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Charge and spin delocalization in mixed-valent vinylruthenium-triarylamine-conjugates with planarized triarylamines

We report on three new vinylruthenium-triarylamine (TA) conjugates with planarized TA substituents. The neutral, mono-, and dioxidized forms of the complexes were scrutinized by UV/vis/NIR, IR, and EPR spectroscopies as well as by quantum chemical calculations. By analyzing the intervalence charge-t...

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Bibliographic Details
Main Authors: Breimaier, Stefanie (Author) , Fröhlich, Nina (Author) , Herberger, Jan (Author) , Linseis, Michael A. (Author) , Kivala, Milan (Author) , Winter, Rainer F. (Author)
Format: Article (Journal)
Language:English
Published: January 13, 2022
In: Organometallics
Year: 2022, Volume: 41, Issue: 5, Pages: 532-546
ISSN:1520-6041
DOI:10.1021/acs.organomet.1c00619
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1021/acs.organomet.1c00619
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Author Notes:Stefanie Breimaier, Nina Fröhlich, Jan Herberger, Michael Linseis, Milan Kivala, and Rainer F. Winter
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Summary:We report on three new vinylruthenium-triarylamine (TA) conjugates with planarized TA substituents. The neutral, mono-, and dioxidized forms of the complexes were scrutinized by UV/vis/NIR, IR, and EPR spectroscopies as well as by quantum chemical calculations. By analyzing the intervalence charge-transfer (IVCT) transitions of the mixed-valent radical cations, we obtain information on the extent of electronic coupling between the chemically different redox sites. Completely delocalized Ru-MeTA+ shows a vibrationally structured, non-solvatochromic IVCT band. Decreased blueshifts of the indicative Ru(CO) stretching vibration during the first oxidation and larger A(14N) EPR hyperfine splitting constants in concert with smaller g-values indicate enhanced TA contributions to the singly occupied molecular orbital of the other two complexes Ru-TOTA•+ and Ru-DOTA•+ and hence less symmetrical charge and spin density distributions. This is also reflected by the solvatochromism and the asymmetric shape of the IVCT band with a smaller bandwidth at the low-energy side. Temperature-dependent UV/vis/NIR spectroscopy of mixed-valent Ru-TOTA•+ and Ru-DOTA•+ revealed that the band skewing is due to the vibrational coupling of the IVCT transition to symmetrical vibrations, placing these radical cations near or at the class II/III borderline according to Robin and Day.
Item Description:Gesehen am 20.09.2022
Physical Description:Online Resource
ISSN:1520-6041
DOI:10.1021/acs.organomet.1c00619

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