PHOTOCHEMISTRY OF ARYL-SUBSTITUTED TRIGERMANES - GENERATION AND MECHANISM OF FORMATION OF GERMYLENES

Photochemical reactions of aryl-substituted trigermanes have studied by trapping experiments, matrix isolation, and laser flash-photolysis techniques. Photolysis of the phenylated trigermanes involved both the simple extrusion of germylenes and the formation of germyl radicals and digermyl radicals. The photochemically generated germylenes react with 2,3-dimethylbutadiene or CCl4 to give germacyclopentenes or trichloromethylchlorogermanes, respectively. The germyl radicals and digermyl radicals abstract chlorine atoms from CCl4 to produce chlorogermanes and chlorodigermanes. Two well-separated transient absorption bands (320-330 and 420-450 nm) obtained by laser flash-photolysis of the trigermans in cyclohexane at 293 K were found to be due to phenylated digermyl radicals and germylenes, respectively. The rates of the reactions of phenylated digermyl radicals and germylenes with some substrates have been examined. In 3-methylpentane, glass germylenes show an absorption band at 420-462 nm. The mechanism is discussed. © 1990.