Electronic Structure of the Ground and Low-Lying States of MoLi

Molybdenum lithium compounds and materials are being researched and applied in cutting-edge industries; however, their bonding has not been explored in a systematic way. The present study investigates the MoLi molecule, to shed light on its bonding. Specifically, the electronic structure and bonding of the ground and 40 low-lying states of the MoLi molecule are explored, employing multireference methodologies, i.e., CASSCF and MRCISD(+Q) in conjunction with the aug-cc-pV5z(-PP) basis set. Bond distances, dissociation energies, dipole moments as well as common spectroscopic constants are given, while the potential energy curves are plotted. For the ground state, XΣ+6, it is found that Re = 2.708 Å, De = 24.1 kcal/mol, ωe = 316.8 cm-1, ωexe = 2.11 cm-1, and μ = 3.63 D. Overall, the calculated states present a variety of bonds, from weak van der Waals up to the formation of 2.5 bonds. The dissociation energies of the calculated states range from 2.3 kcal/mol (aΣ+8) to 34.7 (cΠ4), while the bond distances range from 2.513 Å to 3.354 Å. Finally, dipole moment values up to 3.72 D are calculated. In most states, a 2s2pz hybridization on Li and a 4dz25s5pz or 5s5pz hybridization on Mo are found. Moreover, it is observed that the excited Li(P2) atom forms the shortest bonds because its empty 2s0 orbital can easily accept electrons, resulting in a strong σ dative bond. Finally, the present work highlights the exceptional ability of lithium atoms to participate in a variety of bonding schemes, and it could provide the opening gate for further investigation of this species or associated material and complexes.