REACTION OF DI- AND TRI-VALENT CHROMIUM AMIDES WITH O-2

Homoleptic divalent [{Cr(NRR')}(2)(mu-NRR')(2)]. 3thf (R = R' = cycloh exyl 1a; R = 3,5-Me2C6H3, R' = adamantyl 1b) and trivalent chromium am ides [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 corresp onding lithium amide. All of these complexes, with the exception of 2c , reacted with dioxygen to give the hexavalent chromium dioxo bis(amid e) derivative, [Cr(NRR')(2)O-2] 4a and 4b. A possible intermediate [{C r(NRR')(2)}(2)(mu-O)(2)]. C6H5Me was isolated by comproportionating 1b with 4b. A diamagnetic chromium(v) dimeric species, [{Cr(NRR')(2)O}(2 )(mu-O)] 5b was isolated upon treatment of 4b with P(C6H11)(3). The cr ystal structures of complexes 1b, 2b, 2c, 3b, 4a, 4b and 5b have been determined.