Molecular switching complexes with iron and tin as central atom

The precursor [Fe-III(L)Cl] (LH2 = N,N'-bis(2'-hydroxy-benzyliden)-1,6-diamino-3-N-hexane is a high-spin (S = 5/2) complex. This precursor is combined with the bridging units [Sn-IV(X)(4)] (X = CN-, NCS-) to yield star-shaped pentanuclear clusters, [(LFeIII-X)(4)Sn]Cl-4. For X = CN- the Fe-57-Mossbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state, while the Sn-119m-Mossbauer data indicate a valence tautomerism between Sn(IV) and Sn(II). Changing the bridging unit from X = CN- to X = NCS- turns the switchability off. (C) 2009 Published by Elsevier Ltd.