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

The products of the reaction between <i>N</i>,<i>N</i>′-diphosphanylimidazol-2-ylidene (<b>P–C–P</b>) 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 <b>1</b>, which features a Au₆(μ₃-<b>P–C</b>,κ<i>C</i>,κ<i>N</i>,κ<i>P</i>)₃ skeleton. The reaction of lithium imidazolide (<b>P–C–Li</b>) and [AuCl­(tht)] also afforded <b>1</b>, together with an unusual salt of the general formula [Au₅Cl­(μ₃-<b>P–C</b>-κ<i>P</i>,κ<i>C</i>,κ<i>N</i>)₃]₂[AuCl₂]₂ (<b>2</b>), which contains [Au₅(μ₃-<b>P–C</b>-κ<i>P</i>,κ<i>C</i>,κ<i>N</i>)]⁺ 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 Au^I: C–Au–C, N–Au–N, P–Au–P, Cl–Au–Cl, C–Au–N, P–Au–Cl, and Au···Au