New fabrication of lanthanide complexes based on the polyoxometalate ligand of the [α(1,4)-GeW10O38]12− anion

Cation‐Directed Dimeric versus Tetrameric Assemblies of Lanthanide‐Stabilized Dilacunary Keggin Tungstogermanates

“…Closely related dimeric assemblies were reported a few years ago by Li et al. for Ln=Dy, Er 16. These POMs with C 2 point symmetry were obtained from the reaction of the [γ‐GeW 10 O 36 ] 8− precursor with a lanthanide source in warm water at pH 4, and their constituent α‐ Ln 2 subunits show dilacunary Keggin skeletons of the α(1,4) type according to the Pope and Scully notation 17…”

“…It is also worth highlighting that a change in the relative intensities of the signals associated to the Ho 4 and Ho 2 anions is observed after three weeks, in such a way that those which correspond to the series { Ho 4 } 4− and { Ho 2 } 3− become the most intense to the detriment of the formerly predominant { Ho 4 } 6− and { Ho 2 } 4− (Figure S6 in the Supporting Information). We speculate that this could be related to a second process that takes place in solution, and more specifically, to β‐to‐α isomerization of Ho 2 clusters followed by reassembly into αα‐ Ho 4 dimers similar to those reported by Li et al 16. In fact, we were able to observe the co‐crystallization of αα‐ Ln 4 derivatives as thick prisms when needlelike crystals of compounds Na ‐ββ‐ Ln 4 (Ln=Er, Tm, Yb) were stored in their mother liquors for two to three months.…”

“…Closely related dimeric assemblies were reported a few years ago by Li et al for Ln = Dy, Er. [16] These POMs with C 2 point symmetry were obtained from the reaction of the [g-GeW 10 O 36 ] 8À precursor with a lanthanide source in warm water at pH 4, and their constituent a-Ln 2 subunits show dilacunary Keggin skeletons of the a(1,4) type according to the Pope and Scully notation. [17] Two different crystalline phases have been identified by means of single-crystal X-ray diffraction for compounds Na-bb-Ln 4 : phase A in crystals with Ln = Tm to Lu and phase B in those samples in which Ln = Dy to Er.…”

“…[4] Several of the most outstanding polyoxotungstate assemblies in terms of size, topology, and number of tungsten atoms are based on lacunary cluster subunits acting as multidentate O-donor ligands toward 4f-metal linkers. This includes some gigantic species with maximum dimensions around 4-5 nm such as the [As 12 Ce 16 (H 2 O) 36 22 ] 60À elongated assembly, or the series of isomorphic [Ln 16 As 16 W 164 O 576 (OH) 8 (H 2 O) 42 ] 80À macroanions (Ln = Eu, Gd, Tb, Dy, Ho). [5] But the field of 4f-containing POMs is not only driven by the challenging search for spectacular architectures; simple, small anions that display a limited number of 4f centers (e.g., 4f/ POM 1:1 monomers, 2:2 dimers, 1:2 sandwich species) have attracted even more interest because of their remarkable properties.…”

Multidimensional frameworks constructed from Keggin-type heteropoly blue of molybdenum–tungsten cluster

“…Polyoxometalates (POMs), as a fascinating class of metal oxide clusters with a remarkable degree of molecular and electronic tunabilities, have attracted an increasing attention in recent years because of their potential applications in areas such as catalysis, medicine, magnetochemistry and materials. [1][2][3][4][5][6][7][8][9][10][11][12] The metal oxide clusters of POMs are mainly based on V, Mo, and W ions in their highest oxidation states, in which each metal is generally coordinated by six oxygen atoms. Depending on their rich compositions and multi-point chemical bindings, POMs are suitable to construct a great variety of intriguing architectures with structural diversity.…”