Enhanced electronic coupling in a molecular pair of dimolybdenum units bridged by a tetrathioterephthalate dianion.

ABSTRACT

Two covalently bonded dimolybdenum units have been assembled with a tetrathioterephthalate dianion (tttp(2-)), yielding the first full S-donor dimetal molecular dyad [Mo(2)(DAniF)(3)](S(2)CC(6)H(4)CS(2))[Mo(2)(DAniF)(3)] (DAniF = N,N'-di-p-anisylformamidinate). This linear molecule has a Mo(2)...Mo(2) separation of 12 A as determined by X-ray crystallographic analysis. Large potential separations (DeltaE(1/2)) 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.