Dihydrogen Catalysis of the Reversible Formation and Cleavage of C-H and N-H Bonds of Aminopyridinate Ligands Bound to (eta(5)-C5Me5)Ir-III

作者：Zamorano Ana; Rendon Nuria; Lopez Serrano Joaquin; Valpuesta Jose E V; Alvarez Eleuterio; Carmona Ernesto^*

来源：Chemistry - A European Journal, 2015, 21(6): 2576-2587.

DOI：10.1002/chem.201405340

• CH activation
• dihydrogen catalysis
• iridium
• ligand isomerisation
• NH activation

This study focuses on a series of cationic complexes of iridium that contain aminopyridinate (Ap) ligands bound to an ((5)-C5Me5)Ir-III fragment. The new complexes have the chemical composition [Ir(Ap)((5)-C5Me5)](+), exist in the form of two isomers (1(+) and 2(+)) and were isolated as salts of the BArF- anion (BArF=B[3,5-(CF3)(2)C6H3](4)). Four Ap ligands that differ in the nature of their bulky aryl substituents at the amido nitrogen atom and pyridinic ring were employed. In the presence of H-2, the electrophilicity of the Ir-III centre of these complexes allows for a reversible prototropic rearrangement that changes the nature and coordination mode of the aminopyridinate ligand between the well-known (2)-N,N-bidentate binding in 1(+) and the unprecedented -N,(3)-pseudo-allyl-coordination mode in isomers 2(+) through activation of a benzylic CH bond and formal proton transfer to the amido nitrogen atom. Experimental and computational studies evidence that the overall rearrangement, which entails reversible formation and cleavage of HH, CH and NH bonds, is catalysed by dihydrogen under homogeneous conditions.

• 出版日期2015-2-2