Synthesis and structures of Ln(III) 12-crown-4 complexes (Ln = La, Ce, Nd)

Five new mononuclear lanthanide(III) complexes Ln(12-crown-4)(CH 3 CN)I 3 (Ln =La ( 1 ), Ce ( 2 )), [Ln(12-crown-4) 2 (CH 3 CN)I]I 2 (Ln =La ( 3 ), Ce ( 4 )) and Nd(12-crown-4) 2 I]I 2 (CH 3 CN) ( 5 ) have been successfully synthesized via the reaction of LnI 3 with 12-crown-4 in different ratios in CH 3 CN at room temperature . Two half-sandwich type mononuclear Ln(III) crown ether complexes, Ln(12-crown-4)(CH 3 CN)I 3 (Ln = La( 1 ), Ce( 2 )), and three sandwich type mononuclear Ln(III) crown ether complexes, [Ln(12-crown-4) 2 (CH 3 CN)I]I 2 (Ln = La( 3 ), Ce( 4 )), [Nd(12-crown-4) 2 I]I 2 (CH 3 CN) ( 5 ), have been prepared via the reaction of LnI 3 with 12-crown-4 in different ratios in CH 3 CN at room temperature. All complexes were characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and NMR spectroscopy. The 1 H NMR spectrum analysis indicates that complexes 3 , 4 and 5 undergo partial decomposition in solution. In addition, the 1 H NMR spectra of cerium and neodymium complexes compared to the lanthanum complexes show significant paramagnetic shifts.