Low-Temperature Syntheses and Characterization of Novel Layered Tellurites, A₂Mo₃TeO₁₂ (A = NH₄, Cs), and “Zero-Dimensional” Tellurites, A₄Mo₆Te₂O₂₄·6H₂O (A = Rb, K)

Abstract

Hydrothermal synthetic investigations to prepare new A(2)Mo(3)TeO(12) (A = NH(4), Cs, Rb, K) compounds are described. Novel noncentrosymmetric layered tellurites, (NH(4))(2)Mo(3)TeO(12) (1) and Cs(2)Mo(3)TeO(12) (2), have been synthesized by hydrothermal methods. Their structures contain two-dimensional hexagonal tungsten oxide related (Mo(3)TeO(12))(2)(-) anionic layers interleaved with NH(4)(+)/Cs(+) ions. New "zero-dimensional" tellurites, Rb(4)Mo(6)Te(2)O(24).6H(2)O (3) and K(4)Mo(6)Te(2)O(24).6H(2)O (4), containing discrete centrosymmetric (Mo(6)Te(2)O(24))(4)(-) anionic aggregates and alkali metal ions have been synthesized by simple refluxing of stoichiometric reactants in water. In this hexamolybdoditellurite anion, the Mo(6)O(24) flat hexagonal ring, formed from edge sharing of six MoO(6) octahedra, is capped by tellurium on both sides. The two types of anions have the same empirical formula. Cs(2)Mo(3)TeO(12) (2) could be prepared by a solid state reaction as well. All four new tellurites have been structurally characterized by single-crystal X-ray diffraction studies. Pertinent crystal, data are as follows: for 1, hexagonal space group P6(3), a = 7.332(2) Å, c = 12.028(4) Å, Z = 2; for 2, hexagonal space group P6(3), a = 7.3956(10) Å, c = 12.186(2) Å, Z = 2; for 3, monoclinic space group P2(1)/c, a = 10.0564(14) Å, b = 9.877(8) Å, c = 15.724(3) Å, beta = 109.988(11) degrees, Z = 2; for 4, monoclinic space group P2(1)/c, a = 9.878(3) Å, b = 9.724(4) Å, c = 15.301(3) Å, beta = 108.57(2) degrees, Z = 2. Low-temperature syntheses, structure, and powder X-ray diffraction, spectroscopic, and thermal studies of compounds 1-4 are described.

Organic–inorganic hybrid based on the molybdenum tellurite

“…The bands between 600 and 800 cm À1 may be assigned to TeAO and TeAOAMo stretches. The vibrations are consistent with those previously published [28,29]. The characteristic peaks ranging from 1100 to 1600 cm À1 are attributed to the 2,2 0 -bipyridine ligand.…”

“…Furthermore, transition-metal ions with d 0 electronic configuration such as Ti 4+ , Nb 5+ , Mo 6+ , W 6+ , etc, which are susceptible to second-order Jahn-Teller distortions, can be introduced into the metal tellurite systems. Most of these research efforts were focused on alkali/alkaline earth and transition-metal compounds of molybdenum(VI) tellurites [26][27][28][29][30], which are all pure inorganic molybdenum tellurite phases. However, the molybdenum tellurites templated by the organic molecules or covalently attached with metal-organic complex moieties have not been observed hitherto.…”

The Anderson–Evans polyoxometalate: From inorganic building blocks via hybrid organic–inorganic structures to tomorrows “Bio-POM”

“…Anderson-Evans-like structures have also been reported with the octahedral heteroatom being replaced by trigonal pyramidal/tetrahedral atoms (e.g. V V [45,46], As V [47] and Te IV [48,49]) on each side of the planar structure keeping the hexameric addenda ring intact. For color coding of the Figures throughout this review, green/cyan octahedra are used to illustrate addenda atoms that represent either Mo VI or W VI whereas red octahedra represent Mo VI addenda octahedra.…”

Structural characterization of quaternary selenites of tungsten(VI), A 2W3SeO12 (A = NH4, Cs, Rb, K or Tl)

“…Both SOJT distortions lead to acentric coordination environments that are conducive for NCS structures (Halasyamani 2004). For example, Cs 2 Mo 3 TeO 12 (Vidyavathy Balraj & Vidyasagar, 1998) and YVSe 2 O 8 (Kim et al, 2014) have non-centrosymmetric layered structures with these SOJT distortions and exhibit SHG activity. It needs to be mentioned that quaternary selenites and tellurites containing d 0 transition-metal ions, such as YVTe 2 O 8 (Kim et al, 2014), are also known to have centrosymmetric structures and exhibit no SHG activity.…”