Inverse hydrogen bonds between SiH4 and hydrides of Na, Mg and Be

The optimized geometries of the three complexes between MeHn (Me=Na, Mg, Be; n=1 or 2) and SiH4 have been calculated at the B3LYP/6-311++g**, MP2/6-311++g(3df,3pd) and MP2/aug-cc-pvtz levels, respectively. The red-shift inverse hydrogen bonds (IHBs) based on Si-H, an electron donor, were reported. The calculated binding energies with basis set super-position error (BSSE) correction of the three complexes are −5.98, −8.65 and −3.96 kJ mol−1 (MP2/6-311++g(3df, 3pd)), respectively, which agree with the results obtained via MP2/aug-cc-pvtz (−6.18, −9.12 and −4.28 kJ mol−1, respectively). The relative stabilities of the three complexes are in the order of SiH4…MgH2 > SiH4…NaH > SiH4…BeH2. Natural bond orbital theory (NBO) analysis and the chemical shift calculation of the related atoms revealed that the charges flow from SiH4 to MeHn and the chemical shifts of the interacting H shift to downfield. Here, the Si1-H3 of SiH4 acts as both a bond hydrogen donor and an electron donor. Therefore, compared with conventional hydrogen bonds, they formed IHB complexes. Atoms in molecules (AIM) theory have been used to investigate the topological properties of the critical points in the three IHB structures.