Structure of 4,4-Bisphenylsulfonyl-N,N-dimethylbutylamine: Interplay of Intramolecular C-H center dot center dot center dot N, C-H center dot center dot center dot O=S, and pi center dot center dot center dot pi Interactions

Conformations of 4,4-bisphenylsulfonyl-N,N-dimethylbutylamine (BSDBA) were examined by ab initio calculations. Intramolecular C-H center dot center dot center dot N, C-H center dot center dot center dot O, and pi center dot center dot center dot pi interactions are found to play an important role in governing the conformational properties. This finding is supported by charge density analysis based on the theory of atoms in molecules. The calculated molecular structure and H-1 chemical shifts of the methyl derivative (BSTBA) are in excellent agreement with experimental findings. The intramolecular C-H center dot center dot center dot N hydrogen bond in BSDBA is estimated to have a significant interaction energy of 25 kJ mol(-1). The sulfonyl oxygens in BSDBA interact readily with neighbouring methylene, methyl and phenyl hydrogens via C-H center dot center dot center dot O=S hydrogen bonds. In agreement with experiment, solvent effect calculations indicate that these weaker intramolecular interactions prevail in an aprotic polar medium.