Inversion optical

Optical inversions in the reactions of cobalt complexes. J. C. Bailar, Rev. Pure Appl. Chem.. 1966, 16, 91-101 (16). 

The d5Tiamic stereochemistries of M(dtc)3 and [M(dtc)3] (M = Fe, Co, or Rh) complexes have been studied (315). The cobalt complex is non-rigid, but the mechanism of optical inversion could not be determined. The Rh complex is stereochemically rigid up to 200°. The optical inversion of (-l-)546 [Colpyr-dtcla] in chloroform has been studied, by loss of optical activity, by polarimetry (316). 

This curious phenomenon of the inversion of groups about the asymmetric carbon atom first studied by Paul Walden is called Walden inversion or Optical inversion. This was the first study of the influence of spatial structure on the reactivity of compounds and by a series of reactions Walden... 

Optical electron transfer process, 21 179-225 single-ion, see Photoemission Optical inversion, of tis(dithiocarbamate) complexes, 23 222, 253... 

It is also evident from Scheme 3 that the cis-a cis-ji isomerization will be accompanied by optical inversion (A A). This has been observed in acid solution776 for the reaction shown in equation (4) and in basic solution, for the reaction shown in equation (5) although in the latter case296 the configuration of the sec-NH protons in the resulting cis-fi was not established. 

Optical Inversion of Glutamate Residues in Poly-a,L-glutamic Acid. 

Another major effect, found in PGA, is optical inversion of L-glutamate to D-glutamate residues. One implication of the radiation-induced optical inversion in proteins is that some modification of amino acids may pass undetected by the usual chemical analyses which do not distinguish between l- and D-isomers. Furthermore, introducing a D-amino acid residue into a protein could have a far-reaching effect on the secondary and tertiary structures, and this could have a more serious effect on the functional properties of the molecule than changes in the side chains. One biological property of PGA which is affected by irradiation in solution is its hydrolysis by proteolytic enzymes. The conformation of the polymer has a marked effect on its susceptibility to hydrolysis by certain enzymes 27), and we have... 

The rate constant for optical inversion determined from a log a vs time plot is twice that of the rate constant for direct A — A inversion.6 ... 

Table 10. Kinetic data for optical inversion of M(OX>3 3 complexes in neutral aqueous solution...

Optically active dithiocarbamates Co(S2CR2)3 (R = Me, Et, Pr, Bun, Bu1, Bz, Cy, or pip) can be prepared from the potassium dithiocarbamate salts and the optically active K[Co(edta)] or K[Co(pdta)] (pdta = 1,2-propanediaminetetra-acetate).368 The optical inversion of ( + )546-[Co(pyr-dtc)3] (pyr-dtc = NN-dipyrrolidyldithio-carbamate) in chloroform has been studied by loss of optical activity by polarimetry.3 68... 

Stefan Balint, Analysis and Numerical Computation of Solutions of Nonlinear Systems Modeling Physical Phenomena, Especially Nonlinear Optics, Inverse Problems, Mathematical Materials Science and Theoretical Fluid Mechanics, Proceedings of a conference held 19-21 May 1997, in Timisoara, Romania, University of the West Timisoara, Timisoara, Romania, 1997. 

This experiment constitutes a direct confirmation of the causal connection between substitution and optical inversion. Similar experiments were carried out with radioactive bromide and a-phenyl ethyl bromide. 

John C. Bailar, Jr and Robert W. Auten Optical inversion in reactions of cobalt complexes (inorganic Walden inversion)... 

Any detailed description of the mechanism of an octahedral substitution must also account for the stereochemical changes that accompany reaction. Werner recognized this and made use of it in his discussions of the stereochemistry of reactions of cobalt(III) complexes. The available experimental results can be explained on the basis of possible molecular rearrangements and some cautious predictions can even be made. The base hydrolysis of cobalt III)ammines appears to be unique in that it often occurs with rearrangement it also affords the few known examples of optical inversion. These results can be explained by formation of a 5-coordinated species with a trigonal bipyramidal structure. Optically active metal complexes racemize by either an intramolecular or an in-termolecular process. Substitution reactions of platinum metal complexes often occur with retention of configuration. 

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