title: Synthesis, structure and reactivity of Pd and Ir complexes based on new lutidine-derived NHC/phosphine mixed pincer ligands.
abstract: Coordination studies of new lutidine-derived hybrid NHC/phosphine ligands (CNP) to Pd and Ir have been performed. Treatment of the square-planar [Pd(CNP)Cl](AgCl2) complex 2a with KHMDS produces the selective deprotonation at the CH2P arm of the pincer to yield the pyridine-dearomatised complex 3a. A series of cationic [Ir(CNP)(cod)]+complexes 4 has been prepared by reaction of the imidazolium salts 1 with Ir(acac)(cod). These derivatives exhibit in the solid state, and in solution, a distorted trigonal bipyramidal structure in which the CNP ligands adopt an unusual C(axial)-N(equatorial)-P(equatorial)coordination mode. Reactions of complexes 4 with CO and H2yield the carbonyl species 5a(Cl) and 6a(Cl), and the dihydrido derivatives 7, respectively. Furthermore, upon reaction of complex 4b(Br) with base, selective deprotonation at the methylene CH2P arms is observed. The, thus formed, deprotonated Ir complex 8b reacts with H2in a ligand-assisted process leading to the trihydrido complex 9b, which can also be obtained by reaction of 7b(Cl) with H2in the presence of KOtBu. Finally, the catalytic activity of Ir-CNP complexes in the hydrogenation of ketones has been briefly assessed.
authors.affiliation: Instituto de Investigaciones Químicas (IIQ), Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA), CSIC and Universidad de Sevilla, Avda Américo Vespucio 49, 41092, Sevilla, Spain. paneque@iiq.csic.es andres.suarez@iiq.csic.es.
authors.forename: Práxedes
authors.initials: P
authors.lastname: Sánchez
authors.forename: Martín
authors.initials: M
authors.lastname: Hernández-Juárez
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Álvarez
authors.forename: Margarita
authors.initials: M
authors.lastname: Paneque
authors.forename: Nuria
authors.initials: N
authors.lastname: Rendón
authors.forename: Andrés
authors.initials: A
authors.lastname: Suárez