Infrared spectra of group 14 hydrides in solid hydrogen:: Experimental observation of PbH4, Pb2H2, and Pb2H4

Laser-ablated Si, Ge, Sn, and Pb atoms have been co-deposited with pure hydrogen at 3.5 K to form the group 14 hydrides. The initial SiH2 Product reacts completely to SiH4, whereas substantial proportions of GeH2, SnH2, and PbH2 are trapped in solid hydrogen. Further hydrogen atom reactions form the trihydride radicals and tetrahydrides of Ge, Sn, and Pb. The observation of PbH4 at 1815 cm(-1) and PbD4 at 1302 cm(-1) is in agreement with the prediction of quantum chemical calculations for these unstable tetrahydride analogues of methane. In addition, new absorptions are observed for Pb2H2 and Pb2H4, which have dibridged structures based on quantum chemical calculations.