses, IR and UV spectroscopies and molar conductance data, the complexes are proposed to have a square-planar structure. Their catalytic activities for aerob