Year: 2026
Type: preprint
Abstract: Conductive metal-organic frameworks (MOFs) based on low-valent heavy transition metals remain largely unexplored despite the strong metal-ligand covalency and extended orbitals that should favor electronic delocalization. Herein, we report Nb(pyz) 2 Cl 2 (pyz = pyrazine), a layered coordination framework with a metallic electronic ground state. Although charge transport in pressed pellets is limited by thermally activated grain-boundary hopping, the high room-temperature conductivity of 1.2 S cm⁻ 1 , temperature-independent Pauli susceptibility, finite Sommerfeld coefficient (g = 14.0(5) mJ K⁻ 2 mol⁻ 1 ), Wilson ratio close to unity, and periodic density functional theory calculations consistently demonstrate a finite density of states at the Fermi level. X-ray absorption spectroscopy further reveals a strongly delocalized electronic structure involving mixed Nb 4d, Cl 3p, and pyz p* states. These results identify low-valent early-4d ions as promising components for electronically delocalized coordination solids and extend metallic metal-organic frameworks beyond the 3d transition-metal series.
Source: ChemRxiv
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funders: European Commission, Agence Nationale de la Recherche, European Synchrotron Radiation Facility, Centre National de la Recherche Scientifique, Université de Bordeaux, Infrastruktura PL-Grid, HORIZON EUROPE Framework Programme, Academic Computer Centre Cyfronet, AGH University of Science and Technology
OpenAlex ID: W7212053473