Structural, Magnetic and DFT studies on a Charge-Transfer Salt of a Tetrathiafulvalenepyridyl-(1,5-diisopropyl) verdazyl Diradical Cation

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim..

A new tetrathiafulvalene (TTF) donor covalently appended with a 1,5-diisopropylverdazyl radical through a cross-conjugated pyridyl linker (3) has been prepared and characterised. Reaction of 3 with tetracyanoquinonedimethane (TCNQ) afforded the 2:1 charge-transfer complex (3)2 ⋅TCNQ (4), in which the IR and structural data are consistent with 0.25 e- charge transfer from the TTF donor (D) to the TCNQ acceptor (A). The TTF and TCNQ molecules adopt a mixed-stack D⋅⋅⋅D⋅⋅⋅A arrangement that does not facilitate conduction. A solution EPR spectrum of 4 comprises a broad featureless singlet, which is consistent with the presence of a TCNQ radical anion. Theoretical studies were performed to probe the exchange interactions within selected fragments of 4 with and without charge transfer. In the absence of charge transfer, DFT calculations reveal weak antiferromagnetic exchange between verdazyl radicals within the (3)2 monoradical unit. However, partial oxidation of the dimer (3)2 to the diradical cation leads to an S= 1 / 2 ground state, in which the verdazyl radical spins are now aligned co-parallel as a consequence of antiferromagnetic exchange to the additional delocalised TTF-based spin containing unit. The magnetic properties of 4 are consistent with a net S= 1 / 2 spin state per formula unit with dominant antiferromagnetic interactions between spin-bearing building blocks.

Medienart:

E-Artikel

Erscheinungsjahr:

2015

Erschienen:

2015

Enthalten in:

Zur Gesamtaufnahme - volume:80

Enthalten in:

ChemPlusChem - 80(2015), 11 vom: 21. Nov., Seite 1624-1633

Sprache:

Englisch

Beteiligte Personen:

Venneri, Shari [VerfasserIn]
Wilson, Justin [VerfasserIn]
Rawson, Jeremy M [VerfasserIn]
Pilkington, Melanie [VerfasserIn]

Links:

Volltext

Themen:

Charge transfer
Donor-acceptor systems
Journal Article
Magnetic properties
Radicals
Spintronics

Anmerkungen:

Date Revised 24.01.2020

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1002/cplu.201500309

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM305705199