Inorganic compounds, optical activity

Phosphors are inorganic materials which convert incident radiant energy to visible light within a device. The device chosen can be a cathode-ray tube, i.e.- a television tube, or a fluorescent lamp. A phosphor consists of a matrix modified by an additive chosen so that it becomes optically active within the matrix, or compound. This is an example of a substitutional impurity in a lattice wherein the additive, usualty Ccdled an "activator", introduces a lattice defect that is optically active. However, the added impurity still follows all of the rules found for defects in a lattice, as shown by the following example. 

The importance of the theory was further demonstrated by the discovery of the existence of optically active inorganic compounds, and the isolation of the exact number of optical isomers theoretically possible for the spatial arrangement of the atoms.1 Friend 2 and others criticised the theory on the grounds that in simple compounds, such as sodium chloride or cobaltous chloride, the chlorine is ionised and yet is attached to sodium or cobalt atom directly, whereas in the ammino-coinpounds the acid capable of ionisation is that which is not directly attached to metal. For instance, in chloro-pentammino-cobaltic chloride, [CoCI(NH3)5]C12, it is the chlorine outside the first zone which is ionised in solution. Also, the dissociable acidic groups are not attached to any point within the complex, but simply hover round the central complex in an indefinite manner. Thus a definite valency for ionisable... 

New procedures for the synthesis of inorganic complexes have made it possible to prepare several new types of compound. Particularly noteworthy is the discovery by Shibata and his coworkers that the carbonato groups of [Co(C03)3]3 can be displaced stepwise, so that ligands of three different kinds can be introduced readily and compounds such as [Co(en)(pn)(N02)2]+ and [Co(NH3)2(H20)2(CN)2]+ can be prepared.6 The tris-carbonato complex can be obtained in optically active form. 

Werner s final triumph in support of his theory came in the optical resolution of a purely inorganic synthetic complex. Such compounds are still rare, but a few have been prepared in optically active form cw-[Rh(NHS02NH)2(H20)2], [Pt(S5)3]2— and cts,cts,cis-[Co(NH3)2(H20)2-X2]+ (X = CN or N02),28 though the cyano group does contain carbon. 

This purely inorganic compound was resolved into its isomers by Werner as final proof that optical activity was the property of the central coordinating atom only,... 

Library of Congress Cataloging in Publication Data. Main entry under title Theoretical inorganic chemistry. (Topics in current chemistry 56). Bibliography p, Includes index. CONTENTS Jorgensen, C. K. Continuum effects indicated by hard and soft antibases (Lewis acids) and bases. - Brunner, H. Stereochemistry of the reactions of optically active organometallic transition metal compounds, [etc.]. 1. Chemistry, Physical and theoretical- Addresses, essays, lectures. I. Series. 

This article describes the unique features and the theory of solid-state optical activity, and the instrumentation of the UCS J-800KCM. Several examples of chiral photochemistry and solid-state optical activity of inorganic and organic compounds are presented. 

Crystallographic studies of transition metal hydride complexes Stereochemistry of six-coordination Five-coordinate structures Stereochemistry of five-coordinate Co complexes Absolute stereochemistry of chelate complexes Stereochemistry of optically-active transition metal complexes Electron density distributions in inorganic compounds... 

FIGURE 9-2 Werner s Totally Inorganic Optically Active Compound, [Co(Co(NH3)4(OH)2)3lBr6. 

This resolution showed decisively that the anion had the cis (or 1, 2) structure, XXXVIII. Its achievement allowed me to have the honor of joining Alfred Werner as one of the two chemists who have resolved a purely inorganic compound into optically active forms. 

Werner must have felt satisfied that the octahedral arrangement of ligands in 6-coordinate complexes was firmly established, but some critics objected because the resolved complexes contained carbon, and optically active carbon compounds were well known. Werner silenced this objection by preparing and resolving a completely inorganic complex (71), [Co (OH)2Co(NH3)4 3] , in which the chelate ligands around the central Co(III) are the complex ions c2s-[Co(NH3)4(OH)2]. With this accomplishment, the major points of Werner s coordination theory for 6-coordi-nate complexes were firmly established long before modem structural methods were available. 

Since Werner s pioneering work on optical activity in complex inorganic compounds there have been many important developments in the field. One of the more interesting of these is known as the Pfeiffer effect which is a change in the optical rotation of a solution of an optically active substance e,g, ammonium d-a-bromo-camphor-T-sulfonate) upon the addition of solutions of racemic mixtures of certain coordination compounds (e,g, D,L-[Zn o-phen)z](NOz)2, where o-phen = ortho-phenan-throline). Not all combinations of complexes, optically active environments and solvents show the effect, however, and this work attempts to apply optical rotatory dispersion techniques to the problem, as well as to determine whether solvents other than water may be used without quenching the effect. Further, the question of whether systems containing metal ions, ligands, and optically active environments other than those already used will show the effect has been studied also,... 

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