Reduction of the host cationic framework charge by isoelectronic substitution: Synthesis and structure of Hg₇Ag₂P ₈X₆ (X = Br, I) and Hg₆Ag₄P ₈Br₆

The first compounds, Hg₇Ag₂P₈X₈ (X = Br, I) and Hg₆Ag₄P₈Br₆, featuring the partial isoelectronic substitution of Hg²⁺ for Ag ¹⁺ in mercury-pnicogen frameworks have been obtained and structurally characterized. The new compounds are the supramolecular assemblies built of the covalently bonded metal-pnicogen frameworks trapping guests of different complexity. The frameworks feature the perfect ordering of Hg²⁺ and Ag¹⁺ cations and contain P₂^4- and P ₆^6- phosphorus clusters. The substitution of Hg ²⁺ with Ag¹⁺ leads to the reduction in charge of the host cluster-containing cationic matrix and concomitant replacement of the monatomic X^- guest by a lesser amount of the AgBr₃^2- anions.