Vibrational spectra of (1H)-5-amino-1,2,4-triazole, its hydrochloride salt and some of their deuterated homologues have been studied in the 4000 -200 cm(-1) range. Most of the fundamental modes has been located and the protonation effect has been discussed. These results enable us to precise that the protonation site is the pyridinic nitrogen N-4.

The monoclinic phosphates with K(3)Ln(PO4)(2) (Ln = rare earth) formula were synthesized. Their infrared and Raman spectra have been reported and analysed. The results of a force field calculation for K3Nd(PO4)(2) are presented. (C) 2004 Elsevier B.V. All rights reserved.

Les spectres de vibration du {1H}-5-amino-1,2,4-triazole, de son chlorhydrate et de quelques-uns de leurs homologues deuteries ont ete etudies dans la region spectrale 4000 - 200 cm - 1 . La plupart des modesfondamentaux ont ete situes et l'effet de la protonation a ete discute. Les resultats obtenus nous ont permis de proposer l'azote pyridinique N 4 comme site de protonation.

The monoclinic pyrophosphates with AMP2O7 formula were synthesized. Their infrared and Raman spectra have been reported and analysed. The results of a force field calculation for CaCuP2O7 are presented.

In the title compound, mu-3,4'-bi-1,2,4-triazole-di-mu-chlorocopper(II) monohydrate, {[CuCl2(C4H4N6)].H2O}(n), the Cu atom is located in a distorted octahedron consisting of two N atoms and four Cl atoms. The structural unit is an infinite chain in which octahedral groups, connected by shared edges, are also linked by bitriazole molecules. The bitriazole ligand, the Cu atom and the water O atom all lie on independent twofold axes. The structure is held together by hydrogen bonds between the water molecules and the non-coordinated N atoms of the ligand, and by van der Waals forces.

We investigated in preliminary studies the removal of 3(5)-amino-1,2,4-triazole in aqueous solution by the photo degradation processes in the presence of titranium dioxide (TiO2) at different ratios of herbicide/TiO2 (weight/ weight) coupled with simulated sunlight. This photocatalytic degradation was evaluated at pH values 5, 6 and 7. Irradiation was carried out with polychromatic light using heraeus apparatus equipped with xenon lamp having a spectral energy distribution similar to solar irradiation (> 290 nm). The concentration of remaining herbicide was monitored using a high pressure liquid chromatograph (HPLC) equipped with UV detector at 205 nm. The presence of TiO2, induced an increase of the photodegradation of the pesticide with respect to pure water solution. By varying the pH in the range 5-7, no effect on rate of photodegradation of 3-amino-1,2,4-triazole with TiO2 (ratio 1/5) was observed.

An approach to determine the structure of protonated 3,4 ' -di-1,2,4-triazoles was carried out using the semi-empirical M.N.D.O. (modified neglect of diatomic overlap)method. ne results obtained for 3,4 ' -di-1,2,4-triazole show that the isolated state of the NH form has great stability, and lead to the conclusion that its protonation mainly occurs on one of the pyridine nitrogen of the 4-triazolyle group.The vibration spectra of the di-1,2,4-triazolium, 5-methyl di-1,2,4-triazolium and 5-bromo di-1,2,4-triazolium chlorides were studied between 4000 and 200 cm(-1). An attribution of the fundamental modes is proposed, and the effect of protonation on the normal vibration frequencies is discussed. Using these spectroscopic results, the strength and type of hydrogen bonds existing in the crystal could be assessed and a molecular structure proposed.

Raman and infrared spectra of 4-methyl-1,2,4-triazolethione showed that two crystalline phases, one stable and the other metastable, can be obtained from various crystallization processes. The metastable phase transforms into the stable phase at 395 K by an irreversible first-order phase transition. The two phases were characterized spectroscopically and structural properties are discussed. Copyright (C) 2000 John Whey & Sons, Ltd.

The IR and Raman spectra of triclinic diphosphates. AMP(2)O(7) (A :Ca, Ba; M: Mg, Co, Ni, Cu,Zn: Cd) have been analysed. Their study has confirmed the (phenomenon) of incommensurability in the case of BaNiP2O7 and revealed it for BaCoP2O7. The results of a force field calculation for BaCdP2O7 are presented. Correlation between the frequencies of the vibrational modes of the POP group and some structural parameters has been established.

Vibrational spectra of MX(2)TA and MX(2)TA(2) complexes have been studied in the region below 400 cm(-1) using C-2h and D-2h Line-group analysis, respectively. Assignments of stretching vibrations and some bending modes have been made. Some structural features have been outlined. Particularly, v((MN)) frequencies follow the ligand field stabilisation energies and Irving-Williams sequence. This result shows that all the complexes have the same geometry for metallic ion, octahedral one. The comparison of data obtained for TA complexes with those given previously for imidazole compounds show a more important retrodonation for the first ones.

1,2,4-triazole forms with transition, metal(ll) halides complexes of the general formula MX,TA and MX,TA,. A thorough vibrational analysis of these complexes and their deuterated analogs has been performed and fundamental vibrations of the ligand has been assigned. The coordination mode of triazole is proposed. The fact that the Ligand vibrations shift only slightly upon, coordination is accounted for by the existence of pi-back bonding from the metal ion to the ligand.

The vibrational study of 3,4'-bitriazole, 5-methyl-3,4'-bitriazole and 5-bromo-3,4'-bitriazole is reported and an assignment of their fundamentals is proposed on the basis of the existence of only one form in the solid state. The substitution of the hydrogen in 3 position of the {1H} triazolic ring by 4-triazolyl group induces a decrease in the strength of the NH...N hydrogen bond comparatively to 1,2,4-triazole and its C-monosubstituted derivatives. The introduction of a substituent in position 5 of the biheterocycle increases the strength of the self association mainly when the substituent is an electron-attractor group. Using the vN-H wave number values, the estimation of N...N distances in these derivatives is possible.The distinction between the triazolic ring' s vibrations and those of 4-triazolyl group seems impossible, probably because of the conjugation of the two rings. The higher frequency value obtained for the intercyclic bond stretching mode in the BrbTA is explained by an important conjugation and a shorter C-N bond in this case.

Different gels in the (50-x)Na2O-0.52xAl(2)O(3)- 0.48xBi(2)O(3)-(50-x)P2O5 system, where 7.7 less than or equal to x 34.4 were prepared. The gel formation occurred with cc molar ratio of P/(Al+Bi) = 2.25. The NMR spectra showed that the triphosphate aluminium complex predominates in Bi+3 containing gels whereas the diphosphate is present in the gels formed solely from Al+3. IR spectroscopy was used to monitor the thermic evolution of the gels between 20 and 600 degrees C. The phosphate chains appear to be hydrolysed at 200 degrees C but recondense before 600 degrees C.

The basicity toward diiodine of three N-methylated 1,2,4-triazole-thiones has been studied by means of the measure of formation constants in dichloromethane at 298K using UV-Visible spectroscopy. The preferred site of fixation of diiodine is the sulphur atom of the exocyclic thiocarbonyl group. This result agree with "HSAB" Pearson's theory of acids and bases. The experimental results are confirmed by theoretical calculations using ab-initio method and 3-21G basis set. The standard Gibbs energies of complexation in solution are well correlated to the electronic changes Delta E-o calculated by ab-initio method.

The K3Lu1-xYbx(PO4)(2), Rb3Dy(PO4)(2) et K2RbHo-(PO4)(2) compounds exhibit a phase transition (rhombohedral --> monoclinic) produced by a pressure effect. For these compounds, we have determined the pressure value inducing this transition by the et amination of the evolution of infrared spectra recorded using KBr pellets obtained at different pressure. The region of the coexistence of both rhombohedral and monoclinic phases has also been determined.