Heterospin frustration in a metal-fullerene-bonded semiconductive antiferromagnet.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35078998.
- Also identified by DOI 10.1038/s41467-022-28134-w and PMC identifier 8789904.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Lithium-ion-encapsulated fullerenes (Li<sup>+</sup>@C<sub>60</sub>) are 3D superatoms with rich oxidative states. Here we show a conductive and magnetically frustrated metal-fullerene-bonded framework {[Cu<sub>4</sub>(Li@C<sub>60</sub>)(L)(py)<sub>4</sub>](NTf<sub>2</sub>)(hexane)}<sub>n</sub> (1) (L = 1,2,4,5-tetrakis(methanesulfonamido)benzene, py = pyridine, NTf<sub>2</sub><sup>-</sup> = bis(trifluoromethane)sulfonamide anion) prepared from redox-active dinuclear metal complex Cu<sub>2</sub>(L)(py)<sub>4</sub> and lithium-ion-encapsulated fullerene salt (Li<sup>+</sup>@C<sub>60</sub>)(NTf<sub>2</sub><sup>-</sup>). Electron donor Cu<sub>2</sub>(L)(py)<sub>2</sub> bonds to acceptor Li<sup>+</sup>@C<sub>60</sub> via eight Cu‒C bonds. Cu-C bond formation stems from spontaneous charge transfer (CT) between Cu<sub>2</sub>(L)(py)<sub>4</sub> and (Li<sup>+</sup>@C<sub>60</sub>)(NTf<sub>2</sub><sup>-</sup>) by removing the two-terminal py molecules, yielding triplet ground state [Cu<sub>2</sub>(L)(py)<sub>2</sub>]<sup>+</sup>(Li<sup>+</sup>@C<sub>60</sub><sup>•-</sup>), evidenced by absorption and electron paramagnetic resonance (EPR) spectra, magnetic properties and quantum chemical calculations. Moreover, Li<sup>+</sup>@C<sub>60</sub><sup>•-</sup> radicals (S = ½) and Cu<sup>2+</sup> ions (S = ½) interact antiferromagnetically in triangular spin lattices in the absence of long-range magnetic ordering to 1.8 K. The low-temperature heat capacity indicated that compound 1 is a potential candidate for an S = ½ quantum spin liquid (QSL).