Phase diagram of the benzene-dinitratotetrapyridinecopper(II) (guest-host)system and thermodynamic parameters for the host center dot 2guest clathrate dissociation

In the first part of the work, the phase diagram of the benzene -[CuPy4(NO3 )(2)] system has been determined in the -100 to +200 degrees C temperature range using DTA and solubility techniques. The only compound found in the s ystem is the [CuPy4(NO3)(2)]. 2C(6)H(6) clathrate. It is stable up to a tem perature of +104.2(5) degrees C at which it melts incongruently to give liq uid and the solid [CuPy4(NO3)(2)] host phase. At 146.1(5) degrees C exfolia tion into two liquid phases is observed, with the composition of the monote ctic point being close to that of the clathrate. In the second part of the work, thermodynamic parameters of the clathrate dissociation have been dete rmined from benzene vapour pressure strain measurements. For the process 1/ 2 [CuPy4(NO3)(2)]. 2C(6)H(6) (solid) = 1/2 [CuPy4(NO3)(2)] (solid) + C6H6 ( gas) Delta H degrees = 45.3(3) kJ/mole; Delta S(298)degrees = 126(1) J/(mol e K); Delta G(298)degrees = 7.7(5) kJ/mole.