Skeletal deformation vibrations and rotational isomerism of some ketones and olefins

Structural and spectroscopic characterisation of C4 oxygenates relevant to structure/activity relationships of the hydrogenation of α,β-unsaturated carbonyls

In the present work, we have investigated the conformational isomerism and calculated the vibrational spectra of the C4 oxygenates: 3-butyne-2-one, 3-butene-2-one, 2-butanone and 2-butanol using density functional theory. The calculations are validated by comparison to structural data where available and new, experimental inelastic neutron scattering and infrared spectra of the compounds. We find that for 3-butene-2-one and 2-butanol the spectra show clear evidence for the presence of conformational isomerism and this is supported by the calculations. Complete vibrational assignments for all four molecules are provided and this provides the essential information needed to generate structure/activity relationships for the sequential catalytic hydrogenation of 3-butyne-2-one to 2-butanol.

Synthesis, Characterization, and Crystal Structure of Dicalcium Glutarylbis(phosphonate) Dihydrate: A Covalently Pillared Layer Structure with the Potential for Epitaxial Growth on Hydroxyapatite

A new bis(acylphosphonate), glutarylbis(phosphonate) (GlBP), was synthesized. Sodium and calcium salts of the GlBP, disodium dihydrogen glutarylbis(phosphonate), NaHO(3)PC(O)(CH(2))(3)C(O)PO(3)HNa, and dicalcium glutarylbis(phosphonate) dihydrate, Ca(2)[O(3)PC(O)(CH(2))(3)C(O)PO(3)].2H(2)O, were prepared and characterized by chemical analyses, thermogravimetry and Fourier transform infrared spectroscopy (FTIR). The crystal structure of the Ca salt was determined by single-crystal X-ray diffraction. The crystals are orthorhombic with a = 10.970(1) Å, b = 23.694(2) Å, c = 5.580(1) Å, space group Pnma, and Z = 4. This study provides the first example of a structure of a calcium complex involving a nongeminal bis(phosphonate). The structure can be described in terms of a covalently pillared layer-type arrangement of neutral Ca-GlBP-Ca units along the b-axis. Each oxygen atom of the phosphonate group is bonded to a different Ca ion, and each Ca in turn is linked to three phosphonate groups. The Ca octahedra and the phosphonate tetrahedra form a two-dimensional polar sheet perpendicular to the b-axis. The chelate bonds involving the keto groups appear to be important links in the stabilization of the structure and, in turn, to the biological activity of bis(acylphosphonates). A near-perfect lattice match, found between the Ca phosphonate layer and the major crystal faces of hydroxyapatite, indicates that epitaxial growth or incorporation of GlBP can occur on the apatitic surface which may be the mode of action in the inhibition of calcification.