Magnetic behaviour of tetrakis[(2-diethylaminoethanolato)isocyanatocopper(II)], a complex with an antiferromagnetic ground state; the crystal and molecular structure of the triclinic modification

Abstract

The crystal and molecular structure and magnetic behaviour of [{Cu(NCO)(OCH₂CH₂NEt₂)}₄](B) from benzene have been determined. The crystal structure determination was carried out by single-crystal X-ray diffraction methods and refined to R= 0.066 for 4 379 independent reflections: triclinic, space group P, with unit-cell dimensions a= 13.478(3), b= 12.873(3), c= 11.542(3)Å, α= 84.020(5), β= 80.263(5), and γ= 86.863(5)°. Each copper atom is five-co-ordinated by three oxygen and two nitrogen atoms. The magnetic susceptibility measured over the temperature range 5.0–302.5 K shows a maximum at 94 K and thus indicates that antiferromagnetic spin coupling is dominant. The magnetic behaviour can be explained on the basis of the isotropic Heisenberg–Dirac–van Vleck model. The results are compared with the structural and magnetic properties of the tetragonal form (A) of this complex. No phase transition between the two modifications could be found up to the melting point.