Process with Increase in Coordination Number

Irregular Processes with Increase in Coordination Number 

Ionic products can be formed from the disproportionation of certain carbophosphoranes and fluorooxyphosphoranes.2-4,131,132 

Evidently, the interconversion among isomers of a TBP phosphorus compound can occur by this kind of irregular process. A variation of this involves the addition of a suitable anion to the phosphorane. 

The occurrence of base-catalyzed substitutions of one alkoxy group by another in stable oxyphosphoranes was discussed in Section VIII.129 The rate of these substitutions is enormously accelerated by pyridine or by 2,4,6-trimethylpyridine, and depends on the base concentration. A reasonable interpretation is that the coordination number of the phosphorus increases in the transition state or in the intermediate of this reaotion (113) or (H4). 

There is a close relationship between this type of behavior in an isolable TBP phosphorane, and the addition of water to TBP cobalt to form octahedral cobalt which has been postulated in explanations of the base catalyzed hydrolysis of halogenoaminecobalt(IV).133 

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B. Irregular Process with Increase in Coordination Number. . . 118... 

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