Homoleptic Phosphaalkyne Complexes of Silver(I)

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Main Group Chemistry

Background:

• Phosphaalkynes are unsaturated phosphorus compounds analogous to alkynes.
• Silver(I) complexes with weakly coordinating anions are valuable for stabilizing unusual coordination geometries.

Purpose of the Study:

• To synthesize and characterize novel homoleptic silver(I) complexes with phosphaalkynes.
• To investigate the coordination modes of phosphaalkynes to a silver(I) center.
• To explore the reactivity of these complexes with donor molecules.

Main Methods:

• Synthesis of silver(I) salts with weakly coordinating anions ([FAl{OC12F15}3]− and [Al{OC(CF3)3}4]−).
• Coordination of two phosphaalkyne ligands (P≡CtBu) to a silver(I) center.
• Density Functional Theory (DFT) calculations to determine preferred coordination geometries.
• Characterization of the resulting complexes (1–4) using spectroscopic and crystallographic methods.

Main Results:

• Formation of unprecedented homoleptic complexes [Ag(η2-P≡CtBu)2][A] (A = [FAl{OC12F15}3]− or [Al{OC(CF3)3}4]−).
• DFT calculations revealed a perpendicular arrangement in complex 1 and a unique square-planar coordination in complex 2.
• Reactions with donor molecules (acetone and benzene) yielded trigonally planar coordinated silver salts (3 and 4).
• Comprehensive characterization of all synthesized compounds in solution and solid state.

Conclusions:

• Demonstrated the feasibility of side-on coordination of phosphaalkynes to a bare silver(I) center.
• Highlighted the influence of the weakly coordinating anion on the coordination geometry.
• Expanded the known coordination chemistry of phosphaalkynes and silver(I).