Transition metal complexes of derivatized chiral dihydro1,2,4-triazin-6-ones. Part I. Nickel(II) complex of (D)-3-acetyl-5-benzyl-1-phenyl-4,5-dihydro-1,2,4-triazin-6-one oxime. An instance of a carbon-carbon coupling reaction

The reaction of (D)-3-acetyl-5-benzyl-1-phenyl-4,5-dihydro-1,2,4-triazin-6- one oxime (2) with nickel acetate in refluxing ethanol afforded the respect ive square planar Ni(II) complex. This is evidenced from an X-Ray study whi ch reveals that the Ni(II) ion is coordinated to the ring N(4) and oxime ni trogen atoms. The crystallographic data of the complex (3) also unravelled that the nickel-complexation has led to the formation of one pi-bond across the N(14)-C(15) bond and one sigma-bond between a benzylic carbon atom of one ligand and the chiral (C5) carbon atom of the other ligand in the bis-l igand complex (3). Evidently, the complexed Ni(II) ion plays a template eff ect role in initiating such a cascade of pi- and sigma-bond forming reactio ns. H-1-, C-13-NMR and FD-MS spectral data of 3 are in full agreement with its molecular structure.