Isostructurality among five solvates of phenylbutazone

This work describes the crystal structures of phenylbutazone 2:1 solvates with benzene, cyclohexane, 1,4-dioxane, tetrahydrofuran, tetrachloromethane, and chloroform. These solvates are isostructural, with the exception of the chloroform solvate. The solvent molecules are located in channels from which they can escape. Solvent incorporation causes an increase in volume of the unit cell to an extent that depends on the volume of the solvent molecule and the strength of the phenylbutazone-solvent interactions. The van der Waals interactions contribute most to the lattice energy in all these solvates. The volume available to the solvent correlates with the increase of the unit cell parameters. The quality of the crystallographic data of the chloroform solvate is poor as a result of twinning. Crystallographic differences of the chloroform solvate may result from hydrogen bonding between the chloroform molecules and the carbonyl oxygens of the phenylbutazone molecules.