Correlation of the loss of solvent with the crystal structure of a 1 : 1 solvate. Indanetrione 2-(N-p-t-butylbenzoyl-N-phenylhydrazone) acetone solvate

Abstract

The process whereby the 1 : 1 acetone solvate (1) of indanetrione 2-(N-p-t-butylbenzoyl-N-phenylhydrazone)(2) loses solvent has been studied both by X-ray analysis of the structure and by optical microscopy. Crystals of (1) are monoclinic, a= 10.574(4), b= 28.706(14), c= 10.060(4)Å, and β= 121.0(1 )°; space group is P2₁/c, and Z= 4. The structure was solved by the symbolic-addition method and refined to R 0.090 on 3 535 non-zero reflections measured by diffractometer. The acetone molecules are ordered and occupy positions in an infinite channel which runs along the c crystallographic axis in a somewhat zig-zag fashion. The t-butyl groups, which form some of the walls of this channel, exhibit two-fold disorder in the crystal in a 55 : 45 ratio. After sometime the yellow crystals of the solvate (1) were observed, under the microscope, to develop red streaks running along the c direction. As these streaks intensify and become more numerous, a series of black cracked regions appear which run normal to the direction of the red streaks. This behaviour is characteristic of crystals which have lost ca. 33% of the acetone. Single-crystal diffraction photographs taken when the crystals had lost significant amounts of acetone showed considerable disorder in the b* direction (corresponding approximately to the larger cross-sectional direction of the channel), but considerable retention of structure in the a*c* plane. X-Ray powder pictures showed that, when all the acetone was lost from the crystal, the material remaining gave a powder pattern distinct from that obtained from (2) which had crystallised without incorporation of solvent. The observations on a macroscopic scale relating to loss of solvent are correlated with the crystal structure as determined by X-ray diffraction.