Thermodynamic and Kinetic Effects of the Double Coordination of Carbonyl Groups by Bidentate Lewis Acids
作者:Jean Vaugeois、James D. Wuest
DOI:10.1021/ja982725x
日期:1998.12.1
which are bidentate Lewis acids. IR studies in CH2Cl2 established that 1,2-isomer 7 forms doubly coordinated 1:1 complexes with amides in which both atoms of mercury interact simultaneously with the carbonyl oxygen atom of the bound amide, whereas 1,4-isomer 9 forms more weakly bound singly coordinated complexes. Variable-temperature IR studies revealed that for the double coordination of diethylformamide
用 Hg(OOCCF3)2 处理 1,2,3,4-四己基苯或 1,2,4,5-四己基苯产生 1,2-苯二汞双(三氟乙酸酯)7 或其 1,4-异构体 9,它们是双齿的路易斯酸。CH2Cl2 中的 IR 研究确定,1,2-异构体 7 与酰胺形成双配位 1:1 复合物,其中汞的两个原子同时与结合酰胺的羰基氧原子相互作用,而 1,4-异构体 9 形成更弱的结合单独协调的复合体。变温 IR 研究表明,对于二乙基甲酰胺 (DEF) 与 1,2-异构体 7 的双配位,ΔH° = -4.5 ± 0.2 kcal mol-1 和 ΔS° = -6.9 ± 1.0 eu,而对于单配位DEF 的 1,4-异构体 9,ΔH° = -3.4 ± 0.2 kcal mol-1 和 ΔS° = -8.1 ± 1.0 eu。这些测量确定双配位比单配位放热明显更多。此外,变温 NMR 研究表明,围绕二甲基新戊酰胺的 N-C(O)