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[triple bond]CSO3SiMe3 (1) and CH3C[triple bond]CSO3SiMe3(2) lead to the formation of acetylenic sulfonic acids HC[triple bond]CSO3H.2.33H2O (3)and CH3C[triple bond]CSO3H.1.88H2O (4). These acids were reacted with guanidinium carbonate to yield [+C(NH2)3][HC[triple bond]CSO3] (5) and [+C(NH2)3][CH3C[triple bond]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 R2(2)(8) dimer interactions,whereas association of these ions in 6 is achieved through R2(2)(8) and R1(2)(6) interactions. The ribbons in 5 associate into 2D sheets through R2(2)(8) dimer interactions and R3(6)(12) rings, whereas those in 6 are connected through R1(2)(6)and R2(2)(8) dimer interactions and R4(6)(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.