Tricoordinate Nontrigonal Pnictogen‐Centered Radical Anions: Isolation, Characterization, and Reactivity

Abstract

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.

Periodicity in Structure, Bonding, and Reactivity for P-Block Complexes of a Geometry-Constraining Triamide Ligand

“…Given the rapidly evolvings tate of this field, we envisioned that as ystematic longitudinal study examining how ag eometryc onstrainingl igand modulates the structure, electronics, and reactivity at the central element within ap eriodic group (covering P, As, Sb, Bi)w ould be timely and instructive. Relateda nalyses include work by Arduengo on planarO -N-O complexes of P, As, and Sb [11] (but not Bi), [12] very recent work by Wang on radicala nions of P, As, and Sb (but not Bi) within at riamide framework enforcing planarity, [13] and work by Dostàla nd Cain focusing on aromaticity and structural trends for monoanionic N-C-N ligands that also only permit planar geometries. [14] In contrast, here we report ac ombined experimental and theoretical investigation into structure and reactivity of the P, As, Sb,a nd Bi complex of as ingle tethered trianionic N-N-N substituent that samples al arger parameter space in geometric ande lectronic structure due to the ligand's ability to support either bent or planar conformationsa nd resonate between at riamido form and an amido bis-imino form [15] (see H in Figure1).…”