Electronic structure of the dicationic first row transition metal oxides

Multi-reference electronic structure calculations combined with large basis sets are performed to investigate the electronic structure of the ground and low-lying electronic states of the MO2+ diatomic species with M = Ti-Cu. These systems have shown high efficiency in the activation of the C-H of saturated hydrocarbons. This study is the first systematic and accurate work for these systems and our results and discussion provides insights into the reactivity and stability of MO2+ units. We find that they can be divided in three groups. The early transition metals (Ti, V, Cr) have very stable and well separated oxo (M4+O2-) character ground states, the middle transition metals (Mn, Fe) have oxyl (M3+O-) ground states with low-lying oxo excited states, and the late transition metals (Co, Ni, Cu) have well separated oxyl states. The reported spectroscopic constants will aid future experimental investigations, which are sparse in the literature. Periodic trends for the bond lengths, energetics, excitation energies, and wavefunction composition are discussed in detail. Complete basis set limit results indicate the high accuracy of the quintuple-zeta basis sets.

Automated summary

This study investigates the electronic structure of MO2+ diatomic species with M = Ti-Cu using multi-reference electronic structure calculations combined with large basis sets. The systems show high efficiency in activating the C-H of saturated hydrocarbons. Different transition metals are divided into three groups based on their electronic states, providing insights into the reactivity and stability of MO2+ units. The reported spectroscopic constants will aid future experimental investigations, and periodic trends for bond lengths, energetics, excitation energies, and wavefunction composition are discussed in detail, showing the high accuracy of the quintuple-zeta basis sets.