Strong magnetic coupling of spins in Fe(ii) dimers with differently charged thioindigo ligands.

A first coordination {[2.2.2]cryptand(K+)}(2){Fe-II(TI& x2d9;(-))(TI2-)}(2)center dot 2C(6)H(4)Cl(2)(1) complex of iron(ii) containing radical anions and dianions of thioindigo (TI) was obtained. The complex has two high-spin Fe(II)centers bound by two oxygen atoms, and the TI& x2d9;(-)radical anions are coordinated to each Fe-II. As a result, the 4-spin system consisting of TI& x2d9;(-)(S= 1/2)-Fe-II(S= 2)-Fe-II(S= 2)-TI& x2d9;(-)(S= 1/2) coupled spins is formed within a dimer with strong Fe-II-Fe-II(J= -51.1 cm(-1)) and weaker Fe-II-TI& x2d9;(-)interactions of (J= -35.4 cm(-1)).