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X‐Ray Photoelectron Spectroscopy and Reactivity Studies of a Series of Ruthenium Catalysts
Author(s) -
Jarzembska Katarzyna,
Seal Sudipta,
Woźniak Krzysztof,
Szadkowska Anna,
Bieniek Michał,
Grela Karol
Publication year - 2009
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.200900052
Subject(s) - reactivity (psychology) , x ray photoelectron spectroscopy , ruthenium , catalysis , chemistry , carbene , ligand (biochemistry) , osmium , binding energy , photochemistry , organic chemistry , chemical engineering , physics , nuclear physics , medicine , biochemistry , alternative medicine , receptor , pathology , engineering
X‐Ray photoelectron spectroscopy (XPS) was applied to six selected ruthenium precatalysts. The XPS data obtained were compared against reactivity and structural results. The XPS data confirmed some dependencies such as the electron‐donor properties of the substituents at the ruthenium center. Additionally, the data combined with structural and reactivity results explain the differences between the character of Grubbs and Hoveyda catalysts. It was found that changing the PCy 3 ligand to O i Pr (PCy 3 =tricyclohexylphosphane, O i Pr=isopropoxy) has a major influence on relative electron‐donating properties of the N‐heterocyclic carbene ligand (NHC) and PCy 3 groups, which was supported by the relative charges on the Ru center for the examined compounds. Moreover, the turnover frequency (TOF) of a selected example reaction decreased when introducing a NHC group in the case of Grubbs catalysts, but increased in the case of Hoveyda‐type catalysts. The XPS data also explained the relative activity values of some catalysts (higher reactivity of nitro‐Hoveyda than Hoveyda second‐generation catalysts). However, the binding energies do not predict TOFs. Sole examination of the XPS data does not provide a base for reaching unambiguous and binding conclusions as to the relative reactivity of all the investigated systems.