Magnetic properties of polynuclear complexes. Part I. Superexchange in some binuclear nickel(II) complexes

Abstract

The magnetic susceptibilities of a number of binuclear nickel(II) complexes between 80 and 300°K are reported. Most of the compounds exhibit antiferromagnetic exchange, and a curve-fitting procedure is used to obtain values of the exchange parameter J. The compounds studied include Ni₂ paa₃X₄,nH₂O (paa = pyridine-2-aldazine; X = I, ClO₄, or BF₄), Ni₂ dppn₂X₄,nH₂O (dppn = 3,6-di(pyrid-2-yl)pyridazine; X = NO₃ or ClO₄), Ni₂ dppl(NO₃)₂,2H₂O [dppIH = 3,5-di(pyrid-2-yl)pyrazole, a new compound], Ni₂ dhph₂X₄,nH₂O (dhph = 1,4-dihydrazinophthalazine; X = Cl, Br, or I), and Ni₂ en₄(C₂O₄)(NO₃)₂. The values of J for these and other binuclear nickel(II) complexes are discussed in terms of superexchange mechanisms.