Formation of an ethylene-bridged bis(benzisothiazole) dication by oxidative decomplexation of Ni(tsalen) with FeCl3

Treatment of Ni(tsalen), where H2tsalen = bis(thiosalicylidene)imine with FeCl3 results in the isolation of a crystalline compound with the composition [BBITE2+][Ni(tsalen)]4[FeCl4−]2 (I), where BBITE=1,2-bis(1,2-benzisothiazol-2-yl)ethane. The production of the BBITE2+ cation represents a 4-electron oxidation of the tsalen2− ligand, even though FeCl3 is not a strong enough oxidant to promote any outer-sphere oxidation of the Ni(tsalen) complex. The crystal structure of I shows a series of channels which are maintained by non-covalent interactions between the [Ni(tsalen)] and BBITE2+ molecules.