Routes of formation and crystal structure of an alkylperoxycobaloxime: bis[dimethylglyoximato(1–)](4-ethoxycarbonylbut-3-en-2-ylperoxo)(pyridine)cobalt(III)

Abstract

Thermal and photolytic routes from alkylating agents via alkylcobaloximes are described leading to the formation of the complex bis[dimethylglyoximato(1–)](4-ethoxycarbonylbut-3-en-2-ylperoxo)(pyridine)cobalt(III). All the routes converge at the putative intermediate 3-ethoxycarbonyl-1-methylallyl(pyridine)cobaloxime, the Co–C bond of which reacts with dioxygen at room temperature to give the alkylperoxycobaloxime. The formation of the alkylperoxycobaloxime by aerobic photolysis of 2-ethoxycarbonylbut-3-enyl(pyridine)cobaloxime proceeds via the 2-ethoxycarbonylbut-3-enyl radical, which rearranges to the 1-ethoxycarbonylbut-3-enyl radical. This radical reacts with cobaloxime(II) to give hydridocobaloxime and 1-ethoxycarbonylbuta-1,3-diene. Recombination of these species yields 3-ethoxycarbonyl-1-methylallyl(pyridine)cobaloxime and hence the alkylperoxycobaloxime. The structure was identified by an X-ray determination, final R= 0.049 for 1 652 observed diffractometer-collected reflections. Principal dimensions (average) are Co–O 1.923(4), O–O 1.415(7), Co–N(oxime) 1.896(3)Å, Co–O–O 115.3(3)°, and dihedral angle Co–O–O–C 100.0(4)°.