Evidence for Formation of a Co–H Bond from (H2O) 2Co (dmgBF2) 2 under H2: Application to Radical Cyclizations

…, ME Pulling, DP Estes, JR Norton

Index: Li, Gang; Han, Arthur; Pulling, Mary E.; Estes, Deven P.; Norton, Jack R. Journal of the American Chemical Society, 2012 , vol. 134, # 36 p. 14662 - 14665

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Citation Number: 29

Abstract

Under H2, the radical cyclization of appropriate dienes can be catalyzed by cobaloximes. H• can be abstracted from an intermediate (presumably a cobalt hydride) by trityl radicals (Ar3C•) or by TEMPO. The rate-determining step in these reactions is the uptake of H2, which is second order in cobalt and first order in hydrogen; the third-order rate constant is 106 (3) M–2· s–1.