1,1'-Binaphthyl-substituted diphosphene: synthesis, structures, and chiral optical properties.

Area of Science:

• Organophosphorus Chemistry
• Chiral Molecule Synthesis
• Spectroscopy

Background:

• Diphosphenes, molecules featuring a phosphorus-phosphorus double bond (P=P), are reactive and have limited stability.
• Axial chirality, arising from restricted rotation around a single bond, is a key feature in many functional molecules.
• The synthesis and characterization of novel diphosphene structures are crucial for advancing organophosphorus chemistry.

Purpose of the Study:

• To synthesize and characterize a novel 1,1'-binaphthyl-substituted diphosphene.
• To prepare an optically active form of the diphosphene, establishing it as the first chiral diphosphene.
• To investigate the chiroptical properties of the synthesized chiral diphosphene using circular dichroism (CD) spectroscopy.

Main Methods:

• Synthesis of 1,1'-binaphthyl-substituted diphosphene 1.
• Preparation of the optically active enantiomer of diphosphene 1.
• Full characterization of the synthesized diphosphene, including spectroscopic analysis.
• Measurement of circular dichroism (CD) spectra to assess chiroptical properties.

Main Results:

• Successful synthesis and full characterization of 1,1'-binaphthyl-substituted diphosphene 1.
• Demonstration of the first optically active chiral diphosphene.
• Observation of apparent circular dichroism in the longer wavelength region of the CD spectra, attributed to the P=P moiety.

Conclusions:

• The synthesized 1,1'-binaphthyl-substituted diphosphene is the first example of a chiral diphosphene.
• The P=P double bond in the chiral diphosphene moiety is responsible for the observed circular dichroism.
• This work opens new avenues for the development of novel chiral organophosphorus compounds and materials.