Use of Cyclotriphosphazene as a Molecular Scaffold for Building Chiral Multispin Systems

ABSTRACT

Chiral mononitroxide-, dinitroxide-, tetranitroxide- and hexanitroxide- cyclotriphosphazene hybrid compounds, along with a chiral 2,2′-bridged trinitroxide-bis(cyclotriphosphazene) hybrid compound, have been prepared to examine the potential use of the cyclotriphosphazene framework as a molecular scaffold for elaborating chiral multispin systems. EPR spectroscopic studies in solution and in frozen solvent matrixes indicate that strong intramolecular through-space electron-exchange interactions are observed for the tetranitroxide and hexanitroxide hybrid compounds, while magnetic susceptibility measurements show that weak antiferromagnetic interactions are uniformly recognized in the solid states for all of them. The X-ray crystallographic analysis of the dinitroxide hybrid compound ascribes the latter antiferromagnetic behavior to an intermolecular origin.

Keywords:

• chiral multispin system
• chiral nitroxide-cyclotriphosphazene hybrid
• chiral nitroxide radical
• electron paramagnetic resonance spectroscopy
• magnetic susceptibility measurement
• X-ray crystallographic analysis