Revitalizing Spin Natural Orbital Analysis: Electronic Structures of Mixed‐Valence Compounds, Singlet Biradicals, and Antiferromagnetically Coupled Systems

Chemical systems with open‐shell electronic structure have been gaining attention these days. Their potential applications in first‐row transition metal catalysis, molecular wires, photovoltaics and other potential applications have urged the adoption of a simple analysis tool to better understand their open‐shell electronic structures, especially the role played by the unpaired electrons. Despite its lack of popularity, spin natural orbital (SNO) analysis is a tool we found to well‐suit this purpose. We have therefore re‐examined how the SNO could help us analyze some interesting open‐shell systems, including mixed‐valence compounds, singlet biradicals, and antiferromagnetically coupled systems. We found that some interesting patterns emerge from SNO analysis, especially those associated with exchange interaction. © 2019 Wiley Periodicals, Inc.

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