IR spectroscopic study

According to IR-spectroscopic studies, 3-aminoindazole 48 (R = H) and its A -benzyl derivative exist exclusively in the amino forms 48 [76AHC(S1), p. 424],... 

Unexpectedly strong intermolecular hydrogen bonding has been reported by IR spectroscopic studies for tetrahydro-4,7-phenanthroline-l,10-dione-3,8-dicarboxylic acids, which exist in the oxo-hydroxy form 165 in both solid state and in solution [78JCS(CC)369].Tlie conclusion was based on comparison of B-, C-, and D-type bands for 165 and their dimethyl esters (detection of hydrogen bonding) and on analysis of IR spectra in the 6 /xm region (pyridine- and pyridone-like bands). 

In the ring-closure reaction of a-acylaminoketones with hydrazines, some dihydro-1,2,4-triazines were obtained. The possible 1,2-, 2,3-, or 5,6-dihydro structures were excluded by IR spectroscopic studies however, this method, as well as the attempted preparation of fixed derivatives, failed to distinguish between... 

No systematic IR spectroscopic studies have been reported. The value for the C-C double-bond stretching frequency of the enol ether structure in 2,7-dimethyloxepin is 1660cm-1.12... 

Since the vibrational spectra of sulfur allotropes are characteristic for their molecular and crystalline structure, vibrational spectroscopy has become a valuable tool in structural studies besides X-ray diffraction techniques. In particular, Raman spectroscopy on sulfur samples at high pressures is much easier to perform than IR spectroscopical studies due to technical demands (e.g., throughput of the IR beam, spectral range in the far-infrared). On the other hand, application of laser radiation for exciting the Raman spectrum may cause photo-induced structural changes. High-pressure phase transitions and structures of elemental sulfur at high pressures were already discussed in [1]. 

Two methods were also used for the formation and IR spectroscopic study of the diiodocarbene. Only one band at 525 cm assigned to vj of the carbene has been found in the IR spectra of the reaction products of vacuum pyrolysis of tetraiodomethane CI4 and its matrix reaction with atomic lithium. 

An IR spectroscopic study of the radicals CF3, C2F5, C3F7 and i-C3F7 has been carried out. These radicals were formed as products of vacuum pyrolysis in a platinum reactor of the respective fluorinated iodoalkanes and were stabilized in argon matrices at 10-12 K (Snelson, 1970b Butler and Snelson, 1980a,b,c) as shown in (6). 

Nishimura K, Kunimatsu K, Enyo M. 1989. Electrocatalysis on Pd + An alloy electrodes Part III. IR spectroscopic studies on the surface species derived from CO and CH3OH in NaOH solution. J Electroanal Chem 260 167. 

Friedrich KA, Geyzers KP, Linke U, Stimming U, Stumper J. 1996. CO adsorption and oxidation on a Pt(lll) electrode modified by mthenium deposition An IR spectroscopic study. J Electroanal Chem 402 123-128. 

Sonoyama, M., Miyazawa, M., Katagiri, G., and Ishida, H. (1997). Dynamic FT-IR spectroscopic studies of silk fibroin films. Appl. Spectrosc. 51, 545-547. 

A method for observing intermediates directly in the reaction cycle is in situ IR spectroscopy under reaction conditions. As early as 1975, Penninger published a contribution concerning in situ IR spectroscopic studies of cobalt carbonyl modified by tri-u-butylphosphine as a hydroformylation catalyst [58] at relatively low catalyst concentrations of 2 mmoll-1. The observed carbonyl... 

Fourier transform-infrared (FT-IR) spectroscopic studies on SO-SA complexation provides information that may be complementary to that of NMR and other techniques, namely, in particular, on the involvement of functional groups in intermolecular and intramolecular interactions. Attenuated total reflectance (ATR) IR spectroscopy has been used for the study of binding modes of cinchona alkaloid selectors either in solution [95] or in solid state [94], or directly on the CSP [96]. 

Zverev, S.M., Smirov, K.S., and Tsyganenko, A.A. (1988) IR spectroscopic study of low-temperature adsorption of molecular nitrogen on the surface of oxides. Kinet. Katal.,... 

Another noteworthy early IR spectroscopic study of Nafion (125 and 152) membranes, in the acid as well as various counterion forms, was that of Heitner-Wirguin, who assigned a number of characteristic bands and compared the spectra to those of sul-fonated polyethylene (Redcat) membranes. 

Systematic IR spectroscopic studies furnish the following characteristic frequencies for the CFnCl 3 nS— (w = 3, 2, I) and CgFsS groups ... 

As described earlier, high pressure cells have been developed for the use of noble gases as solvents for IR spectroscopic studies, either at low temperature, or at ambient temperature where the supercritical phase exists. A particular focus of this work was the study of reactive complexes containing coordinated noble gas atoms or molecular H2, the latter being particularly relevant to hydrogenation reactions. 

Chen, J., T. Zhu, H. Niki, and G. J. Mains, Long Path FT-IR Spectroscopic Study of the Reactions of CF,0 Radicals with Ethane and Propane, Geophys. Res. Lett., 19, 2215-2218 (1992b). 

The existence of the above complexes has been conclusively proved by use of specially synthesized model compounds (Table 3) and by IR-spectroscopic studies over a wide range of substance concentrations (diluent CC14). 

Cadmium complexes have not been neglected in these and other physical studies. For example, an electron diffraction study of CdBr2 has been made, and it was concluded that the equilibrium structure corresponds to a linear Br—Cd—Br molecule, with a Cd—Br distance of 2.372 A and a Br—Br distance of 4.694 A.105 Raman and IR spectroscopic studies of CdCl2 have also been reported.106 The Cd2+—en system is of interest, and a detailed study of the vibrational spectra (IR and Raman) of [Cd(en)(N02)2] and its deuterated derivative has been reported.107... 

A Raman and IR spectroscopic study of Zn(OAc)2 and Zn(0Ac)2-2H20 has been described in the latter compound the metal is in an octahedral environment, with trans diaxial water ligands and bidentate chelating acetate groups, and in the former compound the metal is in a pseudotetrahedral environment.775... 

In 1989, Nefedov and coworkers have reinvestigated the thermolysis of the above-mentioned allyloxysilane derivatives 16-18 and of 2,2,6-trimethyl-2-silapyrane (21) using vacuum pyrolysis and matrix isolation techniques23. IR spectroscopic studies on the products isolated in the matrices enabled them to probe directly the intermediacy of 10 in these reactions and to discuss its thermal stability. Only in the case of allyloxydimethylsilane (17) did they find direct spectroscopic evidence for the formation of 10 by observation of its most intense band at 798 cm-1 in the matrix IR spectrum of the pyrolysis products. In all other cases silanone 10 was not detected and it was assumed that it is thermally unstable, undergoing fragmentation into SiO and CH3 radicals as shown in Schemes 7, 8 and 9 (the species actually observed in the matrix are indicated). In this paper, Nefedov and coworkers have reaffirmed the thermal and kinetic stability of dimethylsilanone 10 in the gas phase, which they had previously described19. 

---