Two tetranuclear 3d–4f complexes: Syntheses, structures and magnetic properties

The solvothermal reactions of 3,5-bis(trifluoromethyl)benzoic acid (HL) and 2,2′-bipyridine (bipy) with the corresponding metal salts afforded two novel 3d–4f tetranuclear complexes M2Dy2(L)10(bipy)2 (M = Mn 1, Cu 2), which have been characterized by single-crystal X-ray diffraction, infrared spectroscopy, element analyses, powder X-ray diffraction and thermal gravimetric analyses. Complexes 1 crystallizes in the triclinic space group P-1, and the completely deprotonated L ligands possess μ2: η1, η1 and μ2: η2, η1 coordination modes to bridge adjacent metal ions which further connect into 2D layers by hydrogen bonds. Complex 2 crystallizes in the distinct monoclinic space group P21/c, and adjacent metal ions were linked by L ligands with the same coordinated patterns with 1, and supramolecular sheets were formed in the ab plane. Dynamic magnetic susceptibility studies reveal slow magnetic relaxation processes for 2, suggesting SMM type behavior.