Photochemical reactions of digermanyl-substituted naphthalenes have been investigated by chemical studies using trapping agents, laser flash photolysis, and ab initio MO calculations. Irradiation of 1-(pentamethyldigermanyl) naphthalene (1) afforded mainly an isomer, 1- (dimethylgermyl)-8-(trimethylgermyl) naphthalene (4), via photochemical formation of a pair of trimethylgermyl radical and 1-naphthyldimethylgermyl radical, and then recombination ...