Predicting valence tautomerism in diverse cobalt-dioxolene complexes: elucidation of the role of ligands and solvent.

Autor: M Zahir FZ; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au., Hay MA; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au., Janetzki JT; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au., Gable RW; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au., Goerigk L; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au., Boskovic C; School of Chemistry, University of Melbourne Victoria 3010 Australia c.boskovic@unimelb.edu.au lars.goerigk@unimelb.edu.au.
Jazyk: angličtina
Zdroj: Chemical science [Chem Sci] 2024 Mar 12; Vol. 15 (15), pp. 5694-5710. Date of Electronic Publication: 2024 Mar 12 (Print Publication: 2024).
DOI: 10.1039/d3sc04493a
Abstrakt: The ability of molecular switches to reversibly interconvert between different forms promises potential applications at the scale of single molecules up to bulk materials. One type of molecular switch comprises cobalt-dioxolene compounds that exhibit thermally-induced valence tautomerism (VT) interconversions between low spin Co(iii)-catecholate (LS-Co III -cat) and high spin Co(ii)-semiquinonate (HS-Co II -sq) forms. Two families of these compounds have been investigated for decades but have generally been considered separately: neutral [Co(diox)(sq)(N 2 L)] and cationic [Co(diox)(N 4 L)] + complexes (diox = generic dioxolene, N 2 L/N 4 L = bidentate/tetradentate N-donor ancillary ligand). Computational identification of promising new candidate compounds prior to experimental exploration is beneficial for environmental and cost considerations but requires a thorough understanding of the underlying thermochemical parameters that influence the switching. Herein, we report a robust approach for the analysis of both cobalt-dioxolene families, which involved a quantitative density functional theory-based study benchmarked with reliable quasi-experimental references. The best-performing M06L-D4/def2-TZVPP level of theory has subsequently been verified by the synthesis and experimental investigation of three new complexes, two of which exhibit thermally-induced VT, while the third remains in the LS-Co III -cat form across all temperatures, in agreement with prediction. Valence tautomerism in solution is markedly solvent-dependent, but the origin of this has not been definitively established. We have extended our computational approach to elucidate the correlation of VT transition temperature with solvent stabilisation energy and change in dipole moment. This new understanding may inform the development of VT compounds for applications in soft materials including films, gels, and polymers.
Competing Interests: There are no conflicts to declare.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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