Sidney F. A. Kettle

Vibrational spectroscopic characterisation of hydrogen bridged between metal atoms: A model for the adsorption of hydrogen on low-index faces of tungsten

Abstract Vibrational spectra of hydrogen chemisorbed on metal surfaces are discussed in the context of data from model cluster compounds and adsorption sites for hydrogen on low index planes of tungsten are suggested on the basis of reported electron energy loss spectra. A hydrogen adsorption site bridging two metal atoms is proposed for both the low coverage, β 2 , and the high coverage, β 1 , states of hydrogen on W(100) and the change in the symmetric metal-hydrogen stretching frequency is correlated with the reconstruction of the tungsten surface in the β 2 state.

Vibrational spectra and the force field of ethylidyne tricobalt nonacarbonyl: analogies with spectra from the chemisorption of ethylene upon the Pt (111) crystal face

A detailed vibrational analysis is reported for CH3CCo3(CO)9 and for its deuterated analogue, and assignments have been confirmed by means of an approximate normal-coordinate analysis. Some significant revisions of an earlier assignment have been made. Comparison of these spectra with those obtained by electron energy-loss spectroscopy of a species resulting from the chemisorption of acetylene and ethylene on Pt (111) above 300 K supports the identification of the latter as containing a C·CH3 group. The two most probable alternatives are a CH3CHPt2 species or CH3CPt3+adsorbed hydrogen atoms.

The M–H bond stretching frequencies of µ2-bridged metal hydrides and their relationship to the M–H–M interbond angle

A successful theoretical correlation is made of experimental data on the M–H bond stretching modes of µ2-bridged metal hydrides with the M–H–M interbond angle, based on the application of central or valence force field to the MHM unit.

Intermolecular vibrational coupling in glycine

Abstract A study of isotopomers of α-glycine by Raman, inelastic neutron scattering and i.r. methods reveals intermolecular vibrational coupling on modes which, superficially, appear vibrationally insulated.

Solid state studies. XIX. Heteroionic coupling in the vibrational spectra of phase IV of ammonium nitrate in the 1400 cm−1 region

A detailed Raman study of phase IV (room temperature) NH4NO3, ND4NO3, NHnD4−nNO3(0<n<4), and the corresponding species with 15N substitutes in the 1400 cm−1 region reveals that not only do δ(H–N–H) modes couple together, as do ν (N–O) vibrators, but these two sets may couple with each other when they subtend a common factor‐group species. This heteroionic vibrational coupling is particularly important in NH4NO3. Infrared data are not readily accessible but are not inconsistent with this interpretation. The occurrence of heteroionic vibrational coupling is correlated with the crystal structure of phase IV.

Manifestations of latent space group symmetry in the vibrational spectra of three alkali metal perchlorates

The vibrational spectra of crystalline MClO4 where M=K, Rb, and Cs are reinterpreted in terms of a vibrational unit cell (Imma) which is one‐half the size of the crystallographic (Pnma). Single crystal Raman data on these species are reported.

Manifestations of latent space group symmetry in the vibrational spectra of MSO4; where M=Ba, Sr, and Pb

The vibrational spectra of crystalline MSO4 where M=Ba, Sr, and Pb are reinterpreted in terms of a vibrational unit cell (Imma) which is one‐half the size of the crystallographic (Pnma) unit cell.

Vibrational spectra of MNCS single crystals (M = K, Rb)

Abstract Single crystal i.r. and Raman spectra are reported for the isomorphous compounds KNCS and RbNCS. Whilst factor group predictions are in accord with the main spectral features, the multiphonon modes are more complicated. Some can be accounted for by k = 0 frequencies but for others k ≠ 0 critical points are implicated. An experimental distinction appears to exist between the Raman features associated with internal/internal and internal/external combinations. The former are polarisation sensitive whilst the latter are not.

Vibrational spectra of ruthenium, rhodium, osmium and iridium acidopentammines

Abstract In order to study the vibrations of the pentammine [M (NH 3 ) 5 ] unit the low frequency Raman and far i.r. spectra (600-40 cm −1 ) of the complexes [M III (NH 3 ) 5 X]X 2 (M = Ru, Rh, Os, Ir; X = Cl, Br) have been investigated. The fundamental metal-ligand vibrational modes of the solid state spectra have been assigned, mainly on the basis of intensities, deuteriation and correlation with the hexammines, while aqueous solution Raman polarisation measurements were also made where possible. The complexity of the metal-nitrogen stretching region in the i.r. spectra is discussed.

Polymerisation of pentadienyl compounds in the presence of transition-metal compounds: the polymorphic compound deca-1,3,7,9-tetraenediiron hexacarbonyl

Abstract The reaction between Fe(CO) 5 and penta-1,4-dien-3-ol gives two forms of di(pentadienyliron tricarbonyl).