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Hydrogen Generation by Water Reduction with [Cp* 2 Ti(OTf)]: Identifying Elemental Mechanistic Steps by Combined In Situ FTIR and In Situ EPR Spectroscopy Supported by DFT Calculations
Author(s) -
Hollmann Dirk,
Grabow Kathleen,
Jiao Haijun,
Kessler Monty,
Spannenberg Anke,
Beweries Torsten,
Bentrup Ursula,
Brückner Angelika
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201301598
Subject(s) - trifluoromethanesulfonate , electron paramagnetic resonance , chemistry , hydrogen bond , hydrogen , molecule , fourier transform infrared spectroscopy , spectroscopy , hydrogen atom abstraction , in situ , crystallography , catalysis , nuclear magnetic resonance , organic chemistry , physics , quantum mechanics
A detailed mechanism of hydrogen production by reduction of water with decamethyltitanocene triflate [Cp* 2 Ti III (OTf)] has been derived for the first time, based on a comprehensive in situ spectroscopic study including EPR and ATR‐FTIR spectroscopy supported by DFT calculations. It is demonstrated that two H 2 O molecules coordinate to [Cp* 2 Ti III (OTf)] subsequently forming [Cp 2 *Ti III (H 2 O)(OTf)] and [Cp*Ti III (H 2 O) 2 (OTf)]. Triflate stabilizes the water ligands by hydrogen bonding. Liberation of hydrogen proceeds only from the diaqua complex [Cp*Ti III (H 2 O) 2 (OTf)] and involves, most probably, abstraction and recombination of two H atoms from two molecules of [Cp*Ti III (H 2 O) 2 (OTf)] in close vicinity, which is driven by the formation of a strong covalent TiOH bond in the resulting final product [Cp* 2 Ti IV (OTf)(OH)].
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