2-Ammonio-5-chloro-4-methylbenzenesulfonate, its 1-methyl-2-pyrrolidone and dimethyl sulfoxide monosolvates and a corrected structure of 2,2′-(1,4-phenylene)di(4,5-dihydroimidazolium) bis(4-aminobenzenesulfonate) dihydrate

Abstract

2-Ammonio-5-chloro-4-methylbenzenesulfonate, C(7)H(8)ClNO(3)S, (Ia), is an intermediate in the synthesis of lake red azo pigments. The present structure determination from single-crystal data confirms the results of a previous powder diffraction determination [Bekö, Thoms, Brüning, Alig, van de Streek, Lakatos, Glaubitz & Schmidt (2010). Z. Kristallogr. 225, 382-387]. The zwitterionic tautomeric form is confirmed. During a polymorph screening, two additional pseudopolymorphs were obtained, viz. 2-ammonio-5-chloro-4-methylbenzenesulfonate 1-methyl-2-pyrrolidone monosolvate, C(7)H(8)ClNO(3)S·C(5)H(9)NO, (Ib), and 2-ammonio-5-chloro-4-methylbenzenesulfonate dimethyl sulfoxide monosolvate, C(7)H(8)ClNO(3)S·C(2)H(6)OS, (Ic). The molecules of (Ib) have crystallographic m symmetry. The 1-methyl-2-pyrrolidone solvent molecule has an envelope conformation and is disordered around the mirror plane. The structure shows hydrogen-bonded ladders of molecules [graph-set notation C(2)(2)(6)R(2)(2)(12)] in the [010] direction. The benzene groups of adjacent ladders are also stacked in this direction. A different type of hydrogen-bonded ladder [graph-set notation C(6)R(2)(2)(4)R(4)(4)(12)] occurs in (Ic). In (Ia), (Ib) and (Ic), the molecules correspond to the zwitterionic tautomer. The structure of the cocrystal of 4-aminobenzenesulfonic acid with 1,4-bis(4,5-dihydroimidazol-2-yl)benzene [Shang, Ren, Wang, Lu & Yang (2009). Acta Cryst. E65, o2221-o2222] is corrected; it actually contains 4-aminobenzenesulfonate anions and 2,2'-(1,4-phenylene)di(dihydroimidazolium) dications, i.e. 2,2'-(1,4-phenylene)di(4,5-dihydroimidazolium) bis(4-aminobenzenesulfonate) dihydrate, C(12)H(16)N(4)(2+)·2C(6)H(6)NO(3)S(-)·2H(2)O. Hence, all known structures of aminobenzenesulfonic acid complexes contain ionic or zwitterionic molecules; there is no known structure with a neutral aminobenzenesulfonic acid molecule.

Determination of crystal structures and tautomeric states of 2-ammoniobenzenesulfonates by laboratory X-ray powder diffraction

“…For structure solutions the starting molecular geometry for 1, 3 and 4 was taken from the recently determined single-crystal structure of 2 [7] and the substituents were correspondingly modified with Mercury 3.0 [27]. A zwitterionic form, as found for 2, was assumed, but at this stage, very similar results would have been obtained with the neutral tautomeric form as well.…”

“…In 2010 we investigated the crystal structure and the tautomeric state of 2 using X-ray powder diffraction (XRPD), IR and solid-state NMR spectroscopy. All methods revealed the zwitterionic tautomer of 2 [6,7]. In 1985 solid-state NMR investigations indicated that 2-aminobenzenesulfonic acid ( Figure 1, R 1 = R 2 = H) and 2-amino-5-methylbenzenesulfonic acid (R 1 = H, R 2 = CH 3 ) are zwitterionic, but the data on 2-amino-5-nitrobenzenesulfonic acid (R 1 = H, R 2 = NO 2 ) were interpreted as an indication for the neutral amine tautomer in solid state [8].…”