Metal to metal multiple bonds in ordered assemblies

The synthesis and properties of metal--metal (MM) quadruply bonded compounds of molybdenum and tungsten in liquid crystalline phases are described. Covalently linked MM quadruply bonded complexes, dimers of dimers, are shown to give rise to mixed valence complexes upon oxidation and the degree of electron delocalization is shown to be correlated with the [M.sub.2][delta] bridge [pi] interactions. Class III behavior or complete delocalization is observed to [M.sub.2] to [M.sub.2] distances of up to 14 [Angstrom]. When the [M.sub.2] unit is attached to oligothiophenes via a carboxylate tether, the photophysical properties of the thienyl units are greatly modified due to [M.sub.2][delta]-thienyl [pi] conjugation and spin--orbit coupling. This leads to long-lived emissive states and electroluminescence in solid-state devices. mesogens | mixed valency