SYNTHESIS OF A NOVEL OCTAAMINO TETRAPHENOL MACROCYCLIC LIGAND AND STRUCTURE OF A TETRANUCLEAR NICKEL(II) COMPLEX

Facile synthesis of a 38-membered highly flexible macrocyclic ligand, H4L, provides an entry to polynuclear complexes where metal-ligand self-assembly is controlled by the steric requirement of the metal ions. The tetranuclear complex [Ni4L-(mu3-OH)(mu-H2O)2(ClO4)](ClO4)2.2(CH3)2-CO.H2O(1) has been synthesized and characterized. The crystal structure of 1(triclinic, P1BAR; a = 12.167(1) angstrom, b = 12.673(1) angstrom, c = 22.652(2) angstrom, alpha = 101.05(1)degrees, beta = 91.61(1)degrees, gamma = 111.66(1)degrees, Z = 2; R = 0.052, R(w) = 0.058) reveals that the nickel centers connected by four phenoxy and two aqua ligands and a hydroxy bridge are separated from each other by 2.93-5.13 angstrom, and the molecular assembly is stabilized by a large number of intra- and intermolecular hydrogen bonds.