The standard enthalpy of formation of buckminsterfullerene (C₆₀) in the crystalline state has been determined as 2278.1 ± 14.4 kJ mol^–1 using a microcombustion calorimeter. Statistical mechanical calculations of the heat capacity of gaseous C₆₀ as a function of the temperature and a critical survey of the literature data for the enthalpy of sublimation, the heat capacity in the crystalline state, the first, second and third ionization energies and the electron affinity of C₆₀, enabled the enthalpy of formation of gaseous C₆₀ and the enthalpies of formation of the ions C₆₀ ⁺, C₆₀ ²⁺, C₆₀ ³⁺ and C₆₀ ^– to be derived.

The thermosalient effect is still a rare and poorly understood phenomenon, where crystals suddenly jump, bend, twist or explode upon undergoing a thermally activated phase transition. The synthesis and characterisation of the new spin transition Fe(III) compound [Fe(5-Br-salEen)₂][ClO₄] (salEen = N-ethyl-N-(2-aminoethyl)salicylaldiminate) is described and its thermosalient behaviour reported. It is the first example of a thermosalient effect with a spin transition and magnetic, calorimetric, diffraction, microscopy and computational studies are used to characterise these effects. Both thermosalient effect and spin transition occur around 320 K upon heating and are accompanied by an anisotropic unit cell change with conservation of crystal symmetry that causes a large enough stress of the crystal lattice to induce crystal explosion. This stress can ultimately be traced back to a diffusionless and distortive structural perturbation resulting in a coupled spin transition-thermosalient effect.