Ab initio and topological study of interactions between SiH4-nXn, (n=0-3, X = F and Cl) and BH3

Theoretically, silane and its derivatives (SiH4-nXn, n = 0-3, X = F and CI) are found to form hydrogen-bridged complex with borane (BH3) at gas phase. High level ab initio calculations at the MP2/aug-cc-pVTZ level show that the interaction energies (D-e) between SiH4-nXn and BH3 are -6.43 similar to -12.06 kcal/mol corrected by zero-point energy and the basis set superposition error, whereas without the corrections, the D-e values are - 14.73 similar to -21.65 kcal/mol. The SiH4-nXn-BH3 Complexes can be regarded as analogues of B2H6 with one monomer BH3 replaced by SiH4-nXn although only one bridged bond Si-H-B is definitely located via topological analyses of the electron density. Upon bonding, boron becomes four coordinated by receiving a hydrogen atom from SiH4-nXn. In contrast to the compact hydrogen-bridged complexes, the electron donor-acceptor conformers with a bridged halogen atom are only loosely bound (D-e < 2 kcal/mol). The results indicate that BH3 is a better hydrogen attractor in these interactions. The predicted SiH4-nXn-BH3 complexation and hydrogen transfer from SiH4-nXn to BH3 may help to understand the initial stage reactions in producing boron doped Silicon films by chemical vapor deposition.