Synthesis, characterization and crystal structures of some four coordinated nickel(II) complexes with tridentate Schiff base ligands

A number of Ni(II) complexes with tridentate Schiff base ligands with a N2O donor set and coordinating NNN- and SCN- anions have been synthesized and characterized by analytical, spectroscopic and electrochemical techniques. X-ray structure analyses of three of these complexes [(LNi)-Ni-1(NNN)] (1), [(LNi)-Ni-2(NNN)] (2) and [(LNi)-Ni-3(NCS)] (6) [HL1 = Me2NCH2CH2N(Me)C6H4 OH, HL2 = Et2NCH2CH2N(H)C6H4OH, HL3 = Et2NCH2CH2N(H)C6H3BrOH] show that the nickel atom has a square planar geometry. Thermogravimetric studies show m ultiple step decomposition, and electrochemical studies indicate that the c omplexes are irreversibly oxidized to Ni(III) species, which are unstable a nd undergo rapid decomposition. (C) 2001 Elsevier Science B.V. All rights r eserved.