"Triple-Decker Sandwich" Containing Planar {B₂E₂Pd} Ring (E = S or Se).

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Triple-decker complexes are of interest for their unique electronic and structural properties.
• Previous research has focused on various metal combinations, but palladium-centered complexes remain less explored.
• The synthesis of heterometallic complexes offers opportunities for novel reactivity and applications.

Purpose of the Study:

• To synthesize novel triple-decker complexes incorporating a {PdCl2} moiety.
• To investigate the reactivity of specific bimetallic precursors with a palladium source.
• To characterize the resulting complexes and elucidate their structural and bonding features.

Main Methods:

• Reaction of [(Cp*M)2{μ-B2H2E2}] precursors (M = Co, Rh, Ir; E = S, Se) with [PdCl2(COD)].
• Spectroscopic characterization (NMR, Mass Spectrometry, etc.).
• Single-crystal X-ray diffraction for structural determination of key complexes.
• Density Functional Theory (DFT) calculations for electronic structure analysis.

Main Results:

• Successful synthesis of four new trinuclear heterometallic triple-decker complexes, [(Cp*M)2{μ-B2H2E2Pd(Cl)2}].
• Complexes feature a planar bridging palladacycle ligand with Pd(II) in an unusual pseudo-octahedral environment.
• X-ray diffraction confirmed the structures of complexes 5-7, revealing elongated M-Pd bonding.
• DFT studies indicated strong electron donation from the B2E2 fragment to axial metals and weak M-Pd interactions.

Conclusions:

• Novel triple-decker complexes with a central {PdCl2} unit have been synthesized and characterized.
• The electronic structure reveals significant electron donation within the complex, influencing metal-metal bonding.
• These findings contribute to the understanding of heterometallic triple-decker systems and palladium coordination chemistry.