Easily Switchable 18π-, 19π-, and 20π-Conjugation of Diazaporphyrin Double-Pincer Bispalladium Complexes

Takahiro Sakurai; Yuya Hiraoka; Hisaaki Tanaka; Yoshihiro Miyake; Norihito Fukui; Hiroshi Shinokubo

doi:10.1002/anie.202300437

Easily Switchable 18π-, 19π-, and 20π-Conjugation of Diazaporphyrin Double-Pincer Bispalladium Complexes

Angew Chem Int Ed Engl. 2023 Mar 13;62(12):e202300437. doi: 10.1002/anie.202300437. Epub 2023 Feb 14.

Authors

Takahiro Sakurai¹, Yuya Hiraoka¹, Hisaaki Tanaka², Yoshihiro Miyake¹, Norihito Fukui^{1

3}, Hiroshi Shinokubo¹

Affiliations

¹ Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, and Integrated Research Consortium on Chemical Science (IRCCS), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan.
² Department of Applied Physics, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603, Japan.
³ PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama, 332-0012, Japan.

PMID: 36723446
DOI: 10.1002/anie.202300437

Abstract

Ni^II 3,7,13,17-tetrapyridyl-5,15-diazaporphyrin serves as a double tridentate ligand to Pd^II ions to provide a pincer-type bispalladium complex. Electrochemical analysis revealed that the bispalladium complex shows excellent ability to accept electrons and reversible redox properties due to the coordination of the two cationic Pd^II centers to the meso-nitrogen atoms. We isolated and characterized one- and two-electron reduction species of the bispalladium complex. The 20π antiaromatic nature of the two-electron reduction species was confirmed by ¹ H NMR spectroscopy, UV/Vis-near-IR (NIR) absorption spectra, and density functional theory (DFT) calculations. X-ray diffraction revealed highly twisted structures for the bispalladium complexes regardless of the oxidation state.

Keywords: Aromaticity; Metal Complex; NIR Absorption; Porphyrinoids; Redox.

Abstract

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