Demonstration of the “Break‐and‐Seal” Approach to Fullerides of Complex Cations at the Example of KC₆₀(THF)₅·2THF

The “break‐and‐seal” method known to be used for synthesis of sensitive compounds (alkalides, electrides and for living anionic polymerization) was applied for the first time for fulleride synthesis providing highest purity of the reaction conditions. A new fulleride KC 60 (THF) 5 · 2THF was prepared in solution by reacting fullerene C 60 with potassium and dibenzo‐24‐crown‐8 in tetrahydrofurane. Single crystals were grown from solution by the modified “temperature difference method”, single‐ crystal X‐ray analysis was performed revealing the structure [ P 2 1 2 1 2, Z = 4, a = 17.802(5), b = 30.085(9), c = 9.863(3) Å, R 1 = 0.069, wR (all) = 0.191, 5563 independent reflections]. In this compound, the charge of fulleride is –1, the C 60 – radical‐anion being fully ordered. A constitutive structural feature is octahedrally coordinated potassium atoms with five THF and one fullerideas ligands. C 60 – is functioning as a η 3 ‐ligand: [K(η 3 ‐C 60 )(η 1 ‐THF) 5 ] · 2THF.