Chalcogen bond provided supramolecular association of beta-octamolybdate and chalconium cations

Abstract

The interactions of triple σ-(QIV)-hole donating chalconium cations ([Q(bPh)R]+, when Q = S, Se, Te) with nucleophilic beta-octamolybdate ([β-Mo8O26]4–) results in supramolecular association. The main focus of such assembling is on σ-(QIV)-holes recognition by the molybdate in cations with a biphenyl aromatic fragment. This leads to a remarkable diversity of the association patterns producing: i) neutral 4:1 {[Q(bPh)R]4[β-Mo8O26]} complexes with cations stacked by π-π interactions; ii) (Bu4N)+, [Q(bPh)R]+ and [β-Mo8O26]4– complexes of 2:2:1 stoichiometry with π-π interactions; iii) (Bu4N)+, [Q(bPh)R]+ and [β-Mo8O26]4– complexes of 2:2:1 stoichiometry without π-π interactions; iv) {[Q(bPh)R]2}2[β-Mo8O26] salts with π-π stacked cations but lacking any (QIV)∙∙∙O interactions. Moreover, interactions in the system can drive the reorganization of [β-Mo8O26]4– into [α-Mo8O26]4–. The halogen-bonded (QIV)∙∙∙O {(Q(bPh)R)x[β-Mo8O26]4–} (x = 2, 4) assemblies, π-π stacked cationic dimers {(Q(bPh)R)2}2+ and complicated associates based on both types interactions have been the subjects of crystallographic and computational studies.