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在室温下测定了CCl_4溶液中,18-冠-6的亚甲基、Eu(fod)的t—丁基质子的PMR化学位移与溶液组成的相互关系。提出了生成配合物RS,R_2S,R_2,R_3(S为18-冠-6,R为Eu(fod)_3)的模式。求得了平衡常数值(升/摩):K_1=[RS]/([R][S])=2.O×10~5,K_2=[R_2S]/([R][RS])=1.0×10~3,Q_1=[R_2]/[R]~2=4.2×10~2,Q_2=[R_3]/([R_2][R])=4.0×10~1。并测得在配合物RS,R_2S中18-冠-6质子的平均化学位移分别为4.90,10.84(ppm,相对于纯18-冠-6); 在配合物R,R_2,R_3,RS,R_2中t-丁基质子平均化学位移分别为1.53,2.33,0.54,1.02,2.42(ppm,相对于TMS)。 根据配合物的化学位移值,并考虑分子及分子轨道的对称性、位阻等因素提出了配合物R_2,RS,R_2S的可能的结构模型。
The relationship between the PMR chemical shifts and the solution composition of t-butyl proton of Eu (fod) in 18-crown-6 methylene in solution of CCl 4 was measured at room temperature. A new mode of generating complexes RS, R_2S, R_2, R_3 (S is 18-crown-6 and R is Eu (fod) _3) is proposed. K 1 = [RS] / ([R] [S]) = 2.O × 10 ~ 5, K_2 = [R_2S] / ([R] [RS]) = 1.0 × 10 -3, Q_1 = [R_2] / [R] ~ 2 = 4.2 × 10 -2, and Q_2 = [R_3] / ([R_2] [R]) = 4.0 × 10 -1. The average chemical shifts of the 18-crown-6 protons in the complexes RS and R_2S were 4.90 and 10.84 (ppm, relative to pure 18-crown-6), respectively. In the complexes R, R_2, R_3, RS and R_2 The average t-butyl proton chemical shifts were 1.53, 2.33, 0.54, 1.02, 2.42 (ppm vs. TMS), respectively. The possible structural models of complexes R_2, RS and R_2S are proposed according to the chemical shift values of the complexes, considering the symmetry of molecular and molecular orbitals and steric hindrance.