STUDY OF PHOTOCHEMICAL-REACTIONS OF DECAMETHYLCYCLOPENTAGERMANE

The photolysis of decamethylcyclopentagermane (1) in cyclohexane at room temperature proceeds readily along with the generation of dimethylgermylene to give octamethylcyclotetragermane. Photochemically generated dimethylgermylene reacts with 2,3-dimethylbuta-1,3-diene or carbon tetrachloride to give 1,1,3,4-tetramethyl-1-germa-3-cyclopentene or chlorodimethyl(trichloromethyl)germane, respectively. The transient absorption of 1 in cyclohexane at 490 nm, obtained by laser flash photolysis, is due to dimethylgermylene at 293 K. The reaction rates of dimethylgermylene with some trapping agents are examined. In 3-methylpentane, dimethylgermylene also shows an absorption band at 506 nm at 77 K. The photo-generated dimethylgermylene appears to be in the singlet ground state.