Crystal Structures of [Mn2(H2O)4(phen)2(C4H4O4)2] · 2 H2O and [Mn(phen)2(H2O)2][Mn(phen)2(C4H4O4)](C4H4O4) · 7 H2O

Reactions of 1,10‐phenanthroline monohydrate, Na₂C₄H₄O₄ · 6 H₂O and MnSO₄ · H₂O in CH₃OH/H₂O yielded a mixture of [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] · 2 H₂O ( 1 ) and [Mn(phen)₂(H₂O)₂][Mn(phen)₂(C₄H₄O₄)](C₄H₄O₄) · 7 H₂O ( 2 ). The crystal structure of 1 (P1 (no. 2), a = 8.257(1) Å, b = 8.395(1) Å, c = 12.879(2) Å, α = 95.33(1)°, β = 104.56(1)°, γ = 106.76(1)°, V = 814.1(2) ų, Z = 1) consists of the dinuclear [Mn₂(H₂O)₄(phen)₂(C₄H₄O₄)₂] molecules and hydrogen bonded H₂O molecules. The centrosymmetric dinuclear molecules, in which the Mn atoms are octahedrally coordinated by two N atoms of one phen ligand and four O atoms from two H₂O molecules and two bis‐monodentate succinato ligands, are assembled via π‐π stacking interactions into 2 D supramolecular layers parallel to (101) (d(Mn–O) = 2.123–2.265 Å, d(Mn–N) = 2.307 Å). The crystal structure of 2 (P1 (no. 2), a = 14.289(2) Å, b = 15.182(2) Å, c = 15.913(2) Å, α = 67.108(7)°, β = 87.27(1)°, γ = 68.216(8)°, V = 2934.2(7) ų, Z = 2) is composed of the [Mn(phen)₂(H₂O)₂]²⁺ cations, [Mn(phen)₂(C₄H₄O₄)] complex molecules, (C₄H₄O₄)^2– anions, and H₂O molecules. The (C₄H₄O₄)^2– anions and H₂O molecules form 3 D hydrogen bonded network and the cations and complex molecules in the tunnels along [001] and [011], respectively, are assembled via the π‐π stacking interactions into 1 D supramolecular chains. The Mn atoms are octahedrally coordinated by four N atoms of two bidentate chelating phen ligands and two water O atoms or two carboxyl O atoms (d(Mn–O) = 2.088–2.129 Å, d(Mn–N) = 2.277–2.355 Å). Interestingly, the succinato ligands in the complex molecules assume gauche conformation bidentately to chelate the Mn atoms into seven‐membered rings.     

New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] · 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] · 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] · 14 H2O,and (NH4)12[Mo36(NO)4O108(H2O)16] · 33 H2O

The compounds (NMe₄)₅[As₂Mo₈V₄AsO₄₀] · 3 H₂O 2a , (NH₄)₂₁[H₃Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 65 H₂O 3a , (NH₂Me₂)₁₈(NH₄)₆[Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 14 H₂O 3b and (NH₄)₁₂[Mo₃₆(NO)₄O₁₀₈(H₂O)₁₆] · 33 H₂O 4a ( 3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3a, 3b , and 4a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of “extremely” large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo₁₇} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na₃(NH₄)₁₂[H₁₅Mo₅₇Fe₆(NO)₆O₁₈₃(H₂O)₁₈] · 76 H₂O 7a .     

Structural Diversity of Sheets in Rubidium Uranyl Oxoselenates: Synthesis and Crystal Structures of Rb2[(UO2)(SeO4)2(H2O)](H2O), Rb2[(UO2)2(SeO4)3(H2O)2](H2O)4, and Rb4[(UO2)3(SeO4)5(H2O)]

Single crystals of three rubidium uranyl selenates, Rb₂[(UO₂)(SeO₄)₂(H₂O)](H₂O) ( 1 ), Rb₂[(UO₂)₂(SeO₄)₃(H₂O)₂](H₂O)₄ ( 2 ), and Rb₄[(UO₂)₃(SeO₄)₅(H₂O)] ( 3 ), have been prepared by evaporation from aqueous solutions made out of mixtures of uranyl nitrate, selenic acid and Rb₂CO₃. The structures of all compounds have been solved by direct methods on the basis of X‐ray diffraction data sets. The crystallographic data are as follows: ( 1 ): orthorhombic, Pna2₁, a = 13.677(2), b = 11.8707(13), c = 7.6397(9) Å, V = 1240.4(3) ų, R₁ = 0.045 for 2396 independent observed reflections; ( 2 ): triclinic, P1¯, a = 8.4261(12), b = 11.8636(15), c = 13.3279(18) Å, α = 102.612(10), β = 107.250(10), γ = 102.510(10)°, V = 1183.7(3) ų, R₁ = 0.067 for 4762 independent observed reflections; ( 3 ): orthorhombic, Pbnm, a = 11.3761(14), b = 15.069(2), c = 19.2089(17) Å, V = 3292.9(7) ų, R₁ = 0.075 for 3808 independent observed reflections. The structures of the phases 1 , 2 , and 3 are based upon uranyl selenate hydrate sheets composed from corner‐sharing pentagonal [UO₇]^8— bipyramids and [SeO₄]^2— tetrahedra. In the crystal structure of 1 , the sheets have composition [(UO₂)(SeO₄)₂(H₂O)]^2— and run parallel to (001). The interlayer contains Rb⁺ cations and additional H₂O molecules. In structure of 2 , the [(UO₂)₂(SeO₄)₃(H₂O)₂]^2— sheets are oriented parallel to (101). Highly disordered Rb⁺ cations and H₂O molecules are located between the sheets. The structure of 3 is based upon [(UO₂)₃(SeO₄)₅(H₂O)]^4— sheets stacked parallel to (010) and contains Rb⁺ cations in the interlayers. The topologies of the uranyl oxoselenate sheets observed in the structures of 1 , 2 , and 3 are related to the same simple and highly‐symmetric graph consisting of 3‐connected white and 6‐connected black vertices.     

Thermal decomposition of transition metal biphthalates [M(H2O)6](C8H5O4)2 (M = Fe, Co, Ni) and copper biphthalate [Cu(C8H5O4)2(H2O)2]. Synthesis of metal-polymer composites

The decomposition of transition metal biphthalates [M(H₂O)₆](C₈H₅O₄)₂ (M = Fe, Co, Ni) and copper biphthalate [Cu(C₈H₅O₄)₂(H₂O)₂] was studied by thermal analysis and mass spectrometry. The decomposition was shown to proceed in three stages: the temperature of the third stage of decomposition decreased in the series of iron, cobalt, nickel, and copper biphthalates from 365 to 275°C. The mass spectrometric study showed the evolution of CO₂, diphenylene C₁₂H₈, and fluorene (C₆H₄)₂CH₂ that at this stage. It was shown by electron scanning microscopy, X-ray diffraction analysis, and chemical analysis that the final thermolysis product of transition metal biphthalates was a composite consisting of the polymer and incorporated into it round submicronic aggregates with metallic particles inside.     

Synthesis and Crystal Structure of Europium(II) Tartrate Tetrahydrate, [Eu(C4H4O6)(H2O)2](H2O)2

Single crystals of [Eu(C₄H₄O₆)(H₂O)₂](H₂O)₂ were obtained from the combination of solutions of EuCl₂, previously obtained by electrolysis of an aqueous solution of EuCl₃, and tartraric acid, neutralized by LiOH. The crystal structure (orthorhombic, P2₁2₁2₁, Z = 4, a = 948.9(1), b = 954.6(1), c = 1098.4(1) pm; R(F) = 0.0242 and R_w(F²) = 0.0585 for I > 2σ(I); R(F) = 0.0256 and R_w(F²) = 0.0592 for all data) is isotypic with [Ca(C₄H₄O₆)(H₂O)₂](H₂O)₂ and [Sr(C₄H₄O₆)(H₂O)₂](H₂O)₂ exhibiting a three‐dimensional structure. The divalent cations (Eu²⁺, Ca²⁺, Sr²⁺) are eight‐coordinate by oxygen atoms that originate from carboxylate and hydroxyl groups of the tartraric dianion and two of the four water molecules.     

RbCrIII(C2O4)2·2H2O,Cs2Mg(C2O4)2·4H2O and Rb2CuII(C2O4)2·2H2O: three new complex oxalate hydrates

Rubidium chromium(III) dioxalate dihydrate [di­aqua­bis(μ‐oxalato)­chromium(III)­rubidium(I)], [RbCr(C₂O₄)₂(H₂O)₂], (I), and dicaesium magnesium dioxalate tetrahydrate [tetra­aqua­bis(μ‐oxalato)­magnesium(II)­dicaesium(I)], [Cs₂Mg(C₂­O₄)₂(H₂O)₄], (II), have layered structures which are new among double‐metal oxalates. In (I), the Rb and Cr atoms lie on sites with imposed 2/m symmetry and the unique water molecule lies on a mirror plane; in (II), the Mg atom lies on a twofold axis. The two non‐equivalent Cr and Mg atoms both show octahedral coordination, with a mean Cr—O distance of 1.966 Å and a mean Mg—O distance of 2.066 Å. Dirubid­ium copper(II) dioxalate dihydrate [di­aqua­bis(μ‐oxalato)­copper(II)­dirubidium(I)], [Rb₂Cu(C₂O₄)₂(H₂O)₂], (III), is also layered and is isotypic with the previously described K₂‐ and (NH₄)₂Cu^II(C₂O₄)₂·2H₂O compounds. The two non‐equivalent Cu atoms lie on inversion centres and are both (4+2)‐coordinated. Hydro­gen bonds are medium‐strong to weak in the three compounds. The oxalate groups are slightly non‐planar only in the Cs–Mg compound, (II), and are more distinctly non‐planar in the K–Cu compound, (III).     

Ni(II), Pd(II), Cu(II) And Zn(II) complexes with N-(2-Pyridyl)Carbonylaniline (L), Syntheses and X-Ray Crystal structures of [Cu(L)2(H2O)2](No3)2, [Cu(L)2(H2O)2](Clo4)2 and [Zn(L)2(H2O)2](Clo4)2

Reaction of the N-(2-pyridyl)carbonylaniline ligand (L) with Cu(NO₃)₂, Cu(ClO₄)₂, Zn(ClO₄)₂, Ni(NO₃)₂ and PdCl₂ gives complexes with stoichiometry [Cu(L)₂(H₂O)₂](NO₃)₂, [Cu(L)₂(H₂O)₂](ClO₄)₂, [Zn(L)₂(H₂O)₂] (ClO₄)_2, [Ni(L)₂(H₂O)Cl](NO₃) and PdLCl₂. The new complexes were characterized by elemental analyses and infrared spectra. The crystal structures of [Cu(L)₂(H₂O)₂](NO₃)₂, [Cu(L)₂(H₂O)₂](ClO₄)₂, and [Zn(L)₂(H₂O)₂](ClO₄)₂ were determined by X-ray crystallography. The cation complexes [M(L)₂(H₂O)₂] contain copper(II) and zinc(II) with distorted octahedral geometry with two N-(2-pyridyl)carbonylaniline (L) ligands occupying the equatorial sites. The hexa-coordinated metal atoms are bonded to two pyridinic nitrogens, two carbonyl oxygens and two water molecules occupying the axial sites. Both the coordinated water molecules and uncoordinated amide NH groups of the N-(2-pyridyl)carbonylaniline (L) ligands are involved in hydrogen bonding, resulting in infinite hydrogen-bonded chains running in one and two-dimensions.     

Na2Co(H2PO4)4·4H2O

In the title compound, disodium cobalt tetrakis­(dihydrogen­phosphate) tetrahydrate, the Co^II ion lies on an inversion centre and is octahedrally surrounded by two water molecules and four H₂PO₄ groups to give a cobalt complex anion of the form [Co(H₂PO₄)₄(OH₂)]^2?. The three‐dimensional framework results from hydrogen bonding between the anions. The relationship with the structures of Co(H₂PO₄)₂·2H₂O and K₂CoP₄O₁₂·5H₂O is discussed.     

Sur un nouveau Complexe entre l'oxyfluorure d'antimoine et l'oxalate. Structure cristalline de (NH4)4H2(C2O4)3(SbOF) 2 · H2O

On a New Complex of Antimony Oxide Fluoride and Oxalate. Crystal Structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O The crystal structure of (NH₄)₄H₂(C₂O₄)₃(SbOF) ₂ · H₂O has been fixed by X-ray diffraction on single crystal (R = 0.025 for 2124 planes). The antimony atom is complexed by the oxalate anions which are bidendate chelates. Antimony coordination is seven (five oxygen atoms, one fluorine atom, and the lone pair E). Antimony environment is a pentagonal bipyramid, one of the axial positions is occupied by the lone pair, the other one by the fluorine atom.     

Two new open framework cobalt phosphates: NaCo3(OH)(PO4)2.1/4H2O and Na(NH4)Co2(PO4)2.H2O

Two new cobalt phosphates, NaCo₃(OH)(PO₄)₂.1/4H₂O (1) and Na(NH₄)Co₂(PO₄)₂.H₂O (2) have been synthesized hydrothermally and characterized by single crystal X-ray diffraction methods, vibrational (IR and Raman) spectroscopy, thermogravimetric analysis and magnetic measurements. The structure of 1 is a new framework type while 2 is an example of a chiral cobalt phosphate. Both phases contain channels in which the Na⁺, NH₄⁺ cations and H₂O molecules are located.     

Synthesis,Structure and Photoluminescent Properties of [C6N2H14][Nd2(C2O4)2(SO4)2(H2O)4]·H2O,a New Organically Templated Neodymium(III) Oxalate‐sulfate

An organically templated neodymium oxalate–sulfate [C₆N₂H₁₄][Nd₂(C₂O₄)₂(SO₄)₂(H₂O)₄]·H₂O ( 1 ) has been synthesized under hydrothermal conditions and structurally characterized by single‐crystal X‐ray diffraction analysis. In 1 , the neodymium(III) ions are interconnected through oxalate and sulfate groups to form a neodymium oxalate–sulfate hybrid structure. A luminescence spectrum of 1 was recorded, and the luminescence decay time was also measured.     

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.     

Kristallstruktur von (NMe4)2[Re3Br11(H2O)] [Re3Br9(H2O)3](H2O)2

Crystal Structure of (NMe₄)₂[Re₃Br₁₁(H₂O)] [Re₃Br₉(H₂O)₃](H₂O)₂ . (NMe₄)₂[Re₃Br₁₁(H₂O)] [Re₃Br₉(H₂O)₃](H₂O)₂ crystallizes from hydrobromic acid solution of Re₃Br₉ · 2 H₂O and NMe₄Br at 0 – 5°C. The crystal structure (monoclinic; P2₁/m (Nr. 11); a = 967.9(3); b = 1 529.7(4); c = 1 710.9(4) pm; β = 91.66(2)°; Z = 2; R = 0.113; R_w = 0.068) has been determined from four-circle diffractometer data. The structure contains two different cluster units of trivalent rhenium, isolated anionic [Re₃Br₁₁(H₂O)]^2? units and neutral cluster units that are connected through crystal water molecules to chains{[Re₃Br₉(H₂O)₃](H₂O)₂}.     

Synthese und Kristallstruktur von Hydrogensulfaten einwertiger Metalle – Ag(H3O)(HSO4)2, Ag2(HSO4)2(H2SO4), AgHSO4 und Hg2(HSO4)2

Synthesis and Crystal Structure of Metal(I) Hydrogen Sulfates – Ag(H₃O)(HSO₄)₂, Ag₂(HSO₄)₂(H₂SO₄), AgHSO₄, and Hg₂(HSO₄)₂ Hydrogen sulfates Ag(H₃O)(HSO₄)₂, Ag₂(HSO₄)₂ · (H₂SO₄), and AgHSO₄ have been synthesized from Ag₂SO₄ and sulfuric acid. Hg₂(HSO₄)₂ was obtained from metallic mercury and 96% sulfuric acid as starting materials. The compounds were characterized by X‐ray single crystal structure determination. Ag(H₃O)(HSO₄)₂ belongs to the structure type of Na(H₃O)(HSO₄). The silver atom is coordinated by 6 + 2 oxygen atoms. In the structure, there are dimers and chains of hydrogen bonded HSO₄^– tetrahedra. Dimers and chains are connected by the H₃O⁺ ion to form a three dimensional hydrogen network. Ag₂(HSO₄)₂(H₂SO₄) crystallizes isotypic to Na₂(HSO₄)₂(H₂SO₄). The coordination number of silver is 6 + 1. The structure of Ag₂(HSO₄)₂(H₂SO₄) is characterized by hydrogen bonded trimers of HSO₄^– tetrahedra, which are further connected to chains. For the recently published structure of AgHSO₄ the hydrogen bonding system was discussed. There are tetrameres and chains, connected by bifurcated hydrogen bonds. The structure of Hg₂(HSO₄)₂ contains Hg₂²⁺ cations with Hg–Hg distance of 2.509 Å. Every mercury atom is coordinated by one oxygen atom at shorter distance (2.18 Å) and three ones at longer distances (2.57 to 3.08 Å). The HSO₄^– tetrahedra form zigzag chains by hydrogen bonds.     

Das Chloridnitrat PrCl2(NO3) · 5 H2O mit kationischen und anionischen Komplexen gemäß [PrCl2(H2O)6][PrCl2(NO3)2(H2O)4]

The Chloride Nitrate PrCl₂(NO₃) · 5 H₂O with Cationic and Anionic Complexes according to [PrCl₂(H₂O)₆][PrCl₂(NO₃)₂(H₂O)₄] Green single crystals of PrCl₂(NO₃) · 5 H₂O have been obtained from an aqueous solution of PrCl₃ and Pr(NO₃)₃. The crystal structure [monoclinic, P2/c, Z = 4, a = 1228.8(3), b = 648.4(1), c = 1266.0(4) pm, β = 91.91(3)°] contains cationic and anionic Pr³⁺ complexes according to [PrCl₂(H₂O)₆][PrCl₂(NO₃)₂(H₂O)₄]. Both nitrate groups of the anionic complex act as bidentate chelating ligands. Hydrogen bonds are observed with water molecules as donors and chlorine as well as oxygen atoms as acceptors.     

Crystal structure of (C2H7N4O)2[UO2(C2O4)2(H2O)]

The single crystals of (C₂H₇N₄O)₂[UO₂(C₂O₄)₂(H₂O)] were studied by X-ray diffraction. The crystals are monoclinic, space group Pn, Z = 2, unit cell parameters: a = 9.4123(2) Å, b = 8.4591(2) Å, c = 11.8740(3) Å, β = 105.500(10)°, V = 911.02(4) ų. The main structural units of the crystals of I are islet complex groups [UO₂(C₂O₄)₂(H₂O)]^2? corresponding to the crystal chemical group AB ₂ ⁰¹ M¹ (A = UO UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M = H₂O) of uranyl complexes. Uranium-containing mononuclear complexes are connected into a three-dimensional framework through the electrostatic interactions and hydrogen bonding system involving carbamyolguanidinium ions.     

[Mn(H2O)4(C4N2H4)][C6H4(COO)2] – Ein eindimensionales Koordinationspolymer mit kettenartigen [Mn(H2O)4(C4N2H4)]n2n+ Polykationen

[Mn(H₂O)₄(C₄N₂H₄)][C₆H₄(COO)₂] – An One‐Dimensional Coordination Polymer with Chain‐like [Mn(H₂O)₄(C₄N₂H₄)]_n²ⁿ⁺ Polycations Orthorhombic single crystals of [Mn(H₂O)₄(C₄N₂H₄)][C₆H₄(COO)₂] have been prepared in aqueous solution at room temperature. Space group Imm2 (no. 44), a = 1039.00(6) pm, b = 954.46(13) pm, c = 737.86(5) pm, V = 0.73172(12) nm³, Z = 2. Mn²⁺ is coordinated in a octahedral manner by four water molecules and two nitrogen atoms stemming from the pyrazine molecules (Mn–O 215.02(11) pm; Mn–N 228.7(4), 230.7(4) pm). Mn²⁺ and pyrazine molecules form chain‐like polycations with [Mn(H₂O)₄(C₄N₂H₄)]_n²ⁿ⁺ composition. The positive charge of the polycationic chains is compensated for by phthalate anions, which are accomodated between the chains. The phthalate anions are linked by hydrogen bonds to the polycationic chains. Thermogravimetric analysis in air revealed that the loss of water of crystallisation and pyrazine occurs in two steps between 130 and 245 °C. The resulting sample was stable up to 360 °C. Further decomposition yielded Mn₂O₃.     

Two Heteroleptic Zinc(II) Complexes: [Zn(phen)(C9H15O6)2] and [Zn2(phen)2(H2O)2(C10H16O4)2] · 3H2O

Reactions of a freshly prepared Zn(OH)_2‐2x(CO₃)x · yH₂O precipitate, phenanthroline with azelaic and sebacic acid in CH₃OH/H₂O afforded [Zn(phen)(C₉H₁₅O₄)₂] ( 1 ) and [Zn₂(phen)₂(H₂O)₂(C₁₀H₁₆O₄)₂] · 3H₂O ( 2 ), respectively. They were structurally characterized by X‐ray diffraction methods. Compound 1 consists of complex molecules [Zn(phen)(C₉H₁₅O₄)₂] in which the Zn atoms are tetrahedrally coordinated by two N atoms of one phen ligand and two O atoms of different monodentate hydrogen azelaato groups. Intermolecular C(alkyl)‐H···π interactions and the intermolecular C(aryl)‐H···O and O‐H···O hydrogen bonds are responsible for the supramolecular assembly of the [Zn(phen)(C₉H₁₅O₄)₂] complexes. Compound 2 is built up from crystal H₂O molecules and the centrosymmetric binuclear [Zn₂(phen)₂(H₂O)₂(C₁₀H₁₆O₄)₂] complex, in which two [Zn(phen)(H₂O)]²⁺ moieties are bridged by two sebacato ligands. Through the intermolecular C(alkyl)‐H···O hydrogen bonds and π‐π stacking interactions, the binuclear complex molecules are assembled into layers, between which the lattice H₂O molecules are sandwiched. Crystal data: ( 1 ) C2/c (no. 15), a = 13.887(2), b = 9.790(2), c = 22.887(3)Å, β = 107.05(1)°, U = 2974.8(8)ų, Z = 4; ( 2 ) P1¯ (no. 2), a = 8.414(1), b = 10.679(1), c = 14.076(2)Å, α = 106.52(1)°, β = 91.56(1)°, γ = 99.09(1)°, U = 1193.9(2)ų, Z = 1.     

NaIn(CrO4)2·2H2O,the first indium(III) member of the kröhnkite family

Sodium indium(III) chromate(VI) dihydrate, NaIn(CrO₄)₂·2H₂O, synthesized from an aqueous solution at room temperature, is the first indium(III) member of the large family of compounds with kröhnkite [Na₂Cu^II(S^VIO₄)₂·2H₂O]‐type chains. The crystal structure is based on infinite octa­hedral–tetra­hedral [In(CrO₄)₂(H₂O)₂]⁻ chains along [010], linked via charge‐balancing Na⁺ cations. The slightly distorted InO₄(H₂O)₂ octa­hedra are characterized by a mean In—O distance of 2.125 Å. The CrO₄ tetra­hedra are strongly distorted (mean Cr—O = 1.641 Å). The Na atom shows an octa­hedral coordination, unprecedented among compounds with kröhnkite‐type chains. The NaO₆ octa­hedra share opposite edges with the InO₄(H₂O)₂ octa­hedra to form infinite [001] chains. The hydrogen bonds are of medium strength. NaIn(CrO₄)₂·2H₂O belongs to the structural type F2 in the classification of Fleck, Kolitsch & Hertweck [Z. Kristallogr. (2002), 217 , 435–443], and is isotypic with KAl(CrO₄)₂·2H₂O and MFe(CrO₄)₂·2H₂O (M = K, Tl or NH₄). All atoms are in special positions except one O atom.     

Die ersten Hydrogencarbonate mit einer trimeren [H2(CO3)3]4−-Baugruppe: Zur Darstellung und Kristallstruktur von Rb4H2(CO3)3 · H2O und K4H2(CO3)3 · 1,5 H2O

The First Hydrogencarbonates with a Trimeric [H₂(CO₃)₃]^4? Group: Preparation and Crystal Structure of Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1.5 H₂O Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1,5 H₂O were prepared by means of the reaction of (CH₃)₂CO₃ with RbOH resp. KOH in aqueous methanole. Trimer [H₂(CO₃)₃]^4?-anions were found in the crystal structure of Rb₄H₂(CO₃)₃ · H₂O (orthorhombic, Pnma (no. 62), a = 1 218.0(1) pm, b = 1 572.3(6) pm, c = 615.9(1) pm, V_EZ = 1 179.5(5) · 10⁶ pm³, Z = 4, R1(I ≥ 2σ(I)) = 0.027, wR2(I ≥ 2σ(I)) = 0.055). K₄H₂(CO₃)₃ · 1,5 H₂O crystallizes in an OD-structure. The determined superposition structure (orthorhombic, Pbam (no. 55), a = 1 161.8(1) pm, b = 597.0(1) pm, c = 383.85(3) pm, V_EZ = 266.3(1) · 10⁶ pm³, Z = 1, R1(I ≥ 2σ(I)) = 0.035, wR2(I ≥ 2σ(I)) = 0.074) can be derived from the structure of the rubidium compound. The thermal decomposition of the substances is discussed.