SYNTHESIS, CRYSTAL-STRUCTURE AND MAGNETIC-PROPERTIES OF THE TETRANUCLEAR COMPLEX [NI-4(OCH3)(4)(DBM)(4)(CH3OH)(4)](2)(C2H5)(2)O

A novel tetranickel(II) cluster with formula [Ni-4(OCH3)(4)(dbm)(4)(CH 3OH)(4)](2)(C2H5)(2)O (1) in which dbm is the anion of dibenzoylmethan e, was synthesized and structurally characterized. Complex 1 crystalli zes in the monoclinic system, space group P2(1)/c, with unit cell para meters a = 22.33(1), b = 26.03(4), c = 24.97(2) Angstrom, beta = 105.1 4(3)degrees, V = 14012.6(1) Angstrom(3), Z = 4. The structure consists of a tetrameric, cubane like complex with alkoxide oxygen atoms and o ctahedrally coordinated nickel(II) atoms at the corners of the cube. M agnetic susceptibility measurements have been carried out for this com plex. The chi(M)T versus T behavior from 270 to 2 K shows a ferromagne tic coupling between Ni(II) ions. The J value was determinated to be - 9.6 cm(-1). At low temperatures the chi(M)T product of this complex do es not reach the predict value of 10 e.m.u. mol(-1) K for a S = 4 grou nd slate. ZFS and intermolecular interactions may be responsible for t his behavior.