Re-examination of the Metal Carbonyl Complex Infrared Parameter, vco, and Phosphorus Ligand Parameters, pKa, Σχi and Σσph, in Relation to an Evaluation of σ and Ω Components of M-P Bonds
Titel:
Re-examination of the Metal Carbonyl Complex Infrared Parameter, vco, and Phosphorus Ligand Parameters, pKa, Σχi and Σσph, in Relation to an Evaluation of σ and Ω Components of M-P Bonds
Auteur:
Alyea, Elmer C. Song, Shuquan
Verschenen in:
Comments on inorganic chemistry
Paginering:
Jaargang 18 (1996) nr. 4 pagina's 189-221
Jaar:
1996-06-01
Inhoud:
Detailed analyses of the three phosphorus ligand parameters commonly used as gauges of electronic effects in organophosphorus metal chemistry, pKa, Σχi and Σσph, are presented in terms of their use as σ measures in M-P bonds. The Tolman ligand parameter, Σχi, is shown to contain contributions from σ, Ω and steric factors. Though steric effects can be ignored in the Kabachnik parameter, Σσph, which is a purer σ-parameter than Σχi or vco, it suffers from its derivation as a Hammett parameter. It is concluded that pKa is the best choice as a σ-only parameter for phosphorus ligands. Furthermore, vco is shown to be inappropriate as a σ-only or Ω-only parameter, and the force constant k is deemed to be no better than vco as an electronic parameter for M-P bonding.
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