An unprecedented trimer based on monovacant Dawson anion: [(α2-P2W17O61)Ln(H2O)4]321− (Ln = LaIII, CeIII and PrIII)

Abstract

Three unprecedented trimers based on monovacant Dawson-type polyoxotungstates Na12[Ln(H2O)9]2[(α2-P2W17O61H4)La(H2O)4]6·100H2O (Ln = LaIII (1)) and Na24[Ln(H2O)8]2[(α2-P2W17O61H2)Ln(H2O)4]6·56H2O (Ln = CeIII (2), and PrIII (3)) have been successfully synthesized by straightforward “self assembly” processes starting from a 1 : 4 ratio of the saturated Dawson precursor [α-P2W18O62]6− and Ln ions in aqueous solution, which were further characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectra, thermogravimetric (TG) analyses, electrospray ionization mass spectrometry (ESI-MS) and single-crystal X-ray diffraction. The common feature of 1–3 is that they all consist of the trimeric triangular [(α2-P2W17O61)Ln(H2O)4]321− subunit, as we know, the trimeric [(α2-P2W17O61)Ln(H2O)4]321− polyoxoanion is firstly discovered. Furthermore, all three compounds can further generate three dimensional channel architectures through Na+ cations. Meanwhile, the multinuclear solution 31P NMR spectrum of 1 at 300 K in D2O has been investigated, the results are further demonstrated by the technologies of ESI-MS.