Synthesis, characterization, and structure of lanthanide picrate complexes with tetramethylenesulfoxide (TMSO)

A series of complexes with composition M(pic)3(TMSO)3 (M=La, Nd, Sm, Eu, Gd, Er, Yb, and Y) were synthesized and characterized. The electronic absorption spectrum of the Nd complex and the emission spectrum of the Eu complex were recorded and assigned. The unique compound, Sm(pic)3(TMSO)2.5(EtOH)0.5, obtained by recrystallizatiori of Sm(pic)3(TMSO)3 from ethanol, was characterized by single-crystal X-ray analysis. The complex crystallizes in a monoclinic cell space groupP21/n witha=21.809(4)A,b=15.811(3)A,c=12.800(3)A and β=99.87(4)°. The coordination polyhedron about the Sm center is a tricapped trigonal prism involving the three picrates, which act as bidentate ligands via the phenoxo oxygen and an oxygen of an adjacent nitro group, as well as the oxygens of two TMSO ligands. The ninth position is statistically (50%) occupied by an oxygen atom of a third TMSO ligand and an oxygen atom of an ethanol molecule.