Three and four coordinate Fe carbodiphosphorane complexes.

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Ligand Design

Background:

• Carbodiphosphoranes (CDPs) are versatile ligands with strong electron-donating capabilities.
• Iron complexes are crucial in catalysis and materials science.
• Exploring novel ligand environments for transition metals like iron is essential for discovering new reactivity.

Purpose of the Study:

• To synthesize and characterize novel three- and four-coordinate iron complexes featuring the hexaphenylcarbodiphosphorane (HCDP) ligand.
• To investigate the reactivity of these iron-CDP complexes with various reagents, including Grignard reagents and silylamides.
• To explore the potential for modifying the electronic and steric properties of iron complexes through CDP coordination.

Main Methods:

• Reaction of FeCl2(PPh3)2 with hexaphenylcarbodiphosphorane (HCDP) to form a three-coordinate iron adduct.
• Subsequent reactions of the iron-HCDP adduct with benzyl Grignard reagent and lithium bis(trimethylsilyl)amide (LiHMDS).
• Characterization of the resulting complexes using techniques such as X-ray crystallography and solution-state NMR spectroscopy.

Main Results:

• Successful synthesis of a three-coordinate iron carbodiphosphorane complex, Fe(HCDP)Cl2, which exists in equilibrium with its four-coordinate dimer.
• Preparation of a dialkylated iron complex, (HCDP)FeBn2, via reaction with benzyl Grignard.
• Formation of monosilylated iron complexes, Fe(HCDP)Cl(N(SiMe3)2) and Fe(HCDP)(OTf)(N(SiMe3)2), through salt metathesis and anion exchange.

Conclusions:

• Hexaphenylcarbodiphosphorane (HCDP) serves as a robust ligand for stabilizing diverse iron complexes.
• The synthesized iron-HCDP complexes demonstrate tunable reactivity, allowing for the introduction of alkyl and silyl substituents.
• These findings expand the scope of carbodiphosphorane chemistry and offer new avenues for iron-based coordination compounds.