Formation and Characterization of Water-Soluble Hydrido-Ruthenium(II) Complexes of 1,3,5-Triaza-7-phosphaadamantane and Their Catalytic Activity in Hydrogenation of CO2 and HCO3<

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• 作者：Gá ; bor Laurenczy ; Ferenc Joó ; and Levente Ná ; dasdi
• 刊名：Inorganic Chemistry
• 出版年：2000
• 出版时间：October 30, 2000
• 年：2000
• 卷：39
• 期：22
• 页码：5083 - 5088
• 全文大小：88K
• 年卷期：v.39,no.22(October 30, 2000)
• ISSN：1520-510X

文摘

The water-soluble tertiary phosphine complex of ruthenium(II), [RuCl₂(PTA)₄], (PTA = 1,3,5-triaza-7-phosphaadamantane) was used as catalyst precursor for hydrogenation of CO₂ and bicarbonate in aqueous solution,in the absence of amine or other additives, under mild conditions. Reaction of [RuCl₂(PTA)₄] and H₂ (60 bar)gives the hydrides [RuH₂(PTA)₄] (at pH = 12.0) and [RuH(PTA)₄X] (X = Cl^- or H₂O) (at pH = 2.0). In presenceof excess PTA, formation of the unparalleled cationic pentakis-phosphino species, [HRu(PTA)₅]⁺, wasunambiguously established by ¹H and ³¹P NMR measurements. The same hydrides were observed when [Ru(H₂O)₆][tos]₂ (tos = toluene-4-sulfonate) reacted with PTA under H₂ pressure. The rate of CO₂ hydrogenationstrongly depends on the pH. The highest initial reaction rate (TOF = 807.3 h^-1) was determined for a 10%HCO₃^-/90% CO₂ mixture (pH = 5.86), whereas the reduction was very slow both at low and high pH (CO₂ andNa₂CO₃ solutions, respectively). ¹H and ³¹P NMR studies together with the kinetic measurements suggested thatHCO₃^- was the real substrate and [RuH(PTA)₄X] the catalytically active hydride species in this reaction.Hydrogenation of HCO₃^- showed an induction period which could be ascribed to the slow formation of thecatalytically active hydride species.