The weak ligand field in lanthanoid(III) hydrogensulfate‐sulfates

The hydrogensulfate-sulfates Ln(HSO4)(SO4) (Ln: Sm, Eu, Gd, Tb, Dy) have been crystallized from sulfuric acid and their thermal decomposition behavior has studied. crystal structures for all members of the series were refined X-ray single-crystal diffraction data (for all: Tb(HSO4)(SO4) structure type, P21, Z=2, a≈6.66 Å, b≈6.63 c≈6.82 β≈104.6°). Optical spectra (Sm–Dy) magnetic susceptibilities (Eu–Dy) measured. For comparison octahydrates Ln2(SO4)3 ⋅ 8 H2O (Sm, Eu) anhydrous sulfates also characterized by optical spectroscopy measurements. Ligand field analyses (angular overlap model) based on these suggest square-antiprismatic [LnIIIO8] chromophores in a rather weak ligand field, which is comparable only to that ultraphosphates LnP5O14 contrast much stronger observed most other lanthanoid(III) oxo-compounds studied so far.