Enhanced Electronic Coupling in a Molecular Pair of Dimolybdenum Units Bridged by a Tetrathioterephthalate Dianion

Two covalently bonded dimolybdenum units have been assembled with a tetrathioterephthalate dianion (tttp2−), yielding the first full S-donor dimetal molecular dyad [Mo2(DAniF)3](S2CC6H4CS2)[Mo2(DAniF)3] (DAniF = N,N′-di-p-anisylformamidinate). This linear molecule has a Mo2···Mo2 separation of 12 Å as determined by X-ray crystallographic analysis. Large potential separations (ΔE1/2) for the successive oxidations of the two dimetal centers and greatly red-shifted metal-to-ligand charge-transfer absorption have been observed as compared to the terephthalate and dithioterephthalate analogues. In addition, further electrochemical oxidations result in a pair of quasi-reversible two-electron redox waves separated by ca. 250 mV.