Cobalt-mediated decarboxylative homocoupling of alkynyl carboxylic acids

Abstract

Cobalt-mediated decarboxylative Glaser-like C-C bond coupling of carboxylates has been studied in the gas phase using collision-induced dissociation (CID) multistage mass spectrometry (MSn) experiments. Both the identity of the carboxylate RCO2- (R≤Me, HC≡C, MeC≡C, and PhC≡C) and the nuclearity of the complex ([CoCl(O2CR)2]- versus [Co2Cl3(O2CR)2]-) play a role in the types of reactions observed and their relative activation energies. In the first stage of CID, the mononuclear complex [CoCl(O2CMe)2]- undergoes decarboxylation, while the dinuclear [Co2Cl3(O2CMe)2]- undergoes cluster fission to yield [CoCl3]-; all acetylenic carboxylate complexes [CoCl(O2CR)2]- and [Co2Cl3(O2CR)2]- undergo dec..