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Study on the synthesis of the lanthanide chelates of α′-(trifluoromethyl)polyfluoroalkyl β-diketones and their application as 1H NMR shift reagents
Authors:Huang Wei-Yuan  Zhang Long-Qing
Abstract:The synthesis of the lanthanide chelates of α′-(trifluoromethyl)polyfluoroalkyl β-diketones Ln {CF3CF2CF2OCF(CF3)]n COCHCOC(CH3)3}3 1 , n=1; Ln=Eu (1a) , Pr (1b) , Nd (1c) , Sm (1d) , Gd (1e) , Tb (1f) , Dy (1g) , Er (1h). 2 , n=2; Ln=Eu (2a) , Pr (2b) , Nd (2c) , Sm (2d) , Gd (2e) , Tb (2f) , Dy (2g) and Er (2h) ] was reported and the 1H NMR shift properties were studied using alcohol, ketone, ether and amine as substrates. Compounds 1a, 1b, 2a and 2b induce shifts similar to that induced by Ln(fod)3 (Ln=Eu, Pr). However compounds 1a and 2a are superior to Eu(fod)3, because their 1H signal shifts to higher field in the presence of substrate than that of Eu(fod)3, does. For example, Δh for 1a and 2a is close to zero ppm in the presence of alcohol. A very satisfactory first order spectra can be obtained using 1a, 2a, 1b and 2b as 1H NMR shift reagents. 1c, 1f, 1g, 2c, 2f and 2g produce upfield shifts, and 1h and 2h produce downfield shifts. 1c and 2c induce shifts smaller than that of 1b and 2b , whereas 1f, 1g, 1h, 2f, 2g and 2h induce very large shifts.
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