The crystal structure and magnetic properties of tetra-µ3-methoxytetrakis[salicylaldehydato(ethanol)nickel(II)]

Abstract

The crystal structure of [Ni(OMe)(o-O·C₆H₄·CHO)(EtOH)]₄ has been determined by three-dimensional single-crystal X-ray methods. Four molecules of point symmetry (S₄) occupy a tetragonal unit cell with a= 22·17, c= 9·70 Å in space group I4₁/a. The four nickel atoms in the molecule occupy the corners of a nearly regular tetrahedron with a bridging OMe group above each face, giving a roughly cubic Ni₄O₄ unit of symmetry close to T_d. Approximately octahedral co-ordination of the nickel(II) ions is completed by four ethanol molecules and four chelated salicylaldehyde anions. The dimensions of the Ni₄O₄ unit are: Ni–O ca. 2·04 Å, Ni–O–Ni ca. 98°. O–Ni–O ca. 82°. The magnetic susceptibility of the compound between 80 and 300°K indicates a weak ferromagnetic exchange interaction between the Ni²⁺ ions (J/k=+10°), and the behaviour of the analogous methanol derivative is similar (J/k=+6°). The magnetic properties are discussed in terms of the structure.