Binuclear copper(II) complexes of the ligand 1,4-Di-(2′-pyridyl)aminophthalazine

Abstract

Reaction of the binuclear complex [Cu 2(PAP)(OH)Cl 3]·1.5H 2O (PAP = 1,4-di-(2′-pyridyl)-aminophthalazine), which has a hydroxide bridge, a chloride bridge and a diazine (NN) bridge, with various anions in water and buffered (pH 6.86) solutions leads mainly to the formation of spin coupled complexes with room temperature magnetic moments <1.5 B.M. of these complexes retain the hydroxide bridge, in addition to the diazine bridge, and in several systems only two bridge groups exist. Very low magnetic moments (μ <1.2 B.M. are observed for these double bridged complexes, comparable with values observed for triple bridged systems involving large bridging, polyatomic anions. In certain cases prevailing pH conditions are sufficiently basic that ligand deprotonation occurs. Deprotonated complexes are also produced by reaction of [Cu 2(PAP - H)CH 3COO) 3] (PAP  H = deprotonated ligand) with certain anions. Magnetic data have been used to project the possible dimensions of the binuclear centres in several μ-hydroxo bridged complexes, based on a linear relationship between μ (RT) and CuOCu angle observed elsewhere for related complexes.