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

作者：Canac Yves^*; Debono Nathalie; Vendier Laure; Chauvin Remi

来源：Inorganic Chemistry, 2009, 48(12): 5562-5568.

DOI：10.1021/ic900348x

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(l) complexes. IR analysis of a carbonyl complex showed that the a-donating versus pi-accepting character of the cationic ligand is comparable to that of a neutral trialkylphosphite. While the ligand is trans-chelating at a neutral Rh(l) 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.

• 出版日期2009-6-15