Nickel complexes based on thiophenedithiolate ligands - Magnetic properties of metallocenium salts

The nickel complex nBu(4)N[Ni(alpha -tpdt)(2)] (2) (alpha -tpdt = 2,3-thiop henedithiolate) has been prepared and characterized. A salt of this monoani onic paramagnetic complex, [Fe(Cp*)(2)][Ni(alpha -tpdt)(2)] (3), was obtain ed with decamethylferrocene, crystallizing in the monoclinic space group P2 (1)/a with a = 15.443(3), b = 10.237(1), c = 20.360(2) Angstrom, beta = 107 .54(1)degrees, V = 3069.1(7) Angstrom (3), Z = 4. Its structure consists of alternating cationic and anionic layers, with short interlayer contacts de fining alternating cation-anion chains. Magnetic characterization of 3 at l ow applied magnetic fields revealed an antiferromagnetic transition at T-N = 2.56 kappa. Below T-N, 3 displays a metamagnetic behaviour with a critica l field of 0.07 T at 1.6 K. The magnetic properties of this compound are co mpared with those of the analogous salts with diamagnetic gold dithiolate [ Fe(Cp*)(2)][Au(alpha -tpdt)(2)] (4), and diamagnetic decamethylcobaltoceniu m, [Co(Cp*)(2)][Ni(alpha -tpdt)(2)] (5), which are also reported. This comp arison shows that the ferromagnetic interactions observed in 3 are due to c ation-anion intrachain interactions.