Synthesis and structure of lanthanide(III) picrate complexes with 1,3-dithiane-1-oxide

Lanthanide picrate complexes with 1,3-dithiane-1-oxide (DTSO) were synthesi zed by reaction of the hydrated lanthanide picrates (pic) with DTSO in abso lute ethanol. Conductance measurements in acetonitrile solutions show that the complexes behave as non-electrolytes. The parameters obtained (beta=0.9 88, b(1/2)=0.0762 and delta=1.17) from the absorption spectrum of the solid Nd compound for the (2)G(7/2), (4)G(5/2) <-- I-4(9/2), transition indicate that the metal-ligand bonds present weak covalent character, The bands D-5 (0) --> F-7(J) (J=1,2,3) transitions for the emission spectra of the Eu com pound were interpreted in terms of a C-4v symmetry. X-ray single-crystal da ta of the gadolinium compound showed that the crystal system is monoclinic, a=10.5577(10) Angstrom, b=20.221(3) Angstrom, c=21.4802(12) Angstrom, beta =93.969(6)degrees, space group P2(1)/c, Z=4, V=4574.8(8) Angstrom(3). The G d ion achieves a coordination number of nine by the bonding of three bident ate picrate groups via their phenoxo-oxygen and an oxygen of the adjacent n itro moiety and three oxygens of the three DTSO molecules, in a distorted m onocapped square antiprism fashion. X-ray powder patterns show only one iso morphous series. (C) 2000 Elsevier Science S.A. All rights reserved.