Acta Cryst. (2006). E62, o948-o950  [ doi:10.1107/S1600536806003953 ]

The second orthorhombic polymorph of zwitterionic metanilic acid at 130 K

G. Smith, U. D. Wermuth, D. J. Young and J. M. White

Abstract: The low-temperature (130 K) crystal structure of the second orthorhombic polymorph of metanilic acid (3-aminobenzenesulfonic acid), C₆H₇NO₃S, shows the presence of two independent and conformationally similar molecules of the zwitterionic acid (3-ammoniobenzenesulfonate) in the asymmetric unit; these interact through hydrogen bonding to give a cyclic R₂²(14) association. Peripheral hydrogen bonding gives a three-dimensional framework polymer, such as was found in the earlier polymorph [Hall & Maslen (1965), Acta Cryst. 18, 301-306], but the overall structural make-up is significantly different.

Online 8 February 2006

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