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

Abstract

In memory of Professor Rudolf Hoppe on his 100 th anniversaryThe hydrogensulfate-sulfates Ln(HSO 4 )(SO 4 ) (Ln: Sm, Eu, Gd, Tb, Dy) have been crystallized from sulfuric acid and their thermal decomposition behavior has been studied. The crystal structures for all members of the series were refined from X-ray single-crystal diffraction data (for all: Tb(HSO 4 )(SO 4 ) structure type, P2 1 , Z = 2, a � 6.66 Å, b � 6.63 Å, c � 6.82 Å, β � 104.6°). Optical spectra (Sm-Dy) and magnetic susceptibilities (Eu-Dy) have been measured. For comparison the octahydrates Ln 2 (SO 4 ) 3 • 8 H 2 O (Sm, Eu) and the anhydrous sulfates Ln 2 (SO 4 ) 3 (Sm, Eu) have also been characterized by optical spectroscopy and magnetic measurements. Ligand field analyses (angular overlap model) based on these data suggest for the squareantiprismatic [Ln III O 8 ] chromophores in the hydrogensulfatesulfates a rather weak ligand field, which is comparable only to that in ultraphosphates LnP 5 O 14 and in contrast to the much stronger field observed for most other lanthanoid(III) oxocompounds studied so far. Results and DiscussionSynthesis. The well-known lanthanoid(III) sulfate octahydrates Ln 2 (SO 4 ) 3 • 8 H 2 O (Ln: Sm, Eu) [11,19] were crystallized from approx. 40 %wt. sulfuric acid at room temperature (for details see [a