Archetype molecules

The isomerization of the butanes and of neopentane has been studied over various types of evaporated platinum films by Anderson and Baker (68) and Anderson and Avery (108,24). Table II gives some typical results. It is clear that the proportion of parent hydrocarbon reacting to isomeric rather than to hydrogenolytic product is considerably smaller for a hydrocarbon with an unbranched as opposed to a branched chain containing an isostructural unit indeed, neopentane was studied as the archetypal molecule of the latter class. 

APW, see Augmented-plane-wave Archetype molecules, 32 164-165, 171 Arenes... 

The catalytic behavior of small metal particles in heterogeneous catalysts varies with metallic particle size and shape a phenomenon referred as a structure-sensitivity. Simple alkanes such as ethane, propane, n-butane and isobutane can be used as archetype molecules for studying hydrogenolysis reactions as they... 

Reactions of molecules with labeled carbon (13C, UC). Gault and his co-workers pioneered (see, for review, 157) the use of 13C-labeled molecules in experiments by which the operation of adsorbed complexes with either three or five C atoms involved could be tested (see below). 14C has been repeatedly used in problems concerning the dehydrocyclization and aromatization reactions (157,163-166). The authors (163-166) in their research combined the use of labeled molecules with the third method, the study of archetype molecules. 

The study of archetype molecules. This method has been proposed and widely used by Rooney, Burwell, Anderson, and others (see, for review, 155,156,160). In this method a molecule is used which can form an archetype of chemisorbed complex ( caged molecules as derivatives of ada-mantane or ethane in its hydrogenolysis, neopentane in exchange with D2 or in reforming reactions, etc.) or which can form several complexes, but the contribution of these complexes to the overall mechanism is easily derived from the product spectrum [as is the case, for example, with neohexane (167, 168). ... 

The conformational properties of such eight-membered ring molecules have been reviewed fairly recently (74MI51900). Cyclooctane is the archetypical molecule in this class, and the heterocyclic analogs, such as the azocanes, oxocanes and thiocanes, as well as carbocyclic derivatives, such as cyclooctanone, all have closely related conformational features and a brief overview of their conformations will now be given. 

Forge and Anderson studied so-called archetypal molecules to establish the cleavage mode of individual metals.251,265-267 Ethane is an archetype of C2-unit hydro-genolysis (i.e., the cleavage of primary-secondary and secondary-secondary bonds). Neopentane, in turn, is an archetypal molecule for iso-unit hydrogenolysis (i.e., the hydrogenolysis of bonds with at least one tertiary or quaternary carbon atom). 

For all three archetypal molecules ethane, ethene, and ethyne, and also for propane, the MP2/6-31Gr(d,p) results are particularly close to... 

Hydrogen peroxide is an archetypal molecule for internal rotational, but in spite of its small size its structure has been difficult to determine. The torsional... 

The metal clusters of the iron triad M3(CO)i2, 4 M = Fe, 5 M = Ru, and 6 M = Os, despite being some of the simplest carbonyl clusters known, are fascinating molecules, which still present interesting structural and dynamic problems. Because of their simplicity, they have been, and indeed remain, archetypal molecules for discussions on fluxional mechanisms. The two heavier congeners 5 and 6 have a clearer and less complicated history. In the solid state they are isostructural, and possess... 

The archetypal molecule in a study of the interaction of organic molecules with clusters must be benzene. Fig. 14 illustrates some of the variations of structure that have been observed for benzene with metal ions or metal clusters. In many of the cluster systems the benzene molecule is bonded to more than one metal centre and the rationalisation for calling these benzene compounds poses the problem of... 

Consider the growth of films of the archetype molecule, tris(8-hydroxyquin-oline) (Alqj), having d -10 A. The mean free path is calculated using Equation 2.25, assuming that the collision diameter for a mixture of Alqj in a N2 carrier gas is the average of the respective diameters of the two species in selfdiffusion viz. d = Vi(dAlq3+dN2)-... 

Batsanov SS (1998) H2 an archetypal molecule or an odd exception Struct Chem 9 65-68 Pauling L (1960) The nature of the chemical bond, 3rd edn. Cornell Univ Press, Ithaca, New... 

Since our aim here is presenting the overall features of these quantities, we will focus on their basic properties, showing their basic topological portraits in a small set of archetypal molecules. We will stress the similarities and differences with other known fields, as weU as their potential usefulness. 

The term aromatic was originally applied to many of the synthesized derivatives of benzene because they exhibited that olfactory feature. Benzene itself would never be so described. However, benzene is the quintessential and archetypal molecule which exhibits the concept of aromaticity in all its many structural and chemical manifestations. 

The easiest way to see how particular fragments are isolobal is illustrated in Scheme 21.1. The archetypical molecule of organic chemistry is methane, 21.2. Breaking one C—H bond in a homolytic sense generates the methyl radical, 21.3. It... 

A quite different but important breakthrough has been reported that describes for the first time some successful kinetic studies of simple thermal reactions in a zeolite cage. The archetypical molecule [Mo(CO)6], and the zeolite NasgY, were chosen for the study and reactions with PMe3 and... 

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