| 词条 | Tolman's rule |
| 释义 |
Tolman's rule states that, in a certain chemical reaction, the steps involve exclusively intermediates of 18- and 16 electron configuration. The rule is an extension of the 18-electron rule. This rule was proposed by American chemist Chadwick A. Tolman.[1] As stated above, Tolman's rule, even for reactions that proceed via 2e− steps, is incorrect because many reactions involve configurations of fewer than 16 e−. Many examples of homogeneous catalysis involving organometallic complexes involve shuttling of complexes between 16 and 18 electron configurations. 16-electron complexes often form adducts with Lewis bases and, if low-valent, undergo oxidative addition. {{math|CH3I + cis-[Rh(CO)2I2]− → [(CH3)Rh(CO)2I3]−}} Conversely, complexes of 18 electron configuration tend to dissociate ligands or undergo reductive elimination: {{math|[Rh(PPh3)3ClH2 → [Rh(PPh3)3Cl + H2}} References1. ^{{cite journal|last=Tolman|first=C.A.|title=The 16 and 18 electron rule in Organometallic Chemistry and Homogeneous Catalysis|journal=Chem. Soc. Rev.|year=1972|pages=337–353|doi=10.1039/CS9720100337}} 3 : Organometallic chemistry|Chemical bonding|Empirical laws |
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