Ligand‐Controlled CO₂ Activation Mediated by Cationic Titanium Hydride Complexes, [LTiH]⁺ (L=Cp₂, O)

Abstract

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 .

CO2 Activation and Hydrogenation by PtHn− Cluster Anions

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Mechanistic study on iron(II)‐mediated direct arylation of benzene with chlorobenzene

“…Quintessentially, Schwarz and coworkers have demonstrated, by using prototypical models, that how and why the reactivity of a “catalyst” in comparison with its counterparts can be increased, decreased, or not significantly affected . Experimental studies in combination with computational work help to elucidate the ligand effects and to uncover the mechanistic insights at a strictly molecular level, so as to guide the rational ligand design . In addition to innocent ligand, the redox active non‐innocent ligands constitute a vibrant field in coordination and organometallic chemistry .…”

“…Furthermore, we have shown that there are probably quite different mechanisms, although the pathways have similar structural features . Therefore, by using high‐level quantum chemical calculations, in combination with frontier orbital analysis, we aimed to clarify the roles of ligands so as to provide guidance for rational catalyst design.…”

Theoretical investigations of spin‐orbit coupling and intersystem crossing in reaction carbon dioxide activated by [Re(CO)2]+

“…For instance, transition metal cation [M] + and transition‐metal oxide clusters M x O y possesses an excellent efficiencies in the reduction of CO 2 . Futher, activation of CO 2 by a metal hydride ion [LTiH] + (L = Cp2, O), PtH n − , FeH − . In addition, M + (CO2) n (M = Co, Rh, Ir; n = 2‐15) and M − (CO2) n complexes (M = Au, Ag, Co, Mn, Cu, Fe, and Ni) ion‐molecule complexes are coordinated with carbon dioxide, this is also a current research hotspot.…”