The synthesis of the 2-ferrocenyl-1,10-phenanthroline ligand 1 has been improved, and its reactivity toward palladium is described. This study allows evidencing that 1 can coordinate to the metal center in an N-N bidentate fashion or undergo ortho metalation, thus acting as a terdentate N-N-C pincer ligand. Examples of the former coordination mode include complexes [Pd(Cl)(Me)(1)] (2) and [Pd(Me)(NCMe)(1)][PF6] (3), whereas cyclometalation is observed in [Pd(1)(O2CCF3)] (5), [Pd(1)(MeCN)][PF6] (6), and [Pd(1)(PPh3)][O2CCF3] (7). These cyclometalated adducts are chiral, racemic compounds. X-ray crystal structures of compounds 5, 6, and 7 have been determined, confirming the presence of a five-membered palladacycle and evidencing that in the solid state packing occurs through weak pi-pi interactions between the phenanthroline rings of the ligands.
Palladium chemistry of 2-ferrocenyl-1,10-phenanthroline ligand
MILANI, Barbara;ZANGRANDO, ENNIO
2007-01-01
Abstract
The synthesis of the 2-ferrocenyl-1,10-phenanthroline ligand 1 has been improved, and its reactivity toward palladium is described. This study allows evidencing that 1 can coordinate to the metal center in an N-N bidentate fashion or undergo ortho metalation, thus acting as a terdentate N-N-C pincer ligand. Examples of the former coordination mode include complexes [Pd(Cl)(Me)(1)] (2) and [Pd(Me)(NCMe)(1)][PF6] (3), whereas cyclometalation is observed in [Pd(1)(O2CCF3)] (5), [Pd(1)(MeCN)][PF6] (6), and [Pd(1)(PPh3)][O2CCF3] (7). These cyclometalated adducts are chiral, racemic compounds. X-ray crystal structures of compounds 5, 6, and 7 have been determined, confirming the presence of a five-membered palladacycle and evidencing that in the solid state packing occurs through weak pi-pi interactions between the phenanthroline rings of the ligands.Pubblicazioni consigliate
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