Synthesis of benzene ruthenium triazolato complexes by [3+2] cycloaddition reactions of activated alkynes and fumaronitrile to benzene ruthenium azido complexes

The dinuclear complex (η⁶-C₆H₆)Ru(μ-N₃)Cl]₂ (1) is obtained by the reaction of (η⁶-C₆H₆)RuCl₂]₂ with sodium azide in ethanol. The benzene ruthenium β-diketonato complexes of the general formula (η⁶-C₆H₆)Ru(L∩L)Cl] {L∩L = O,O′-acac (2); O,O′-bzac (3); O,O′-dbzm (4)} are obtained in methanol by the reaction of (η⁶-C₆H₆)RuCl₂]₂ with the corresponding β-diketonates. These complexes further react with sodium azide in ethanol to yield complexes of the type (η⁶-C₆H₆)Ru(L∩L)N₃] L∩L = O,O′-acac (5); L∩L = O,O′-bzac (6); L∩L = O,O′-dbzm (7)]. The complexes 5-7 are obtained as well by treating 1 with sodium salts of β-diketonates. These neutral benzene ruthenium azido complexes undergo 3+2] dipolar cycloaddition reaction with activated alkynes (MeO₂CCCCO₂Me, EtO₂CCCCO₂Et) or fumaronitrile (NCHCCHCN) to yield the corresponding benzene ruthenium triazolato complexes; (η⁶-C₆H₆)Ru(O,O′-acac){N₃C₂(CO₂Me)₂}] (8), (η⁶-C₆H₆)Ru(O,O′-acac){N₃C₂(CO₂Et)₂}] (9), (η⁶-C₆H₆)Ru(O,O′-acac){N₃C₂HCN}] (10), (η⁶-C₆H₆)Ru(O,O′-bzac){N₃C₂HCN}] (11) and (η⁶-C₆H₆)Ru(O,O′-dbzm){N₃C₂HCN}] (12). These complexes are fully characterized on the basis of microanalyses, FT-IR and FT-NMR spectroscopy. The molecular structure of (η⁶-C₆H₆)Ru(O,O′- acac){N₃C₂(CO₂C₂H₅)₂}] (9) is confirmed by single crystal X-ray diffraction study.