SYNTHESES, STRUCTURAL VARIETIES AND CHROMOTROPIC PROPERTIES OF DINUCLEAR NICKEL(II) COMPLEXES WITH A TETRAKETONATE AND AN N-ALKYLATED ETHYLENEDIAMINE

Six dinuclear nickel(II) complexes of the form Ni2(teke)(tmen)2X2 have been prepared, with teke being a tetraketonate such as 1,1,2,2-tetraa cetylethanediide (taet) or 1,2-diacetyl-1,2-dibenzoylethanediide (dabe ), tmen a N,N,N,N-tetramethylethylenediamine, and X- is an anion, name ly BPh4-, CIO4- or NO3-. The crystal structure of Ni2(taet)(tmen)2(CIO 4)2.3H2O was determined by X-ray methods, in which the geometries of t he two Ni(II) ions in the dinulcear cation are different. One has an o ctahedral structure and the other is square planar. The structures of the two nickel moieties in the tetraphenylborate and the nitrate compl exes are square planar - square planar and octahedral-octahedral, resp ectively. These complexes, which are very soluble in organic solvents, show characteristic chromotropic behaviour in solution due to solvent donor and acceptor properties.