Crystal structure of a new digermanate: Al2Ge2O7

The structure of Al₂Ge₂O₇ has been determined by using a single crystal. The symmetry is monoclinic ($\text{C2}\text{c}\text{, Z = 4}$) with unit cell parameters a = 7.132(1) Å, b = 7.741(1) Å, c = 9.702(2) Å, β = 110.62(2)°. The structure is characterized by digermanate groups (Ge₂O₇) and by AlO₅ bipyramids with two common edges forming (AlO₃)_∞ chains. The relationship with the thortveitite structure is discussed in terms of coordination polyhedra.     

[Ni(H2O)6]2[Na(H2O)3]2[V10O28]·4H2O,bis(nickel hexahydrate) bis(sodium trihydrate) decavanadate tetrahydrate

Polyoxometallates are capable of including transition metals in their crystal structures as either discrete cations or heteroatoms. The title compound crystallizes with triclinic symmetry and consists of a centrosymmetric [V₁₀O₂₈]^6? anion, a trimeric {[Na(H₂O)₃][Ni(H₂O)₆][Na(H₂O)₃]}⁴⁺ cation, an [Ni(H₂O)₆]²⁺ cation and four water molecules of crystallization. The compound possesses two Ni atoms (each on independent inversion centres), one as a discrete cation and one in a disodium–nickel trimeric cation involved in the one‐dimensional polycation–polyanion hybrid polymer. The polymers are bound together via hydrogen bonds to the water mol­ecules and the nickel(II) hexahydrate cation. Several structures of decavanadate compounds having transition metal atoms, monovalent cations and [V₁₀O₂₈]^6? anions in the ratio 2:2:1 have been reported previously. However, the present compound differs from these in its arrangement of monovalent cations and transition metal atoms.     

Structure,chemical reactions and the hydration-dehydration process of the hydrated sodium intercalates Na0.6 (D2O)2Vs2 and Na0.6 (D2O)2VSe2

The structures of the stage II hydration compounds Na_0.6 (D₂O)₂VS₂ and Na_0.6 (D₂O)₂VSe₂ were investigated by neutron diffraction. The lattices are rhombohedral (as are those of the parent compounds). There are two water layers between VS₂(VSe₂) slabs, the oxygen of the water molecules being in hexagonal close packing with the chalcogen atoms; Na lies between the D₂O layers in octahedral coordination. The best agreement was found for a model with one D atom in the plane of the oxygen atoms and the other D atom between the O and S layers. The hydration and dehydration process was studied by X-ray diffraction. Some chemical reactions are described.     

K2[Hg(SO3)2]·2.25H2O

The characteristic feature of the structure of the title compound, dipotassium bis(sulfito‐κS)mercurate(II) 2.25‐hydrate, is a layered arrangement parallel to (001) where each of the two independent [Hg(SO₃)₂]²⁻ anions are grouped into centrosymmetric pairs and are surrounded by two K⁺ cations to give the overall layer composition {K₂[Hg(SO₃)₂]₂}²⁻. The remaining cations and the uncoordinated water molecules are situated between these layers. Within the [Hg(SO₃)₂]²⁻ anions, the central Hg atoms are twofold coordinated by S atoms, with a mean Hg—S bond length of 2.384 (2) Å. The anions are slightly bent [174.26 (3) and 176.99 (3)°] due to intermolecular O...Hg interactions greater than 2.8 Å. All coordination polyhedra around the K⁺ cations are considerably distorted, with coordination numbers ranging from six to nine. Although the H atoms of the five water molecules (one with symmetry 2) could not be located, O...O separations between 2.80 and 2.95 Å suggest a system of medium to weak O—H...O hydrogen bonds which help to consolidate the structural set‐up. Differences and similarities between the bis(sulfito‐κS)mercurate(II) anions in the title compound and those in the related salts (NH₄)₂[Hg(SO₃)₂] and Na₂[Hg(SO₃)₂]·H₂O are discussed.     

New silicate-germanate Cs2Pb2[(Si0.6Ge0.4)2O7] from the series A2Pb2[B2O7], A = K,Cs, B = Si,Ge with the umbrella-like [PbO3]4- group

New silicate-germanate Cs₂Pb₂[(Si_0.6Ge_0.4)₂O₇] was synthesized in multi-components hydrothermal solution with 20 w.% concentration of Cs₂CO₃ mineralizer, pH = 10. Novel mixed compound belongs to the structure type A₂Pb₂[B₂O₇] previously indicated for powders with A = K, B=Si or Ge. Singe crystal structure determination of Cs₂Pb₂[(Si_0.6Ge_0.4)₂O₇] revealed the need for the correction of the space group of the earlier suggested structural model from P-3 to P-3m1, as well as for the splitting of the Pb-atom position. Umbrella-like groups [PbO₃]^4- are located between [(Si,Ge)O₄]^4- tetrahedra in mica-like honeycomb layers and play the role of tetrahedra with the Pb-lone-pair as the forth apex. Crystal chemical comparison revealed similarities and differences with the classical structure type of α-celsian Ba[Al₂Si₂O₈] with the tetrahedral double layer. Recently investigated nonlinear optical acentric borates Pb₂(BO₃)(NO₃) and Pb₂(BO₃)Cl are both related to this structural type, possessing umbrella-like groups [PbO₃]^4- and honeycomb layers [Pb₂(BO₃)]⁺ with the BO₃-triangles on the tetrahedral positions.     

Die IR-Spektren von [Cr(O2)2(NH3)3] und K3[Cr(O2)2(CN)3]

The infrared spectra of the title compounds are reported and discussed. The influence of the peroxide groups on the bond properties of the other ligands and some characteristics of the metal—peroxide interactions are analyzed.     

New coordination modes in potassium edta salts: K2[H2edta]·2H2O,K3[Hedta]·2H2O and K4[edta]·3.92H2O

Three potassium edta (edta is ethylenediaminetetraacetic acid, H₄Y) salts which have different degrees of ionization of the edta anion, namely dipotassium 2‐({2‐[bis(carboxylatomethyl)azaniumyl]ethyl}(carboxylatomethyl)azaniumyl)acetate dihydrate, 2K⁺·C₁₀H₁₄N₂O₈²⁻·2H₂O, (I), tripotassium 2,2′‐({2‐[bis(carboxylatomethyl)amino]ethyl}ammonio)diacetate dihydrate, 3K⁺·C₁₀H₁₃N₂O₈³⁻·2H₂O, (II), and tetrapotassium 2,2′,2′′,2′′′‐(ethane‐1,2‐diyldinitrilo)tetraacetate 3.92‐hydrate, 4K⁺·C₁₀H₁₂N₂O₈⁴⁻·3.92H₂O, (III), were obtained in crystalline form from water solutions after mixing edta with potassium hydroxide in different molar ratios. In (II), a new mode of coordination of the edta anion to the metal is observed. The HY³⁻ anion contains one deprotonated N atom coordinated to K⁺ and the second N atom is involved in intramolecular bifurcated N—H...O and N—H...N hydrogen bonds. The overall conformation of the HY³⁻ anions is very similar to that of the Y⁴⁻ anions in (III), although a slightly different spatial arrangement of the –CH₂COO⁻ groups in relation to (III) is observed, whereas the H₂Y²⁻ anions in (I) adopt a distinctly different geometry. The preferred synclinal conformation of the –NCH₂CH₂N– moiety was found for all edta anions. In all three crystals, the anions and water molecules are arranged in three‐dimensional networks linked via O—H...O and C—H...O [and N—H...O in (I) and (II)] hydrogen bonds. K...O interactions also contribute to the three‐dimensional polymeric architecture of the salts.     

K2[Mo2O4(C2O4)2(H2O)2]·3H2O

The crystal and molecular structure of dipotassium di‐μ‐oxo‐bis[aqua(oxalato‐O¹,O²)oxomolybdenum(III)] trihydrate, K₂­[Mo₂O₄(C₂O₄)₂(H₂O)₂]·3H₂O, has been determined from X‐ray diffraction data. In the dimeric anion, which has approximate twofold symmetry, each Mo atom is in a distorted octahedral coordination, being bonded to one terminal oxo‐O atom, two bridging O atoms, two O atoms from the oxalato ligand and one from the water mol­ecule. Bond lengths trans to the multiple‐bonded terminal oxo ligand are larger than those in the cis position, confirming the trans influence as a generally valid rule.     

Die Kristallstruktur eines neuen Alkalidigermanats,Na4K2Ge2O7

Na₄K₂Ge₂O₇ is monoclinic, space group P 2₁ (No. 4),a=6.010 (3),b=6.020 (3),c=29.26 (1) Å, γ=119.9 (1)° andZ=4. Its crystal structure has been determined from 1210 single crystal X-ray reflections and refined toR=0.114. The structure contains two independent Ge₂O₇ groups, the (GeOGe) angles of which are 128 and 132°.     

Die Kristallstruktur des Natriumoxohydroxoaluminathydrates Na2[Al2O3(OH)2] · 1,5 H2O

The Crystal Structure of the Sodium Oxohydroxoaluminate Hydrate Na₂[Al₂O₃(OH)₂] · 1.5 H₂O The crystal structure of the sodium oxohydroxoaluminate hydrate Na₂[Al₂O₃(OH)₂] ·s 1.5 H₂O (up to now described as Na₂O · Al₂O₃ · 2.5 H₂O and Na₂O · Al₂O₃ · 3 H₂O, respectively) was solved. The X-ray single crystal diffraction analysis (tetragonal, space group P-42₁m, a = 10.522(1) Å, c = 5.330(1) Å, Z = 4) results in a polymeric layered structure, consisting of AlO_3/2(OH) tetrahedral groups. Between these layers the Na⁺ ions are situated, which form tetrameric groups of face-linked NaO₆ octahedra. The involved O^2? ions are due to Al? O? Al bridges, Al? OH groups and water of crystallization. ²⁷Al and ²³Na MAS NMR investigations confirm the crystal structure analysis. The relations between the crystallization behaviour of the compound and the constitution of the aluminate anions in the corresponding sodium aluminate solution and in the solid, respectively, are discussed.     

Novel K/Mn phosphate hydrates,K2Mn3(H2O)2[P2O7]2 and KMn(H2O)2[Al2(PO4)3]: hydrothermal synthesis and crystal chemistry

Two novel K/Mn phosphate hydrates, namely, dipotassium trimanganese dipyrophosphate dihydrate, K₂Mn₃(H₂O)₂[P₂O₇]₂, (I), and potassium manganese dialuminium triphosphate dihydrate, KMn(H₂O)₂[Al₂(PO₄)₃], (II), were obtained in the form of single crystals during a single hydrothermal synthesis experiment. Their crystal structures were studied by X‐ray diffraction. Both new compounds are members of the morphotropic series of phosphates with the following formulae: A₂M₃(H₂O)₂[P₂O₇]₂, where A = K, NH₄, Rb or Na and M = Mn, Fe, Co or Ni, and AM²⁺(H₂O)₂[M³⁺₂(PO₄)₃], where A = Cs, Rb, K, NH₄ or (H₃O); M²⁺ = Mn, Fe, Co or Ni; and M³⁺ = Al, Ga or Fe. A detailed crystal chemical analysis revealed correlations between the unit‐cell parameters of the members of the series, their structural features and the sizes of the cations. It has been shown that a mixed type anionic framework is formed in (II) by aluminophosphate [(AlO₂)₂(PO₄)₂]_∞ layers, with a cationic topology similar to the Si/Al‐topology of the crystal structures of feldspars. A study of the magnetic susceptibility of (II) demonstrates a paramagnetic behaviour of the compound.     

K3(U3O6)(Si2O7) and Rb3(U3O6)(Ge2O7): a pentavalent-uranium silicate and germanate

A new uranium(V) silicate, K3(U3O6)(Si2O7), and the germanate analogue, Rb3(U3O6)(Ge2O7), have been synthesized under high-temperature, high-pressure hydrothermal conditions and characterized by single-crystal X-ray diffraction. Their structures contain uranate columns formed of triple octahedral chains of the alpha-UF5 type linked by disilicate (or digermanate) units to form a 3-D framework structure. The valence state of uranium is confirmed by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and magnetic susceptibility.