FORMATION OF NICKEL(II) COORDINATION POLYMERS BY A DOUBLE BETAINE - [(NI(L)(H2O)(4))(N)]CL-2N-CENTER-DOT-2NH(2)O AND (NI(L)(2)(H2O)(2))(N)](CLO4)(2N)CENTER-DOT-4NH(2)O [L=(O2CCH2N-O--(CH2CH2)(3)N+CH2CO2-]())

Two novel polymeric nickel(II) complexes of a double betaine with a ri gid tris(ethylene) bridge between the pair of nitrogen atoms, namely [ {Ni(L)(H2O)(4)}(n)] Cl-2n.2nH(2)O (1) and [{Ni(L)(2)(H2O)(2)}(n)] (ClO 4)(2n).4nH(2)O (2) [L = (O2CCH2N+)-O--(CH2CH2)(3)N+CH2CO2-], have been prepared and characterized by X-ragi crystallography. The nickel(II) atom in either complex is coordinated by unidentate carboxylate groups and aqua ligands in a distorted octahedral geometry. The crystal stru cture of (1) features an infinite zigzag chain composed of an alternat e arrangement of metal atoms and double betaine ligands, and hydrogen bonding among adjacent chains leads to a three-dimensional network. Co mplex (2) exhibits a wave-like layer structure corresponding to the (2 00) family of planes.