Structural basis for the acidity of sulfonamides. Crystal structures of dibenzenesulfonamide and its sodium salt

Abstract

To ascertain what role structural factors-and, hence, by implication, bonding factors-play in the pronounced acidity of dibenzenesulfonamide (pKa = 1.45), the structures of the acid itself, (C6H6S02)2NH, and the sodium salt, Na+(C6H5S02)2N-, have been determined. For (CeH5S02)2NH: space group, P2i/c; Z = 4; d0 = 1.470

Bis(phenylsulfonyl)methane, (PhSO2)2CH2, and Dibromobis(phenylsulfonyl)methane, (PhSO2)2CBr2

“…Thus for MR3 = SiPh3, the M--X--M angle varies from 180 ° (imposed by a centre of inversion) for X = O (Glidewell & Liles, 1978), through 138.1 (4) ° for X = NH (Glidewell & Holden, 1981) to 128.8(7) ° for X = CH2 (Glidewell & Liles, 1982). Similarly, for MR3 = SO2Ar, the M--X--M angle is 127.7 (3) ° for X = NH and Ar = Ph (Cotton & Stokeley, 1970), 111.5(7) ° for X = CH2 and Ar = 4-BrC6H4 (Berthou, J6minet & Laurent, 1972) and 120.7 (3) ° for X = C==CH2 and Ar = Ph (De Lucchi, Pasquato, Modena & Valle, 1985). An interesting member of this latter series has X = CI2, but the reported structure for (PhSO2)2CI2 shows a number of highly unusual features (Stergioudis, Bozopoulos, Kavounis & Rentzeperis, 1989).…”

“…Firstly, the two central S--C bonds are very different in length [1.72 (2) and 1.83 (2)A,], whereas in each of (PhSO2)2NH (Cotton & Stokeley, 1970) and (PhSO2)2C~-CH2 (De Lucchi, Pasquato, Modena & Valle, 1985), the two independent values are identical within experimental uncertainty, and in (4-BrC6H4SO2)2CH2 (Berthou, J6minet & Laurent, 1972) the molecule lies on a crystallographic twofold axis. Second, the O--S--O angles in (PHSO2)2CI2 are reported as 110.0 (8) and 112.4 (7) °, whereas in all other neutral disulfones (Cotton & Stokeley, 1970;Berthou, J6minet & Laurent, 1972;De Lucchi, Pasquato, Modena & Valle, 1985;Foss, Kvammen & Marcy, 1985), the O--S--O angles lie in the range 118.5(3)-121.0(3) °. Third, the non-bonding I-..S distances span a wide range from 3.09(2) to 3.42(2).&.…”

Sulfonimidation via ring-opening of 2-oxazolines with acidic sulfonimide nucleophiles

“…Our accidental discovery of sulfonimidation of 2-phenyl-2-oxazoline (1) to give sulfonimide 5 using HN(SO 2 Ph) 2 prompted us to more closely scrutinize this unique nucleophile. Sandwiched between two powerful electron-withdrawing phenylsulfonyl groups, the NH proton on the molecule is exceptionally acidic with a pK a value of 1.45, 21 with a calculated value of 3.24, 22 approximately as strong as phosphoric acid. As a result, we suspected that dibenzenesulfonimide is acidic enough to protonate the nitrogen atom on 1.…”

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

“…This work could not have been done much earlier without the new accurate experimental data. A quick glance at the list of these structures reveals that, except for BSULFA, NABSUF (Cotton & Stockely, 1970) and MSULIN (Attig & Mootz, 1975), the others have been published since 1983 (among them 28 published since 1990), 2 years after our paper (K~ilm~in et al, 1981), dealing with the properties of the SvI[O,O',N,C] tetrahedra. Our present work is supported also by the fact that the novel compounds classified in subgroups IIIB and I/IC extend Table 2 (6) substantially the range of the S--N bond lengths observed in the --O2S--NQ--SO 2-moieties.…”

“…Of the 40 compounds retained, BSULFA and NABSUF [dibenzenesulfonamide and sodium dibenzenesulfonimide (Cotton & Stockely, 1970)] are closely related to NEWONE. Thus, NABSUF -without the second and third substituents of the phenyl rings -is the 'skeleton' of NEWONE, while BSULFA is the protonated form of NABSUF (Fig.…”