Initial use of the di-2-pyridyl ketone/sulfate “blend” in 3d-metal cluster chemistry: Preparation, X-ray structures and physical studies of zinc(II) and nickel(II) cubanes

Abstract

The use of di-2-pyridyl ketone ((py) 2CO)/sulfate “blend” in nickel and zinc chemistry has yielded the neutral cubane clusters [Ni 4(SO 4) 2{(py) 2C(OH)O} 4]·4MeOH·3H 2O ( 1·4MeOH·3H 2O) and [Zn 4 (SO 4) 2{(py) 2C(OH)O} 4 (H 2O) 2]·6H 2O ( 2·6H 2O). The preparation of the two complexes was achieved by the reaction of MSO 4·×H 2O [M = Ni, x = 6 ( 1); M = Zn, x = 7 ( 2)] with (py) 2CO and LiOH·H 2O in MeOH/H 2O (for both complexes) or MeOH/MeCN (only for 1). The structures of both compounds have been determined by single-crystal X-ray crystallography. Di-2-pyridyl ketone exists in its monoanionic gem-diol form and functions as an η 1: η 3: η 1: μ 3 ligand. Both complexes have been characterized by spectroscopic techniques (IR, Raman). Thermal decomposition (TG, DTG and DTA) data for 2 are also discussed. The magnetic properties of 1 have been studied by variable-temperature dc magnetic susceptibility techniques. The studies indicate both ferromagnetic and antiferromagnetic coupling between the four Ni II atoms. A three- J model was found to be adequate for describing the thermal variation of the molar magnetic susceptibility.