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Agostic interaction and intramolecular proton transfer from the protonation of dihydrogen ortho metalated ruthenium complexes.

Authors :
Toner A
Matthes J
GrĂ¼ndemann S
Limbach HH
Chaudret B
Clot E
Sabo-Etienne S
Source :
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2007 Apr 24; Vol. 104 (17), pp. 6945-50. Date of Electronic Publication: 2007 Mar 13.
Publication Year :
2007

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.

Details

Language :
English
ISSN :
0027-8424
Volume :
104
Issue :
17
Database :
MEDLINE
Journal :
Proceedings of the National Academy of Sciences of the United States of America
Publication Type :
Academic Journal
Accession number :
17360384
Full Text :
https://doi.org/10.1073/pnas.0608979104