Unconventional H-Bonds: SH∙∙∙N Interaction
Quantum calculations at the MP2/aug-cc-pVDZ level are used to analyze the SH N H-bond in complexes pairing H2S and SH radical with NH3, N(CH3)3, NH2NH2, and NH2N(CH3)2. Complexes form nearly linear H-bonds in which the SAH covalent bond elongates and shifts its stretching frequency to the red. Binding energies vary from 14 kJ/mol for acceptor NH3 to a maximum of 22 kJ/mol for N(CH3)3 and N(CH3)2NH2. Analysis of geometric, vibrational, and electronic data indicate that the SH N interaction involving SH is slightly stronger than that in which the closed-shell H2S serves as donor.