Theoretical and Experimental Background

We begin with a brief overview of the findings from the limited number of theoretical calculations, photoelectron and electronic-spectroscopic studies, and other physical measurements on terminal metal-alkynyl complexes in order to provide a context for discussing the results of X-ray 

We describe the results from photoelectron-spectroscopic and molecular-orbital calculations together because these studies are frequently conducted in tandem. The primary conclusion from this work is that, in most of the complexes studied, the alkynyl ligand is good o--donor and 7r-donor, but is a poor 7r-acceptor. 

The first and most influential molecular-orbital calculation on metal-alkynyl complexes is that of Kostin and Fenske, who applied the Fenske-Hall method to the complexes FeCp(C=CH)(PH3)2 and FeCp-(C=CH)(C0)2 (11). They concluded that the M-CCH bonds in these complexes are nearly pure a in character. The large energy gap (ca. 15 eV) between the occupied metal orbitals and ir (C=CH) levels severely limits the ir-accepting quality of the latter, with the total electron population for the pair of tt orbitals being 0.22 e for FeCp(C=CH)(PH3)2 and 0.14 e for FeCp(C=CH)(CO)2. The filled ir(C=CH) orbitals, in contrast, mix extensively with the higher-lying occupied metal orbitals these filled-filled interactions result in the destabilization of the metal-based orbitals. The HOMOs of both complexes possess substantial coefficients at the alkynyl jS-carbon this was noted to be consistent with the alkynyl-localized reactivity of these complexes. 

The conclusions of Kostid and Fenske for FeCp(C=CH)(CO)2 received firm experimental support a decade later from the work of Lichtenberger and co-workers, who carried out photoelectron-spectroscopic measurements and Fenske-Hall and extended-Huckel calculations on the complexes FeCp(C=CR)(CO)2 (R = H, Ph, r-Bu, C=CH) and FeCp (C=C-Bu )(CO)2 il2a,b)- Comparisons among the ionization energies of these compounds and to those of the methyl, chloro, and cyano derivatives of FeCpX(CO)2, as well as the nature of the vibronic structure observed in the spectra of FeCp(C=CH)(CO)2 and FeCp(C=CBu )(CO)2, led to several important conclusions. First, whereas cyanide stabilizes 

An exception to this picture of alkynyl ligands as w-donors is provided by Thompson and co-workers, who reported ab imVin calculations on the d° complexes TiCp2(C=CR)2 (R = H, Me) (14). They noted that there is little evidence in their computational results for RCC - M 7r-donation in these compounds, but that there is significant mixing between the alkynyl and Cp 7T levels. Unfortunately, attempts to measure photoelectron spectra of these compounds were unsuccessful. 

---

Gopper, G. L. Gapillary Electrophoresis Part 1. Theoretical and Experimental Background, /. Chem. Educ. 1998, 75, 343-347. 

At the same time, solid-state physicists intensively dealt with synthetic analogues of luminescent minerals as phosphors and quantum electronic materials, providing the theoretical and experimental background for further applications in high technology material sciences. These achievements are shortly summarized in Table 1.2. 

The application of FT-IR and high resolution solid state NMR to the structural characterization of epoxies is described. Theoretical and experimental background is given and progress to date in these two fields summarized. 

The organization of this review is as follows In Section II we describe the theoretical and experimental background of the field. Section HI reviews experimental work on the criticality of ionic fluids. Section IV presents the basic theoretical methods for describing ionic phase transitions at the mean-field level. Results obtained by these techniques are reviewed in Section V. Section VI reviews the theoretical work concerned with the nature of the critical point. The review closes in Section VII with a brief summary and outlook. 

Neutron scattering is still an immature technique capable of development in many directions and this review makes an attempt to identify those areas where it can provide unique information about catalysts and where progress can be expected in the future. This review is complementary to a number of others which have appeared in recent years which cover the applications of neutron scattering to the studies of the dynamics and structure of physisorbed gases1 and molecular vibrations.2 In addition the theoretical and experimental background to this present review has been described elsewhere3 and it will not be repeated. Ref. 3 also contains a discussion of those properties of the neutron which make it especially valuable as an experimental probe. 

A comprehensive review of the theoretical and experimental background needed to determine these parameters is given by Das and Hahn 4S> and by Reif and Cohen 40). More recent treatments of the whole subject may be found in the monograph by Lucken 143> and the review article by Schempp and Bray 1S9L A review on studies of nuclear quadrupole interactions for the period 1960 and 1966 is given by Weiss 125) and experimental data up to 1966 have been compiled by Biryukov et al 139>. 

This book is a view of enzyme catalysis by a physico-chemist with long-term experience in the investigation of structure and action mechanism of biological catalysts. This book is not intended to provide an exhaustive survey of each topic but rather a discussion of their theoretical and experimental background, and recent developments. The literature of enzyme catalysis is so vast and many scientists have made important contribution in the area, that it is impossible in the space allowed for this book to give a representative set of references. The author has tried to use reviews, and general principles of articles. He apologizes to those he has not been able to include. 

This book aims to provide a coherent, extensive view of the current situation in the field of chemical kinetics. Starting from the basic theoretical and experimental background, it gradually moves into specific areas such as fast reactions, heterogeneous and homogeneous catalysis, enzyme-catalysed reactions and photochemistry. It also focusses on important current problems such as electron-transfer reactions, which have implications at the chemical as well as biological levels. The cohesion between all these chemical processes is facilitated by a simple, user-friendly model that is able to correlate the kinetic data with the structural and the energetic parameters. 

---