[Cu(men)2(BF4)2] (men = N-methyl-1,2-diaminoethane): Preparation, crystal structure, spectroscopic and magnetic properties

Single crystals of [Cu(men)(2)(BF4)(2)] (men = N-methyl-1,2-diaminoethane) (1) were isolated from an aqueous-ethanolic system Cu2+-men-BF4-. The crystal structure of 1 consists of [Cu(men)(2)(BF4)(2)] molecules. Copper ion exhibits usual distorted octahedral coordination; there are two coordinated men ligands in the equatorial plane with Cu-N bonds of 2.0451(12) and 2.0035(12) angstrom, while the axial positions are occupied by fluorine atoms from BF4- anions with Cu-F bond of 2.5091(11) angstrom. The packing of the [Cu(men)(2)(BF4)(2)] molecules is governed by N-H center dot center dot center dot F type hydrogen bonds. The measured ESR spectrum corroborated the presence of Jahn-Teller anisotropy of Cu(II) with g(parallel to) = 2.20 and g(perpendicular to) = 2.06. The magnetic studies in the temperature range 300-2 K reveal that 1 follows the Curie-Weiss law with parameters g = 2.1612(1) and 0 = -0.233(1) K suggesting the presence of weak antiferomagnetic interactions. (C) 2009 Elsevier B.V. All rights reserved.