A database study of the bonding and conformation of bis-sulfonylamide/-imide moieties

The bonding and conformational characteristics of bissulfonylamides and analogous imides are compared. Structures (44 altogether) containing R-SO₂-NQ-SO₂-R' units were retrieved from the Cambridge Structural Database. They are either neutral (Q-H, alkyl or aryl groups, hereto atoms such as O and S) or charged (Q = e^-) and bearing the functions R, R' = Me, Et or Ph, respectively. The principal conformations of the -SO₂-NQ-SO₂- bridge (open versus folded) are represented by sodium dibenzenesulfonamide (BSULFA) and dibenzenesulfonimide (NABSUF). In addition to the compounds possessing Q = alkyl or aryl functions, complexes with N-metal bonds could clearly be distinguished. The dominant forms of S^VI-X (X = O, N C) bonds are characterized and correlated with the bond angles formed around the S atoms. The marked difference between the archetypes of the S-N bonds (i.e. nitrogen charged or neutral) indicated that the interdependence of the S-X bonds, i.e. the size and the shape of the S^VI[O,O',N,C] tetrahedra, are principally governed by the environment of the N atoms. The conformation symmetry and dissymmetry of the charged and neutral -SO₂-NQ-SO₂- moieties are described in terms of the internal rotations about the bonds in the R-S-N-S-R' fragment.