Planar four-coordinate nickel(II) complexes of tridentate ligands incorporating azo-oxime-carboxyl chelation : synthesis and structure

Department of Chemistry, St. Xavier's College, 30, Park Street, Kolkata-700 016, India E-mail : sanjibg6@hotmail.com Department of Environmental Science, University of Kalyani, Kalyani-741 235, India E-mail: sommukh445@hotmail.com Fax : 91-33-25828282 Manuscript received 30 December 2004, accepted 18 July 2005. The tridentate azo-oxime-carboxylate ligands HON = C(Ar)N = NC6H4CO2H, H2ArL (H2PhL, Ar = Ph; H2Tol, Ar = ptolyl) have been used to synthesize dimeric and monomeric nickel(II) complexes of type [Ni2(ArL)2] and [NiII(ArL)(nBuNH2)]. The X-ray structure of [NiII(PhL)(n-BuNH2)] authenticates the planar four-coordinate NiN3O geometry. The amino group of each molecule is hydrogen-bonded (N-H---O) to the uncoordinated carboxylate oxygen of the adjacent molecule resulting in an infinite supramolecular chains with hydrogen bonded N-H---O distance 2.949(5) Å