We report the synthesis, crystal structures and magnetic investigations of four octahedral dysprosium complexes based on silanolate or stannanolate ligands of respective formula cis-[Dy(OSiPh3)2(THF)4][BPh4]·THF·C6H6 (1), cis-[Dy(OSnPh3)2(THF)4][BPh4]·THF·C6H6·C6H14 (2), fac-[Dy(OSiPh3)3(THF)3]·THF (3) and fac-[Dy(OSiPh3)3(bipy)(THF)]·THF (4) (where THF = tetrahydrofuran, Ph = phenyl, bipy = 2,2′-bipyridine). Whereas complexes 1–3 exhibit a field-induced slow relaxation of the magnetization, 4 is a zero-field single-molecule magnet, which could be rationalized by the introduction of the bidentate bipy ligand providing a more important linearity of the (Si)O–Dy–O(Si) angle through distortion of the coordination sphere.
