Structural manipulation through control of hydrogen bonding faces: the effects of cation substitution on the guanidinium sulfonate structure

Abstract

The crystal structures of eleven ionic compounds containing the substituted guanidinium cations [C(NH₂)₂(NHR)]⁺ (R = Me, Et) or [C(NH₂)₂(NMe₂)]⁺ and the sulfonate anions [RSO₃]⁻ (R = 1-naphthalene, 2-naphthalene, D-(+)-10-camphor, Me, Ph) have been determined in order to investigate the effects of removing N–H groups on the symmetrical guanidinium sulfonate hydrogen-bonded layer structure. Analysis of the supramolecular structures of these compounds, together with those of previously reported compounds in the same series, has shown that the monoalkylguanidinium sulfonates generally respond to the loss of a hydrogen bond donor by forming one of two hydrogen bonds patterns—shifted ribbon sheets or adapted sheets—and the way in which these sheets are arranged in the gross structure is, in most cases, similar to that of the related unsubstituted guanidinium sulfonate. In contrast, dimethylguanidinium sulfonates form structures based on cation⋯anion pairs that are inter-connected into ribbons or sheets.