SCO ATLAS: Mapping Spin-Crossover Thermodynamics across Experimentally Grounded Fe(II)N6 Complexes
Year: 2026
Type: preprint
Abstract: Research on the Spin-crossover (SCO) phenomenon has generated extensive experimental and computational data, distributed across hundreds of different sources, limiting systematic comparison and data reuse. Here, we introduce the SCO ATLAS, a data infrastructure that connects experimental sources with quantum chemistry computations and derived analyses, and we demonstrate its use through a first analysis devoted to the gas-phase thermodynamics of transition metal complexes (TMC) based on Fe(II)N6. Currently, the ATLAS includes 723 CSDderived crystallographic systems, from which 602 unique TMCs were retained for analysis. We map the thermodynamic landscape governing their molecular spin-state stability, identify the ranges of electronic and vibrational contributions compatible with SCO near room temperature, and show that ligand denticity modulates both components. Normal-mode analysis traces the denticity dependence of the vibrational entropy primarily to changes in ligand motion and the first coordination sphere. The homoleptic complexes are organized into 96 ligand families, with family identity accounting for approximately one-third of the within-denticity variation in ∆Helec. Across the complete dataset, ∆Helec is most strongly associated with the HS Fe–N distance. The released data, calculations and analysis tools provide a reusable framework for navigating SCO chemical space and developing future extensions of the ATLAS.
Source: ChemRxiv
Author: Sergi Vela
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7220735342