The following bromobismuthates of organic cations (dipyridinoalkane derivatives) are synthesized and characterized: (4-NH2PyC5)BiBr5 ( I), (2-MePyC2)BiBr5 ( II), (2-NH2PyC10)BiBr5 · 0.65H2O ( III),...

The concept of using redox-active ligands, which has become extremely widespread in organometallic chemistry, is often considered from ‘their effect on the metal center properties’ point of view and ‘how to modify the ligands’. In this paper, we present the reverse side of this effective approach – a dramatic change of redox properties of ligands under the influence of a redox-inert metal. Germanium derivatives based on 2,3-dihydroxynaphthalene (1) and N,N′-bidentate ligands, namely 2,2′-bipyridine (2) and 1,10-phenanthroline (3), were obtained and characterized by CV, UV-vis spectroscopy, DFT calculations and in the case of 3 X-ray diffraction. It was shown that the HOMO of the complexes is almost completely located on the naphthalene fragment while the LUMO is on the N,N-ligands. At the same time, there are no boundary molecular orbitals on the germanium atom, but it forms the axial part of the molecule holding two opposite motifs together. Moreover, it sharply affects the level of HOMO and LUMO. Derivatives 2 and 3 are more easily oxidized compared to 2,3-dihydroxynaphthalene by 0.31–0.34 V (7–8 kcal mol⁻¹) and are more easily reduced compared to N,N-donors by 1.08–1.15 V (25–26.5 kcal mol⁻¹). All this together makes it possible to form a system with a narrow HOMO/LUMO gap (∼2 eV). The crystal structure of 3 consists of alternating monomolecular easily oxidizing and easily reducing layers formed due to intermolecular interactions, in particular π-stacking. In addition, in contrast to 1 that starts to decompose noticeably at the temperatures from 200 °C, 2 and 3 have an extremely high thermal stability. They remain stable with no signs of decomposition and melting up to 400 °С. We believe that this approach to the formation of the supramolecular structure may present prospects for obtaining new functional materials.

Hybrid bromobismuthates of N-alkylated derivatives of 2- and 3-methylpyridine, (C₁₅H₂₀N₂)₂Bi₂Br₁₀ (I), (C₁₇H₂₄N₂)₂Bi₂Br₁₀ (II), (C₁₈H₂₆N₂)₃(Bi₂Br₉)₂ (III), (C₁₄H₁₈N₂)(H₃O)BiBr₆ ∙ 2H₂O (IV), (C₁₄H₁₈N₂)₂BiBr₆IBr₂ (V), (C₁₆H₂₂N₂)₃(Bi₂Br₉)₂ (VI), and (C₁₈H₂₆N₂)₃(Bi₂Br₉)₂ (VII), are synthesized in concentrated HBr and characterized by physicochemical methods. The structures of complexes I–VII are studied by X-ray structure analysis (CIF files CCDC nos. 1946844–1946850). Complexes I and II contain anions [Bi₂Br₁₀]^4–. Anions [Bi₂Br₉]^3– are found in the structures of compounds III, VI, and VII. Bis(3-methyl-1-pyridino)ethane bromobismuthate IV contains cations H₃O⁺ and anions [BiBr₆]^3– and, unlike other bromobismuthates, decomposes at low temperatures. In presence of HI vapors, double bromobismuthate V containing the [BiBr₆]^3– and IBr₂^– anions crystallizes along with compound IV.

During a formation of four mixed hybrid halobismuthates (two of them have new structures) from solutions containing both Br⁻ and I⁻ ions, solid products enriched with iodine were isolated. Either oxidation or drying of mother liquors resulted in products with even higher iodine contents, up to pure iodobismuthates. All the compounds were characterized by a set of comprehensive methods (NMR, X-ray, DRS, etc.).