Dinuclear Complexes Containing Ferrocenyl and Oxomolybdenum(V) Groups Linked by Conjugated Bridges:  A New Class of Electrochromic Near-Infrared Dye

Dinuclear complexes with ferrocenyl and oxomolybdenum(V) fragments linked by a conjugated spacer have been prepared and studied by spectroelectrochemistry; the first oxidation (ferrocene --> ferrocenium) affords spectra characteristic of localized ferrocenium and oxo-Mo(V) fragments, but the second oxidation [Mo(V)-->Mo(VI)](VIII results in very intense new transitions in the near-IR region which we ascribe to a fully allowed pi --> pi* transition of the bridging group, which now has quinonoidal character.