Type isomers

Paraffin Isomer Type of Carbon Bond to -OH Alcohol... 

Rothe, GM, Determination of Molecular Mass, Stoke radius. Frictional Coefficient and Isomer-Type of Non-denatured Proteins by Time-Dependent Pore Gradient Gel Electrophoresis, Electrophoresis 9, 307, 1988. 

Losses from 21 to 23% in P-carotene, a-carotene, and lutein contents were observed during storage of carrot juice under light (1500 lux) at 25°C for 12 wk. The losses were accompanied by increased concentrations of the 13-cis isomer type of P-carotene, a-carotene, and lutein during dark storage, while the formation of 9-cw-P-carotene, 9-cii-a-carotene, and 13-cii-lutein was favored under light storage. ... 

MP2 perturbation theory applied in a theoretical study of C2H30Li, CH2=CH(OLi), CH3(C=0)Li and CH2=C(OH)Li (a model of unsaturated a-lithio ether) has revealed that mutation between the three different isomer types is almost impossible. ... 

Compound Isomer type NH2/F relationship R IC50 (pM) Inhibition type pKa log D ... 

A brief tabulation of these and some other isomer types recognized by Wemer is given by F. Basolo and R. G. 

As for neutral tetrazoles, the 13C NMR spectra of isomeric tetrazolium ions strongly depend on the isomer type. The signals for C-5 in 1,3-disubstituted tetrazolium salts are downfield by 7-16ppm compared to the corresponding... 

Disubstituted complexes Re2(CO)gL2 may have diaxial (6) or staggered transoid (7) isomers, while several other possibilities are found for trisubstituted Re2(CO)yL3 (L = PR3, CNR, P(0R)3) see Isomer, Types of). 

Early experiments to search for the Cr(CO)s molecnle involved flash photolysis of cyclohexane solutions of Cr(CO)6 with UV-visible detection. Problems arose owing to impurities in the solvent interacting with unsaturated intermediates. Although some evidence was obtained for naked Cr(CO)s it was not possible to confirm the existence of this species nor to distinguish between sqnare pyramidal, C4 (17), and trigonal bipyramidal, D h (18), geometries see Isomer, Types of). 

Another example of a translational isomer type is illustrated in Figure 5.7. In this case isomerism is possible because of the unsymmetrical nature of the ethylene glycol links in the cyclic polyether. At room temperature the respective cationic isomers 11 and 12 were observed to occur in the approximate ratio 64 36 in both deuterated acetone and acetonitrile. 

The isomer type of a molecule is thought to be unequivocally determined, without any intermediate forms such as those based on superpositions of different isomers. 

PtH2L2],If the rate of formation of tra s-[PtH2L2] is slow relative to the coupling reaction trans-[PtH(solvent)L2] + trans-[PtH2L2] the trans-trans isomer is formed. If, however, the formation of trons-[PtH2L2] is faster than the coupling reaction, the equilibrium crs-trans-[PtH2L2] is established and the trans-cis isomer. Type II, is preferentially formed. In any case the latter is thermodynamically more stable relative to the former. ... 

Complete the following concept map that shows how the following isomer types are related stereoisomers, stmctural isomers, optical isomers, all isomers, geometric isomers. 

Raman spectroscopy is sensitive to polymer conformation. For example, a polymer blend of polybutadiene-polystyrene in which polybutadiene is used to increase toughness of the polystyrene can be examined by Raman microscopy to identify its heterogeneity. Polybutadiene has three isomer conformations (cis-1,4, trans-1,4 and syndiotactic-1,2). These three types of isomers can be identified from C=C stretching modes as shown in Figure 9.36. The Raman spectra of the copolymer indicate the difference in amounts of isomer types at the edge and the center of the polybutadiene-polystyrene sample. Relative amounts of these isomer types affect the mechanical properties of the copolymer. 

Table 1. Some Possible Isomer Types Arising from [3-1-2] Cycloadditions Between a Monosubstituted Methyienecyclopropane (MCP) and a Nonsymmetrical, Disubstituted Alkene (XHC=CHY)...

Fig. 35.1. Four low-lying isomer types of (H20)6 the cage (A), ring (B), prism (C) and book (D) isomers.

For corresponding isomers of type 2 and 3, the type 3 isomer should be generally less strongly adsorbed. Thus for the adsorption on alumina of the diaminonaphthalenes (/5), the 1,2 and 1,3 isomers (type 2) are more strongly adsorbed than the 1,8 isomer (type 3). 

Coordination isomerism is another relatively rare, though well-known, phenomenon, exemplified in the compounds [Cr(NH3)6][Co(CN)6]/[Cr(CN)6][Co(NH3)6] and [Cr(en)20x]-[Cr(ox)2en]/[Cr(en)3][Cr(ox)3] (ox = 204 ). It is related to the structural isomerism that might be expected to be encountered in polynuclear systems (Figure 3). Although examples of such isomer types are known, e.g. the chiral cobalt(III) hexol , [Co Co(OH)2(NH3) 4]3] , and the chromium(III) rhodoso ion with the alternative achiral structure shown in Figure 3, no isomeric pairs have been thoroughly characterized. 

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