The search for main‐group element‐based radicals is one of the main research topics in contemporary chemistry because of their fascinating chemical and physical properties. The Group 15 element‐centered radicals mainly feature a V‐shaped two coordinate structure, with a couple of radical cations featuring trigonal tricoordinated geometry. Now, nontrigonal compounds R3E (E=P, As, Sb) were successfully synthesized by introducing a new rigid tris‐amide ligand. The selective one‐electron reduction of R3E afforded the first stable tricoordinate pnictogen‐centered radical anion salts; the pnictogen atoms retain planar T‐shaped structures. EPR spectroscopy and calculations reveal that the spin density mainly resides at the p orbitals of the pnictogen atoms, which is perpendicular to the N3E planes.

This review presents the recent advances in the synthesis, characterization, reactivity and physical properties of isolable main group elements radicals.

The reduction of 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) with alkali metals resulted in four radical anion salts (1, 2, 4 and 5)and one diradical dianion salt (3). Single-crystal Xray diffraction and electron paramagnetic resonance (EPR) spectroscopyr eveal that 1 contains the monoradical anion TPTC À stackedi no ne-dimensional (1D) with K + (18c6) and 2 can be viewed as a1Dmagnetic chain of TPTC À ,while 4 and 5 form radical metal-organic frameworks (RMOFs). 1D pore passages,w ith ad iameter of 6.0 ,c ontaining solvent molecules were observed in 5.V ariable-temperature EPR measurements showt hat 3 has an open-shell singlet ground state that can be excited to at riplet state,c onsistent with theoretical calculation. The work suggests that the direct reduction approach could lead to the formation of RMOFs.