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(α-HSiW11O39)(H2O)3]·12H2O (1), [Cu(en)2(H2O)]2[Eu(α-HGeW11O39) (H2O)3]·12H2O (2), Na2[Cu(en)2(H2O)]4[Sm(α-PW11O39)(CH3COO)(H2O)]2·10H2O (3) and [Cu(en)2 (H2O)]5[Cu(en)2][Tb(α-GeW11O39)(CH3COO)(H2O)]2·14H2O (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(α-HXW11O39)(H2O)3]4− (Ln = TbIII, EuIII; X = SiIV, GeIV) units via W–O–Ln–O–W bridges whereas 3 and 4 display typical organic–inorganic hybrid dimeric structures consisting of [(α-XW11O39)Ln(H2O)(η2,μ-1,1)-CH3COO]210/12− 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(α-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. [ABSTRACT FROM AUTHOR]