Neutron powder-profile study of chlorofluoromethane.
The crystal structure of chlorofluoromethane, CH(2)ClF, has been determined at 100 and 30 K using indexing, packing considerations and Rietveld refinement of neutron powder profiles. There is only one phase, in monoclinic space group P2(1) and with two molecules in the unit cell occupying general positions. The structure has close packing in several directions and there are weak hydrogen bonds forming zigzag chains.
Structure of solid fluoroform
The structure of fluoroform, CHF3, was determined at 4·2, 40 and 70 K using neutron powder profile analysis. There is only one phase with a monoclinic space group P21/c. At the lowest temperature the lattice parameters are: a = 4·7561(1) A, b = 6·6280(2) A, c = 8·5232(2) A β = 122·02(2)°. Starting positions and orientations of the four molecules in the unit cell were determined to high accuracy using an energy minimization process with atom-atom potentials. The structure is made up of weakly hydrogen bonded sheets with adjacent sheets related by centres of symmetry.
Raman and infrared spectra of solid dibromodifluoromethane
Raman and infrared spectra of soiid dibromodifluoromethane are reported for both the lattice and internal mode regions at temperatures between 12 K and the melting point. No evidence was found for a solid-state phase transition. Plausible assignments of all observed spectroscopic features are suggested. The spectra are compatible with a non-centrosymmetric unit cell containing four molecules.