Iron pyrrole-based PNP pincer ligand complexes as catalyst precursors

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Catalysis

Background:

• Pincer ligands feature a backbone and two arms, typically coordinating to a metal center in a meridional configuration.
• Pyrrole-based PNP pincer ligands offer unique electronic and steric properties for metal complexation.

Purpose of the Study:

• To synthesize and characterize novel iron complexes featuring the pyrrole-based 2,5-bis[(diisopropylphosphanyl)methyl]pyrrolide (PN^pyrP) pincer ligand.
• To explore the potential of these iron complexes as precursors for new iron catalysts.

Main Methods:

• Synthesis of three distinct iron complexes: [Fe(PN^pyrP)Cl(PMe₃)(CO)], [Fe(PN^pyrP)Cl(py)], and [Fe(PN^pyrP)Cl(CO)₂].
• Structural characterization of the synthesized complexes using X-ray crystallography to determine their coordination geometries.

Main Results:

• Complex I ([Fe(PN^pyrP)Cl(PMe₃)(CO)]) exhibits a distorted octahedral geometry with Cl and CO in apical positions.
• Complex II ([Fe(PN^pyrP)Cl(py)]) is a five-coordinate square-pyramidal complex with pyridine apical.
• Complex III ([Fe(PN^pyrP)Cl(CO)₂]) is similar to Complex I, featuring cis-configured carbonyl ligands and positional disorder.

Conclusions:

• The successful synthesis of these iron-PNP pincer complexes provides a foundation for developing new iron-based catalytic systems.
• The diverse coordination environments observed highlight the versatility of the PN^pyrP ligand in stabilizing different iron oxidation states and geometries.