Synthesis, Characterization And Reactivity Of Metallabenzenes And Relative Compounds

Metallabenzenes are six-membered metallacycles analogous to benzene,in which one CH group has been replaced with an isolobal transition-metal fragment within a benzenoid ring.Since the first isolation of a metallabenzene was reported in 1982,rapid progress has been made in the chemistry of transition metal containing metallabenzenes.Furthermore,the synthetic methods have been developed including the "5+1 cyclization" by our group.In this work,the studies of the osmabenzenes, ruthenabenzenes and related compounds which are synthesized by "5+1 cyclization" are brief described below:(1)The reactivity of the intermediate of osmabenzene:Several novel osmium complexes have been synthesized,and characterized by NMR spectroscopy as well as X-ray diffraction study.An osmacyclic complex containing anη²-allene ligand has been isolated in the reaction of the key intermediate OsCl₂(CH=C(PPh₃)-CH(OH)C≡CH)(PPh₃)₂ with 1,10-phenanthroline.The complex has well thermal stability,and is air-stable either in the solid state or in the solution.Treatment of the intermediate of osmabenzene with sodium dicyanoamide produced osmium complex containing two tethered five-membered rings in the central structrue.(2)The synthesis of some novel organic compounds based on ring-opening reaction of ruthenabenzene:three stable aromatic organic compounds with different substitutes have been synthesized and isolated from the reactions of ruthenabenzene with aldehyde in the presence of Lewis acids.The three compounds have also been characterized by NMR spectroscopy and X-ray diffraction.It is worth to mention that the three compounds have remarkable thermal stability(Usually,Cp^- ions are unstable and can only be stabilized through coordinating to transition metal centre).In addition, a glutaraldehyde substituted by the phosphonium groups has been prepared from the reaction of ruthenabenzene and has been fully characterized.The notable anti-oxidated ability of the glutaraldehyde has been confirmed by chemical and electrochemical oxidation experiments.(3)Synthesis of ruthenabenzenes by the method of one pot reaction in presence of ionic liquid:When the ionic liquid is used as reaction media in the synthesis of ruthenabenzene,the yield can be increased evidently.Addtionally,the effect of several different ionic liquids in the one pot reaction have been studied.As showed by in situ NMR,the reactions in the presence of[Bmim]BF₄ and[Bmim]PF₆ are not air-sensitive and have no other side products.