Synthesis of Poly(dithienogermole)s

Reactions of 4,4-dichlorodithienogermoles with sodium, followed by reprecipitation of the organic products, provided poly­(dithenogermane-4,4-diyl)­s. The absorption edges were at lower energies than that of a monomeric dithienogermole derivative. Comparison of the optical properties of the polygermanes with those of their respective polygermoxanes (prepared by oxidizing the polygermanes) and copolymers composed of dithienogermole and di-n-butylgermane units indicated that the red-shifted absorption edges were likely associated with conjugation of the dithienogermole π-orbital with the polygermane backbone σ-orbital. This was further supported by optical studies on the dimeric compound 4,4′-bis­(4-ethyldithienogermole) and density functional theory calculations on tetrameric models.