title: Agostic interaction and intramolecular proton transfer from the protonation of dihydrogen ortho metalated ruthenium complexes.
abstract: Protonation of the ortho-metalated ruthenium complexes RuH(H(2))(X)(P(i)Pr(3))(2) [X = 2-phenylpyridine (ph-py) (1), benzoquinoline (bq) (2)] and RuH(CO)(ph-py)(P(i)Pr(3))(2) (3) with [H(OEt(2))(2)](+)[BAr'(4)](-) (BAr'(4) = [(3,5-(CF(3))(2)C(6)H(3))(4)B]) under H(2) atmosphere yields the corresponding cationic hydrido dihydrogen ruthenium complexes [RuH(H(2))(H-X)(P(i)Pr(3))(2)][BAr'(4)] [X = phenylpyridine (ph-py) (1-H); benzoquinoline (bq) (2-H)] and the carbonyl complex [RuH(CO)(H-ph-py)(P(i)Pr(3))(2)][BAr'(4)] (3-H). The complexes accommodate an agostic C H interaction characterized by NMR and in the case of 1-H by x-ray diffraction. Fluxional processes involve the hydride and dihydrogen ligands in 1-H and 2-H and the rotation of the phenyl ring displaying the agostic interaction in 1-H and 3-H. NMR studies (lineshape analysis of the temperature-dependent NMR spectra) and density functional theory calculations are used to understand these processes. Under vacuum, one equivalent of dihydrogen can be removed from 1-H and 2-H leading to the formation of the corresponding cationic ortho-metalated complexes [Ru(H(2))(THF)(X)(P(i)Pr(3))(2)](+) [X = ph-py (1-THF), bq (2-THF)]. The reaction is fully reversible. Density functional theory calculations and NMR data give information about the reversible mechanism of C H activation in these ortho-metalated ruthenium complexes. Our study highlights the subtle interplay between key ligands such as hydrides, sigma-dihydrogen, and agostic bonds, in C H activation processes.
authors.affiliation: Laboratoire de Chimie de Coordination du Centre National de la Recherche Scientifique, Associé à l'Université Paul Sabatier, 205 route de Narbonne, 31077 Toulouse Cedex 04, France.
authors.forename: Andrew
authors.initials: A
authors.lastname: Toner
authors.forename: Jochen
authors.initials: J
authors.lastname: Matthes
authors.forename: Stephan
authors.initials: S
authors.lastname: Gründemann
authors.forename: Hans-Heinrich
authors.initials: HH
authors.lastname: Limbach
authors.forename: Bruno
authors.initials: B
authors.lastname: Chaudret
authors.forename: Eric
authors.initials: E
authors.lastname: Clot
authors.forename: Sylviane
authors.initials: S
authors.lastname: Sabo-Etienne