Synthesis and DFT calculations of spirooxaphosphirane complexes

Area of Science:

• Organometallic Chemistry
• Phosphorus Chemistry
• Synthetic Organic Chemistry

Background:

• Phosphinidenoid complexes are reactive intermediates with potential in synthesizing novel organophosphorus compounds.
• Cyclic ketones serve as versatile substrates for cycloaddition reactions.

Purpose of the Study:

• To synthesize and characterize the first P-C5Me5 substituted C(3)-spirofused oxaphosphirane complexes.
• To investigate the influence of spiro ring size on the stability and electronic properties of these complexes.

Main Methods:

• In situ formation of Li/Cl phosphinidenoid complexes [Li(12-crown-4)][M(CO)5(ClPC5Me5)] (M = Cr, Mo, W).
• Reaction of phosphinidenoid complexes with cyclobutanone, cyclopentanone, and cyclohexanone.
• Characterization using NMR, IR, MS, and single-crystal X-ray diffraction.
• Density Functional Theory (DFT) calculations on oxaphosphirane complexes.

Main Results:

• Successful synthesis of novel C(3)-spirofused oxaphosphirane complexes.
• Observation of different reaction outcomes in Et2O versus THF, leading to phosphinoate complexes and unusual co-ligands.
• X-ray structures confirmed the formation of target complexes.
• DFT calculations showed decreased ring strain and altered electronic properties with increasing spiro ring size.

Conclusions:

• The study reports the first synthesis of P-C5Me5 substituted C(3)-spirofused oxaphosphirane complexes.
• Ring strain and electronic properties are sensitive to the size of the spirocyclic system.
• The findings provide insights into the reactivity of phosphinidenoid complexes and the structural characteristics of spirocyclic organophosphorus compounds.