Werner’s coordination theory

Werner s coordination theory, 1, 6 Whewellite structure, 6, 849 Wickmanite structure, 6, 849 Wilkinson s catalyst, 6, 239 Wilson s disease, 5, 721 copper, 6,648 removal, 6,769 copper complexes, 2,959 copper metabolism, 6,766 radiopharmaceutical agents, 6,968 Wolfram s red salt, 5,427 Wurzite... 

Noyes himself had been a student of Ostwald. Lewis had spent the academic year 190001 at the institutes of Ostwald and Nernst. Colloquium topics at MIT in the period from roughly 1905 to 1910 included both chemical and physical topics Alfred Werner s coordination theory of valence, tautomerism, and the absolute size of atoms. 

Claus first postulate was vigorously attacked by Karl Weltzien (1813—1870),40 while Hugo Schiff (1834—1915)43 attacked not only Claus first postulate but also his second. All of Claus three postulates reappeared modified almost four decades later in Werner s coordination theory. Claus third postulate closely adumbrates Werner s concepts of the coordination number and of the transition series between metal ammines and metal salt hydrates. 

Whereas Kekule disposed of complex compounds by banishing them to the limbo of molecular compounds , other chemists developed highly elaborate theories to explain their constitution and properties. The most successful and widely accepted of such pre-Werner theories was the chain theory,47 advanced by Christian Wilhelm Blomstrand (1826-1897)4 and developed by Sophus Mads Jorgensen (1837—1914).46 49 50 Although Werner s ideas eventually triumphed, this did not invalidate Jorgensen s observations. On the contrary, his experiments have proven completely reliable and provided the experimental foundation not only for the Blomstrand—Jorgensen chain theory but also for Werner s coordination theory. 

The circumstances surrounding the creation of Werner s coordination theory provide us with a classic example of the flash of genius . One night in late 1892, Werner awoke at 2 a.m. with the... 

Octahedral Six Coordinate In addition to the tris-bidentate complexes and the unidentate complexes discussed above, there are many other examples of chiral metal complexes that are based on octahedral geometry. For example, there are a number of reports of edge-sharing binuclear structures containing four bidentate chelates. The individual metal centers in these binuclear species can exist as either A or A enantiomers, and, therefore, the overall structure can be chiral AA and AA, or the achiral (meso) AA pair as illustrated in Figure 5.12a and b. Studies of complexes of this type were important in the proof of Werner s coordination theory. In these pioneering studies, Werner was able to prove by experiment the existence of the three isomers (AA, AA, and AA) of [Co2(p-NH2)( l-NC>2)(en)2]4 +. 23 For Cr(III) complexes, Werner showed that the / >.vo-AA- Cr2(p-OH)2(en)414 1 may be prepared by... 

Koord. Khim. ( Russ. J. Coord. Chem. ) 19(5), 331-408 (1993) (issue dedicated to 100 years of Werner s coordination theory). 

A recent review [440], published 100 years after Werner s coordination theory was first presented, was dedicated to the complex compounds obtained on the basis of polypyrazolyl-borates or scorpionates. Complexes of this kind, an example of which is presented by structure 234, have been obtained with practically all p, /-elements and they can be examined as N-containing analogoues (MN4 coordination unit) of p-diketonates 2 (M04 coordination unit) ... 

Werner s Coordination Theory and his Controversy with J0rgensen... 

WERNER S COORDINATION THEORY AND HIS CONTROVERSY WITH JORGENSEN... 

Table 1 A Comparison of Blomstrand-Jorgensen s Chain Theory with Werner s Coordination Theory. (Ref. 2b. Reproduced by permission of Dover Publications, Inc.)...

With few exceptions, Werner s coordination theory was accepted by most chemists, and most twentieth-century contributions have been developments, extensions, or confirmations of it rather than ideas incompatible with or opposed to it. One of the earliest of these post-Wemer developments is the concept of inner complex salts. ... 

Werner failed to recognize that polynuclear coordination compounds represent a transition between mononuclear complexes and the infinite structure of the crystal lattice. However, Paul Pfeiffer, Paul Niggli (1888-1953), and others reported crystal structures agreeing with Werner s coordination theory, as revealed by the new X-ray diffraction technique. ... 

Comparison of Blomstrand s Chain Theory and Werner s Coordination Theory... 

The early interaction between Werner s coordination theory and crystal structure is discussed in terms of the problems about valence that then prevailed. 

A Ifred Werner s coordination theory was intuitive. The substantiation of his flash of genius required many years of work. In the absence of physical methods on which we rely, he had to devise compounds which would permit one to distinguish among the various geometrical and binding situations which were considered. Werner had to consider all reasonable geometries, as well as a number of proposed descriptions which we would now dismiss as unreasonable, but which had to be refuted. 

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. 

Tt is well-known that Werner determined the structure of a number of metal complexes by skillfully combining his famous coordination theory with chemical methods (30). Modern physico-chemical methods such as x-ray diffraction and infrared spectroscopy, used in the study of Werner complexes, have paralleled the development of these techniques. The results of these investigations have not only confirmed the validity of Werner s coordination theory but have also provided more detailed structural and bonding information. In early 1932, Damaschun (13) measured the Raman spectra of seven complex ions, such as [Cu(NH3)4]" and [Zn(CN)4j and these may be the first vibrational spectra ever obtained for Werner complexes. In these early days, vibrational spectra were mainly observed as Raman spectra because they were technically much easier to obtain than infrared spectra. In 1939, Wilson 35, 36) developed a new theory, the GF method," which enabled him to analyze the normal vibrations of complex molecules. This theoretical revolution, coupled with rapid developments of commercial infrared and Raman instruments after World War II, ushered in the most fruitful period in the history of vibrational studies of inorganic and coordination compounds. 

One of the most important and interesting results obtained from Werner s coordination theory is the prediction and verification of various types of isomerism. It is, therefore, appropriate to review recent infrared studies in this area and to show how infrared spectroscopy can be used to distinguish various types of isomers. 

Figure 2.2 Isomeric structures of C0CI3 (en)2 as predicted by Werner s Coordination Theory (VII,VIII) and Jorgensen s Chain Theory (IX,X).

Q2.5 Revisit the table in question 2.1. Given the number of reactive chlorides in the following table, predict the coordination structure for each of the following formulas according to Werner s coordination theory. 

TABLE 2.3 Molar conductivities (Tl-1 mol-1 cm2) for Several Platinum and Cobalt Complexes. Predict Values for WCT (Werner s Coordination Theory) and JCT (Jorgensen s Chain Theory) Given the Information Below. Measured Values are from the Literature3-5,9... 

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