Thermodynamic Properties of Copper Complexes Used as Catalysts in Atom Transfer Radical Polymerization

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• 作者：Nicola Bortolamei ; Abdirisak A. Isse ; Valerio B. Di Marco ; Armando Gennaro ; Krzysztof Matyjaszewski
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：November 23, 2010
• 年：2010
• 卷：43
• 期：22
• 页码：9257-9267
• 全文大小：1048K
• 年卷期：v.43,no.22(November 23, 2010)
• ISSN：1520-5835

文摘

The thermodynamic properties of some copper complexes, among those frequently used as catalysts in controlled/living radical polymerization, has been studied in CH₃CN + 0.1 M (C₂H₅)₄NBF₄. A combination of different techniques, namely potentiometry, spectrophotometry and cyclic voltammetry, has been used to determine the stability constants of all possible complexes of Cu^I and Cu^II present in binary and ternary systems composed of Cu^I or Cu^II, a halide ion (X = Cl⁻, Br⁻) and a polyamine ligand (L = pentamethyldiethylenetriamine, tris(2-dimethylaminoethyl)amine). The binary Cu−X systems show only mononuclear CuX_x complexes, where x = 1, 2, 3, 4 for Cu^II, and x = 1, 2 for Cu^I. Conversely, in the case of the binary Cu−L systems, besides the mononuclear complexes CuL_l, where l = 1 or 2, also dinuclear complexes Cu₂L were found. The ternary systems give rise to a mixture of mononuclear and dinuclear complexes of general formula Cu_mL_lX_x. Besides the 1:1:1 complex obtained in all combinations, the following species were found: Cu^IILX₂, Cu^I₂LX and Cu^I₂LX₂. The stability constants of all these species were determined and used to construct speciation diagrams for both Cu^I and Cu^II species. Such diagrams show that often conditions favoring the quantitative formation of Cu^IIL, Cu^IIL₂, or Cu^IILX can be easily realized, whereas isolation of a single predominant Cu^I species can hardly be achieved. Speciation diagrams for Cu^I as a function of C_X/C_Cu^I show interesting results that may be helpful in rationalizing the role of termination reactions in atom transfer radical polymerization.