Transmission of Electronic Effects through the {closo-1-CB9} and {closo-1-CB11} Cages: Apparent Dissociation Constants for Series of [closo-1-CB9H

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• 作者：Jacek G. Pecyna ; Bryan Ringstrand ; Piotr Kaszy艅ski
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：May 7, 2012
• 年：2012
• 卷：51
• 期：9
• 页码：5353-5359
• 全文大小：377K
• 年卷期：v.51,no.9(May 7, 2012)
• ISSN：1520-510X

文摘

The apparent ionization constants pK_a鈥?for series of carboxylic acids [closo-1-CB₉H₈-1-COOH-10-X]^{鈭?/sup> (1) and [closo-1-CB₁₁H₁₀-1-COOH-12-X]鈭?/sup> (2), where X = H, I, n-C₆H₁₃, +NMe₃, +N₂, +SMe₂, OC₅H₁₁, were measured in EtOH/H₂O (1/1, v/v) at 24 掳C. Correlation analysis of the pK_a鈥?values using Hammett substituent constants 蟽_p(X) gave the reaction constant 蟻 = 0.87 卤 0.04 for series 1 and 蟻 = 1.00 卤 0.09 for series 2. These values are higher than for derivatives of PhCH鈺怌HCOOH (蟻 = 0.70 卤 0.09 in 55% EtOH) and correspond to 56% and 65% efficiencies in transmission of electronic effects by [closo-1-CB₉H₁₀]鈭?/sup> (E) and [closo-1-CB₁₁H₁₂]鈭?/sup> (F), respectively, as compared to benzene (A). Experimental results were supported with DFT calculations of relative acidity for series of acids derived from A, E, and F in aqueous medium.}