Jorgensen s chain theory

Table 1 A Comparison of Blomstrand—Jorgensen s Chain Theory with Werner s Coordination Theory2...

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

Figure 2.1 Examples of molecular formulas according to Jorgensen s Chain Theory.

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).

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... 

Blomstrand s chain theory was adopted, modified and developed by his close fiiend in Copenhagen, Sophus-Mads Jorgensen (1837-1914) (7), who brilliantly defended it until Werner in 1907 - ten years after Blomstrand s death - synthesized c/5-tetraamminedichlorocobalt(ni) chloride (cis-[CoC 20 tl2) C ) (8). Then, with the words "Nu er striden afgjort" (Now the battle is over), Jorgensen graciously conceded defeat (9). 

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. 

In 1883, Jorgensen reported that tertiary amines form compounds analogous to metal - ammines. Because tertiary amines contain no replaceable hydrogen, Jorgensen s discovery eliminated Graham s ammonium theory (Section 3.1) from serious consideration, leaving the chain theory and Kekule s concept of molecular compounds in the running. In Werner s words, Kekule s dichotomy merely substituted a beautiful word for a confused concept . Therefore, for almost a quarter of a century, until displaced by Werner s coordination theory, the chain theory became the most popular and satisfactory explanation of metal-ammines. 

Spectroscope developed Bunsen and Kirchhoff 1869 Mendeleev s first periodic table organizes 63 known elements 1885 Balmer formula for visible H spectrum 1894 First "inert gas" discovered 1895 X rays discovered Roentgen 1896 Radioactivity discovered Becquerel 1874 Tetrahedral carbon atom Le Bel and van t Hoff 1884 Dissociation theory of electrolytes Arrhenius 1869 Chain theory of ammonates Blomstrand 1884 Amendments to chain theory Jorgensen 1892 Werner s dream about coordination compounds... 

The Blomstrand-Jorgensen chain theory was the most successful of the early theories that attempted to explain the known series of cobalt ammonates. This theory combined trivalent cobalt atoms, divalent ammonia radicals, and monovalent chlorides to produce structures that accounted for some of the formulas, conductivities, and reactions of these compounds. However, when an analog of a critical compound was finally synthesized, the chain theory s prediction was wrong, and it started to lose favor. 

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