NHC-Derived Bis(amidiniophosphine) Ligands of Rh(I) Complexes: Versatile cis−trans Chelation Driven by an Interplay of Electrostatic and Orbital Effects

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• 作者：Yves Canac ; Nathalie Debono ; Laure Vendier ; Remi Chauvin
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：June 15, 2009
• 年：2009
• 卷：48
• 期：12
• 页码：5562-5568
• 全文大小：760K
• 年卷期：v.48,no.12(June 15, 2009)
• ISSN：1520-510X

文摘

The synthesis, structure, and electronic properties of a dicationic bis(amidiniophosphine) based on an o-phenylene bridge is described. In spite of the presence of two facing P-conjugated positive charges, this electron-poor diphosphine is shown to act as a versatile chelating ligand in a series of stable rhodium(I) complexes. IR analysis of a carbonyl complex showed that the σ-donating versus π-accepting character of the cationic ligand is comparable to that of a neutral trialkylphosphite. While the ligand is trans-chelating at a neutral Rh(I) center, it switches to cis-chelating at a cationic Rh⁺ center. This and other unusual geometrical features revealed by X-ray diffraction analyses are interpreted by a subtle interplay between antisymbiotic trans preference, electrostatic repulsion, and relative Lewis acidity of the transition metal centers.