Matrix isolation investigation of the interaction of SiH4 with NH3 and (CH3)(3)N

Co-deposition of samples of SiH4 and NH3 or the methylamines into argon and nitrogen matrices has led to the first isolation and characterization of 1 :1 complexes between these reactants. Several Si-H stretching modes were ob served, shifted as a result of complex formation. The Si-H axial stretch, i n particular, shifted to lower energy upon complexation, with a shift that increased monotonically with the intrinsic basicity of the amine. The symme tric deformation mode of the complexed NH3 subunit shifted to higher energy , and retained evidence of hindered rotation about its C-3 axis in solid ar gon, but not in solid nitrogen. The shifts of these vibrational modes were in good agreement with previous ab initio calculations, as well as calculat ions performed here. All of the spectral evidence points to a very weak bin ding energy in these complexes, in agreement with calculations.