A Novel Cyclopentadienone and its Ruthenium and Iron Tricarbonyl Complexes

A simple and efficient protocol allows the oxidation of the cyclopentadiene derivative 5H-dibenzo[e,h]-dibenzo[3,4 : 6,7]cyclohept[1,2-a]azulene (Cp(C)H) provide according ketone Cp(C)O. Comparable to the situation found for Cp(C)H, the bending of the four annulated six-membered rings defines the C-2 symmetric molecular structure of Cp(C)O. The cyclopentadienone Cp(C)O readily reacts with [Ru-3(CO)(12)] and [Fe-3(CO)(12)] to generate tricarbonyl complexes of the type [(eta(4)-Cp(C)O)M(CO)(3)]. In contrast to [(eta(4)-Cp(C)O)Ru(CO)(3)], the tricarbonyliron(0) complex is sensitive to oxygen and moisture. Refluxing [(eta(4)-Cp(C)O)Ru(CO)(3)] in isopropanol makes the hydrido-bridged complex [((eta(4)-Cp(C)O)(2)H)Ru-2(CO)(4)H] accessible, an analogue to Shvo's catalyst. Both ruthenium complexes and their ligand Cp(C)O were characterized spectroscopically and by single crystal x-ray diffraction. The activity of [(eta(4)-Cp(C)O)Ru(CO)(3)] was investigated for a series of transfer hydrogenation reactions.

Automated summary

An efficient oxidation protocol was developed for a cyclopentadiene derivative, and the resulting products were investigated for their activity in various reactions. The study indicated that the complexes formed in the reaction are sensitive to oxygen and moisture, and can play a key role in catalytic reactions.