MH2P2O7 (M = Co, Ni): metamagnetic interaction between the zigzag octahedral chains

CoH2P2O7 and NiH2P2O7, which contain edge-sharing zigzag octahedral chains, were hydrothermally synthesized and structurally characterized. Both compounds exhibit field-induced metamagnetic behavior because of the strong intrachain ferromagnetic and relatively weak interchain antiferromagnetic interactions.     

Degradation thermique et etude vibrationnelle de MII(NH4)4(P3O9)2x4H2O(M II=Cu2+, Ni2+, Co2+)

We have studied the thermal behaviour under atmospheric pressure of isotypic tetrahydrate cyclotriphosphates M^II(NH₄)₄(P₃O₉)₂x4H₂O (M ^II=Cu, Ni and Co), between 25 and 1400°C, by X-ray diffraction, thermal analyses (TG and DTA) and infrared spectrometry. This study shows that the series of the compounds M^II(NH₄)₄(P₃O₉)₂x4H₂O (M ^II=Cu, Ni and Co) after elimination of water, in two different stages, and ammonia leads, at 400°C to cyclotetraphosphate M₂ ^IIP₄O₁₂ crystallized and to a thermal residue with a formula H₄P₄O₁₂ which undergoes under a thermal degradation by evolving water and pentoxide phosphorus. The kinetic characteristics of the dehydration and elimination of ammonia have been determinated. The vibrational spectra of Cu(NH₄)₄(P₃O₉)₂x4H₂O were examined and interpreted, in the domain of the valency frequencies, on the basis of the crystalline structure of its isotypic compound Co(NH₄)₄(P₃O₉)₂x4H₂O whose cycle has the site symmetry C₁, of our results of the calculation of the IR frequencies and the successive isotopic substitutions of the equivalent atoms (3P, 3Oi and 6Oe belonging to the P₃Oi₃Oe₆ ring) of the P₃O₉ ³⁻ cycle with high symmetry D_3h. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal properties of [MII(phen)3]2V4O12·phen·22H2O (M II=Co,Ni, Cu,phen=1,10-phenanthroline)

Thermal decomposition of three tetravanadates, [M^II(phen)₃]₂V₄O₁₂·phen·22H₂O, where M ^II is Co (1), Ni (2), Cu (3) and phen is 1,10-phenanthroline, was studied by dynamic method (for 1 and 2) or isothermally (for 3). The thermal decomposition of the studied compounds is a multi-step process which involve: discontinuous dehydration, release of uncoordinated, and of coordinated phenanthroline molecules. In course of the latter process, a phase transition of the cyclo-tetravanadates to polymeric metavanadates occurred. Metavanadates with chain structure of the anion were the final decomposition products of all tetravanadates studied. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hydrogen bonding in diaquatetrakis(urea‐κO)MII dinitrates,with M = Ni and Co

The isomorphous title compounds, [Ni{(NH₂)₂CO}₄(H₂O)₂](NO₃)₂ and [Co{(NH₂)₂CO}₄(H₂O)₂](NO₃)₂, feature discrete centrosymmetric cations in octahedral coordinations, formed by four urea molecules linked via their O atoms to the central ion in equatorial positions and two water molecules in trans positions. The complexes are packed in a pseudo‐hexagonal manner separated by the nitrate counter‐ions. All H atoms are involved in moderate hydrogen bonds of four types: N—H...O=C, N—H...O—N, O—H...O—N and N—H...O—H. Graph‐set analysis was applied to distinguish the hydrogen‐bond patterns at unitary and higher level graph sets.     

NaMn6(P2O7)2(P3O10) and KCd6(P2O7)2(P3O10)

The crystal structures of two new diphosphates, sodium hexamanganese bis­(diphosphate) triphosphate, NaMn₆(P₂O₇)₂(P₃O₁₀), and potassium hexacadmium bis­(diphosphate) triphosphate, KCd₆(P₂O₇)₂(P₃O₁₀), confirm the rigidity of the M₆(P₂O₇)₂(P₃O₁₀) matrix (M is Mn or Cd) and the relatively fixed dimensions of the tunnels extending in the a direction of the unit cell. The compounds are isomorphous; the P₂O₇^4? anion and the alkali metal cations lie on mirror planes. Bond‐valence analysis of the bonding details of the atoms found within the tunnels permits a prediction of the conductivity.     

K2M(H2P2O7)2·2H2O (M = Ni,Cu, Zn): ortho­rhom­bic forms and Raman spectra

The crystal structures of three isotypic ortho­rhom­bic dihydrogendiphosphates, namely dipotassium copper(II)/nickel(II)/zinc(II) bis­(dihydrogendiphosphate) dihydrate, K₂M(H₂P₂O₇)₂·2H₂O (M = Cu, Ni and Zn), have been refined from single‐crystal data. The M²⁺ and K⁺ cations are located at sites of m symmetry, and the P atoms occupy general positions. These compounds also exist in triclinic forms with very similar structural features. The structures of both forms are compared, as well as the geometry of the MO₆ octa­hedron, which is considerably elongated towards the water mol­ecules for M = Ni and Cu. Such elongation has not been observed among the other representatives of the family. A Raman study of the whole series K₂M(H₂P₂O₇)₂·2H₂O (M = Mn, Co, Ni, Cu, Zn and Mg) is reported.     

Syntheses,Crystal Structures and Properties of the Tetrametaphosphimates MII2(PO2NH)4 · 8 H2O with MII = Mg,Mn, Co and Zn

Mg₂(PO₂NH)₄ · 8 H₂O ( 1 ), Mn₂(PO₂NH)₄ · 8 H₂O ( 2 ), Co₂(PO₂NH)₄ · 8 H₂O ( 3 ) and Zn₂(PO₂NH)₄ · 8 H₂O ( 4 ) were obtained as microcrystalline powders by combining aqueous solutions of K₄(PO₂NH)₄ · 4 H₂O and MX₂ · y H₂O (M = Mg, Mn, Co, Zn; X = Cl, NO₃). Single crystals were obtained by crystallization in gelatine gels in U‐tubes or test‐tubes. 2 and 4 were characterized by thermogravimetry and 4 was additionally characterized by temperature dependend in situ powder diffractometry. The structures of 1 , 2 , 3 and 4 were found to be isotypic and were solved by single‐crystal X‐ray methods: P 2₁/c, Z = 2 ( 1 : a = 645.4(2), b = 1050.1(2), c = 1283.3(3) pm, β = 104.66(3)°; 2 : a = 648.7(2), b = 1063.1(2), c = 1310.8(3) pm, β = 103.93(3)°; 3 : a = 643.3(2), b = 1049.0(2), c = 1286.7(3) pm, β = 104.28(3)°; 4 : a = 644.18(5), b = 1049.22(7), c = 1282.43(8) pm, β = 104.122(6)°). The structure is composed of MO₆ octahedra and (PO₂NH)₄^4— anions. The P₄N₄ rings of the (PO₂NH)₄^4— anions exhibit a slightly distorted chair conformation, which is supported by IR data and has been described by torsion angles, Displacement Asymmetry Parameters and Puckering Parameters. Via M²⁺ ions and hydrogen bonds, the tetrametaphosphimate anions are connected forming layers perpendicular to [100]. These layers are connected by hydrogen bonds.     

Jahn-Teller-Verzerrungen von Übergangsmetallionen in tetraedrischer Koordination – die Strukturen von Cat[MII(NCS)4] (MII: Co,Ni, Cu) und von Spinellmischkristallen MIICr2O4(MII: Zn?Ni,Zn?Cu,Cu?Ni)

Jahn-Teller Distortions of Transition Metal Ions in Tetrahedral Coordination — The Structures of Cat[M^II(NCS)₄]^II (M^II: Co, Ni, Cu) and of Mixed Crystals M^IICr₂O₄(M^II: Zn? Ni, Zn? Cu, Cu? Ni) of the Spinel Type The structure determination of compounds Cat[M^II(NCS)₄] with Cat = p-xylylenebis(triphenylphosphonium)²⁺ and M^II = Co, Ni, Cu [space group P2₁/n, Z = 4] yielded pseudotetrahedral M^IIN₄-polyhedra, which are distorted by packing forces and vibronic coupling effects of the Jahn-Teller type. Spinel mixed crystals with M^II = Zn? Ni, Zn? Cu, Ni? Cu in the tetrahedral sites exhibit phase transition to tetragonal and o-rhombic structures, induced by cooperative Jahn-Teller interactions. The distortion symmetries of the M^IIN₄ and M^IIO₄ tetrahedra are analysed on the basis of the respective electronic groundstate and the possible Jahn-Teller active vibrational modes.     

Kristallstrukturbestimmungen an vier monoklinen Weberiten Na2MIIMIIIF7 (MII = Fe,Co; MIII = V,Cr)

Crystal Structure Determinations of Four Monoclinic Weberites Na₂M^IIM^IIIF₇ (M^II = Fe, Co; M^III = V, Cr) By solid state reaction of the binary fluorides single crystals of the following weberites were prepared and their monoclinic structure (space group C2/c, Z = 16) determined by X-ray methods: Na₂FeVF₇ (a = 1 271.0(3), b = 742.9(1), c = 2 471.6(5) pm, β = 100.03(3)°; R₁ = 0.043 (1 545 Reflexe); Fe? F = 203.8, V? F = 193.0 pm); Na₂FeCrF₇ (a = 1 262.5(3), b = 739.1(1), c = 2 460.5(5) pm, β = 99.93(3)°; R₁ = 0.029 (2 340); Fe? F = 203.6, Cr? F = 190.5 pm); Na₂CoVF₇ (a = 1 270.3(5), b = 739.1(3), c = 2 465.1(10) pm, β = 100.02(3)°; R₁ = 0.028 (2 250); Co? F = 201.6, V? F = 193.6 pm); Na₂CoCrF₇ (a = 1 257.8(3), b = 733.5(1), c = 2 441.5(5) pm, β = 99.64(3)°; R₁ = 0.030 (2 227); Co? F = 201.2, Cr? F = 190.2 pm). Concerning the above average distances within the distorted [MF₆] octahedra and the shape of [NaF₈] coordination details are given and discussed.     

X-ray diffraction and vibrational data for a series of triphosphates type MIINa3P3O10.12H2O (MII = Cu,Ni and Mg) and their anhydrous forms MIINa3P3O10

Chemical preparation methods, X-ray diffraction and vibrational data are reported for six triphosphates type M^IINa₃P₃O₁₀.12H₂O (M^II = Cu, Ni and Mg) and their anhydrous forms M^IINa₃P₃O₁₀. These condensed phosphates are respectively, CuNa₃P₃O₁₀.12H₂O, MgNa₃P₃O₁₀.12H₂O, NiNa₃P₃O₁₀.12H₂O, CuNa₃P₃O₁₀, NiNa₃P₃O₁₀ and MgNa₃P₃O₁₀. The hydrate triphosphates were prepared by the method of ion-exchange resin, where as their anhydrous forms were prepared by total thermal dehydration of M^IINa₃P₃O₁₀.12H₂O (M^II = Cu, Ni and Mg).CuNa₃P₃O₁₀.12H₂O, MgNa₃P₃O₁₀.12H₂O and NiNa₃P₃O₁₀.12H₂O are isotypic, and crystallize in the monoclinic system, space group is P2₁/n, Z = 4, the unit-cell parameters are: CuNa3P3O10.12H2O, a = 15.052(8) Å, b = 9.234(3) Å,c = 14.767(8) Å and β = 90.03(5)°. MgNa3P3O10.12H2O: a = 15.049(1) (1) Å, b = 9.245(4) Å, c = 14 0.722(3) (2) Å and β = 90.00(5)°.NiNa₃P₃O₁₀.12H₂O: a = 15.010(1) Å, b = 9.208(4) Å, c = 14.710(2) Å and β = 90.00(5)°.The anhydrous forms CuNa₃P₃O₁₀, MgNa₃P₃O₁₀ and NiNa₃P₃O₁₀ crystallize in the monoclinic system, space group is P2₁/n, Z = 4, the unit-cell parameters are: CuNa₃P₃O₁₀, a = 12.464(0) Å, b = 8.437(7) Å, c = 12.083(1) Å and β = 109.77(8) °; MgNa₃P₃O₁₀: a = 11.931(4) (1) Å, b = 12.912(2) Å, c = 10.057(0) Å and β = 113.83(2)° and NiNa₃P₃O₁₀: a = 12.686(8)Å, b = 9.271(2) (4) Å, c = 11.440(3) Å and β = 102,95(5)°.     

Syntheses and Crystal Structures of the Cyclotriphosphate Hydrates Nd(P3O9)·3H2O,Nd(P3O9)·4.5H2O,RE(P3O9)·5H2O (RE = Pr,Nd), and Na3RE(P3O9)2·6H2O (RE = Pr,Nd)

Several rare‐earth cyclotriphosphate hydrates were obtained from mixtures of sodium cyclotriphosphates and the respective rare‐earth chlorides. Nd(P₃O₉) · 3H₂O [P$\bar{6}$ , Z = 3, a = 677.90(9), c = 608.67(9) pm, R₁ = 0.016, wR₂ = 0.038, 312 data, 36 parameters] was obtained by a solid state reaction and is isotypic with respective rare‐earth phosphate hydrates, while all the others adopt new structure types. Nd(P₃O₉) · 4.5H₂O [C2/c, Z = 8, a = 1644.6(3), b = 756.11(15), c = 1856.1(4) pm, β = 97.25(3)°, R₁ = 0.032, wR₂ = 0.081, 1763 data, 194 parameters], Nd(P₃O₉) · 5H₂O [P2₁/c, Z = 4, a = 773.75(15), b = 1149.1(2), c = 1394.9(3) pm, β = 106.07(3)°, R₁ = 0.042, wR₂ = 0.082, 1338 data, 194 parameters], Pr(P₃O₉) · 5H₂O [P$\bar{1}$ , Z = 2, a = 745.64(15), b = 889.07(18), c = 934.55(19) pm, α = 79.00(3), β = 80.25(3), γ = 66.48(3), R₁ = 0.059, wR2 = 0.089, 1468 data, 193 parameters], Na₃Nd(P₃O₉)₂ · 6H₂O [P2₁/n, Z = 4, a = 1059.78(18), b = 1207.25(15), c = 1645.7(4) pm, β = 99.742(17), R₁ = 0.047, wR₂ = 0.119, 1109 data, 351 parameters] and Na₃Pr(P₃O₉)₂ · 6H₂O [P2₁/n, Z = 4, a = 1061.42(16), b = 1209.0(2), c = 1635.5(3) pm, β = 99.841(13), R₁ = 0.035, wR₂ = 0.062, 1323 data, 350 parameters] were obtained by careful crystallization at room temperature. A thorough structure discussion is given. The infrared spectrum of Nd(P₃O₉) · 4.5H₂O is also reported.