Crystal structures of Co3(SeO3)3·H2O and Ni3(SeO3)3·H2O,two new isotypic compounds

Summary The crystal structures of the new, hydrothermally synthesized, isotypic compounds Co₃(SeO₃)₃·H₂O and Ni₃(SeO₃)₃·H₂O were determined by direct and Fourier methods and refined toR _w=0.023, 0.032 using single crystal X-ray data up to sin/=0.81 Å^–1 [space group P ,a=8.102 (2), 7.986 (3) Å;b=8.219 (2), 8.133 (3) Å;c=8.572 (2), 8.422 (3) Å, =69.15 (1), 69.50 (1)°; =62.88 (1), 62.50 (1)°; =67.23 (1), 67.64 (1)°;Z=2]. The structures are built up from [Me ₅(SeO₃)₆·2H₂O]^2– sheets containing three crystallographically different types of octahedrally coordinatedMe ²⁺ and trigonal pyramidal coordinated Se⁴⁺ atoms, respectively. These sheets are linked only by a fourth type ofMe ^2+[6] atom. All coordination polyhedra deviate significantly from their ideal shapes, bond lengths within the extremly distortedMe(4)O₆ polyhedra range from 1.983 (2) Å to 2.403 (2) Å in Co₃(SeO₃)₃·H₂O and from 1.987 (4) Å to 2.301 (3) Å in the Ni compound, O-Se-O bond angles were found between 92.8 (2)° and 104.9 (1)°. Hydrogen bond lengths are 2.802 (3)Å and 2.600 (4)Å in the Co compound, and 2.762 (6) Å and 2.561 (6) Å in Ni₃(SeO₃)₃·H₂O. The latter is one of the shortest known hydrogen bonds donated by a water molecule.

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Die Kristallstrukturen von Co₃(SeO₃)₃·H₂O und Ni₃(SeO₃)₃·H₂O, zwei neue isotype Verbindungen

Zusammenfassung Die Kristallstrukturen der neuen, hydrothermal synthetisierten, isotypen Verbindungen Co₃(SeO₃)₃·H₂O und Ni₃(SeO₃)₃·H₂O wurden mit direkten und Fourier-Methoden bestimmt und unter Verwendung von Einkristallröntgendaten bis sin/=0.81 Å^–1 aufR _w-Werte von 0.023, 0.032 verfeinert [Raumgruppe P ,a=8.102 (2), 7.986 (3) Å;b=8.219 (2), 8.133 (3) Å;c=8.572 (2), 8.422 (3) Å, =69.15 (1), 69.50 (1)°; =62.88 (1), 62.50 (1)°; =67.23 (1), 67.64 (1)°;Z=2]. Die Strukturen werden von [Me ₅(SeO₃)₆·2H₂O]^2– Schichten aufgebaut, die je drei kristallographisch unterschiedliche Arten von oktaedrisch koordiniertenMe ²⁺ und trigonal pyramidal koordinierten Se⁴⁺ Atomen enthalten. Diese Schichten sind nur durch eine vierte Art vonMe ^2+[6] Atomen verknüpft. Alle Koordinationspolyeder weichen deutlich von ihren Idealformen ab, Bindungslängen in den extrem verzerrtenMe(4)O₆ Polyedern variieren zwischen 1.983 (2) Å und 2.403 (2) Å in Co₃(SeO₃)₃·H₂O und zwischen 1.987 (4) Å und 2.301 (3) Å in der Ni-Verbindung, O-Se-O-Bindungswinkel liegen zwischen 92.8 (2)° und 104.9 (1)°. Wasserstoffbrückenlängen sind 2.802 (3) Å und 2.600 (4) Å in der Co-Verbindung, und 2.762 (6) Å und 2.561 (6) Å in Ni₃(SeO₃)₃·H₂O. Letztere ist eine der kürzesten bekannten Wasserstoffbrücken eines Wassermoleküls.

     

Hexaaquacobalt(II) and hexaaquacadmium(II) 4-nitro-2,3,5,6-tetraoxopyridinates [M(H2O)6](C5HN2O6)2 · 2H2O (M = Co and Cd): Synthesis, structures, and properties

The complexes [Cd(H₂O)₆](C₅HN₂O₆)₂ · 2H₂O (I) and [Co(H₂O)₆](C₅HN₂O₆)₂ · 2H₂O (II) were obtained in the crystalline state by reactions of cobalt chloride and cadmium chloride with ammonium 4-nitro-2,3,5,6-tetraoxopyridinate, (NH₄)₂ · (C₅HO₆N₂)₂. Their cocrystallization gave the heterometallic complex [Cd_0.32Co_0.68(H₂O)₆](C₅HN₂O₆)₂ · 2H₂O (III). The crystal and molecular structures of complexes I-III were determined by X-ray diffraction. It was demonstrated that the complexation reactions occur by replacement of two ammonium cations 4-nitro-2,3,5,6-tetraoxopyridinate by the complex cations [M(H₂O)₆]²⁺. The tetraoxopyridinate anions and the complex cations are hydrogen-bonded through the coordinated and crystallization water molecules as well as through the O atoms of the organic anion. The thermolysis of complexes I and II was examined by TGA.     

Synthesis and Crystal Structure of [Ni(H2O)6][Ni(H2O)2(C4H2O4)]·4H2O

Reaction of a freshly prepared Ni(OH)_{2?2 x} (CO₃) _x ·yH₂O with maleic acid in H₂O at room temperature afforded [Ni(H₂O)₆][Ni(H₂O)₂(C₄H₂O₄)]·4H₂O, which consists of [Ni(H₂O)₆]²⁺ cations, [Ni(H₂O)₂(C₄H₂O₄)]^2? anions and lattice H₂O molecules. Ni atoms in cations are octahedrally coordinated and Ni atoms in anions are each octahedrally coordinated by bidentate chelating maleato ligands and two water molecules at trans positions. Cations and anions are interlinked by hydrogen bonds to form 1D chains, which are hexagonally arranged and connected by the lattice water molecules. When heated in a flowing argon stream, the compound decomposes, with complete dehydration being followed by dissociation of nickel maleate into NiO and maleic anhydride.     

Crystal structure and Raman spectra of [Fe(H2O)6]3+(ClO 4 ? )3·3H2O

Single crystal X-ray diffraction is used to study the structure of colorless crystals isolated from the saturated aqueous solution of trivalent iron perchlorate (TIP) in 67.5% perchloric acid. It is found that the compound crystallizes in the trigonal crystal symmetry; parameters of the hexagonal unit cell: a = b = 16.079(2) ?, c = 11.369(2) ?, ?? = ?? = 90°, ?? = 120°, space group R{ie907-1}(S ₆), Z = 6, ??_calc = 2.021 g/cm³. The structural form of the crystal hydrate is [Fe(H₂O)₆]³⁺(ClO ₄ ^? )₃·3H₂O. The structure contains two independent complex iron cations. Each of them is in the special position {ie907-2}, but retains the regular octahedral structure: average bond lengths are r(Fe-O) = 1.997(1) ?, {ie907-3}O-Fe-O bond angles differ from 90° by only 0.93°. Independent [Fe(H₂O)₆]³⁺ cations form short H-bonds (O??O 2.64 ?) with three crystallization water molecules and somewhat longer H-bonds (O??O 2.73 ?) with three ClO ₄ ^? anions. The ClO ₄ ^? anion is disordered over two positions with occupancies of 0.62(2) and 0.37(2). Both positions correspond to the general position. The outer-sphere crystallization water molecule is characterized by the tetrahedral direction of H-bonds, which it forms with two anions and two independent [Fe(H₂O)₆]³⁺ cations. All water molecules are in the general position. The Raman spectroscopic study of polycrystalline samples reveals weak bands belonging to the internal vibrations of two types of water molecules. The least broad bands are assigned to the transitions of crystallization water molecules whose symmetry is insignificantly lowered by two anion-molecular Hbonds. Anomalously broad bands are assigned to the transitions of a coordinated water molecule whose symmetry is more lowered by intermolecular and anion-molecular H-bonds.     

XPS study of the electronic structure of heterometallic complexes [Fe2MO(O2CCH3)6(H2O)3] · 3H2O (M = Co,Ni)

Heterometallic compounds of general formula [Fe ₂ ^III M^IIO(O₂CR)₆(H₂O)₃] · 3H₂O (R = CH₃, M = Co, Ni; R = CCl₃, M = Co, Ni) have been studied by XPS. The compounds have been identified as high-spin complexes with metal atoms in oxidation states M(II) and M(III). Analysis of the XPS data revealed the tendency of the XPS pattern and magnetic parameters of molecules to change with a change in the electronic nature of metal atoms. The assignment is based on the degree of covalence of the M-O bond. In chloro-substituted heterocomplexes, electron density delocalization on the metal atoms with metal-to-ligand charge transfer through three bonds (M-O-C-C) is observed. The substitution in terminal groups leads to the change in the electron density distribution between the carboxylate and terminal groups.     

Tetraaquabis(pyridine)metal(II) saccharinate tetrahydrate, [M(H2O)4(py)2](sac)2·4H2O; M = Co,Ni. Crystal structure determination

The crystal structure determination of the title compounds showed that they are isomorphous, revealing the general formula [M(H₂O)₄(py)₂](sac)₂·4H₂O. Their structures are built up of [M(H₂O)₄(py)₂]²⁺ cations, saccharinato anions and non-coordinated water molecules. The metal atom lies on the inversion center and is octahedrally coordinated by four water oxygens and two pyridine nitrogen atoms. The crystal structure packing is achieved through the hydrogen bonds of O_w⋯O_w, O_w⋯O and O_w⋯N type. Coordinated water molecules are hydrogen bonded to non-coordinated ones at the same time participating in hydrogen bonding with carbonyl oxygen and nitrogen atom from the saccharinato anions. Non-coordinated water molecules participate in hydrogen bonding with the oxygen atoms belonging to the saccharinato CO and SO₂ groups. The hydrogen bond network between the oxygen atoms belonging to the SO₂ group of the saccharinato anions and one of the non-coordinated water molecules (OW3) constructs the centrosymmetric cavity in the structure.     

Solid solutions,clathrate structures,and vibrational spectra of plastic crystals of HClO4·5.5H2O

The results of a low-temperature spectroscopic investigation of crystals of the highest hydrate of perchloric acid have been presented. A brief review of the literature data on the problem of the structure of crystals of HClO₄·5.5H₂O (I) has been given. It follows from the review that the negative results obtained by Mootz et al. [J. Am. Chem. Soc., Vol. 109, No. 4, 1200 (1987)] when they refined a clathrate test model of the cubic structure of I is attributable to the mesomorphic structure of the crystals, which is characteristic of a plastic phase. The results of an analysis of the IR and Raman spectra of the optically anisotropic plastic phase of I and the isotropic plastic phase have made it possible to specify some details of the clathrate model. The vibrational spectra of deuterated and undeuterated solid solutions of I with components of the acid-water system have been interpreted in the framework of the improved clathrate model. Laws governing the structure of the labile polyhedrons in the water-cation host structure and the formation of the anion sublattice, which is insensitive to variation of the composition, have been revealed for the two phases of variable composition -HClO₄·nH₂O (n=5.4 to 5.6 at –180°C) and -HClO₄·nH₂O (n=5.2 to 6.0 at –180°C).Institute of New Chemical Problems, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 51–61, March–April, 1991.     

Vibrational spectra of pentafluoroperoxo metallates,K2M(O2)F5·H2O (M = Nb,Ta)

The i.r. (4000-50 cm⁻¹) and laser Raman spectra (4000-50 cm⁻¹) of potassium pentafluoroperoxo niobate monohydrate and potassium pentafluoroperoxo tantalate monohydrate have been investigated. The observed spectra have been analysed on the basis of spectral comparison with related compounds and of the normal vibration calculations employing modified Urey-Bradley force functions. While some coupling has been observed for the niobate, the vibrations of the tantalate are nearly localized.     

Mono-Sulfonated Derivatives of Triphenylphosphine, [NH4]TPPMS and M(TPPMS)2 (TPPMS = P(Ph)2(m-C6H4SO− 3); M = Mn2+, Fe2+, Co2+ and Ni2+). Crystal Structure Determinations for [NH4][TPPMS]·½H2O, [Fe(H2O)5(TPPMS)]TPPMS, [Co(H2O)5TPPMS]TPPMS and [Ni(H2O)6](TPPMS)4·H2O

Preparation of the ammonium salt of TPPMS, [NH₄]TPPMS, TPPMS = PPh₂(m-C₆H₄SO^? ₃), greatly enhances water solubility and provides an efficient route to other metal complexes of TPPMS, M(TPPMS)₂ M = Mn²⁺, Co²⁺, Fe²⁺ and Ni²⁺. For Co²⁺ and Fe²⁺ the metal has an octahedral ligand environment with five water molecules and one TPPMS coordinated through the sulfonate oxygen; the second TPPMS is not coordinated. For Ni²⁺ the octahedral coordination sphere is composed of water molecules and the TPPMS ligands are not coordinated. Structures are fully reported for [NH₄]TPPMS·½H₂O and [Fe(H₂O)₅(TPPMS)]TPPMS and partially reported for [Co(H₂O)₅TPPMS]TPPMS and [Ni(H₂O)₆]TPPMS₂·H₂O. All of the structures show hydrophobic regions consisting of aromatic rings and hydrophilic regions with hydrogen-bonding interactions.     

MF2 vibrations and librations of water molecules in the series MF2·4H2O (M = Fe,Co, Ni or Zn)

The infrared absorption spectra of the series MF₂·4H₂O (M = Fe, Co, Ni or Zn) and of the respective deuterates were recorded at 296 and ∼ 100 K in the 1200-400 cm⁻¹ wavenumber region. Using the known ZnF₂·4H₂O structure as a model, the number of i.r. active librations and MF₂ vibrations was predicted with the aid of a group theoretical treatment. The librations were distinguished from the MF₂ and MO vibrations and assigned, using isotopic ratios and correlations between the unit cell volumes, the uncoupled OH and OD stretch vibrations of HDO and the twisting libration. The six librations are assigned to two types of water molecules with low symmetry and with different hydrogen bond strengths, and are compatible with an orthorhombic Pca2₁ structure. The v₁ and v₃ intramolecular MF₂ vibrations are assigned, using ZnF₂·4H₂O crystal data and matrix-isolated v₁ and v₃ (v_1.3) values as guide. Shifts of v_1.3 and v₁/v₃ relative to the matrix-isolated values suggest smaller MF bond lengths. The shifts in the values of v_1.3 and v₁/v₃ upon deuteration and lowering of the temperature indicate smaller MF bond lengths and FMF angles.     

Syntheses and Crystal Structures of Two Cyano-bridged Bimetallic Complexes [Ce(DMSO)4(H2O)3Fe(CN)6]·H2O and [La(DMSO)4(H2O)3Co(CN)6]·H2O (DMSO = Dimethylsulfoxide)

Two new bimetallic cyano-bridged complexes [Ce(DMSO)4(H2O)3Fe(CN)6]·H2O 1 and [La(DMSO)4(H2O)3Co(CN)6]·H2O 2 have been prepared by the ball milling reaction method and structurally characterized by X-ray single-crystal structure analyses. Crystallographic data for 1:C14H32CeFeN6O8S4, Mr = 736.67, monoclinic, space group P21/n, a = 14.952(1), b =13.7276(9), c = 15.392(1) (A), β = 108.288(1)°, V = 2999.6(4) (A)3, Z = 4, Dc= 1.631 g/cm3,μ =2.304 mm-1, F(000) = 1480, R = 0.0593 and wR = 0.1611; and those for 2: C14H32CoLaN6O8S4,Mr=738.54, monoclinic, space group P21/n, a = 14.945(3), b = 13.731(3), c = 15.300(3) (A), β=107.806(1)°, V= 2989.3(11) (A)3, Z = 4, Dc = 1.641 g/cm3,μ = 2.288 mm-1, F(000) = 1480, R =0.0383 and wR = 0.1132. In both complexes the lanthanide ion is eight-coordinated in a square antiprism arrangement, and the Fe(Ⅲ) or Co(Ⅲ) ion in a nearly regular octahedral environment.The [LnM(CN)6(DMSO)4(H2O)3]·H2O (Ln = Ce and M = Fe for 1; Ln = La and M = Co for 2)species are held together via hydrogen bonds by coordinated water molecules, lattice water molecules and nitrogen atoms of cyanide groups to form a three-dimensional framework.     

Bending modes of the water molecules and the MO stretching modes in the series MF2 · 4H2O (M = Fe,Co, Ni,Zn)

The infrared spectra of the series MF₂·4X₂O (M = Fe, Co, Ni, Zn; X = H, D) are reported in the frequency ranges of the bending vibrations of the water molecules (ν₂) at 296 and ∼100 K and the MO lattice vibrations (ν_MO) at 296 K. Four ν_MO vibrations consisting of two doublets are identified using deuterium substitution. The various ν_ZnO vibrations correlate well with the metal-oxygen distances R(ZnO), and this correlation is further used to calculate R(MO)'s of the remainder of the series and to refine R(ZnO). Four ν₂(H₂O, HDO, D₂O) vibrations, consisting of two sharp overlapping bands flanked by two broad shoulders, are identified. The number of ν₂(H₂O) components, the sequence of ν₂ in the series and the correlation with R(MO) suggest that the ν₂ frequencies are mainly determined by R(MO). Using this assignment the two types of ν₂ bands are assigned to the two types of crystallographically distinct water molecules found in the MF₂·4H₂O structure.     

Ternary MIn2S4 (M = Mn,Fe, Co,Ni) Thiospinels – Crystal Structure and Thermoelectric Properties

A combined structural, magnetic and thermoelectric study of polycrystalline ternary MIn₂S₄ (M = Mn, Fe, Co, Ni) thiospinels is presented. All compounds crystallize with MgAl₂O₄-type structure. Rietveld refinement analysis confirmed that the preferred crystallographic position of transition metal element changes from mainly tetrahedral 8a for Mn to exclusively octahedral 16d for Ni (i.e. increase of the inversion parameter). Magnetic susceptibility measurements revealed M-elements to possess 2+ oxidation state in MIn₂S₄. All these compounds order antiferromagnetically with Néel temperatures T_N ranging from 5–13 K. The studied thiospinels are n-type semiconductors with large values of electrical resistivity ρ > 0.6 Ω · m at room temperature. An increase of the inversion parameter leads to a reduction of the determined activation energies, as well as to a more disorder-like behavior of thermal conductivity. The highest thermoelectric Figure of merit ZT was observed for MIn₂S₄ with M = Fe, Ni, which adopt inverse spinel structure.     

The conditions of formation of heterometallic complexes in the GeCl4 (SnCl4)-citric acid-M(CH3COO)2-H2O systems. The crystal and molecular structures of [M(H2O)6][Ge(HCit)2] · 4H2O (M = Mg, Mn, Co, Cu, Zn) and [M(H2O)6][Sn(HCit)2] · 4H2O (M = Mg, Co, Ni)

Fourteen bis(citrato)germanates(IV) and bis(citrato)stannates(IV) were prepared, in particular, [M(H₂O)₆][Ge(HCit)₂] · 4H₂O (M = Mg (I), Mn (II), Fe (III), Co (IV), Ni (V), Cu (VI), Zn (VII)) and [M(H₂O)₆][Sn(HCit)₂] · nH₂O (M = Mg, n = 4 (VIII); Mn, n = 2 (IX); Fe, n = 4 (X); Co, n = 4 (XI); Ni, n = 4 (XII); Cu, n = 4 (XIII); Zn, n = 3 (XIV)) (H₄Cit is citric acid). The purity and the composition of the products were determined by a set of physicochemical methods including elemental analysis, thermogravimetry, and IR spectroscopy. The structures of I, II, IV, VI, VII, VIII, XI, and XII were determined by X-ray diffractometry. All eight crystals composed of centrosymmetrical octahederal [M(H₂O)₆]²⁺ cations, [Ge(HCit)₂]^2? (or [Sn(HCit)₂]^2?) anions, and crystal water molecules are isostructural. The structural units in I, II, IV, VI, VII, VIII, XI, and XII are connected by systems of hydrogen bonds to form a three-dimensional framework.     

Crystal structure of CsLnFe(CN)6·5H2O (Ln=Ce,Pr, Nd), CsCeFe(CN)6·4H2O,and TlTmRu(CN)6·3H2O

We have investigated the crystal structures of CsLnFe(CN)₆·nH₂O (Ln=lanthanide, n=4,5), as well as TlTmRu(CN)₆·3H₂O. These phases can be thought of as derivatives of LnFe(CN)₆·4H₂O, where, simultaneously, an alkali ion (or Tl⁺) is introduced while the valence of Fe is reduced from Fe³⁺ to Fe²⁺. A new arrangement of the structural units is observed in the CsLnFe(CN)₆·5H₂O, where the coordination of the Ln-ion is changed to a bisdisphenoid. The resulting LnN₅O₃ units alternate with Fe(CN)₆ units to form an overall rocksalt-type ralted lattice that accommodates the alkali ions in interstitial sites. Due to the arrangement of the water molecules, a layer structure results.     

Comparison of the crystal structures of Co2(X 2O7)·2H2O,X=P and As

Summary Crystals of Co₂(X ₂O₇)·2H₂O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, =94.77(2)/94.74(2)°, space group P2₁/n,R=0.032/0.046,R _w=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO₄ tetrahedra connected via a common corner to anX ₂O₇ group the average P-O bond lengths are approximately equal (1.540 and 1.543 Å), but As-O differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio Me-O/X-O and the angle O-X-O.

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Vergleich der Kristallstrukturen von Co₂(X ₂O₇)·2H₂O,X=P und As

Zusammenfassung Kristalle von Co₂(X ₂O₇)·2H₂O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, =94.77(2)/97.74(2)°, Raumgruppe P2₁/n,R=0.032/0.046,R _w=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX ₂O₇-Gruppen verknüpftenXO₄-Tetraedern sind die mittleren P-O-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert As-O signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten Me-O/X-O und dem WinkelX-O-X.

     

Synthesis, Crystal Structure and Luminescence Property of [Co(hmz)2(H2O)4]·2H2O

A new mononuclear Co(Ⅱ) complex, [Co(hmz)2(H2O)4]·2H2O, has been synthesized by the reaction of Co(CH3COO)2·4H2O with 1-(4-hydroxyphenyl)-5-mercaptotetrazole (Hhmz). It crystallizes in the monoclinic system, space group P21/n with a = 13.502(5), b = 6.718(3), c = 13.972(6) (A), β = 117.532(4)°, V = 1123.9(8) (A)3, Z = 2, M r = 553.45, F(000) = 570, Dc = 1.635 g/cm3, μ = 1.008 mm-1, the final R = 0.0272 and wR = 0.0684 for 2194 observed reflections (Ⅰ＞ 2σ(Ⅰ)). The Co(Ⅱ) is six-coordinated by two nitrogen atoms from two hmz-1 ligands and four water molecules, forming an octahedral geometry. The intermolecular hydrogen bonding and offset-panel π-π stacking interactions between the adjacent molecules extend the compound into a three- dimensional supramolecular framework. The title compound emits strong blue fluorescent light (λem(max) = 427 nm) at room temperature and is red-shifted compared with free ligand Hhmz (λem(max) = 342 nm).     

Synthesis and characterization of cobalt(II) and manganese(II) xylaratogermanates: The molecular and crystal structures of the [M(H2O)6][Ge(μ3-L)2{M(H2O)2}2] · 4H2O · nCH3CN Complexes (M = Co, n = 0; M = Mn, n = 1)

A synthetic procedure was developed, and heteropolynuclear coordination compounds—the products of the interaction of germanium tetrachloride with xylaric (trihydroxyglutaric) acid HOOC-CH(OH)-CH(OH)-CH(OH)-COOH (H₅L) and the acetates of the 3d metals Mn(II) and Co(II)—were prepared. The compounds were characterized by elemental analysis, thermogravimetry, and IR spectroscopy. The X-ray diffraction analysis of the [M(H₂O)₆][Ge(μ₃-L)₂{M(H₂O)₂}₂] · 4H₂O · nCH₃CN complexes, where M = Co, n = 0 (I) and M = Mn, n = 1 (II), was performed. The crystals of I are monoclinic, a = 10.752(2) Å, b = 11.830(2) Å, and c = 10.772(2) Å, β = 94.741(3)°, V = 1365.4(5) ų, Z = 2, space group P2₁/n, R1 = 0.0309 for 3200 reflections with I > 2σ(I). The crystals of II are triclinic, a = 9.5330(17) Å, b = 9.7415(17) Å, and c = 10.3935(18) Å, α = 115.024(2)°, β = 97.580(3)°, γ = 111.535(3)°, V = 764.9(2)ų, Z = 1, space group $P\bar 1$ , R1 = 0.0621 for 3028 reflections with I > 2σ(I). The bimetallic anions [Ge(μ₃-L)₂{M(H₂O)₂}₂]^2?, the cations [M(H₂O)₆]²⁺, and crystal water molecules form the basis of compounds I and II (the acetonitrile molecule is also a constituent of compound II). In the centrally symmetrical trinuclear complex anion, the Ge(1) atom is bound to two M(1) atoms through two completely deprotonated bridging ligands. The Ge(1) atom is coordinated to the six alcohol oxygen atoms of two ligands L^5? at the apexes of a distorted octahedron (the average Ge(1)-O distances in I and II are 1.8858(14) and 1.892(3)Å, respectively). The coordination polyhedron of the M(1) atom in the complex anion is a strongly distorted octahedron. The base of the coordination polyhedron is formed by the two bridging alcohol oxygen atoms (the average M(1)-O distances in I and II are 2.1756(14) and 2.255(3) Å, respectively) of two L^5? ligands and by the oxygen atoms of two water molecules (the average M(1)-O distances in I and II are 2.0693(17) and 2.175(4) Å, respectively). In the centrally symmetrical complex cation, the coordination polyhedron of the M(2) atom is a somewhat distorted octahedron. The M(2)-O(H₂O) bond lengths in I and II vary in the ranges of 2.0137(17)-2.1555(17) and 2.140(5)-2.172(4) Å, respectively (the average lengths are 2.0375(17) and 2.166(4) Å, respectively). The cations and anions are joined by a branched system of hydrogen bonds.     

Intermediate states on the way to edge-sharing BO4 tetrahedra in M6B22O39·H2O (M=Fe, Co)

The new borates Fe(II)(6)B(22)O(39)·H(2)O (colourless) and Co(II)(6)B(22)O(39)·H(2)O (dichroic: red/bluish) were synthesised under the high-pressure/high-temperature conditions of 6 GPa and 880 °C (Fe)/950 °C (Co) in a Walker-type multi-anvil apparatus. The compounds crystallise in the orthorhombic space group Pmn2(1) (Z=2) with the lattice parameters a=771.9(2), b=823.4(2), c=1768.0(4) pm, V=1.1237(4) nm(3), R(1)=0.0476, wR(2)=0.0902 (all data) for Fe(6)B(22)O(39)·H(2)O and a=770.1(2), b=817.6(2), c=1746.9(4) pm, V=1.0999(4) nm(3), R(1)=0.0513, wR(2)=0.0939 (all data) for Co(6)B(22)O(39)·H(2)O. The new structure type of M(6)B(22)O(39)·H(2)O (M=Fe, Co) is built up from corner-sharing BO(4) tetrahedra and BO(3) groups, the latter being distorted and close to BO(4) tetrahedra if additional oxygen atoms of the neighbouring BO(4) tetrahedra are considered in the coordination sphere. This situation can be regarded as an intermediate state in the formation of edge-sharing tetrahedra. The structure consists of corrugated multiple layers interconnected by BO(3)/BO(4) groups to form Z-shaped channels. Inside these channels, iron and cobalt show octahedral (M1, M3, M4, M5) and strongly distorted tetrahedral (M2, M6) coordination by oxygen atoms. Co(II)(6)B(22)O(39)·H(2)O is dichroic and the low symmetry of the chromophore [Co(II)O(4)] is reflected by the polarised absorption spectra (Δ(t)=4650 cm(-1), B=878 cm(-1)).     

Low frequency vibrational spectra of crystalline and glassy metaborates Ba2MII(B3O6)2 (MII  Mg,Ca, Ni,Co, Cd)

The low frequency vibrational spectra (Raman and IR) of crystalline metaborates Ba₂M^II(B₃O₆)₂ (M^II  Mg, Ca, Ni, Co, Cd) are interpreted on the basis of a factor group analysis and with the help of ²⁴Mg²⁶Mg and ⁴⁰Ca⁴⁴Ca isotopic shifts. The far-IR spectra of the glasses appear as the envelope of the spectra of the corresponding crystalline compounds for M^II  Mg, Ca and Cd, but they exhibit an additional broad absorption centred near 400 cm⁻¹ for M^II  Co, Ni and Zn. This absorption is assigned to a fourfold coordination of part of the M^II cations, the remaining being in sixfold coordination (as in the crystal) and responsible for a broad absorption in the 300-200 cm⁻¹ region. The possible existence of correlations between coordination and vibrational frequencies is discussed for either alkali and alkaline-earth cations, or transition elements.