title: Two stable phosphorus-containing four-membered ring radical cations with inverse spin density distributions.
abstract: Two phosphorus-containing four-membered ring radical cations 1(•+) and 2(•+) have been isolated and characterized by UV-vis absorption spectroscopy, electron paramagnetic resonance (EPR), and single-crystal X-ray diffraction. Compared with neutral molecules 1 and 2, radical 1(•+) has elongated P-P bonds and more pyramidalized phosphorus atoms, while shortened P-Nring distances and larger angles around phosphorus centers are observed for 2(•+). EPR studies indicate that for 1(•+) spin density mainly resides on the exocyclic nitrogen atoms with very minor contribution from endocyclic phosphorus atoms, while the situation is opposite for 2(•+). Such an inverse spin density distribution is controlled by the exocyclic substituents, which is supported by DFT calculations.
authors.affiliation: State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210093, China.
authors.forename: Yuanting
authors.initials: Y
authors.lastname: Su
authors.forename: Xin
authors.initials: X
authors.lastname: Zheng
authors.forename: Xingyong
authors.initials: X
authors.lastname: Wang
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhang
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Sui
authors.forename: Xinping
authors.initials: X
authors.lastname: Wang