Dioxygen Activation with Molybdenum Complexes Bearing Amide-Functionalized Iminophenolate Ligands.

Area of Science:

• Coordination Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Molybdenum complexes are investigated for catalytic applications.
• Iminophenolate ligands offer tunable electronic and steric properties.
• Internal hydrogen bonding can influence molecular structure and reactivity.

Purpose of the Study:

• Synthesize novel iminophenolate ligands with amidopropyl side chains.
• Prepare dioxidomolybdenum(VI) complexes with pendant hydrogen bond donors.
• Investigate the dioxygen activation capabilities of these complexes and compare them with a related complex.

Main Methods:

• Ligand synthesis and characterization.
• Preparation and spectroscopic characterization of molybdenum complexes.
• X-ray diffraction analysis for structural determination.
• In situ catalytic studies for dioxygen activation.

Main Results:

• Two novel iminophenolate ligands (HL2, HL3) with amidopropyl side chains were synthesized.
• Dioxidomolybdenum(VI) complexes [MoO2L] were prepared and characterized.
• Complexes 1-3 activated dioxygen, forming oxido peroxido complexes [MoO(O2)L].
• Molybdenum(IV) species were unstable for ligands with amidopropyl side chains.
• Structural and catalytic properties were systematically compared, highlighting the influence of internal hydrogen bonds.

Conclusions:

• Novel iminophenolate ligands facilitate the synthesis of reactive molybdenum complexes.
• The prepared complexes exhibit dioxygen activation capabilities.
• Internal hydrogen bonds play a crucial role in the geometry and catalytic performance of these molybdenum complexes in aerobic oxidation reactions.