Vibrational spectra of cyclopentadienyl chlorides of titanium,zirconium and hafnium. internal rotation and thermodynamic functions

The infrared and Raman spectra of some cyclopentadienyl compounds of the transition metals, namely Ti(C₅H₅)Cl₃ and M(C₅H₅)₂Cl₂ (M = Ti, Zr and Hf), are reported and discussed. The infrared spectra of the gaseous species isolated in argon matrices at 10 K provide structural information about the single molecules. Particular attention has been paid to the low-frequency region in order to achieve more reliable assignments for the internal-rotation modes. The structural data and the fundamental frequencies derived from the spectra are employed in a calculation of the thermodynamic functions for these compounds in the ideal gas state.     

Vibrational spectra and structure of “staircase” carbonyl π-complexes of transition metals

FTIR spectra have been studied for staircase cyclopentadienyl complexes containing two or three metal carbonyl fragments bound by the metal-carbon bond Cp(CO)₂Fe-CpmMn(CO)₃ (1), Cp(CO)₂Fe-CpmFe(CO)₂CH₂Ph (2), Cp(CO)₂Fe-Cpm(CO)₂Fe-CpmMn(CO)₃ (3), Cp(CO)₂Mo-Cpm(CO)₂Fe-CpmMn(CO)₃ (4), Cp(CO)₃W-Cpm(CO)₂Fe-CpmMn(CO)₃ (5), Cp(CO)₂Fe-Cpm(CO)₂Fe-BmCr(CO)₃ (6), Cr(CO)₃Bm-CpmFe(CO)₂CH₂Ph (7), where Cp = ₅-C₅H₅, Cpm = ¹⁵-C₅H₄, Bm = ¹⁶-C₆H₅. Temperature-dependent FTIR spectra were measured inn-pentane solutions over a wide temperature range and in the low-temperature solid matrices of argon and nitrogen. Rotamers, formed due to rotation about the metal-carbon -bond, were found in solutions and matrices. A molecular mechanics calculation of1 proved the possibility of such rotation.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1952–1956, November, 1994.The authors are grateful to the Russian Foundation for Basic Research (project code No 93-03-18592) and to the International Science Foundation (project code No MEQ000).     

Infrared polarised spectrum of bis-(dimethyldithiophosphato)nickel(II)

The polarisation behaviour of the infrared absorptions of a single crystal of bis-(dimethyldithiophosphato) nickel(II) with (001) as the predominant face is studied. Because only a and b polarisation can be measured on (001), the b_2u and b_3u normal modes, which are polarised on b, cannot be distinguished, whilst the b_1u modes are observed on a. The most characteristic absorptions of the compound are assigned on the basis of the polarisation results. The comparison of the crystal with the solution spectrum indicates that the absorptions at 396 and 357 cm^?1 undergo crystal field splitting in the solid.     

Coordination compounds of biological interest: thermal properties of some compounds of saccharin (o-benzoic sulfimide) with divalent metal ions

The thermal properties of cobalt(II) and copper(II) complexes of saccharin (sacc) (o-benzoic sulfimide) have been studied, and are compared with those of ternary complexes of cobalt(II) and copper(II) having both saccharin and pyridine as ligands. The thermal behaviour is discussed in terms of the bonds between the central ion and the ligands. The frequency shifts of the carbonyl and sulfonyl groups support the hypotheses derived from the thermal data. The thermal stability scale CO(II) /s> Cu(II) is always obtained while the stability constant scale is CO(II) < Cu(II).     

The infrared spectrum of C2F5Cl in cryogenic matrices

We have measured the infrared spectrum of pentafluoroethyl chloride in cryogenic matrices of argon, nitrogen, krypton, and xenon from 880 to 1360 cm^?1. Numerous combination bands were observed; assignments and symmetries are reported for most. Appreciably more structure was observed in argon than in other matrices. The observed splitting of the fundamental bands in an argon matrix into two or more components may be due to multiple trapping sites.     

Infrared spectroscopic evidence of the Mg3O3 molecule formed by reaction of magnesium and oxygen atoms in inert gas matrices at 20.4°K

The reaction of magnesium and oxygen atoms in argon, krypton, xenon and oxygen matrices at 20.4° K was studied by infrared spectroscopy between 200 and 4000 cm^?1. The appearance of a band in the magnesium-oxygen stretching region, reproducible in all the matrices, indicates that reaction takes place. Oxygen-13 isotopic substitution suggests that the absorption is due to Mg₃O₃, whose formation is supported by the crystal structure of the solid phase. The force constants are calculated as f_R = 2.3 mdyne/Å and F_?/R² = 0.44 mdyne/Å assuming a planar six-membered ring of alternate magnesium and oxygen atoms with bond angles O-Mg-O 100° and Mg-O-Mg 140°.     

Vibrational spectra and rotational barriers of methyl titanium halides CH3TiX3 and CD3TiX3 (X = Cl,Br, I)

The IR and Raman spectra of gaseous and solid CH₃TiX₃ and CD₃TiX₃ species (X = Cl, Br, I) are reported. The gas phase spectra have been recorded between 4000 and 20 cm^?1 at pressures of 1 atm and 4 atm at 350 K and the Raman spectra of the solid phase recorded at 4.2 K. Internal rotation barriers and thermodynamic functions have been calculated.     

Infrared spectra of matrix-isolated gaseous ternary oxides: Part V. The sodium—phosphorus—oxygen system

The IR spectra of vapour from a Na₃PO₄, Na₅P₃O₁₀ and Na₂O-P₂O₅, mixture have been obtained in solid nitrogen at 12 K. The results suggest that it is possible to isolate both NaPO₃ and NaPO₂ when sodium tripolyphosphate and the Na₂O-P₂O₅ mixture are vaporized. There was no evidence of the NaPO molecule, reported to be one of the most abundant vapour species in mass-spectrometric work on the vaporization of Na₅P₃O₁₀.