Structural, Magnetic and DFT studies on a Charge‐Transfer Salt of a Tetrathiafulvalenepyridyl‐(1,5‐diisopropyl) verdazyl Diradical Cation
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Bibliographic record
Abstract
Abstract 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 = 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 = spin state per formula unit with dominant antiferromagnetic interactions between spin‐bearing building blocks.
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| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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