Structural and microstructural description of the glacial state in triphenyl phosphite from powder synchrotron X-ray diffraction data and Raman scattering investigations

Abstract The structure and microstructure (refinement of the isotropic size and microstrain parameters) of the glacial state in triphenyl phosphite (TPP, P(OC 6 H 5 ) 3 ) transformed at 222K have been determined from powder synchrotron X-ray diffraction data through a Rietveld and a Le Bail refinement, respectively. It is shown that the glacial state is composed of crystallites of the stable crystal phase coexisting with non-transformed supercooled liquid, the apparent size of the crystallites—depending on the aging temperature at which the glacial state is isothermally formed, [Phys. Rev. B 60 (1999) 9390]—being equal to 329.2(2) A at 222K. The molecular conformation is slightly less mirror-symmetric than the one in the crystal state, and correlatively only one of the two unusual weak intermolecular C–H⋯O hydrogen bonds already observed in the latter state is encountered in the glacial one. Additional Raman scattering investigations confirm the previous result and reveal in addition that no hydrogen bonding interaction is observed neither in the glass nor in the liquid states.