Thomas C. Waddington

The dynamics of ring rotation in ferrocene, nickelocene and ruthenocene by incoherent quadi-elastic neutron scattering☆

Abstract Incoherent quasi-elastic neutron scattering has been used to study the reorientational motions of the cyclopentadienyl rings in ferrocene, nickelocene and ruthenocene. The results for ferrocene show that the activation energy for ring rotation drops above the 164 K phase transition to 4.4 ± 0.5 kJ mol −1 (which is approximately half its low temperature value) but the rings still appear to jump between only five orientations on the observable time scale. At room temperature, the rings in nickelocene appear to behave the same as in ferrocene but in ruthenocene they reorientate much less frequently and resemble those in ferrocene below 164 K.

Acetates and acetato-complexes. Part 2. Spectroscopic studies

The effect of different modes of co-ordination on the i.r. spectrum of the acetate ion is reviewed. Infrared and 1H n.m.r. spectra of a series of metal acetates and acetato-complexes are reported. and the type of co-ordination identified: B2O(O2CMe)4 and Na[B2O(O2CMe)5] contain both bridging and unidentate acetate; Al(O2CMe)3 probably contains bridging acetate only: Si(O2CMe)4, Ge(O2CMe)4, K2[Si(O2CMe)6], and K2[Ge(O2CMe)5] contain only unidentate acetate: Zr(O2CMe)4 and Pb(O2CMe)4 contain only chelating acetate: K2[Sn(O2CMe)6], K2[Pb(O2CMe)6], and [NMe4][Sn(OMe)5] contain both chelating and unidentate acetate; and Sn(O2CMe)4 contains symmetrical and unsymmetrical chelating acetate.

Hydrogen bonding in potassium hydrogen maleate and some simple derivatives studied by inelastic neutron scattering spectroscopy

Abstract Inelastic neutron scattering spectra (300–2500 cm −1 ) of KH(CHCO 2 ) 2 , KD(CHCO 2 ) 2 , KH(CDCO 2 ) 2 and KH(CHCO 2 · CClCO 2 ) have been obtained and the vibrations of the hydrogen bond, with the exception of ν 2 (OHO), assigned. This is the first assignment of these vibrations in a centrosymmetric intramolecularly hydrogen bonded complex. ν as (OHO) was found to be heavily mixed and to give rise to a strong doublet in the INS spectra.

The vibrational spectrum of hydrogen adsorbed on palladium black measured using inelastic neutron scattering spectroscopy

Abstract The incoherent inelastic neutron scattering spectrum of hydrogen adsorbed on palladium black contains two bands centred at 916 and 823 cm −1 . These are assigned to the vibrations parallel and perpendicular to the surface respectively, of hydrogen bound at a bridging site. This assignment differs from that previously given from an infrared study of hydrogen adsorbed on palladium hydride.

A 31P NMR and 35Cl NQR investigation of some hexachlorophosphates

Abstract The 31P NMR spectra in both solid state and solution, and the 35Cl NQR spectra in the solid, have been recorded for some hexachlorophosphates and for the compounds [C8H12N]2PCl7PCl7 and C14H14PCl7. The presence of the PCl6− ion as the only phosphorus-containing anion has been confirmed in all cases. Data are also reported for the chlorotriphenylphosphonium ion in Ph3PCl+PCl6−.

Lattice potential energies for calcite, aragonite and vaterite: Estimation of the charge distribution on the carbonate ion, the enthalpy of formation, ΔHf°(CO32−) (g) and the enthalpy of solvation, ΔHsolv°(CO32−) (g) of the gaseous CO32− ion

Abstract The total lattice potential energy, Upot, for the process: CaCO 3 (c)⇝ Ca 2+ (g)+ CO 3 +− (g) has been computed, as a function of the distributed charge on the anion, for the three pleomorphic forms (calcite, aragonite and vaterite) using recent crystal structure data. The term by term calculations reported represent the most extensive consideration of these systems to date and allow an assignment of the distribution of charge in the CO32− ion corresponding to qo = −0·54 and an estimation of the quadrupole moment of the ion as −6·5 × 10−26 esu.cm2. The enthalpy of formation ΔHf°(CO32−) (g) of the ion is estimated to be −321 kJ mol−1, and the average lattice potential energy of CaCO3, Upot = 2804 kJ mol−1. The solvation energy of the CO32− ion, ΔHsolv°(CO32−) (g) is estimated to be −1249 kJ mol−1.

The identification of some new cyano-derivatives of phosphorus(III) in solution by means of 31P NMR spectroscopy

Abstract The mixed phosphorus(III) cyano-halides PX(CN)2, PX2(CN) and PXY(CN) (X ≠ Y  Cl, Br, I) have been identified in solution by means of 31P NMR spectroscopy. The chemical shifts of the ternary compounds PXY(CN) are in good agreement with predictions based on the theories of Letcher and Van Wazer.

Theoretical studies on the hydrogen dichloride, HCl–2, ion and radical, HCl2·

MO LCAO SCF calculations have been performed to investigate the molecular structure, physical properties and thermodynamic stability of the ioslated hydrogen dichloride ion. For the hydrogen dichloride ion in tetramethylammonium hydrogen dichloride these calculations have been combined with electrostatic lattice energy calculations aimed at investigating the effect of moving the hydrogen atom in the hydrogen dichloride ion on the lattice energy of the crystal. The calculated properties are compared with experimental values, where available, with which they are found to be generally in good agreement. The calculations show that for corresponding Cl—Cl distances to those in the ion, the HCl2· radical has a potential well which does not show a minimum at proton-chlorine distances longer than the bond length of hydrogen chloride.

The use of a high resolution NMR spectrometer for recording solid state 31P spectra

Abstract The determination of 31 P NMR spectra of solids using a high resolution NMR spectrometer and a computer of average transients is reported. It appears that chemical shifts can be measured quite accurately by this method and structural information about the solid compound obtained. Results for solid compounds which contain phosphorus directly bonded to fluorine, chlorine, bromine, oxygen, nitrogen, carbon and hydrogen are reported.

Inelastic neutron scattering spectra of alkali metal (Na, K) bifluorides: The harmonic overtone of v3

Abstract Inelastic neutron scattering spectra of MFHF (M  Na and K) have been measured up to energy transfers of ca. 4000 cm−1 Both 0 → 1 and 0 → 2 transitions of the bending (v2), and antisymmetric stretching (v3) modes were observed. A normal harmonic (i.e. no quartic contribution) model for the dynamics of the bifluoride ion is entirely consistent with our observations. Evidence of phonon dispersion was observed in the band shape of v3, but no structure attributable to the LO mode could be found. The similarity of the band shapes of v3 for both NaFHF and KFHF is interpreted in terms of a very short range coupling mechanism.