Laser Ablation of Hexamesitylcyclotrigermane and Hexamesitylcyclosiladigermane in a Molecular Beam

The highly strained group 14 compounds hexamesitylcyclotrigermane, (Mes2Ge)3 (Mes = mesityl = 2,4,6-trimethylphenyl), and hexamesitylcyclosiladigermane, [(Mes2Ge)2(Mes2Si)], were laser ablated under argon and introduced into a molecular beam. The neutral fragmentation products were photoionized downstream following ablation/gas expansion and characterized by time-of-flight mass spectrometry. The primary products arose from the expected fragmentation of the three-membered ring. For (Mes2Ge)3, the major products were Mes2Ge: and Mes2GeGeMes2. For the case of [(Mes2Ge)2(Mes2Si)], fragmentation occurred, giving along with Mes2Ge: and Mes2GeGeMes2, three additional products: Mes2Si:, Mes2GeSiMes2, and Mes2SiSiMes2. The formation of Mes2SiSiMes2 indicates that significant bimolecular chemistry occurs in the ablation plume. Laser ablation of (Mes2Ge)3 in argon streams seeded with oxygen bases such as nitrous oxide, ethylene oxide, and diethyl ether resulted in the preferential loss of Mes2Ge relative to Mes2GeGeMes2. For the case of N2O, an additional digermene to germylgermylene rearrangement is suggested.