Structural manipulation of hydrogen bond networks using sulfonated phosphane ligands and their complexes: Competition and interplay between strong and weak hydrogen bonds

Abstract

Using the sulfonated phosphane [PPh2(C6H4-m-SO3)]-, L-, we have demonstrated that metal centres can readily be incorporated into guanidinium sulfonate (GS) hydrogen-bonded networks, and that the increase in steric bulk on going from [C(NH2)3][L] (1) to [C(NH2)3][AuCl(L)] (2) leads to a flattening of the GS sheets. The crystal structures of [C(NH2)3][LS] 3 and [C(NH2)3][LSe] 4 (LS- = [SPPh2(C6H4-m-SO3)]-, LSe- = [SePPh2(C6H4-m-SO3)]-) reveal disorder in both the sulfonate groups and the guanidinium cations, which is a consequence of pseudo-sixfold phenyl embraces between the anions. These interactions, identical to those observed in Ph3PS and Ph3PSe, position the sulfonate groups too close together for regular quasihexagonal hydrogen bonding motifs to be formed. The regular GS hydrogen bonding patterns can also be disrupted by using an anion containing two sulfonate groups such as that in [C(NH2)3]2{cis-[PdCl2 (L)2]} (5). In this case the incorporation of two sulfonate groups from each anion into the same hydrogen-bonded sheet also serves to constrain the distance between the sulfur atoms to a value incommensurate with that enabling a guanidinium cation to hydrogen bond to both groups. In this case irregular GS sheets are formed involving fewer N-H⋯O hydrogen bonds than in 1 and 2. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.