Intramolecular through-space double-electron transfer between a pair of redox-active guanidine units aligned by dithiolate bridges

• Verfasst von: Wild, Ute [VerfasserIn]
• Verfasst von: Hübner, Olaf [VerfasserIn]
• Verfasst von: Meiners, Paul [VerfasserIn]
• Verfasst von: Kaifer, Elisabeth [VerfasserIn]
• Verfasst von: Enders, Markus [VerfasserIn]
• Verfasst von: Himmel, Hans-Jörg [VerfasserIn]
• Titel: Intramolecular through-space double-electron transfer between a pair of redox-active guanidine units aligned by dithiolate bridges
• Verf.angabe: Ute Wild, Olaf Hübner, Paul Meiners, Elisabeth Kaifer, Markus Enders, and Hans-Jörg Himmel
• E-Jahr: 2023
• Jahr: 22 August 2023
• Umfang: 13 S.
• Fussnoten: Gesehen am 13.11.2023
• Titel Quelle: Enthalten in: Chemistry - a European journal
• Ort Quelle: Weinheim : Wiley-VCH, 1995
• Jahr Quelle: 2023
• Band/Heft Quelle: (2023) vom: Aug., Artikel-ID e202302418, Seite 1-13
• ISSN Quelle: 1521-3765
• DOI: doi:10.1002/chem.202302418
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: chemical exchange
• Sach-SW: double-electron transfer
• Sach-SW: guanidine
• Sach-SW: oxidation
• Sach-SW: redox-active organic molecules
• K10plus-PPN: 1870133552

Abstract

Using unconventional synthesis protocols, two redox-active triguanidine units are connected by a dithiolate bridge, aligning the two redox-active units in close proximity. The reduced, neutral and the tetracationic redox states with two dicationic triguanidine units are isolated and fully characterized. Then, the dicationic redox states are prepared by mixing the neutral and tetracationic molecules. At low temperatures, the dications are diamagnetic (singlet ground state) with two different triguanidine units (neutral and dicationic). At room temperature, the triplet state with two radical monocationic triguanidine units is populated. At low temperature (210 K), chemical exchange by intramolecular through-space electron-transfer between the two triguanidine units is evidenced by EXSY NMR spectroscopy. Intramolecular through-space transfer of two electrons from the neutral to the dicationic triguanidine unit is accompanied by migration of the counterions in opposite direction. The rate of double-electron transfer critically depends on the bridge. No electron-transfer is measured in the absence of a bridge (in a mixture of one dicationic and one neutral triguanidine), and relatively slow electron transfer if the bridge does not allow the two triguanidine units to approach each other close enough. The results give detailed, quantitative insight into the factors that influence intramolecular through-space double-electron-transfer processes.