STUDIES ON CROWN-ETHER COMPLEXES .28. SYNTHESIS, CHARACTERIZATION ANDSTRUCTURE OF THE COMPLEXES OF HEAVIER LANTHANIDE NITRATES (GD-LU) WITH DIBENZO-24-CROWN-8

The heavier lanthanide nitrate complexes with dibenzo-24-crown-8 (DB24 C8) have been prepared in acetonitrile. These new complexes with the g eneral formula [Ln(NO3)3(OH2)3].(DB24C8) (Ln = Gd-Lu) have been charac terized by means of elemental analysis, IR spectra, H-1 NMR spectra an d conductivity measurements. The crystal and molecular structure of [G d(NO3)3(OH2)3].(DB24C8) has been determined by single-crystal X-ray di ffraction. The gadolinium(III) ion is coordinated to the six oxygen at oms of three bidentate nitrate groups and three water molecules. The c rown ether molecule is hydrogen bonded to these three water molecules. The average Gd-O(nitrate) and Gd-O(water) distances are 2.464(4) and 2.388(3) angstrom, respectively. The average O(water) ... O(crown ethe r) separation is 2.787 angstrom. The coordination polyhedron is a dist orted tricapped trigonal prism.