Electronic Structure of the Low‐Lying States of the Triatomic MoS₂ Molecule: The Building Block of 2D MoS₂

Abstract

Molybdenum disulfide (MoS2) is the building component of 1D‐monolayer, 2D‐layered nanosheets and nanotubes having many applications in industry, and it is detected in molecular systems observed in nature. Here, the electronic structure and the chemical bonding of sixteen low‐lying states of the triatomic MoS2 molecule are investigated, while the connection of the chemical bonding of the isolated MoS2 molecule to the relevant 2D‐MoS2, is emphasized. The MoS2 molecule is studied via DFT and multireference methodologies, i.e., MRCISD(+Q)/aug‐cc‐pVQZ(‐PP)Mo. The ground state, 3B1, is bent (Mo‐S=2.133 Å and φ(SMoS)=115.9°) with a dissociation energy to atomic products of 194.7 kcal/mol at MRCISD+Q. In the ground and in the first excited state a double bond is formed between Mo and each S atom, i.e., . These two states differ in which d electrons of Mo are unpaired. The Mo‐S bond distances of the calculated states range from 2.108‐2.505 Å, the SMoS angles range from 104.1‐180.0°, and the Mo‐S bonds are single or double. Potential energy curves and surfaces have been plotted for the 3B1, 5A1 and 5B1 states. Finally, the low‐lying septet states of the triatomic molecule are involved in the material as a building block, explaining the variety of its morphologies.

Electronic Structure and Chemical Bonding of the First-, Second-, and Third-Row-Transition-Metal Monoborides: The Formation of Quadruple Bonds in RhB, RuB, and TcB

“…As a final remark, it has been reported that the states of the diatomic and triatomic molecules of sulfides are involved in complexes and solid or 2D materials as building blocks, explaining the variety of their morphologies [19,20]. Similarly, the present data may present a new approach to exploring the properties of solid state and 2D metastable polymorphic materials involving transition-metal borides, while they may assist in explaining the catalytic properties of complexes, including transition-metal boride bonds.…”

“…Ground states of the MBs along with "recommended" bond distances, dissociation energies, and dipole moments were calculated, and = Ti, Cr, Nb, Mo, Ta, and W) [18]. It has been reported that the electronic structure and the chemical bonding of diatomic and triatomic molecules are strongly related to their structure, the variety of their morphologies, and the properties of their 2D materials and solid state [19,20]. Therefore, an investigation of the electronic structure and the bonding of the diatomic transition-metal borides, which constitute the simplest building blocks of the compounds or materials in question, would lay the foundation for understanding the very complex solid-metal borides and even their bulk properties.…”