A Series of Two-Coordinate Group-15 Element (P, As, Sb, Bi) Centered Radicals Having Bulky Alkyl Groups

Two-coordinate group-15 element centered radicals that bear a lone pair and an unpaired electron on the same group-15 atoms have received much attention in group-15 element chemistry. We previously synthesized an isolable dialkylphosphinyl radical, 2,2,5,5-tetrakis(trimethylsilyl)-1-phosphacyclopentane-1-yl (1P) and its antimony and bismuth analogues (stibinyl radical 1Sb and bismuthinyl radical 1Bi) as persistent radicals. We report herein (1) synthesis of an isolable cyclic dialkylarsinyl radical 1As that exists in the radical form both in solution and in the solid state and (2) comprehensive study of a series of neutral two-coordinate pnictogen-centered radicals (1P, 1As, 1Sb, 1Bi) including UV-vis spectra, redox properties, and reactions.