Magnetic behavior of the novel pentagonal-bipyramidal erbium(III) complex (EtNH)[Er(HDAPS)Cl]: high-frequency EPR study and crystal-field analysis.

We report the synthesis, crystal structure and magnetic properties of the new heptacoordinated mononuclear erbium(III) complex (EtNH)[Er(HDAPS)Cl] (HDAPS = 2,6-diacetylpyridine bis-(salicylhydrazone)) (1). The coordination polyhedron around the Er(III) ion features a slightly distorted pentagonal bipyramid formed by the pentagonal NO chelate ring of the HDAPS ligand in the equatorial plane and two apical chloride ligands. Detailed high-frequency/high-field electron paramagnetic resonance (HF-EPR) studies of 1 result in the precise determination of the crystal field (CF) splitting energies (0, 290 and 460 GHz) and effective -values of the three lowest Kramers doublets (KDs) of the Er(III) ion.