Pyridine vapour pressure over [MPy4(NO3)2]·2Py (M = Co, Ni) clathrates

Pyridine vapour formation from the title clathrates is accompanied by the destruction of both the clathrate phase and the host complex: 1/3[MPy₄(NO₃)₂]·2Py(solid) = 1/3[MPy₃(NO₃)₂](solid) + Py(gas); the standard thermodynamic parameters of these processes are ΔH⁰= 59.5(2) and 64.6(4) kJ mol^–1, ΔS2980=156.6(6) and 168(1) J mol^–1 K^–1, ΔG2980=12.8(2) and 14.4(6) kJ mol^–1, for the Co- and Ni-clathrate, respectively.