Bis(tetraisopropylcyclopentadienylnickel)dichalcogenides:  Complexes of the Novel [{CpME}₂] Type (E = S, Se, Te)

The dinuclear dichalcogenides [{(C5HR4)NiE}(2)] (R = CHMe2; E = S (2), Se (3), Te (4)) have been synthesized from [{(C5HR4)NiBT}(2)] (1) (R = CHMe2) and the corresponding disodium dichalcogenides. Crystal structure analyses show four-membered Ni2E2 rings with weak, but significant E . . .E interaction. 1-4 were characterized electrochemically and reveal nickel-centered oxidations, bridging ligand-centered reductions, and the formation of mixed-valent Ni(II)/Ni(III) species.