Guanidinium alkynesulfonates with single-layer stacking motif: interlayer hydrogen bonding between sulfonate anions changes the orientation of the organosulfonate R group from "alternate side" to "same side".

Hydrolyses of HC CSO3SiMe3 (1) and CH3 CSO3SiMe3 (2) lead to the formation of acetylenic sulfonic acids HC CSO3H center dot 2.33H(2)O (3) and CH3C CSO3H center dot 1.88 H2O (4). These acids were reacted with guanidinium carbonate to yield [C+(NH2)(3)][HC CSO3-] (5) and [C+(NH2)(3)][CH3C CSO3-] (6). Compounds 1-6 were characterized by spectroscopic methods, and the X-ray crystal structures of the guanidinium salts were determined. The X-ray results of 5 show that the guanidinium cations and organosulfonate anions associate into 1D ribbons through R-2(2)(8) dimer interactions, whereas association of these ions in 6 is achieved through R-2(2)(8) and R-2(1)(6) interactions. The ribbons in 5 associate into 2D sheets through R-2(2)(8) dimer interactions and R-6(3)(12) rings, whereas those in 6 are connected through R-2(1)(6) and R-2(2)(8) dimer interactions and R-6(4)(14) rings. Compound 6 exhibits a single-layer stacking motif similar to that found in guanidinium alkane- and arenesulfonates, that is, the alkynyl groups alternate orientation from one ribbon to the next. The stacking motif in 5 is also single-layer, but due to interlayer hydrogen bonding between sulfonate anions, the alkynyl groups of each sheet all point to the same side of the sheet.