Matrix infrared spectroscopic and computational investigation of late lanthanide metal hydride species MH_x(H₂)_y (M = Tb-Lu, x = 1-4, y = 0-3)

American Chemical Society Laser-ablated late lanthanide metal atoms were condensed with pure hydrogen at 4 K, and new infrared absorptions are assigned to binary metal hydrides on the basis of deuterium substitution and density functional theory frequency calculations. The dominant absorptions in the 1330-1400 cm^-1 region are identified as LnH₃ complexes with very weak ligand bands near 3900 cm^-1. With ytterbium, YbH and YbH2 were the major initial products, but YbH₃ increased at their expense upon sample irradiation. Evidence is also presented for the LuH and ErH molecules and the tetrahydride anions in solid hydrogen.