Cobaloximes with mixed dioximes having C and S side chains: Synthesis, structure and reactivity

Ten mixed dioxime complexes RCo(L)(dmgH)Py [R = Cl, Me, Et, Bu, Benzyl] [L = dSPhgH (1–5) and dSEtgH (6–10)] have been synthesized and characterized by NMR. Formation of 1 and 6 is very fast and takes only 5 and 15 min in ethanol. Molecular oxygen insertion in 5 and 10 is monitored and forms mixture of products within 5 min. The crystal structure of 1, 4, 5, 6, 8 and 10 is reported. Benzyl ring is oriented over dmgH wing in both 5 and 10 and has a weak C–H…π interaction (3.33 Å and 3.22 Å) and this causes high upfield shift of the dmgH protons. Electrochemical study on 1, 4, 5, 6, 8 and 10 is also reported. Because of increased electron donation by SEt group, 6 is more difficult to reduce than 1.