The interactions between peripheral and central units in supramolecular and metallosupramolecular structures: The characterization of some mono-, di-and trinuclear complexes of a vicinal oxime-imine ligand

The 1:1 molar ratio reaction of p-phenylenediamine with isonitrosoacetylace tone in chloroform led to the formation of the half unit ligand (HL); (1). Two types of the trans octahedral (L)(2)Ni . 2H(2)O complex were characteri zed; the green molecular complex (2) and the associated supramolecular dark brown complex (3). Molecular association in (3) took place via intermolecu lar hydrogen bonding between the amino group of a molecule and the oxygen s ites of an adjacent molecule, The 1:1 molar ratio reactions of (2) with the metal acetates M(OAc)(2) (M = divalent nickel, copper or cobalt) produced the self-assembly structure (4) whereby the metal acetate is coordinated to the amino groups of the nickel(II) complex. Reaction of the dinuclear (4) with another metal acetate (1:1 molar ratio) gave the trinuclear terminated structure (5). Similar reactions of (3) with nickel acetate (1 : 1 or 1 :2 ) led to formation of complexes with metallosupramolecular structures. An a ntiferromagnetic interaction between the peripheral and central paramagneti c units was observed from those complexes with copper(II) at the peripheral location. In all these cases the metal ions are bridged via the aromatic S chiff-base moiety. The suggested structures of the mono-, di- and trinuclea r coordination compounds are in accordance with the analytical, spectral an d magnetic moment data.