Tuning PtII‐Based Donor–Acceptor Systems through Ligand Design: Effects on Frontier Orbitals, Redox Potentials, UV/Vis/NIR Absorptions, Electrochromism, and Photocatalysis

• Published in: Chemistry : a European journal 2020-01, Vol.26 (6), p.1314-1327
• Main Authors: Sobottka, Sebastian, Nößler, Maite, Ostericher, Andrew L., Hermann, Gunter, Subat, Noah Z., Beerhues, Julia, Behr‐van der Meer, Margarethe, Suntrup, Lisa, Albold, Uta, Hohloch, Stephan, Tremblay, Jean Christophe, Sarkar, Biprajit
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination compounds; Coupling (molecular); Dehydrogenation; Density functional theory; donor–acceptor systems; Electrochemistry; Electrochromism; Electron flux density; Ligands; Oxidation; Oxygen; Photocatalysis; Photochemicals; Platinum; Pyridines; redox-active ligands; spectroelectrochemistry; Sulfonamides; Time dependence
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201903700

Asymmetric platinum donor–acceptor complexes [(pimp)Pt(Q2−)] are presented in this work, in which pimp=[(2,4,6‐trimethylphenylimino)methyl]pyridine and Q2−=catecholate‐type donor ligands. The properties of the complexes are evaluated as a function of the donor ligands, and correlations are drawn among electrochemical, optical, and theoretical data. Special focus has been put on the spectroelectrochemical investigation of the complexes featuring sulfonyl‐substituted phenylendiamide ligands, which show redox‐induced linkage isomerism upon oxidation. Time‐dependent density functional theory (TD‐DFT) as well as electron flux density analysis have been employed to rationalize the optical spectra of the complexes and their reactivity. Compound 1 ([(pimp)Pt(Q2−)] with Q2−=3,5‐di‐tert‐butylcatecholate) was shown to be an efficient photosensitizer for molecular oxygen and was subsequently employed in photochemical cross‐dehydrogenative coupling (CDC) reactions. The results thus display new avenues for donor–acceptor systems, including their role as photocatalysts for organic transformations, and the possibility to introduce redox‐induced linkage isomerism in these compounds through the use of sulfonamide substituents on the donor ligands. Outcomes of ligand design: A series of platinum‐based donor–acceptor complexes is presented. The effect of the donor ligands on the frontier orbitals, redox potentials, redox‐induced isomerism, and photocatalysis is probe.