BiCuI4(Pyridine)5 a neutral ligand-supported compound of BiI3 and CuI

• Published in: Inorganic chemistry communications 2022-11, Vol.147
• Main Authors: Giunta, Katherine S., McKee, Shara N., Nicholas, Aaron D., Pike, Robert D.
• Format: Article
• Language: English
• Subjects: bismuth compounds; diffuse reflectance spectroscopy; electronic structure calculations; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; NLMO; x-ray diffraction
• ISSN: 1387-7003; 1879-0259

Reaction of equimolar pyridine (Py) solutions BiI3 and CuI produces the Py-supported 1:1 bimetallic complex BiCuI4(Py)5 in quantitative yield. The title complex is only the second neutral complex to feature Cu–I–Bi bridging and shows an octahedral trans-[BiI4(Py)2] unit joined to a distorted tetrahedral CuI(Py)3 unit by an iodide bridge. The complex shows low thermal stability, decomposing under modest heating or vacuum to produce a mixture of BiI3 and CuI. Thus, it is a potential entry/precursor to BiI3/CuI chemistry. Natural Localized Molecular Orbital (NLMO) calculations were performed to analyze the nature of the Cu–I–Bi bonds, revealing that the title compound lies on the cusp of being [Cu(Py)3]+[BiI4(Py)2]–. Diffuse reflectance spectroscopy measurements show a strong absorption band with an optical bandgap energy of 1.94 eV. Theoretical density of states (DOS) and time-dependent density functional theory (TD-DFT) experiments to map the electronic structure assign the primary electronic transition as a mixed halide/metal-to-ligand charge transfer between Cu–I–Bi donor orbitals and Py π* acceptor orbitals.