Organic-inorganic hybrids based on monovacant Keggin-type polyoxotungstates and 3d-4f heterometals

Four organic-inorganic hybrid monolacunary Keggin polyoxotungstate-based 3d-4f heterometallic derivatives [Cu(en)(2)(H2O)](2)[Tb(alpha-HSiW11O39)(H2O)(3)]center dot 12H(2)O (1), [Cu(en)(2)(H2O)](2)[Eu(alpha-HGeW11O39) (H2O)(3)]center dot 12H(2)O (2), Na-2[Cu(en)(2)(H2O)](4)[Sm(alpha-PW11O39)(CH3COO)(H2O)](2)center dot 10H(2)O (3) and [Cu(en)(2) (H2O)](5)[Cu(en)(2)][Tb(alpha-GeW11O39)(CH3COO)(H2O)](2)center dot 14H(2)O (4) (en = ethylenediamine) have been hydrothermally prepared and characterized by elemental analyses, IR spectra, thermogravimetric (TG) analyses and X-ray single-crystal diffraction. 1 and 2 are isomorphic and exhibit the interesting one-dimensional chain arrangements built by monovacant-lanthanide substituted Keggin-type [Ln(alpha-HXW11O39)(H2O)(3)]4(-)(Ln = Tb-III, Eu-III; X = Si-IV, Ge-IV) units via W-O-Ln-O-W bridges whereas 3 and 4 display typical organic-inorganic hybrid dimeric structures consisting of [(alpha-XW11O39)Ln(H2O)(eta(2),mu-1,1)-CH3COO](2)(10/12-) units modified by [Cu(en)(2)(H2O)](2+) fragments. To the best of our knowledge, 1 and 2 represent the rare 1D chain-like monovacant Keggin-type 3d-4f heterometallic polyoxotungstates containing both unusual 1 : 1 [Ln(alpha-XW11O39)](4/5-) units and en ligands, whereas 3 and 4 represent the first monovacant Keggin-type phosphotungstates or germanotungstates containing both 3d-4f heterometals and mixed ligands of en and acetate. Furthermore, the variable-temperature magnetic susceptibilities of 1 and 3 have been investigated.