Ligand-Controlled CO2 Activation Mediated by Cationic Titanium Hydride Complexes, [LTiH](+) (L=Cp2 , O).
CO2 activation mediated by [LTiH](+) (L=Cp2 , O) is observed in the gas phase at room temperature using electrospray-ionization mass spectrometry, and reaction details are derived from traveling wave ion-mobility mass spectrometry. Wheresas oxygen-atom transfer prevails in the reaction of the oxide complex [OTiH](+) with CO2 , generating [OTi(OH)](+) under the elimination of CO, insertion of CO2 into the metal-hydrogen bond of the cyclopentadienyl complex, [Cp2 TiH](+) , gives rise to the formate complex [Cp2 Ti(O2 CH)](+) . DFT-based methods were employed to understand how the ligand controls the observed variation in reactivity toward CO2 . Insertion of CO2 into the Ti-H bond constitutes the initial step for the reaction of both [Cp2 TiH](+) and [OTiH](+) , thus generating formate complexes as intermediates. In contrast to [Cp2 Ti(O2 CH)](+) which is kinetically stable, facile decarbonylation of [OTi(O2 CH)](+) results in the hydroxo complex [OTi(OH)](+) . The longer lifetime of [Cp2 Ti(O2 CH)](+) allows for secondary reactions with background water, as a result of which, [Cp2 Ti(OH)](+) is formed. Further, computational studies reveal a good linear correlation between the hydride affinity of [LTi](2+) and the barrier for CO2 insertion into various [LTiH](+) complexes. Understanding the intrinsic ligand effects may provide insight into the selective activation of CO2 .
Institut für Chemie, Technische Universtät Berlin, Strasse des 17. Juni 135, 10623, Berlin (Germany).
Shi-Ya
SY
Tang
Institut für Chemie, Technische Universtät Berlin, Strasse des 17. Juni 135, 10623, Berlin (Germany).
Nicole J
NJ
Rijs
Institut für Chemie, Technische Universtät Berlin, Strasse des 17. Juni 135, 10623, Berlin (Germany).
Jilai
J
Li
Institut für Chemie, Technische Universtät Berlin, Strasse des 17. Juni 135, 10623, Berlin (Germany).
Maria
M
Schlangen
Institut für Chemie, Technische Universtät Berlin, Strasse des 17. Juni 135, 10623, Berlin (Germany). Helmut.Schwarz@tu-berlin.de.
Helmut
H
Schwarz
ESI mass spectrometry; bond activation; carbon dioxide; decarbonylation; ion-mobility mass spectrometry; metal hydrides