Syntheses And Properties Of Radicals Based On The Triarylamine

Group 15 element-based radicals,as an important branch of main group radical species,have been a popular research topic in recent years.Owing to their intrinstic high reactivity,most radicals readily undergo polymerization,oxidation,dimerization and so forth.Due to the unstable chemical nature,most radicals can only be detected in solution and can not be isolated in solid form,which prevents further investigation and practical applications.Therefore,it is important to explore a new method to stabilize radicals.This thesis will review the previous work on diradicals as well as polyradicals.A conclusion will be made about the isolation,characterization and theoretical calculations of several types of triarylamine-based radical cations stabilized by weak coordinating anions?[Al?ORF?₄]^-?.1.In the first part,based on the triarylamine,compounds 1-3 were successfully synthesized.By using weakly coordination anion,1²⁺ and 2²⁺ were stabilized,at the same time,3²⁺ was isolated as crystals single,and its structure has determined by X-ray diffraction.Their geometric and electronic structures in the ground state were investigated by UV-vis,EPR,superconducting quantum interference device?SQUID?measurements and DFT calculations.The two radical centers in 1²⁺ and 2²⁺ have very weak interaction thus they are best described as biradical.While 3²⁺ is an open-shell singlet radicaloid in the solid state,both EPR and SQUID measurements show that 3²⁺is readily thermally activated from singlet to triplet state owing to its small singlet-triplet energy gap.DFT calculations show that as the increase of the rigidity of linker,the spin densities from 1²⁺ to 3²⁺ Decome more equalization.The work provides new and stable structural motifs with diradical character.2.In the second part,compounds 4-11 were successfully synthesized,which utilized the carbazole as a kind of linker to connect two triarylamine.Using weak coordinating anion,4²⁺,6²⁺ and 8²⁺ were stabilized.Their diradical characters were investigated by EPR,SQUID and DFT calculations.Their ground states of electronic structure are all open-shell singlet.Among them,6²⁺ is readily thermally excited to spin triplet state due to its small single-triplet energy gap.11³⁺ is a chemical stable triradical compoulu.EPR spectrum of 11³⁺ shows a typical pattern of fine five lines.Our work provides a new type of triradical compound which is stable at room temperature as well as a series of diradical with tri?triarylamine?as backbone.