Solid acidity computational chemistry

There has been a phenomenal growth of interest in theoretical simulations over the past decade. The concomitant advances made in computing power and software development have changed the way that computational chemistry research is undertaken. No longer is it the exclusive realm of specialized theoreticians and supercomputers rather, computational chemistry is now accessible via user-friendly programs on moderately priced workstations. State-of-the-art calculations on the fastest, massively parallel machines are continually enlarging the scope of what is possible with these methods. These reasons, coupled with the continuing importance of solid acid catalysis within the world s petrochemical and petroleum industries, make it timely to review recent work on the theoretical study of zeolite catalysis. 

The aforementioned progress in NMR spectroscopy (and other experimental methods as well) in combination with computational chemistry has reached a stage in which an understanding of the most general features of organic reactions on solid acids may reasonably be expected in several years. This does not yet quite exist this report is written in a time at which the sophisticated application of NMR and computational quantum chemistry to solid acids is becoming widespread, and specialists in various areas are suddenly having to evaluate evidence from other specialties. 

The intent of this report is thus twofold We first review those less familiar aspects of NMR spectroscopy, including its combination with computational quantum chemistry, and then we attempt to critically evaluate the application of NMR to solid acidity. We restrict ourselves primarily to aluminosili-... 

The reaction between a Lewis acid R3M and a Lewis base ER3 is of fundamental interest in main group chemistry. Synthetic and computational chemists have investigated the influence of both the Lewis acid and the base on the solid state structure and the thermodynamic stability of the corresponding adduct, that is usually expressed in terms of the dissociation enthalpy De. This led to a sophisticated understanding of the nature of dative bonding interactions. In particular, reactions of boranes, alanes and gallanes MR3 with amines and phosphines ER3, typically leading to adducts of the type R3M <— ER3, have been studied.10... 

The generation of carbocations in strongly acidic media, and the characterization of their structure by NMR in the 1950s was a breathtaking accomplishment that led to the award of the Nobel Prize in Chemistry to George Olah. Over the past 50 years NMR spectroscopy has evolved as the most important experimental method for the direct study of structure and dynamics of carbocations in solution and in the solid state. Hans-Ullrich Siehl provides an excellent review of computational studies to model experimental NMR spectra for carbocations. This chapter provides an example of how the fruitful interplay between theory and experiment has led to a better understanding of an important class of reactive intermediates. 

This chapter details the chemistry of nitrosomethanides and their corresponding acids and is primarily devoted to the subject as a whole and to its basic concepts, ranging from molecules to polymers, from synthesis to reaction mechanisms and from molecular to solid state structures, topics which are often aided by computational results. 

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