Crystal, molecular structure, and magnetic properties of bis(tetra-n-butylammonium)bis(4-(dicyanomethylene)1,2-di-mercaptocyclopent-1-ene-3,5-dionato-S,S')cuprate(II), [n-Bu₄N]₂[Cu(dcmdtcroc)₂]: a dimer with weak ferromagnetic coupling

Abstract

An extended dithiolene complex (n-Bu₄N)Cu(demdtcroc)2 has been prepared and characterized by X-ray diffraction and magnetic studies. The crystal structure reveals the anion to be nonplanar and the dihedral angle between the two chelate planes to be 36.76°. The compound crystalizes in the space group Pbca with eight molecules per unit cell. The structural parameters are a 18.087 (7) Å,b=32.325 (9)Å,c = 18.236 (7) Å, with the intradimer Cu-Cu distance being 4.88 Å. The magnetic susceptibility measurements fitted to the Bleaney-Bower's expression and corrected for molecular field corrections yielded an intradimer ferromagnetic coupling (2J = 12 cm^-1) and a very weak interdimer antiferromagnetic coupling (J'= —0.04 cm^-1). The powder EPR spectra observed, consistent with the structure and susceptibility findings, show well-resolved triplet spectra at room temperature and a considerable increase in intensity as the temperature is lowered. The spin Hamiltonian parameters have been derived not only from angular variation EPR study of single crystal but also from the computer simulation of polycrystalline EPR spectra at two different frequencies.