Decagonal C60 crystals grown from n-hexane solutions: solid-state and aging studies

Decagonal C60 crystals grown from n-hexane solutions correspond to an orthorhombic 1:1 solvate (a=10.249 Å, b=31.308 Å, c=10.164 Å). It forms with negative excess volume (−55.5 Å3 per formula unit) and transforms on heating into fcc C60 (desolvation enthalpy of +50.6 kJ per solvate mole, close to the sublimation enthalpy for pure n-hexane) while n-hexane desorption from fcc C60 is accompanied by an enthalpy of +48.6 kJ per solvent mole. Thus solvate formation is preferred to solvent adsorption. Orthorhombic C60·1 n-hexane undergoes no degradation when stored in air for 9 years at room temperature in the dark.