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The interaction of different proton donors with ionic (Bu4NBH4) and neutral (BH3NEt3, BH3P(OEt)3) boron hydrides was studied by IR and NMR spectroscopy in solution (CH2Cl2, C6H14, and C6D12). A close similarity was observed between the spectral and thermodynamic properties of these unusual BH···HX and those of classical H bonds. The typical characteristics of hydrogen bonding, such as linearity of the fragment H···HX, lengthening of X−H and H−B bonds, and strong electron redistribution, were confirmed by ab initio calculations.

Ab initio molecular orbital and density functional theory (DFT) calculations were performed to investigate energies, geometries, and reactivities of halomethyl cations and their protonated analogues. On the basis of calculated energies the observed superelectrophilic activation of the halomethyl cations in superacid solutions is discussed. The protonated halomethyl cations have considerable kinetic and thermodynamic stability. 13C NMR chemical shifts of selected systems were calculated by IGLO method and compared with experimental data.