Hexamethylcyclotrisilazane1009-93-4100 % similar 2,2,4,4,6,6,8,8-Octamethylcyclotetrasilazane1020-84-4100 % similar Bis(trimethylsilyl)amine999-97-338 % similar Lithium bis(trimethylsilyl)amide4039-32-131 % similar