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The i.r. and Raman spectra of the niobate and tantalate of “1 × 2 block” type structure AIIBV2O6 (AII = Ca, Sr, Ba, Pb) are presented and analyzed. The complete vibrational analysis of BaNb2O6 is presented and a force field is proposed for this type of compounds, the potential energy distribution is given and some characteristic normal modes are drawn in comparison with the normal modes of the double octahedron B2O10 which is the basic motif of the “1 × 2 block” type structure.

The i.r. and Raman spectra of antimonates MIISb2O6 and tantalates MIITa2O6 belonging to the trirutile structure are studied. The vibrational assignment is obtained by means of the comparison of the spectra, the use of the correlation method and normal coordinate calculations. A force field characteristic of this type of compounds is proposed.

The i.r. and Raman spectra of antimonates M II Sb 2 O 6 (M II = Pb, Ca, Sr, Ba, Cd) belonging to the ‘PbSb 2 O 6 type’ structure are studied. A vibrational assignment is proposed and the normal coordinate calculations permitted us to calculate the force field and to characterize the chemical bonds in these compounds.

The Raman and infrared spectra of CaNb2O6 are assigned by normal coordinate analysis according to Shimanouchi’s method. The Raman spectroscopy results enabled us to refine the force field, which was then checked by the infrared spectroscopy results. The obtained force constants show that there are three different types of Nb–O bonds in the columbite structure and that the Ca–O bonds are of electrostatic nature. The potential energy distribution calculation gives us a precise assignment for all the observed frequencies.

Unpolarized Raman spectra of the compounds M 3 UO 2 F 5 ( M = K, Rb, Cs, NH 4 ) were recorded in the region 1000-100 cm −1 at room and liquid nitrogen temperatures. Polarized Raman spectra of single crystals K 3 UO 2 F 5 , Rb 3 UO 3 F 5 were measured at room temperature and permitted a complete assignment of the A 1 ′, E 2 ′ and E 1 ′ fundamental modes of the UO 2 F 5 3− ion of the D,7, symmetry group. Factor group analysis was applied to the interpretation of the spectra. Site and correlation splitting due to the internal modes of the UO 2 F 5 3− ion are discussed.

The Raman spectra of partially deuterated ethylenediamine (5 and 95% on NH 2 groups) have been recorded between − 46 and − 196°C in the region of the NH and ND stretching vibrations. The vibrational frequencies of the isotopically diluted NH and ND bonds enabled us to demonstrate the importance of the hydrogen bonds in the cohesion of the crystals and during the allotropic transformation, and also to show the influence of the asymmetric effect on the form of the normal modes of vibration of the NH 2 groups.

The Raman spectra of the solid compounds LiI, 3 en; LiX, 2 en (X = Cl, Br, I; en = NH 2 CH 2 CH 2 NH 2 ) and their analogues with en-d 4 (en-d 4 = ND 2 CH 2 CH 2 ND 2 ) have been investigated. The assignment of all the observed bands in the region of the NH 2 (ND 2 ) and CH 2 stretching vibrations is made according to the crystal structure of these compounds. The influence of hydrogen bonding and of Fermi resonance between the ν s (NH 2 ) and 2δ(NH 2 ) levels and between the corresponding levels of the ND 2 and CH 2 groups has been discussed. The spectroscopic results obtained are in good agreement with the crystallographic structures of the compounds.

Infrared (4000-100 cm −1 ) and Raman (1000-100 cm −1 ) spectra of the complexes M 4 (UO 2 ) 2 F 8 -2H 2 O (M = Rb, Cs) were reported. Factor group analysis was used to classify the normal vibration modes of the binuclear ion (UO 2 ) 2 F 4− 8 and to interpret the spectra. Polarized Raman spectra of Rb 4 (UO 2 ) 2 F 8 -2H 2 O made it possible to assign the Raman fundamental vibrations of the anion (UO 2 ) 2 F 4− 8 . The infrared fundamental vibrations of this anion was made by comparison with those of the mononuclear UO 2 F 3− 5 anion. The result of the normal coordinate analysis of the (UO 2 ) 2 F 4− 8 ion was used to support the preceding assignment and to analyze the effect of the association of a double fluorine bridge with two UO 2 F 5 groups on the spectra and on the G.V.F.F. constants, compared to those of the mononuclear ion UO 2 F 3− 5 .

The normal coordinate analysis of CaTa 2 O 6 , BaTa 2 O 6 (II) and SrNb 2 O 6 compounds (type II) of “1×2 block” structural type was performed in order to define more precisely the assignment of the observed i.r. and Raman vibration frequencies. The results obtained showed that the I and II types of “1×2 block” type structure (I: BaNb 2 O 6 , BaTa 2 O 6 (I) and the values of the force constants agreed with the nature of the Nb(Ta)O bridge.

Resume Infrared and Raman spectra of the niobates of columbite structure M Nb2O6 (M = Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd) were recorded in the region 1100-50 cm−1. All of them are similar at the shorter wavelengths (> 400 cm−1) but depend on the cation at lower frequencies. By comparison of i.r. and Raman spectra, the main vibration frequencies have been assigned.

Polarized Raman spectra of Cs3UO2F5 in which the UO2F5 3− ion is in its statistical position have made it possible to assign definitely the Raman fundamental vibration modes as follows : v1(A′1) = 784, v2(A′1) = 423, v8(E′2) = 325, v8(E′2) = 219 and v10(E″1) = 259 cm−1.