One- versus two-electron oxidation of complexed guanidino-functionalized aromatic compounds

• Verfasst von: Trumm, Christine Helga [VerfasserIn]
• Verfasst von: Hübner, Olaf [VerfasserIn]
• Verfasst von: Walter, Petra [VerfasserIn]
• Verfasst von: Leingang, Simone [VerfasserIn]
• Verfasst von: Wild, Ute [VerfasserIn]
• Verfasst von: Kaifer, Elisabeth [VerfasserIn]
• Verfasst von: Eberle, Benjamin [VerfasserIn]
• Verfasst von: Himmel, Hans-Jörg [VerfasserIn]
• Titel: One- versus two-electron oxidation of complexed guanidino-functionalized aromatic compounds
• Verf.angabe: Christine Trumm, Olaf Hübner, Petra Walter, Simone Leingang, Ute Wild, Elisabeth Kaifer, Benjamin Eberle, and Hans-Jörg Himmel
• E-Jahr: 2014
• Jahr: 06 November 2014
• Umfang: 12 S.
• Fussnoten: Gesehen am 06.11.2020
• Titel Quelle: Enthalten in: European journal of inorganic chemistry
• Ort Quelle: Weinheim : Wiley-VCH, 1998
• Jahr Quelle: 2014
• Band/Heft Quelle: (2014), 35, Seite 6039-6050
• ISSN Quelle: 1099-0682
• DOI: doi:10.1002/ejic.201402840
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Aromaticity
• Sach-SW: Copper
• Sach-SW: Guan­id­ine
• Sach-SW: Oxidation
• Sach-SW: Redox chemistry
• K10plus-PPN: 1738059286

Abstract

Herein, we report a rational synthetic access to dinuclear CuII complexes with radical monocationic guanidine ligands. The starting point was the first directed synthesis of a dinuclear CuII complex of the redox-active, neutral guanidino-functionalized aromatic (GFA) compound 1,2,4,5-tetrakis(tetramethylguanidino)benzene (1) as ligand by treatment of 1 with Cu(OAc)2. The neutral complex [1Cu(OAc)22] was then oxidized with several oxidizing reagents. With I2 two-electron oxidation occurred, thus leading to green salts of the dication [1Cu(OAc)22]2+. In contrast, with AgPF6 or AgSbF6 one-electron oxidation was observed to yield red salts of the monocation [1Cu(OAc)22]+, which is a three-spin system with one unpaired electron at each copper atom and at the ligand unit. Superconducting quantum interference device (SQUID) magnetometric measurements confirm a quartet electronic ground state that arises from strong ferromagnetic copper-ligand coupling. Intense charge-transfer transitions in the visible region (576 and 536 nm) were observed in the electronic absorption spectra and assigned to strong ligand-ligand (1·+←OAc) charge-transfer (LLCT) excitations. These LLCT bands open up the possibility of photoinduced redox reactions with [1Cu(OAc)22]+ driven by restoration of the aromatic system at the GFA ligand.