Benzenedithiolate-bridged MoFe complexes: structures, oxidation states, and reactivities

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• Molybdenum-iron complexes are crucial in various catalytic processes.
• Understanding the synthesis and structure of heterobinuclear complexes provides insights into bonding and reactivity.
• Benzendithiolate ligands offer unique bridging capabilities in multinuclear metal complexes.

Purpose of the Study:

• To synthesize and characterize novel benzendithiolate-bridged MoFe complexes.
• To elucidate the structural features and bonding in these complexes.
• To investigate the reactivity and formation pathways of the synthesized complexes.

Main Methods:

• Synthesis of MoFe complexes via reaction of a molybdenum precursor with iron pentacarbonyl.
• Single-crystal X-ray diffractometry for structural determination.
• ⁵⁷Fe Mössbauer spectroscopy and X-ray photoelectron spectroscopy (XPS) for metal oxidation state analysis.

Main Results:

• Two benzendithiolate-bridged MoFe complexes, [(Me₃P)₂(CO)₂Mo(μ-S₂C₆H₄)Fe(CO)₃] (1) and [(Me₃P)(CO)₃Mo(μ-S₂C₆H₄)Fe(CO)₃] (2), were successfully synthesized.
• Structural analysis revealed direct Mo-Fe bonds supported by bridging benzendithiolate and semi-bridging carbonyl ligands.
• Reactivity studies indicated that complex 2 likely forms from complex 1, and reaction of 2 with PMe₃ yields a diiron complex (4).
• Spectroscopic studies determined the oxidation states in complex 2 to be Fe⁰ and Mo^II.

Conclusions:

• The synthesis and characterization of novel MoFe complexes expand the scope of heterobinuclear organometallic chemistry.
• The proposed formation pathway provides mechanistic insights into the assembly of such complexes.
• The determined metal oxidation states are crucial for understanding their electronic properties and potential catalytic applications.