Formation of Metallocene Single-Molecule Junctions Via Metal-Metal Bonds

Area of Science:

• Organometallic Chemistry
• Molecular Electronics
• Surface Science

Background:

• Metallocenes, like ferrocene, are typically assumed to interact with surfaces via van der Waals forces.
• Understanding single-molecule junction formation is crucial for advancing molecular electronics.

Purpose of the Study:

• To investigate the junction formation mechanism of group VIII metallocenes (ferrocene, ruthenocene, osmocene) with gold electrodes.
• To explore the nature of bonding in metallocene-based single-molecule devices.

Main Methods:

• Scanning tunneling microscope-based break junction (STM-BJ) technique.
• Ambient condition measurements.
• Ab initio quantum transport calculations.

Main Results:

• Ruthenocene and osmocene form stable molecular junctions with gold electrodes without chemical linkers.
• A ring-slippage mechanism involving metal-metal (Ru-Au, Os-Au) bond formation is proposed and supported by calculations.
• Metallocenes bind to gold electrodes via their metal centers in the +3 oxidation state.

Conclusions:

• Metallocenes can form direct metal-metal bonds with gold electrodes, challenging previous assumptions.
• This study demonstrates a novel method for creating stable organometallic single-molecule devices.
• The findings pave the way for more versatile and robust molecular electronic applications.