| Popis: |
Lithium-ion-encapsulated fullerenes (Li+@C60) are 3D superatoms with rich oxidative states. However, no current studies have reported Li+@C60 as ligands. Here, we report a conductive and magnetically frustrated metal–fullerene-bonded framework {[Cu4(Li+@C60)(L)(py)4](NTf2)(hexane)n (1) prepared from redox-active dinuclear metal complex Cu2(L)(py)4 and lithium-ion-encapsulated fullerene salt (Li+@C60)(NTf2−), where ligand L denotes 1,2,4,5-tetrakis(methanesulfonamido)benzene, py pyridine, and NTf2− the bis(trifluoromethane)sulfonamide anion. Electron donor Cu2(L)(py)2 bonds to acceptor Li+@C60 via eight Cu‒C bonds. Cu–C bond formation stems from spontaneous charge transfer (CT) between Cu2(L)(py)4 and (Li+@C60)(NTf2−) by removing the two-terminal py molecules, yielding triplet ground state [Cu2(L)(py)2]+(Li+@C•‒ 60), evidenced by absorption and electron paramagnetic resonance (EPR) spectra, magnetic properties, and quantum chemical calculations. Moreover, Li+@C•‒ 60 radicals (S = ½) and Cu2+ ions (S = ½) interact antiferromagnetically in triangular spin lattices in the absence of long-range magnetic ordering up to 1.8 K; thus, compound 1 is a potential candidate for an S = ½ quantum spin liquid. |
