Study on synthesis of lanthanide chelates of fluorochloroalkyl β‐diketones useful as shift reagents

Several lanthanide chelates of the fluorochloroalkyl β‐diketones Ln(CF 2 ClCOCHCOR) 3 ·nH 2 O were prepared (2, Ln=Eu; 2a, R=C(CH 3 ) 3 , n=0; 2b, R=C 6 F 5 , n=0; 2c, R=CF 2 Cl, n=2. 3, Ln=Pr; 3a, R=C (CH 3 ) 3 , n=0; 3b, R=C 6 F 5 , n=l; 3c, R=CF 2 Cl, n=2. 4, Ln=La, R=C 6 H 5 , n=0) and the NMR shift data of compounds 2 and 3 had been determined using alcohols, ether, ketones and amine as substrates. With alcohol, ether and ketone, compounds 2 induces shifts similar to that induced by Eu (fod) 3 . However due to the high solubility of the chelates in non‐polar organic solvents such as CHCl 3 and CCl 4 and the absence of 1 H signal from compounds 2b and 2c, their application as a series of new 1 H NMR shift reagents seems promising.