Reaction of FcCCC(O)R (Fc = ferrocenyl) with Ru3(CO)12 leading to unexpected nitro-group reduced ruthenoles and 1,2-CO-inserted triruthenium clusters

Abstract

The reaction of Ru₃(CO)₁₂ with ferrocene-containing alkynyl ketones FcCCC(O)R (Fc = ferrocenyl; R = Ph (1); 2-thienyl (2); 4-CH₃O–Ph (3); 4-NH₂–Ph (4); 4-NO₂–Ph (5); ferrocenyl (6)) proceeds in toluene with the formation of triruthenium clusters (1a–6a), ruthenoles (1b–5b, 5c and 1d–5d) and unexpected 1,2-CO-inserted triruthenium clusters (1c–4c). 1a–6a were isolated from the reaction of Ru₃(CO)₁₂ with one equivalent of 1–6, respectively. Ruthenoles 1b–5b, 5c and 1d–5d were collected by adding 1–5 to the corresponding 1a–5a in a molar ratio of 1 : 1, respectively. Unexpectedly, the nitro group in one of the two phenyl rings in both 5c and 5d molecules was reduced to an amino group, while their ruthenole skeletons are retained. When 1–4 were added to the corresponding 1a–4a in a molar ratio of 1 : 1, respectively, the unusual triruthenium clusters (1c–4c) were isolated, involving 1,2-insertion of a terminal coordinated carbonyl between two CC units of the ynone molecules. No reaction between 6a and 6 was observed. And the familiar cyclotrimerization products were not found. All new compounds were characterized by NMR, FT-IR, and MS-ESI and most of them were structurally confirmed by single crystal X-ray diffraction. The results suggested that the ferrocenyl groups in the 1,3-ynones exhibit strong electron and steric effects on the reaction process and product distribution during their reactions with Ru₃(CO)₁₂.