Regulating Function of Methyl Group on the Strength of Dihydrogen Bond in HBeH-HCCH and HMgH-HCCH Complexes

The regulating function of methyl group on the strength of dihydrogen bond was investigated in HBeH-HCCH and HMgH-HCCH complexes at the MP2/6-311++G(3df,2p) level. The bond lengths, infrared spectra, interaction energies, and charge transfers were analyzed. The presence of methyl group in the proton acceptor enhances the strength of dihydrogen bond, whereas its presence in the proton donor weakens the strength of dihydrogen bond. The charge analyses indicate that the methyl group in the proton donor and acceptor is electron-donating, thus the methyl group in the proton donor plays a negative role, whereas in the proton acceptor it plays a positive role in the formation of dihydrogen bond.