Aurophilicity-Triggered Assembly of Novel Cyclic Penta- and Hexanuclear Gold(I) Complexes with Rigid Anionic NHC-Type Ligands

The products of the reaction between N,N′-diphosphanylimidazol-2-ylidene (P–C–P) and gold­(I) precursors depend on the nature of the anions associated with the latter. In contrast to the reported reaction with [Au­(tht)2(OTf)], the use of [AuCl­(tht)] led to the new hexanuclear complex 1, which features a Au6(μ3-P–C,κC,κN,κP)3 skeleton. The reaction of lithium imidazolide (P–C–Li) and [AuCl­(tht)] also afforded 1, together with an unusual salt of the general formula [Au5Cl­(μ3-P–C-κP,κC,κN)3]2[AuCl2]2 (2), which contains [Au5(μ3-P–C-κP,κC,κN)]+ subunits. In the solid state, one of these Au5 cations is associated with an [AuCl2]− anion, while two other cations interact through their unique dicoordinated N–Au–N center with a [AuCl2]− anion, with the charge of the resulting monocation being compensated for by another [AuCl2]− anion to give a Au12 salt. Remarkably, the latter displays seven different bonding types at AuI: C–Au–C, N–Au–N, P–Au–P, Cl–Au–Cl, C–Au–N, P–Au–Cl, and Au···Au.