Low-Coordinate Iron(II) Amido Half-Sandwich Complexes with Large Internal Magnetic Hyperfine Fields

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• The study builds upon the series of low-coordinate, quasi-linear iron amido half-sandwich complexes.
• Previous research established related complexes like Fe-tms and Fe-tBu.

Purpose of the Study:

• To synthesize and characterize new half-sandwich and mixed metallocene iron complexes.
• To investigate the electronic and magnetic properties of these novel iron compounds.

Main Methods:

• Synthesis of iron complexes: [Cp'Fe{N(dipp)(SiMe3)}] (Fe-dipp) and [Cp'Fe{(η5-C6H3Pr2)═N(SiMe3)}] (Fe-chd).
• Characterization using NMR spectroscopy, X-ray diffraction, zero-field 57Fe Mössbauer spectroscopy, and magnetic susceptibility measurements.
• Computational analysis using ab initio and density functional theory (DFT) calculations.

Main Results:

• Fe-dipp and Fe-chd were successfully synthesized and characterized.
• All investigated complexes (Fe-dipp, Fe-tBu, Fe-tms) exhibit an S=2 electronic ground state.
• Mössbauer spectroscopy revealed slow paramagnetic relaxation and large internal magnetic hyperfine fields (e.g., 96.4 T for Fe-dipp).
• Magnetic measurements indicated significant axial zero-field splitting and slow magnetization relaxation.

Conclusions:

• The synthesized iron complexes possess unique electronic and magnetic properties.
• The findings complement the understanding of low-coordinate iron amido complexes.
• Experimental data is strongly supported by theoretical calculations.