Theoretical Study of the Interaction of the Ti Atom with CO₂:  Cleavage of the C−O Bond

Abstract

The interaction of s2d2 and sd3 Ti atoms with the CO2 molecule has been studied using density functional theory at the gradient-corrected level. The ground state Ti inserts with no energy barrier into a CO bond resulting in an OTiCO insertion product. The intrinsic reaction coordinate for the insertion process has been defined and the reaction mechanism has been investigated by analyzing various structures along this path. The singlet and triplet states of the final product are very close in energy. The comparison of the predicted vibrational frequencies and isotopic shifts for both states with those from matrix isolation infrared data reveals that the insertion product formed in low-temperature argon matrix corresponds to singlet state OTiCO. Ti(CO2) complexes in various coordination modes have also been located on the triplet and quintet potential energy surfaces, from which the triplet state (O,O) coordination mode is the most stable one lying, however, about 30 kcal/mol above the OTiCO molecule.

The gas phase reaction between CO2 and lanthanide atoms. A test of a model for the isokinetic effect

“…Again, the main product was the insertion species OZr CO. The process was found to be barrierless, indicating that activation of CO 2 by Zr atoms requires no energy input, like already observed by one of us for Ti atoms [15]. DFT calculations performed by Qin et al on Zr(CO 2 ) complexes [14b] have shown that the η 2 -(O,O) and η 2 -(C,O) structures in the 5A' state are the most stable in energy but do not correspond to local minima, indicating that other reaction channels may be involved in the reaction.…”

“…For both alternatives, however, a side-on or a η 2 -(O,O) complex seem the most logical ones (Complexes III and II, above ). Furthermore, in (CO)MO compounds, the CO ligand is very labile and easily leads to the dissociation products CO + MO [15].…”

Carbon Dioxide Coordination Chemistry and Reactivity of Coordinated CO2

“…The interaction of s 2 d 2 and s 1 d 3 Ti atoms with CO 2 has been studied by Papai et al [39] using DFT calculations. It has been shown that the ground -state Ti atom could insert with no energy barrier into a CO bond, and this would result in an OTiCO insertion product (see Figure 4.3 ).…”

Metal Coordination ofCO2

“…For example, the interaction of s 2 d 2 and s 1 d 3 Ti atoms with CO 2 has been studied by Papai et al 48 using DFT calculations. It has been shown that the ground-state Ti atom inserts with no energy barrier into a C-O bond, resulting in an OTiCO insertion product (see Figure 6).…”