Covalent Bonding Between Ir and High-Oxidation State Sb Constrained by Quinoline Scaffolds

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Materials Science

Background:

• High-valent antimony (Sb(V)) and low-valent iridium (Ir(I)) complexes are crucial in catalysis.
• Understanding metal-metal bonding is key to designing new functional materials.

Purpose of the Study:

• To synthesize and characterize a novel bimetallic Sb-Ir complex.
• To investigate the nature of the Sb-Ir bond and its implications for electronic properties.

Main Methods:

• Reaction of a Sb(V) proligand with an Ir(I) precursor in acetonitrile.
• X-ray crystallography for structural determination.
• Density Functional Theory (DFT) calculations for electronic structure analysis.

Main Results:

• Isolation of a unique bimetallic Sb-Ir complex with an unprecedentedly short Sb-Ir bond (2.51502(18) Å).
• Experimental and computational evidence for significant covalent character in the Sb-Ir bond.
• The electronic structure suggests a mixed Sb(IV)-Ir(II) character, impacting the Ir center's π-basicity.

Conclusions:

• The study reports the shortest Sb-Ir bond, highlighting novel coordination chemistry.
• The covalent nature of the Sb-Ir bond challenges traditional oxidation state assignments.
• The findings provide insights into the electronic properties of Sb-Ir complexes, relevant for future catalyst design.