Polymeric heterometallic Pb–Ag iodometallates, iodoplumbates and iodoargentates with lanthanide complex cations as templates

Abstract

Heterometallic Pb–Ag iodometallates [Ln(DMF)₈]₂Pb₃Ag₁₀I₂₂ [Ln = Ce(1), Pr(2)] were prepared by the reactions of PbI₂, AgNO₃ and KI in dimethylformamide (DMF) templated by [Ln(DMF)₈]³⁺ complexes formed in situ by stirring LnCl₃ in DMF. The same reactions in the absence of AgNO₃ or PbI₂ afforded iodoplumbate [Pr(DMF)₉]₂[Pr(DMF)₈]Pb₁₁I₃₁ (3), and iodoargentates [Ln(DMF)₈]Ag₆I₉ [Ln = Ce(4), Pr(5)], respectively. Compounds 1 and 2 contain a ternary one-dimensional polymeric [Pb₃Ag₁₀I₂₂]⁶⁻ anion self-assembled from five AgI₄, one PbI₆ and one PbI₄ primary units via edge- and face-sharing. Twelve PbI₆ octahedra are interlinked via sharing of common faces to generate a 1D zigzag [Pb₁₁I₃₁⁹⁻]_n chain in 3, which represents a new member of iodoplumbate aggregates. In 4 and 5, three AgI₄ tetrahedra connect through common edges to form the [Ag₆I₁₂]⁶⁻ building block. The [Ag₆I₁₂]⁶⁻ blocks are further interlinked by sharing common edges, resulting in the 1D [Ag₆I₉³⁻]_n chain. Optical absorption spectra showed that the synthesized Ag-iodoplumbate and iodoplumbate have potential for being used as semiconductors. Our results show that heterometallic halometallate properties can be tuned by combining structural units with different symmetries, enabling the synthesis of specific functional materials.