Solid state studies of the C60. 2(CH3)CCl3 solvate Original Research Article

At room temperature, the hexagonal C60. 2(CH3)CCl3 solvate (a = 10.13(1) Å, c = 10.84(1) Å), made of alternating layers of C60 and solvent molecules, forms with a negative excess volume, and its desolvation enthalpy is virtually the same as the sublimation enthalpy of the pure solvent. Crystallographic and calorimetric studies vs temperature indicate that hexagonal C60. 2(CH3)CCl3 changes at 211.7 K (1.3 kJ mol−1 of solvate) into an intermediate triclinic phase which transforms at 189.7 K (4.1 kJ mol−1 of solvate) into another triclinic phase. A crystallographic analysis in the series of hexagonal C60. 2 YCCl3 solvates (Y = H, Cl, Br, CH3) reveals that: (i) the change in the unit-cell volume values is due to a change in axis c whose value depends on the size of Y, (ii) the molar volume of the solvates depends linearly on the molar volume of the solvents. Ageing studies at room temperature show that C60. 2(CH3)CCl3 loses its solvent molecules within a few days or a few months, depending on storage conditions.