Electronic Properties of a Structural Model of Single-Atom Co-Adsorption to MoS 2 Edge Sites

Molecular-level insight into how single-atom transition metal dopants modulate electronic structure at the edge sites of MoS2 remains an underdeveloped area of research that is essential for the design of efficient catalysts. The present work describes the synthesis of a cobalt-substituted thiomolybdate dimer, (CpMo)2(Cp*Co)(μ3-S)2(μ2-S2CH2), which serves as a molecular model for cobalt adsorption at the MoS2 edge. Spectroscopic and magnetic measurements establish a diamagnetic, closed-shell ground state for the heterobimetallic complex. Time-dependent density functional theory (TD-DFT) calculations indicate significant electronic communication across the “CoMo2S4” assembly. Electrochemical studies reveal three reversible redox processes, assigned to a Co-centered reduction and Mo-based oxidations. Access to the reduced and oxidized species was possible, allowing for investigation into redox-dependent changes to electronic structure. Reduction centered at the cobalt atom generates a Co(II)Mo(III)2 complex, whereas one-electron oxidation affords a mixed-valent Co(III)Mo(IV)Mo(III) species that features electron delocalization across the “Mo2” subunit. Our findings demonstrate that cobalt incorporation significantly impacts the charge distribution and magnetic properties of the thiomolybdate, providing insight into the effects of transition metal uptake at MoS2 edge sites.