Accumulation and Reaction of Diphenylgermyl Anion and Diphenylgermyl Dianion by Electrochemical Reduction of Diphenylgermane

Abstract

Diphenylgermyl anion (Ph₂GeH⁻) was successfully generated and accumulated in the cathode compartment at −50°C by typically 1 F mol⁻¹ electrolysis of diphenylgermane in DMF using tetrabutylammonium tetrafluoroborate as the supporting electrolyte. Similarly, diphenylgermyl dianion (Ph₂Ge⁼) was successfully generated and accumulated at −50°C by typically 3 F mol⁻¹ electrolysis of diphenylgermane. Accumulation of the anion species was confirmed by NMR spectroscopy of the corresponding electrolyte solutions and observation of alkylated products in reactions with various haloalkanes. The anion and the dianion gave the alkylated and dialkylated products in 20–30% yields upon reactions with various haloalkanes, respectively. Stability of the anions were also examined by NMR spectroscopy and it was found that the both anions were almost stable at −40°C, but they slowly decomposed at −20°C, and rapidly decomposed at the room temperature. A typical anion character, one electron transfer ability, was evaluated by measuring their oxidation potentials. Diphenylgermyl anion and diphenylgermyl dianion showed similar oxidation potentials. However, that of diphenylgermyl dianion needs verification by future measurements.