title: Synthesis and Reactivity toward H2 of (η(5)-C5Me5)Rh(III) Complexes with Bulky Aminopyridinate Ligands.
abstract: Electrophilic, cationic Rh(III) complexes of composition [(η(5)-C5Me5)Rh(Ap)](+), (1(+)), were prepared by reaction of [(η(5)-C5Me5)RhCl2]2 and LiAp (Ap = aminopyridinate ligand) followed by chloride abstraction with NaBArF (BArF = B[3,5-(CF3)2C6H3]4). Reactions of cations 1(+) with different Lewis bases (e.g., NH3, 4-dimethylaminopyridine, or CNXyl) led in general to monoadducts 1·L(+) (L = Lewis base; Xyl = 2,6-Me2C6H3), but carbon monoxide provided carbonyl-carbamoyl complexes 1·(CO)2(+) as a result of metal coordination and formal insertion of CO into the Rh-Namido bond of complexes 1(+). Arguably, the most relevant observation reported in this study stemmed from the reactions of complexes 1(+) with H2. (1)H NMR analyses of the reactions demonstrated a H2-catalyzed isomerization of the aminopyridinate ligand in cations 1(+) from the ordinary κ(2)-N,N' coordination to a very uncommon, formally tridentate κ-N,η(3) pseudoallyl bonding mode (complexes 3(+)) following benzylic C-H activation within the xylyl substituent of the pyridinic ring of the aminopyridinate ligand. The isomerization entailed in addition H-H and N-H bond activation and mimicked previous findings with the analogous iridium complexes. However, in dissimilarity with iridium, rhodium complexes 1(+) reacted stoichiometrically at 20 °C with excess H2. The transformations resulted in the hydrogenation of the C5Me5 and Ap ligands with concurrent reduction to Rh(I) and yielded complexes [(η(4)-C5Me5H)Rh(η(6)-ApH)](+), (2(+)), in which the pyridinic xylyl substituent is η(6)-bonded to the rhodium(I) center. New compounds reported were characterized by microanalysis and NMR spectroscopy. Representative complexes were additionally investigated by X-ray crystallography.
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC), and Universidad de Sevilla Av. Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Zamorano
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC), and Universidad de Sevilla Av. Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: Nuria
authors.initials: N
authors.lastname: Rendón
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC), and Universidad de Sevilla Av. Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: José E V
authors.initials: JE
authors.lastname: Valpuesta
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC), and Universidad de Sevilla Av. Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: Eleuterio
authors.initials: E
authors.lastname: Álvarez
authors.affiliation: Instituto de Investigaciones Químicas (IIQ) Departamento de Química Inorgánica and Centro de Innovación en Química Avanzada (ORFEO-CINQA) Consejo Superior de Investigaciones Científicas (CSIC), and Universidad de Sevilla Av. Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Carmona