ИСТИНА

A comparative study of thermally and photochemically activated reactions of Ru3(CO)12 with aminovinylketones is reported. It is established that the thermally activated reactions proceed differently for secondary and tertiary aminovinylketones. The reaction with tertiary aminovinylketones (studied with 4-dimethylaminobut-3-en-2-one as an example) yields mononuclear complexes containing five-membered oxaruthenacycles (a) as the main product. Meanwhile, the reaction with secondary aminovinylketones (with 1-(4-tolyl)-3-phenylaminoprop-2-en-1-one as an example) affords mononuclear metallochelates with six-membered azaoxaruthenacycles (b). The difference in reactivity is primarily governed by the trans-and cis-arrangements of olefinic protons in the initial aminovinylketones. The photochemical reactions were excited with UV light of two wavelengths, viz., ≥ 210 nm and ≥ 350 nm, which are effective in the rupture of Ru-CO and Ru-Ru bonds, respectively. Tertiary aminovinylketones react with Ru3(CO)12 only upon excitation at ≥ 210 nm. The reaction affords complexes with five-membered oxaruthenacycles, similar to the case of thermally activated reactions, but with the Ru3(CO)12 cluster moiety remained intact (c). No reaction is activated with irradiation at ≥ 350 nm. Secondary aminovinylketones do not react with Ru3(CO)12 under the conditions of photochemical activation at all. Probably, the lone electron pairs of the oxygen atoms and N-H groups that are apparently responsible for the thermal reaction possess insufficient activity without additional heating due to their involvement in strong hydrogen bonding.