Molecular and electronic structures of paramagnetic gallium complexes with differently charged o-quinone ligands

• Published in: Russian chemical bulletin 2022-07, Vol.71 (7), p.1441-1452
• Main Authors: Maleeva, A. V., Trofimova, O. Yu, Ershova, I. V., Arsenyeva, K. V., Pashanova, K. I., Yakushev, I. A., Cherkasov, A. V., Aysin, R. R., Piskunov, A. V.
• Format: Article
• Language: English
• Subjects: Absorption spectra; Benzoquinone; Charge transfer; Chemical synthesis; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Crystal structure; Full Articles; Gallium; Inorganic Chemistry; Ligands; Molecular structure; Organic Chemistry; Pyridines; Quinones; Single crystals
• ISSN: 1066-5285; 1573-9171
• DOI: 10.1007/s11172-022-3550-y

A series of new paramagnetic six-coordinate gallium complexes based on 3,6-di- tert -butyl- o -benzoquinone with N-donor ligands, such as pyridine (Py), 2,2′-dipyridyl (2,2′-dipy), and 4,4′-di- tert -butyl-2,2′-dipyridyl (Bu t -dipy), were synthesized and structurally characterized. The molecular structures of the synthesized compounds were established by single-crystal X-ray diffraction. The complexes with bidentate N-donor ligands have the cis arrangement of the o -quinone ligands, whereas the compound with coordinated pyridine molecules has the trans arrangement of the diolate moieties. The synthesized compounds are characterized by spin density delocalization between the differently charged redox-active ligands. Regardless of the metal coordination environment, the near-IR region of the electronic absorption spectra of all the synthesized complexes show a low-intensity charge-transfer band between the catecholate and o -semiquinolate ligands, which was confirmed by DFT calculations.