Diastereomeric -1,4,7,10-Tetrakis((R)-2-hydroxy-2-phenylethyl)- 1,4,7,10-tetraazacyclododecane and Its Alkali-Metal Complex I

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• 作者：Sonya L. Whitbread ; Peter Valente ; Mark A. Buntine ; Philip Clements ; Stephen F. Lincoln ; and Kevin P. Wainwright
• 刊名：Journal of the American Chemical Society
• 出版年：1998
• 出版时间：April 1, 1998
• 年：1998
• 卷：120
• 期：12
• 页码：2862 - 2869
• 全文大小：174K
• 年卷期：v.120,no.12(April 1, 1998)
• ISSN：1520-5126

文摘

<SUP>13C NMR studies are consistent withs/gifchars/Delta.gif" BORDER=0 >-1,4,7,10-tetrakis((R)-2-hydroxy-2-phenylethyl)-1,4,7,10-tetraazacyclododecane (s/gifchars/Delta.gif" BORDER=0 >R-thpec12) and its eight-coordinatealkali-metal complexes,s/gifchars/Delta.gif" BORDER=0 >[M(R-thpec12)]⁺,existingpredominantly as single square antiprismatic s/gifchars/Delta.gif" BORDER=0 > diastereomers indimethylformamide. Molecular orbitalcalculations show the parallel square oxygen and nitrogen planes todelineate the square antiprismatic structureof s/gifchars/Delta.gif" BORDER=0 >R-thpec12 ands/gifchars/Delta.gif" BORDER=0 >[M(R-thpec12)]⁺ where the basketdefined by the four phenyl groups ofs/gifchars/Delta.gif" BORDER=0 >R-thpec12becomes increasingly shallow as the M⁺ radius increasesfrom Na⁺ to Cs⁺ and the four oxygens movefurtherapart. An intramolecular exchange process, involving doubleinversion of all four nitrogen centers, occurs ins/gifchars/Delta.gif" BORDER=0 >R-thpec12 for which k(298.2 K) = 46300 ±1800 s^-1, s/gifchars/Delta.gif" BORDER=0 >H^{s/entities/thermod.gif">} =40.8 ± 0.4 kJ mol^-1, ands/gifchars/Delta.gif" BORDER=0 >S^{s/entities/thermod.gif">} = -18.8 ± 1.7J K^-1 mol^-1.In [M(R-thpec12)]⁺ this process ischaracterized by k(298.2 K) = 233 ± 2, 98 ± 1, 4900±100, 33500 ± 1000, and 34500 ± 1100 s^-1,s/gifchars/Delta.gif" BORDER=0 >H^{s/entities/thermod.gif">} = 34.6 ± 0.3, 46.1 ± 0.2, 42.7 ±0.3, 39.1 ± 0.3, and 38.5± 0.3 kJ mol^-1, ands/gifchars/Delta.gif" BORDER=0 >S^{s/entities/thermod.gif">} = -83.5 ± 1.1, -52.2 ± 0.7,-31.1 ± 1.2, -27.2 ± 1.2, and -28.9 ± 1.3 JK^-1mol^-1, respectively, when M⁺= Li⁺, Na⁺, K⁺,Rb⁺, and Cs⁺. For intermolecularligand exchange on s/gifchars/Delta.gif" BORDER=0 >[M(R-thpec12)]⁺, decomplexation is characterized byk_d(298.2 K) = 396 ± 3, 156 ± 3, and152000 ± 6000 s^-1,s/gifchars/Delta.gif" BORDER=0 >H_d^{s/entities/thermod.gif">} = 46.0 ± 0.3, 62.3 ±0.5, and 69.8 ± 0.5 kJ mol^-1, ands/gifchars/Delta.gif" BORDER=0 >S_d^{s/entities/thermod.gif">} = -40.9 ± 1.0, 6.0± 1.9, and 88.4 ±2.1 J K^-1 mol^-1,respectively, when M⁺ = Li⁺,Na⁺, and K⁺. The stability constant,K, ofs/gifchars/Delta.gif" BORDER=0 >[M(R-thpec12)]⁺varies as M⁺ changes in the sequence Li⁺(3.13 ± 0.05), Na⁺ (4.25 ± 0.05), K⁺(4.10 ± 0.05), Rb⁺ (3.57± 0.05), Cs⁺ (3.47 ± 0.05), and Ag⁺(8.14 ± 0.03), where the figures in parentheses arelog(K/(dm³mol^-1))determined in dimethylformamide by potentiometric titration at 298.2 Kand I = 0.05 mol dm^-3(NEt₄ClO₄).