Redox Isomeric Surface Structures Are Preferred over Odd-Electron Pt¹.

Area of Science:

• Surface Chemistry
• Coordination Chemistry
• Heterogeneous Catalysis

Background:

• Metal-ligand coordination networks on surfaces are crucial for bifunctional metallochemistry.
• Controlling redox states of metals within these networks is key for applications like catalysis.

Purpose of the Study:

• To investigate the formation of mixed-valence platinum structures on the Au(100) surface using a specific tetrazine ligand.
• To understand the coordination behavior and stability of different platinum oxidation states (Pt0 and PtII) within a surface-assembled network.

Main Methods:

• Co-deposition of platinum and a substituted tetrazine ligand on the Au(100) surface.
• Systematic variation of metal:ligand stoichiometry.
• Scanning tunneling microscopy (STM) for structural analysis.
• Density functional theory (DFT) calculations for detailed geometric insights.

Main Results:

• Formation of a Pt0/PtII mixed-valence structure at a 2:1 metal:ligand ratio.
• Evidence that the ligand's electronic properties and platinum's oxidation state preferences drive the mixed-valence state.
• STM revealed irregular chain structures consistent with mixed valence states.
• DFT calculations provided insights into distinct local coordination geometries for each Pt valence state.

Conclusions:

• Demonstrated the successful formation of mixed-valence states in on-surface metal-organic networks.
• This work expands the available single-site metal structures for surface chemistry and catalysis.
• Confirms the coexistence of redox-isomeric Pt0 and Pt2+ surface structures within this specific ligand environment.