Reaction of di- and tri-valent chromium amides with O2†
Abstract
Homoleptic divalent [{Cr(NRR′)}2(µ-NRR′)2]·3thf (R = R′ = cyclohexyl 1a; R = 3,5-Me2C6H3, R′ = adamantyl 1b) and trivalent chromium amides [Cr(NRR′)3] (R = R′ = C6H11 2a; R = 3,5-Me2C6H3, R′ = adamantyl 2b; RR′ = 2,2,6,6-Me4C5H6N 2c) were synthesized by reaction of [CrCl2(thf)2] or [CrCl3(thf)3] with the appropriate amount of the corresponding lithium amide. All of these complexes, with the exception of 2c, reacted with dioxygen to give the hexavalent chromium dioxo bis(amide) derivative, [Cr(NRR′)2O2] 4a and 4b. A possible intermediate [{Cr(NRR′)2}2(µ-O)2]·C6H5Me was isolated by comproportionating 1b with 4b. A diamagnetic chromium(V) dimeric species, [{Cr(NRR′)2O}2(µ-O)] 5b was isolated upon treatment of 4b with P(C6H11)3. The crystal structures of complexes 1b, 2b, 2c, 3b, 4a, 4b and 5b have been determined.