Vibrational spectra and internal rotation barriers of cyclopentadienyl germanium trihalides: (C5H5)GeCl3, (C5H5)GeBr3 and (C5H5)GeI3

IR and Raman spectra of gaseous and solid CpGeX₃ species (Cp  C₅H₅ and X = Cl, Br, I) are reported. The results are compared with those obtained previously for CpTiCl₃. Internal rotation barriers and thermodynamic functions are reported.     

The thermal behaviour of the hydroxide mixtures used for the synthesis of MgFe2O4 spinel

The thermal behaviour of hydroxide mixtures, precursors to the synthesis of MgFe₂O₄ spinel powders, was investigated.The mixtures of hydroxides were prepared by coprecipitation reaction from nitrate solutions with an Mg/Fe atomic ratio of 12. The results were related to the thermal behaviour of separately precipitated components of the hydroxide mixtures. Samples prepared by mechanically mixing the separately precipitated hydroxides were also studied.The spinel formation temperature was identified by performing XRD analysis on powder samples heated to different temperatures. The presence of spinel from the thermal decomposition of coprecipitated mixtures was detected at a temperature as low as 380°C. The separate formation of MgO and Fe₂O₃ from the thermal decomposition of mechanical mixtures was observed; nevertheless the formation of MgFe₂O₄ through a solid state reaction between the oxides was noted at a temperature as low as 500°C.The Authors wish to thank Dr. L. Petrilli and Mr. F. Dianetti for carrying out the elemental chemical analyses at the Microanalysis Service of the C. N. R. laboratories of the Area della Ricerca di Roma.     

Infrared matrix isolation of,and bonding in,the oxides of group vib elements: O3, SO2, SeO2, and TeO2

Vibrational frequencies, force constants and geometrical parameters of the oxides of group VIB elements in rare gas matrices are compared with those in the gas phase. Bonding in these species is discussed.     

Matrix and ab initio infrared spectra of germanium carbonyls

Germanium monocarbonyl has been prepared by high-temperature vaporization of Ge with excess carbon powder or CO co-condensation and trapped in various matrices at 12 K. Fourier transform infrared spectra, ab initio (MP2 and CISD) and density function (Becke3LYP) calculations suggested a linear species with the formula GeCO. A weak feature appearing only in annealed N₂ and CO matrices containing GeCO has tentatively been assigned to germanium dicarbonyl on grounds of isotopic substitution and theoretical calculations. SCF and CI methods predict a bent structure for this complex.     

Infrared matrix and polarised spectrum of bis(diethyldithio-carbamato)-nickel(II)

The IR spectra (300–4000 cm^?1) of bis-(N,N-diethyldithiocarbamato)-nickel(II) as N₂ matrix and oriented polycrystalline layer are reported. All the observed bands are assigned and classified on the grounds of their polarisation in the symmetry classes of D_2h, the highest possible molecular symmetry.Remarkably, polarisation of the absorptions around 1000 cm^?1 rules out the assignment to any C-S stretching, in contrast with previous assignments. The room temperature crystal spectra do not show evidence for crystal splitting. The matrix spectrum shows features related to the existence of rotamers around the H₂C-N bond, which give useful assistance in the assignment.