1, Qthiagermirane (18). Photolysis of thiagermirane 18 yields dimesitylgermylene (16) and adamantanethione (3) derived from germathiocarbonyl ylide 22. Oxidation of thiagermirane 18 by mCPBA gives 3-(2-adamantyl)-4, 4-dimesityl-l, 2, 4-oxathiagermetane S-oxide (27). X- ray analyses were done for thiagermirane 18 and 1, 2, 4-oxathiagermetane S-oxide 27.