The reactions of Ge, Sn, Pb, Sb, Bi, and Te atoms with silane molecules were studied using matrix-isolation Fourier transform infrared spectroscopy and density functional theoretical (DFT) calculations. All metals generate the inserted complexes HM-SiH, which were stabilized in an argon matrix, while HM═SiH and HM≡SiH were not observed. DFT and CCSD(T) calculations show the insertion complex HM-SiH is the most stable isomer with a near right angle H-M-Si moiety. However, silydene complexes HM═SiH (M = C, Si) were calculated and identified as the most stable complexes with the lighter elements. The bonding difference is mainly due to relativistic effects, which is that for heavier metal atoms valence s and p orbitals have a lower tendency to form hybrid orbitals.

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Infrared spectra of matrix isolated dibridged Si(μ-H)MH and tribridged Si(μ-H)MH molecules (M = Zr and Hf) were observed following the laser-ablated metal atom reactions with SiH during condensation in excess argon and neon, but only the latter species was observed with titanium. Assignments of the major vibrational modes, which included terminal MH, MH and hydrogen bridge Si-H-M stretching modes, were confirmed by the appropriate SiD isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). The Si-H-M hydrogen bridge bond is calculated as weak covalent interaction and compared with the C-H···M agostic interaction in terms of electron localization function (ELF) analysis and noncovalent interaction index (NCI) calculations. Furthermore, the different products of Ti, Zr, and Hf reactions with SiH are discussed in detail.

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