Radical and diradical states of bis(molybdenocene dithiolene) complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Bis(dithiolene) complexes are crucial in redox-active materials.
• Understanding the influence of bridging ligands on electronic properties is key.
• Molybdenum dithiolene complexes offer tunable redox behavior.

Purpose of the Study:

• To synthesize and characterize novel bis(dithiolene) proligands with heteroatomic linkers.
• To investigate the electrochemical and spectroelectrochemical properties of resulting bimetallic molybdenum complexes.
• To rationalize the electronic structure and redox behavior using computational methods.

Main Methods:

• Synthesis of bis(dithiolene) proligands with 1,4-dithiine and dihydro-1,4-disiline linkers.
• Formation and characterization of bimetallic bis(cyclopentadienyl)molybdenum dithiolene complexes.
• Electrochemical techniques including cyclic voltammetry and spectroelectrochemistry.
• (Time-Dependent) Density Functional Theory ((TD-)DFT) calculations for property rationalization.

Main Results:

• Successful synthesis and characterization of two novel bis(dithiolene) proligands and their bimetallic molybdenum complexes.
• Sequential oxidation of redox centers observed via cyclic voltammetry, with varying potential differences based on the heteroatomic bridge.
• Bis-oxidized complexes exhibit either diradical character or a closed-shell dicationic state, dependent on the bridge's nature.

Conclusions:

• The heteroatomic bridge significantly modulates the electronic communication and redox properties of bimetallic molybdenum dithiolene complexes.
• The observed oxidation states (diradical vs. dicationic) are directly linked to the structural and electronic characteristics of the bridging unit.
• These findings contribute to the design of novel redox-active organometallic materials with tunable electronic properties.