A series of organic-inorganic hybrids based on lanthanide-substituted Dawson-type phosphotungstate dimers and copper-en linkers

A family of organic-inorganic hybrid monolacunary Dawson phosphotungstate-based TM-Ln hetero-metallic derivatives Na₂H(H ₂en)₆[Cu(en)₂][Ln^III(α ₂-P₂W₁₇O₆₁)₂] ·men·nH₂O (Ln = Tb^III, m = 2, n = 26 for 1; Ln = Eu^III, m = 2, n = 28 for 2; Ln = Sm^III, m = 4, n = 24 for 3; Ln = Ce^III, m = 1, n = 21 for 4) (Ln = lanthanide, TM = transition metal, en = 1,2-ethylenediamine) have been hydrothermally synthesized and structurally characterized by elemental analysis, powder X-ray diffraction (PXRD), IR spectra, thermo-gravimetric (TG) analyses and single-crystal X-ray diffraction. Notably, 1-4 are isomorphic and represent the first family of 1-D chain-like architectures constructed by 1:2-type mono-Ln substituted Dawson-type [Ln^III(α₂-P₂W₁₇O ₆₁)]₂^17- dimeric units and [Cu(en) ₂]²⁺ connectors, in which the sandwich-type Ln-substituted monolacunary Dawson phosphotungstate fragment is found for the first time in TM-Ln-polyoxotungstate chemistry. Furthermore, the variable-temperature magnetic susceptibility of 1 has been investigated.