Copper- and Silver-Containing Heterometallic Iodobismuthates: Features of Thermochromic Behavior

Abstract

Nine heterometallic iodobismuthates with the general formula Cat2{[Bi2M2I10}] (M = Cu(I), Ag(I), Cat = organic cation) were synthesized. According to X-ray diffraction data, their crystal structures consisted of {Bi2I10} units interconnected with Cu(I) or Ag(I) atoms through I-bridging ligands, forming one-dimensional polymers. The compounds are thermally stable up to 200 °C. Optical band gaps (Eg), estimated at room temperature via diffuse reflectance measurements, range from 1.81 to 2.03 eV. Thermally induced changes in optical behavior (thermochromism) for compounds 1–9 were recorded, and general correlations were established. The thermal dependence of Eg appears to be close to linear for all studied compounds.

Ternary Complexes of BiI3/CuI and SbI3/CuI with Tetrahydrothiophene

“…It solved in orthorhombic space group Pbcn , as half-independent. All Bi–I, Cu–I, and Cu–S bond lengths were within conventional ranges. − Bond angles around Bi were within 3° of 90° octahedral (O h ) and around Cu within 6.5° of 109.5° tetrahedral ( T d ). The structure is composed of O h BiI 6 units that are bridged to T d CuI 2 (THT) 2 units via pairs of μ 2 -I, forming via Cu­(μ 2 -I) 2 Bi rhombs, see Figure .…”

“…A good deal of literature exists for charge-separated halobismuthate­(III) and haloantimonate­(III) salts, − ,,− much of it with alkali or organic ammonium cations. Additionally, there are multiple reports of halobismuthate and haloantimonate anions containing Cu­(I) or Ag­(I), such as Bi 2 Cu 2 I 10 2– , or paired with Cu­(I) or Ag­(I) cations, ,− many of which show relatively small band gaps. However, neutral ligand-supported iodobismuthate/cuprate and iodoantimonate/cuprate compounds remain extraordinarily rare.…”