Synthesis, crystal structures, and characterization of three mercury(II) halides inorganic–organic hybrid compounds with 1,4-diazabicyclo[2.2.2]octane ligand

Three new hybrid mercury halides compounds with 1,4-diazabicyclo[2.2.2]octan (DABCO) ligand, namely, Hg2(μ2-I)2I3(H-DABCO) (1), {[Hg5(μ2-I)6I4(μ2-DABCO)2][Hg2I4(μ2-DABCO)]}n (2) and {[Hg2(μ2-Br)2Br2(μ2-DABCO)]·2(HgBr2)}n (3), have been synthesized. Compound 1 crystallizes in a P21 chiral space group and is a discrete dinuclear mercury(II) compound with inorganic Hg2(μ2-I)2I3 unit. Compound 2 consists of 1D neutral [Hg5(μ2-I)6I4(μ2-DABCO)2]n broad polymeric array containing uncommon inorganic decanuclear [Hg10(μ2-I)12I8]n clusters, and neutral guest Hg2(μ2-DABCO)I4 molecules. Compound 3 is composed of a neutral [Hg2(μ2-Br)2Br2(μ2-DABCO)]n polymeric chain and guest inorganic HgBr2 molecules. In all cases, the halide ions participate in the framework connectivity as bridging ligands. A variety of coordination geometries displayed by the metal sites such as linear, trigonal and tetrahedral are observed in these compounds. Of the three compounds, only compound 3 displays photoluminescence with a emission maximum at 528 nm upon excitation at 468 nm. In addition, these compounds are characterized by IR, elemental analysis, and thermogravimetric analysis.