STUDIES OF REACTIONS OF SMALL HYDROCARBONS WITH TRANSITION METALS USING MATRIX ISOLATION FTIR SPECTROSCOPY (INFRARED; IRON; NICKEL)

[摘要] The reactions and photochemistry of iron and nickel atoms and dimers with small hydrocarbons have been investigated in an argon matrix at 15 K using Fourier transform infrared spectroscopy.Atomic iron was found to interact with an acetylenic hydrogen in the first example of a transition metal hydrogen-bonding to an alkyne. With UV photolysis this complex rearranged to ethynyliron hydride, HFeC$sb{2}$H. At higher iron concentrations a $pi$-coordinated diiron adduct Fe$sb{2}$(C$sb{2}$H$sb{2}$) was formed.Atomic nickel formed a $pi$ complex with acetylene which photorearranged with $lambda geq 400$ nm irradiation to nickel vinylidene, NiCCH$sb{2}$. Photoreversibility was demonstrated with UV irradiation. A dinickel acetylene adduct analogous to Fe$sb{2}$(C$sb{2}$H$sb{2}$) was formed at higher nickel concentrations.In reactions between nickel and ethylene oxide, activation of the C-O bond by atomic nickel resulted in formation of the first unligated nickel oxometallacycle, nickelaoxetane. Upon irradiation with $lambda geq 500$ nm this metallacycle underwent two metathesis pathways. One pathway produced an ethylene nickel oxide $pi$ complex NiO(C$sb{2}$H$sb{4}$) which subsequently rearranged to vinylnickel hydroxide, C$sb{2}$H$sb{3}$NiOH, with UV photolysis. Another metathesis route resulted in a methylenenickel formaldehyde $pi$ complex, CH$sb{2}$Ni(H$sb{2}$CO), which rearranged upon $lambda geq 400$ nm irradiation to hydridonickelmethyl carbonyl, HNiCH$sb{3}$(CO) decomposed to methane and nickel carbonyl with UV photolysis.In studies of nickel with cyclopropane in an argon matrix, atomic nickel inserted into a C-C bond of cyclopropane to form nickelacyclobutane. Irradiation with $lambda geq 500$ nm caused metathesis of this metallacycle and formation of methylenenickel ethylene $pi$ complex, CH$sb{2}$Ni(C$sb{2}$H$sb{4}$). CH$sb{2}$Ni(C$sb{2}$H$sb{4}$) rearranged to vinylnickelmethyl, C$sb{2}$H$sb{3}$NiCH$sb{3}$, which decomposed and released methane upon extended UV photolysis.

[发布机构] Rice University

[效力级别] chemistry