Abstract. C10H2007P2, orthorhombic, Pbca, a = 26.88 (2), b = 9.99 (1), c = 11.13 (1) ,~; V = 2988.8 A3; M r = 314.22; D x = 1.39, D m = 1.39 g cm-3; Z = 8; F(000) = 1328.0; 2(Cu Ka) = 1.5418 A; gr(Cu Ktt) ---0.6. The structure was solved by direct methods and refined by least-squares methods with anisotropic temperature factors to an R value of 0. 121 for 1179 observed reflections. The symmetry of the bicyclic molecules is C~. The conformation around the bridge bonds P-O-P is staggered. The two structurally independent dioxaphosphorinane rings have partially flattened chair conformations with the double-bonded O atom in an equatorial and the linking O atom in an axial position. An analysis of the causes of the flattening observed in the 1,3,2-dioxaphosphorinane rings was carried out and the structural results are compared with those for bis(5,5-dimethyl-2-oxo-l,3,2-dioxaphosphorinanyl) sulphide.
X-ray diffraction studies show that molecules of the 1,2,3,5-tetramethoxybenzene (TMOB)(2) x 1,2,4,5-tetracyanobenzene complex form ...CCDCCDCC... columns with the short distances between molecular planes of C and D molecules equal to 3.186 A. The vibrational spectra recorded by using the inelastic neutron scattering, Raman, IR, and quasielastic neutron scattering (QENS) techniques aided by density functional theory calculations for the isolated molecules and the crystalline state enabled all four inequivalent librational modes, ascribed to the methoxy groups, to be analyzed. A rather good consistency was found between the experimental frequencies and those calculated for the crystal. The consistency was also achieved between the experimental structure of molecules and the theoretically reproduced one. A close similarity of the structures of the TMOB molecule isolated and in the complex is taken as a sign of dominating intramolecular interaction. The QENS spectra contain three Lorentzians of relative intensities of 1:1:2. Thus the two most strongly hindered of the four inequivalent methoxy groups in the crystalline lattice are characterized by rather similar barrier heights in good agreement with the packing analysis.
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