Evaluation of copper nanocatalyst performance in S-methyl thioformate synthesis from carbon monoxide: Structural and mechanistic insights

S-methyl thioformate (MTF) holds promise in pharmaceutical applications due to its antimicrobial properties and role in synthesizing therapeutic agents for diseases such as cancer and diabetes. This study employs density functional theory (DFT) to investigate the catalytic synthesis of MTF from carbon monoxide (CO) and methanethiol (CH₃SH) using a Cu₂₀O₂₀ nanocatalyst model. Three reaction pathways were explored based on varying reactant ratios: Path A (1:1 CO:CH₃SH leading to CH₃SCOH), Path B (2:1 CO:CH₃SSH, leading to HCOSCH₃ + COS), and Path C (1:2 CO:CH₃SH, leading to CH₃SCOH + H₂S). Thermodynamic and kinetic analyses reveal Path A as the most favorable, characterized a lower energy barrier (15–20 kcal.mol⁻¹) and enhanced charge transfer (0.26 |e|), leads to efficient MTF formation. Natural Bond Orbital (NBO) analysis of MTF conformations indicates the cis form is more stable, attributed to optimized bond lengths, electron distributions, and hyper conjugative interactions. These findings provide mechanistic insights for optimizing catalytic processes in sulfur chemistry, with implications for developing stable pro-drugs.