Mono- and dinuclear tetraphosphabutadiene ferrate anions

Area of Science:

• Organometallic Chemistry
• Inorganic Phosphorus Chemistry
• Coordination Chemistry

Background:

• The synthesis of novel phosphorus-containing ligands and complexes is crucial for advancing materials science and catalysis.
• Iron complexes with unique ligand environments offer opportunities for exploring new reactivity and bonding modes.
• The reactivity of elemental white phosphorus (P4) with transition metals remains an active area of research.

Purpose of the Study:

• To synthesize and characterize novel iron-phosphorus complexes utilizing white phosphorus.
• To investigate the coordination chemistry of the cyclo-P4(2-) ligand with iron centers.
• To explore the reactivity of these iron-phosphorus complexes with electrophiles and protic sources.

Main Methods:

• Reduction of a bromoiron precursor, [CpArFe(μ-Br)]2, using potassium naphthalenide or sodium amalgam.
• Reaction of the reduced iron species with white phosphorus (P4) in the presence of crown ethers or THF.
• Characterization of the resulting iron-phosphorus complexes using techniques such as X-ray crystallography and NMR spectroscopy.
• Protonation and silylation reactions of the synthesized diiron-P4 complex.

Main Results:

• Synthesis of a potassium complex [K(18-c-6){CpArFe(η4-P4)}] featuring a planar cyclo-P4(2-) ligand coordinated to an iron center.
• Formation of a related diiron complex [Na2(THF)5(CpArFe)2(μ,η4:4-P4)] through reduction with sodium amalgam.
• Protonation of the diiron complex yielded a protonated species [Na(THF)3][(CpArFe)2(μ,η4:4-P4)(H)].
• Reaction of the diiron complex with trimethylchlorosilane led to the formation of a nortricyclane compound P7(SiMe3)3.

Conclusions:

• The study successfully demonstrates the utility of alkali metal reductions for accessing iron complexes with a cyclo-P4(2-) ligand.
• The synthesized complexes provide insights into the coordination modes and stability of P4 ligands in organometallic frameworks.
• The reactivity studies highlight the potential for further functionalization and transformation of these iron-phosphorus compounds.