Single-electron hydrogen bonds in the methyl radical complexes H3C⋯HF and H3C⋯HCCH: an ab initio study

The methyl radical (CH3) complexes with hydrogen fluoride (HF) and ethyne (HCCH) are reported to show the existence of a single-electron hydrogen bond. Their geometrical structures are optimized at the MP2/aug-cc-pVDZ and MP2/aug-cc-pVTZ levels and C3v stationary structures are obtained for the two complexes. The single-electron hydrogen bond energies of H3C⋯HF and H3C⋯HCCH are calculated at six levels of theory [SCF, MP2, MP3, MP4, CCSD, and CCSD(T)] and their harmonic vibrational frequencies are calculated at the MP2/aug-cc-pVTZ level.