Coexistence of spin-crossover and antiferromagnetic coupling phenomena in the novel dinuclear Fe(II) complex [Fe(dpa) (NCS)2]2bpym

The iron(II) spin crossover dinuclear compound [Fe(dpa)(NCS)(2)](2) bpym where dpa = 2,2'-dipyridylamine and bpym = 2,2'-bipyrimidine has been synthesized and characterized. Variable-temperature magnetic susceptibility and Fe-57 Mossbauer spectroscopy data provide evidence for a rather complete and continuous S = 2 (HS) <----> S = 0 (LS) spin-crossover behavior taking place in the temperature range 400-50 K (T-1/2 - 245 K) without the presence of a plateau at 50% of conversion. The absence of such plateau, which is characteristic of all dinuclear compounds so far studied, is interpreted in terms of synergetic effect between intramolecular and intermolecular interactions. (C) 2003 Elsevier Science B.V. All rights reserved.