Theoretical Study of M⁺−CO₂ and OM⁺CO Systems for First Transition Row Metal Atoms

Abstract

The coordination of carbon dioxide to first transition row metal cations and the insertion reaction of the metal into one CO bond of carbon dioxide have been studied theoretically. The geometry and the vibrational frequencies of the M+−CO2 and OM+CO structures have been determined using the hybrid three-parameter B3LYP density functional approach. Binding energies have also been determined at the CCSD(T) level using large basis sets. The linear end-on M+−OCO structure is the most favorable coordination for CO2, due to the electrostatic nature of the bonding. In the inserted OM+CO structures, the bonding arises from the electrostatic interaction between the ground state of OM+ and CO. For the early transition metals (Sc+, Ti+, and V+), the insertion reaction is exothermic and the inserted OM+CO structure is more stable than the linear M+−OCO isomer, because of the very strong MO+ bond that is formed.

The Carbon Dioxide Molecule and the Effects of Its Interaction with Electrophiles and Nucleophiles

“…This suggests that the interaction of CO 2 with an electrophilic center through one of the 1π g lone pairs is not accompanied by any significant back donation of electron density into the 2π u orbitals of the heterocumulene, which, therefore, are left empty. This is the case of transition metals from groups 8 to 12 binding CO 2 that form M + (CO 2 ) n adducts with n varying from 1 to 4 [127]. The major stabilizing strength is the donation O-to-metal cation as the πÀback donation is close to zero.…”

Theoretical study of the reactions of lanthanide ions (Ce+, Pr+) with CO2 in the gas phase

“…Because the bonding is mainly electrostatic, the interaction between carbon dioxide and lanthanide ions produces only a small asymmetry in the two CAO bond lengths; the CAO bond length adjacent to the metal ion increases about 0.02Å , while the other CAO bond length decreases about 0.02Å . This variation is very similar to the reaction of first transition-metal cations with CO 2 [4], which indicate that no significant p back-donation from the lanthanide ions to CO 2 is present.…”

“…Here, we explore the PESs for the crossing seam and the possibility of process for the CAO bond activation of carbon dioxide by Ce þ and Pr þ . The flip of spin may be expected to occur from the quartet state to doublet state in the region prior to 4 TS 01 (for Ce þ ), and the triplet state to singlet state in the region after 3 TS 01 (for Pr þ ), respectively. Spin inversion is a nonadiabatic process and requires an inspection for a crossing seam on different potential energy surfaces.…”

“…V C 2010 Wiley 1. Introduction B ecause they can provide fundamental information about catalytic bond activation, a large number of studies both experimental and theoretical have been devoted to the reactions of transition metal atoms or ions with small molecules (i.e., NO, CO, NO 2 , CO 2 , N 2 O, H 2 , CH 4 , etc.) [1].…”

Metal Coordination ofCO2

“…As CO 2 has a negative quadrupole moment, cationic metals are electrostatically bound to CO 2 in an end-on way and there is no significant π-backdonation from the metal cation to CO 2 . 17 The M + -CO 2 bond distances depend on both the size of the ion and its electronic configuration. Similarly, the binding energies depend on the electrostatic attraction between M + and CO 2 , which follows the trend in the ion size and in the repulsion between the cation d orbitals and the CO 2 occupied orbitals, the order of repulsion being 3dσ > 3dπ > 3dδ.…”