Reaction of an Osmium(VI) Nitrido Complex with Enamines generated in situ from Ketones and Anilines

Abstract

The reaction of [OsVI(N)(L)(CN)3]− (OsN, HL = 2-(2-hydroxy-5-nitrophenyl)-benzoxazole) with a mixture of acetone and 2,4,6-trimethylaniline (MesNH2) affords [OsIII(L)(CN)3(L1)]− (L1 = N-mesityl-2-(mesitylimino)propanimidamide), where L1 is derived from the combination of an acetone molecule, a nitrido ligand, and two MesNH2. The reaction of OsN with acetone and the less bulky aniline gives [OsIII(L)(CN)3(L3)]− (L3 = 1,3-diphenylguanidine) and phenylacetamide, where L3 is derived from the combination of three anilines, one acetone, and the nitrido ligand; this reaction results in C-C bond cleavage of acetone. C-C bond cleavage of ketone also occurs in the reaction of OsN with 2-butanone and aniline. Mechanistic studies indicate that the initial step in these reactions is the condensation of the ketone and the amine to give an enamine, which then undergoes nucleophilic addition to Os≡N.