The Dehydrogenation of Nickel(II) Chelates of rac- and meso-2,2'-diphenol and Related Compounds.

Article abstract of DOI:10.1246/bcsj.56.99

Nickel(II) acetate tetrahydrate and rac- and meso-2,2'-<(1,2-diphenylethylene)bis(iminomethylene)>diphenol (rac- and meso-BzPhen-H2) formed pale green complexes in methanol.A pyridine solution of these complexes deposited deep red diimine complexes after prolonged heating under aerobic conditions.The saturated ligand system of the initial complexes was dehydrogenated to an unsaturated one by molecular oxygen.From the pyridine solution of the meso-isomer, <2,2'-<(cis-1,2-diphenylethenylene)bis(nitrilomethylidyne)>diphenolato>nickel(II) () was isolated in addition to the diimine complex ().In this case, the -HN-<*>H-<*>H-NH- bridge was dehydrogenated to =N-<*>=<*>-N= conjugated double bonds; that is, a fully conjugated metal chelate was formed by the dehydrogenation of the coordinated ligand.