Infrared and Raman Studies of ir-Complexes

Hydrogenation Reactions Catalyzed by Transition Metal Complexes, 17, 319 Infrared Intensities of Metal Carbonyl Stretching Vibrations, 10, 199 Infrared and Raman Studies of ir-Complexes, 1, 239 Insertion Reactions of Compounds of Metals and Metalloids, 5, 225 Insertion Reactions of Transition Metal-Carbon Bonded Compounds 1. Carbon Monoxide Insertion, 11, 87... 

It is only very recently that we have seen the first results of detection by infrared and Raman spectroscopy of organometallic complexes within cells. The first experiments were carried out with microscopes attached to infirared or Raman spectrometers, followed by other studies taking advantage of new techniques, specifically AFM-IR and surface-enhanced Raman spectroscopy (SERS). 

Many of the recent studies that examine Raman and infrared spectroscopy have been mentioned in previous sections of this chapter.However, a vibrational spectroscopic smdy by Comerlato and coworkers used HE and B3LYP with the SBKJC EPC for tin to examine IR and Raman spectra of the anionic [NEt4]2[Sn(dmit)3] complex. Comparison of the calculated scaled frequencies to experimental values revealed that the B3LYP method is more accurate than the HE method. The latter method is well known to overestimate frequencies by about 10%. 

This volume also contains one of the first reviews of the Surface Enhancement of Infrared Spectra by Professor Peter Griffiths, one of the leading pioneers in the area of IR Spectroscopy over the last 50 years. There is a chapter on the analytical measurement of salt concentrations in water using Raman spectroscopy by Dr Marc Fontana (and colleagues), and a review of the study of metal complexes using Raman, Resonance Raman and stimulated Raman methods by Professor John McGarvey (and colleagues). 

Although both the Raman and the infrared (IR) techniques provide information on vibrational modes in molecules, the two techniques are complementary. In a molecular system, the vibrational modes that are weak in IR are generally strong in Raman and vice versa. Moreover, fewer bands are active in Raman spectra, which is advantageous in the studies of complex systems. 

Analyses of such geological materials sometime require basic identification studies of fine-grained pigments and stones that cannot be identified by eye or microscopically. For the identification of such fine-grained materials. X-ray diffraction (XRD) and Raman infrared spectroscopy are commonly employed, as will be illustrated in the case studies. XRD is more commonly applied to powders, but can be difficult to interpret on complex assemblages of more than a few minerals. Raman IR has an advantage in the case of solid stones of being nondestructive. 

The conformation of derivatives of bicyclo[3.3.1]nonane has been the subject of many studies, based on proton nuclear magnetic resonance ( H-NMR), C-NMR, infrared (IR) and Raman spectroscopy, dipole measurements, X-ray crystallography, complexation experiments and various types of computational studies. Most of this work has been reviewed in detail (26,118, 119), and here we only report a summary of the general aspects. 

Infrared spectroscopy provides a valuable qualitative indication of the degree of covalency of a given Pb-ligand interaction and also has been used (with much less success) to determine the coordination number of Pb(II). There have been limited studies of Pb(ll) complexes by IR (149, 151-162) and Raman (163-166) spectroscopies. The interpretation of these results is most successful when coupled with structural data from X-ray crystallography. X-ray absorption spectroscopy [extended X-ray absorption fine structure (EXAFS) or X-ray absorption near edge spectroscopy (XANES)], PES, or NMR spectroscopy (149, 154, 155, 157, 158, 160-162). 

It is clear from the above considerations that the most often used and widely reported XRD analysis becomes insufficient to provide detailed information about amorphous phases. The benefits of in-depth studies of mechanochemical reaction mechanisms by selection of appropriate analytical tools, able to provide data on a short-range (local) structural scale, such as nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) spectroscopy, infrared spectroscopy (IR), Raman spectroscopy, etc., were demonstrated by the pioneering work of Senna, Watanabe and coworkers (Watanabe et al., 19%, 1997 Senna, 1997). In those cases, the synthesis of selected complex oxide systems have been studied from starting mixtures comprising typacaUy hydroxide and oxide compounds extensive data on these studies can be foimd in Avvakumov et al. (2001). 

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