Hydrothermal synthesis, thermal, structural, spectroscopic and magnetic studies of the Mn5−xCox(HPO4)2(PO4)2(H2O)4 (x=1.25, 2, 2.5 and 3) finite solid solution

The Mn_5−xCo_x(HPO₄)₂(PO₄)₂(H₂O)₄ (x=1.25, 2, 2.5, 3) finite solid solution has been synthesized by mild hydrothermal conditions under autogeneous pressure. The phases crystallize in the C2/c space group with Z=4, belonging to the monoclinic system. The unit-cell parameters obtained from single crystal X-ray diffraction are: a=17.525(1), b=9.0535(6), c=9.4517(7) Å, β=96.633(5) ° being R1=0.0436, wR2=0.0454 for Mn75Co25; a=17.444(2), b=9.0093(9), c=9.400(1) Å, β=96.76(1) ° being R1=0.0381, wR2=0.0490 for Mn60Co40; a=17.433(2), b=8.9989(9), c=9.405(1) Å, β=96.662(9) ° being R1=0.0438, wR2=0.0515 for Mn50Co50 and a=17.4257(9), b=8.9869(5), c=9.3935(5) Å, β=96.685(4) ° being R1=0.0296, wR2=0.0460 for Mn40Co60. The structure consists of a three dimensional network formed by octahedral pentameric entities (Mn,Co)₅O₁₆(H₂O)₆ sharing vertices with the (PO₄)³⁻ and (HPO₄)²⁻ tetrahedra. The limit of thermal stability of these compounds is, approximately, 165 °C, near to this mean temperature the phases loose their water content in two successive steps. IR spectra show the characteristic bands of the water molecules and the phosphate and hydrogen-phosphate oxoanions. The diffuse reflectance spectra are consistent with the presence of MO₆ octahedra environments in slightly distorted octahedral geometry, except for the M(3)O₆ octahedron which presents a remarkable distortion and so a higher Dq parameter. The mean value for the Dq and B-Racah parameter for the M(1),(2)O₆ octahedra is 685 and 850 cm⁻¹, respectively. These parameters for the most distorted M(3)O₆ polyhedron are 825 and 880 cm⁻¹, respectively. The four phases exhibit antiferromagnetic couplings as the major magnetic interactions. However, a small spin canting phenomenon is observed at low temperatures for the two phases with major content in the anisotropic-Co(II) cation.     

Ga3(HPO3)4F4(H3DETA) (DETA=diethylenetriamine): A new open-framework fluorinated gallium phosphite with pentameric building unit

Ga₃(HPO₃)₄F₄(H₃DETA) is a new open-framework fluorinated gallium phosphite obtained by mild hydrothermal synthesis using diethylenetriamine as templated agent and characterized by single crystal X-ray diffraction, the powder X-ray diffraction, IR spectroscopy, TGA, ICP and elemental analyses. It crystallizes in the monoclinic space group C2/c, a=12.741(6) Å, b=12.068(6) Å, c=11.988(5) Å, β=94.902(8)^o, V=1836.6(15) Å³, Z=4. The construction of 3D open-framework structure in the title compound may be viewed as the assembly of pentameric building units and HPO₃ groups. The pentameric building unit is the first to be found, which lead to form the three types of channels along a-, b- and c-axes, respectively, in gallium phosphite. The triprotonated DETA cations are inserted within the 10-membered ring channels and interact with anions of the framework via hydrogen bonds.     

Hydrothermal synthesis and structural characterization of two organically templated zincophosphites with three-dimensional frameworks, (C6H14N2)·[Zn3(HPO3)4] and (C4H12N2)·[Zn3(HPO3)4]

Two organically templated zincophosphites, (C₆H₁₄N₂)·[Zn₃(HPO₃)₄] and (C₄H₁₄N₂)·[Zn₃(HPO₃)₄] have been prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction. (C₆H₁₄N₂)·[Zn₃(HPO₃)₄] crystallizes in the triclinic space group , with cell parameters, a=9.363(4) Å, b=10.051(4) Å, c=10.051(4) Å, α=85.777(13)°, β=82.091(9)°, and γ=79.783(9)°. (C₄H₁₄N₂)·[Zn₃(HPO₃)₄] crystallizes in the monoclinic space group P2₁/c, with cell parameters, a=9.9512(3) Å, b=10.1508(3) Å, c=17.8105(5) Å, and β=95.6510(10)°. Although the two structures are different, they have the same anionic framework compositions of [Zn₃(HPO₃)₄]²⁻. Their frameworks are built up from strictly alternating ZnO₄ tetrahedra and HPO₃ pseudo pyramids by sharing vertexes. There exist channels with an eight-membered ring window along the a- and c-axis. Powder X-ray diffraction, IR spectroscopy, ³¹P MAS solid-state NMR, thermogravimetric and differential thermal analyses were also carried out.     

Hydrothermal synthesis and characterization of layered vanadium phosphite: [HN(C2H4)3N][(VO)2(HPO3)2(OH)(H2O)]·H2O

A novel compound, [HN(C₂H₄)₃N][(VO)₂(HPO₃)₂(OH)(H₂O)]·H₂O, was hydrothermally synthesized and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic system with the space group C2/c and cell parameters a=11.0753(3) Å, b=17.8265(6) Å, c=16.5229(5) Å, and β=92.362(2)°. The structure of the compound consists of vanadium phosphite layers which are built up from the infinite one-dimensional chains of [(VO)(H₂O)(HPO₃)₂]²⁻ of octahedral VO₅(H₂O) and pseudo pyramidal [HPO₃], and bridging binuclear fragments of [VO(OH)]₂. Thermogravimetric analysis and magnetic susceptibility data for this compound are given.     

Syntheses, structures and magnetic properties of two new one-dimensional cobalt (II) phosphites with organic amines acting as ligands

Two new one-dimensional (1D) inorganic-organic hybrid cobalt (II) phosphites Co(HPO₃) (py) (1) and [Co(OH)(py)₃][Co(py)₂][HPO₂(OH)]₃ (2) have been prepared under solvothermal conditions in the presence of pyridine (py). Compound 1 crystallizes in the monoclinic system, space group p2(1)/c, a=5.3577(7) Å, b=7.7503(10) Å, c=17.816(2) Å, β=94.327(2)°, V=737.67(16) Å³, Z=4. Compound 2 is orthorhombic, Cmcm, a=16.3252(18) Å, b=15.7005(16) Å, c=13.0440(13) Å, β=90.00° V=3343.4(6) Å³ and Z=4. Compound 1 possesses a 1D ladder-like framework constructed from CoO₃N tetrahedral, HPO₃ pseudo-pyramids and pyridine ligands. While compound 2 is an unusual inorganic-organic hybrid 1D chain, which consists of corner-shared six-membered rings made of CoO₃N₃/CoO₄N₂ octahedra and HPO₃ pseudo-pyramids through sharing vertices.     

Building three-dimensional metal phosphites from the corner-shared four-membered rings chain

Three new compounds, a one-dimensional (1D) zinc phosphite, (C₄H₈N₂H₄)[Zn(HPO₃)₂] (I), two three-dimensional (3D) metal phosphites (C₄H₈N₂H₄)[Zn₃(HPO₃)₄] (II) and (C₄H₈N₂H₄)[Zn_(3−x)Co_x(HPO₃)₄(H₂O)₂] (x≈0.83) (III) have been synthesized under hydrothermal conditions templated by piperazine and characterized by single-crystal X-ray diffraction, XRD, IR, UV-vis spectra and SQUID magnetometer. Compound I displays 1D chain-like structure, containing corner-shared (cs) four-membered rings. Interestingly, the structures of II and III show 1D chains similar to those observed in I. It is noteworthy that III represents the first cobalt-substituted zinc-phosphite. Crystal data: I, monoclinic, C2/c, a=17.748(2) Å, b=7.428(9) Å, c=8.8071(11) Å, β=105.345(3)°, V=1091.9 Å³, Z=4. II, Monoclinic P2₁/c, a=9.9435(4) Å, b=10.1438(3) Å, c=17.8164(5) Å, β=95.665(2)°, V=1788.27 Å³, Z=4, and III, Monoclinic P2₁/c, a=7.2338(2) Å, b=15.0238(5) Å, c=9.2153(3) Å, β=107.741(2)°, V=953.88(5) Å³, Z=2.     

A novel layered bimetallic phosphite intercalating with organic amines: Synthesis and characterization of Co(H2O)4Zn4(HPO3)6·C2N2H10

A new layered cobalt-zinc phosphite, Co(H₂O)₄Zn₄(HPO₃)₆·C₂N₂H₁₀ has been synthesized in the presence of ethylenediamine as the structure-directing agent. The compound crystallizes in the monoclinic system, space group Cc (No. 9), a=18.2090(8), b=9.9264(7), c=15.4080(7) Å, β=114.098(4)°, V=2542.3(2) Å³, Z=4, R=0.0323, wR=0.0846. The structure consists of ZnO₄ tetrahedra, CoO₆ octahedra and HPO₃ pseudopyramids through their vertices forming bimetallic phosphite layers parallel to the ab plane. Organic cations, which reside between the inorganic layers, are mobile and can be exchanged by NH₄⁺ cations without the collapse of the framework.     

Synthesis, characterization and magnetic property of a new 3D iron phosphite: |C4N3H14|[Fe3(HPO3)4F2(H2O)2] with intersecting channels

A new open-framework iron (III) phosphite |C₄N₃H₁₄|[Fe₃(HPO₃)₄F₂(H₂O)₂] has been solvothermally synthesized by using diethylenetriamine (DETA) as the structure-directing agent. Single-crystal X-ray diffraction analysis reveals that the compound crystallizes in the monoclinic space group C2/c having unit cell parameters a=12.877(3) Å, b=12.170(2) Å, c=12.159(2) Å, β=93.99(3)°, V=1900.9(7) Å³, and Z=4 with R₁=0.0447, wR₂=0.0958. The complex structure consists of HPO₃ pseudo-tetrahedra and {Fe₃O₁₄F₂} trimer building units. The assembly of these building units generates 3D inorganic framework with intersecting 6-, 8-, and 10-ring channels. The DETA cations are located in the 10-ring channels linked by hydrogen bonds. The Mössbauer spectrum shows that there exhibit two crystallographically independent iron (III) atoms. And the magnetic investigation shows the presence of antiferromagnetic interactions. Further characterization of the title compound was performed using X-ray powder diffraction (XRD), infrared (IR) spectra, thermal gravimetric analyses (TGA), inductively coupled plasma (ICP) and elemental analyses.     

Crystal structure and magnetic properties of Na2Ni(HPO3)2

Na₂Ni(HPO₃)₂, obtained as light yellow-green crystals under mild hydrothermal conditions, crystallizes in the orthorhombic Pnma space-group with lattice parameters: a=11.9886(3), b=5.3671(2), c=9.0764(3) Å, V=584.01 Å³, Z=4. The structure consists of zig-zag chains of NiO₆ octahedra bridged by two HPO₃²⁻ and the chains are further connected through HPO₃²⁻ to four nearest chains to form a three dimensional framework, delimiting intersecting tunnels in which the sodium ions are located. The Na cations reside in the irregular Na(1)O₅, Na-O of 2.276-2.745 Å, and Na(2)O₉, Na-O of 2.342-2.376 Å, environments. The presence of the phosphite monoanion has been further confirmed by IR spectroscopy. Due to the 3D framework of Ni connected by O-P-O bridges, the magnetic susceptibility behaves as a paramagnet above 100 K (C=1.49(2) emu K mol⁻¹, μ_eff=3.45 μ_B, Θ=−39(2) K) and below 6 K, it orders antiferromagnetically as confirmed the sharp drop and the non-Brillouin behavior of the isothermal magnetization at 2 K.     

Hydrothermal synthesis, characterization and fluorescence property of a novel layered fluorinated gallium phosphite with heptameric building unit

A new fluorinated gallium phosphite, Ga₃F₂(2,2′-bipy)₂(HPO₃)₂(H_1.5PO₃)₂1, which is the first layered gallium phosphite with neutral framework, has been hydrothermally synthesized in the presence of 2,2′-bipyridine (2,2′-bipy) acting as a ligand. The as-synthesized product was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), ICP-AES and elemental analyses and fluorescent spectrum. Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group C2/c (No. 15) with cell parameters a=17.633(3) Å, b=9.883(2) Å, c=16.793(3) Å, β=109.88(3)°, V=2752.1(9) Å³ and Z=4. The construction of two-dimensional (2D)-layered structure in compound 1 may be viewed as the assembly of heptameric building unit, which is the first to be found in gallium phosphate/phosphite. The heptameric building unit exists in two types of configuration, which alternately connect through oxygen atoms from HPO₃ pseudo-pyramids to form a layer with 10-membered ring windows viewed along the a-axis. The adjacent layers are stably packed together and exhibit interesting three-dimensional (3D) supramolecular array via π-π interactions of the 2,2′-bipy groups. Additionally, compound 1 shows strong fluorescent property in solid state at room temperature.     

(C6H17N3)[Zn4(PO4)2(HPO3)2]: a new layered zinc phosphate-phosphite templated by 1-(2-Aminoethyl) piperazine

Employing 1-(2-Aminoethyl) piperazine as a template, a new organically templated layered zinc phosphate-phosphite (C₆H₁₇N₃)[Zn₄(PO₄)₂(HPO₃)₂] has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group Cc with a=5.3272(11) Å, b=17.146(3) Å, c=22.071(4) Å, β=94.58(3)°, V=2009.5(7) Å³, Z=4, R₁=0.0201 (I>2σ(I)) and wR₂=0.0812 (all data). The inorganic network is based on strictly alternating ZnO₄ tetrahedral units and P-centered units including PO₄ tetrahedra and HPO₃ pseudo-pyramids forming a double layered structure that contains columns of double six-membered rings. The diprotonated 1-(2-Aminoethyl) piperazine molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

(C5H16N2)·[Zn3(HPO3)4]·H2O: A new three-dimensional zincophosphite with 12-membered ring channels and infinite edge shared 4-membered ring ladders

Employing 3-dimethylamino-1-propylamine as a template, a new three-dimensional (3-D) zincophosphite (C₅H₁₆N₂)·[Zn₃(HPO₃)₄]·H₂O has been prepared under hydrothermal conditions and characterized by single-crystal X-ray diffraction (XRD), FTIR, elemental analysis, powder XRD, and thermogravimetric analysis (TGA). The compound crystallizes in the triclinic space group , with cell parameters, a=8.9884(2) Å, b=10.326(2) Å, c=11.917(2) Å, α=66.98(3)°, β=89.01(3)°, and γ=78.98(3)°, V=997.2(3) Å³ and Z=2. The connectivity of the ZnO₄ tetrahedra and HPO₃ pseudo pyramids results in inifinite edge-sharing, ladderlike chains of 4-membered rings, which are further linked by Zn-O-P bonds to form a 3-D structure that with interesting 12-membered ring channels along the [100] and [001] directions. The diprotonated amine molecules sit in the middle of the channels along the [100] direction and interact with the framework via hydrogen bonds. There also exist channels with 8-membered ring window along the [100] and [010] directions.     

Synthesis and structural investigation of the compounds containing HF2 anions: Ca(HF2)2, Ba4F4(HF2)(PF6)3 and Pb2F2(HF2)(PF6)

Three new compounds Ca(HF₂)₂, Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) were obtained in the system metal(II) fluoride and anhydrous HF (aHF) acidified with excessive PF₅. The obtained polymeric solids are slightly soluble in aHF and they crystallize out of their aHF solutions. Ca(HF₂)₂ was prepared by simply dissolving CaF₂ in a neutral aHF. It represents the second known compound with homoleptic HF environment of the central atom besides Ba(H₃F₄)₂. The compounds Ba₄F₄(HF₂)(PF₆)₃ and Pb₂F₂(HF₂)(PF₆) represent two additional examples of the formation of a polymeric zigzag ladder or ribbon composed of metal cation and fluoride anion (MF⁺)_n besides PbF(AsF₆), the first isolated compound with such zigzag ladder. The obtained new compounds were characterized by X-ray single crystal diffraction method and partly by Raman spectroscopy. Ba₄F₄(HF₂)(PF₆)₃ crystallizes in a triclinic space group P1¯ with a=4.5870(2) Å, b=8.8327(3) Å, c=11.2489(3) Å, α=67.758(9)°, β=84.722(12), γ=78.283(12)°, V=413.00(3) Å³ at 200 K, Z=1 and R=0.0588. Pb₂F₂(HF₂)(PF₆) at 200 K: space group P1¯, a=4.5722(19) Å, b=4.763(2) Å, c=8.818(4) Å, α=86.967(10)°, β=76.774(10)°, γ=83.230(12)°, V=185.55(14) ų, Z=1 and R=0.0937. Pb₂F₂(HF₂)(PF₆) at 293 K: space group P1¯, a=4.586(2) Å, b=4.781(3) Å, c=8.831(5) Å, α=87.106(13)°, β=76.830(13)°, γ=83.531(11)°, V=187.27(18) Å³, Z=1 and R=0.072. Ca(HF₂)₂ crystallizes in an orthorhombic Fddd space group with a=5.5709(6) Å, b=10.1111(9) Å, c=10.5945(10) Å, V=596.77(10) Å³ at 200 K, Z=8 and R=0.028.     

Synthesis, crystal structure and magnetic characterization of metal(II) coordination polymers based on 2-carboxyethylphosphonic acid and 1,10-phenanthroline (metal=Cu, Co, Cd)

Three non-isostructural metal(II) coordination polymers (metal=copper, cobalt, cadmium) were synthesized under the same mild hydrothermal conditions (T=408 K) by mixture of the corresponding metal acetate with 2-carboxyethylphosphonic acid and 1,10-phenanthroline (1:1:1 M ratio) and their structures were determined by single-crystal X-ray diffraction. Cu₂(HO₃PCH₂CH₂COO)₂(C₁₂H₈N₂)₂(H₂O)₂ and Cd₂(HO₃PCH₂CH₂COO)₂(C₁₂H₈N₂)₂ are triclinic (space group P-1) with a=7.908(5) Å, b=10.373(5) Å, c=11.515(5) Å, α=111.683(5)°, β=95.801(5)°, γ=110.212(5)° (T=120 K), and a=8.162(5) Å, b=9.500(5) Å, c=11.148(5) Å, α=102.623(5)°, β=98.607(5)°, γ=113.004(5)° (T=293 K), respectively. In contrast, [Co₂(HO₃PCH₂CH₂COO)₂(C₁₂H₈N₂)₂(μ-OH₂)](H₂O) is orthorhombic (space group Pbcn) with a=21.1057(2) Å, b=9.8231(1) Å, c=15.4251(1) Å (T=120 K). For these three compounds, structural features, including H-bond network and the π-π stacking interactions, and thermal stability are reported and discussed. None of the materials present a long-range magnetic order in the range of temperatures investigated from 300 K down to 1.8 K.     

Synthesis and structural characterization of two polymorphs of Fe(2,2′-bpy)(HPO4)(H2PO4)

Two polymorphs of an organic-inorganic hybrid compound, Fe(2,2′-bpy)(HPO₄)(H₂PO₄) (1 and 2) (2,2′-bpy=2,2′-bipyridine), have been synthesized by hydrothermal methods and structurally characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility. Crystal data are as follows: Polymorph 1, monoclinic, space group P2₁/n (No. 14), a=10.904(2) Å, b=6.423(1) Å, c=19.314(3) Å, β=101.161(3)°, and Z=4; Polymorph 2, monoclinic, space group P2₁/c (No. 14), a=11.014(1) Å, b=15.872(2) Å, c=8.444(1) Å, β=109.085(3)°, and Z=4. Polymorph 1 adopts a chain structure in which each iron atom is coordinated by two nitrogen atoms from 2,2′-bpy ligand and four phosphate oxygen atoms. These infinite chains are extended into a 3-D supramolecular array via π-π stacking interactions of the lateral 2,2′-bpy ligands. The structure of polymorph 2 consists of the same building units, namely FeO₄N₂ octahedron, HPO₄ and H₂PO₄ tetrahedra, and 2,2′-bpy ligand, which are linked through their vertices forming an undulated sheetlike structure with 4,12 network. Adjacent layers are extended into a 3-D array via π-π stacking interactions of the aromatic groups. Magnetic susceptibility measurement results confirm that the iron atoms in both compounds are present in the +3 oxidation state.     

Solvothermal synthesis and structure of a novel 3D zincophosphite |Co(en)3|[Zn4(HPO3)5(H2PO3)] containing helical chains

A new three-dimensional (3D) zincophosphite |Co(en)₃| [Zn₄(HPO₃)₅(H₂PO₃)] (1) has been solvothermally synthesized by using a racemic mixture of a chiral cobaltammine complex Co(en)₃Cl₃ as the structure-directing agent. Single-crystal X-ray diffraction analysis reveals that compound 1 crystallizes in the monoclinic space group P2₁/c (no. 14) with a=18.6180 (4) Å, b=8.7601(18) Å, c=17.4840(4) Å, β=93.42(3)°, V=2846.4(10) Å³, Z=4 with R₁=0.0530. Its structure is built up from strict alternation of ZnO₄ tetrahedra and HPO₃ pseudo-tetrahedra, giving rise to a 3D inorganic framework with 4-, 6-, 8-, 10- and 12 MRs, and the metal complex molecules, both the Δ and Λ enantiomers, sit in 10-MRs channels. In addition, it is worth noting that left- and right-handed helical chains exist in the framework, which is induced by chiral metal complex Co(en)₃Cl₃ template molecules. Further characterization of compound 1 has been performed, including X-ray powder diffraction, ICP, CHN, IR and TG analyses.     

Syntheses, structures and Raman spectra of Cd(BF4)(AF6) (A = Ta, Bi) compounds

The compounds, Cd(BF₄)(TaF₆) and Cd(BF₄)(BiF₆), have been synthesized and characterized by single-crystal X-ray diffraction and Raman spectroscopy. Both isostructural compounds crystallize in the monoclinic P2₁/c space group with a = 8.2700(6) Å, b = 9.3691(6) Å, c = 8.8896(7) Å, β = 94.196(3)°, V = 686.94(9) Å³ for Cd(BF₄)(TaF₆) and a = 8.3412(8) Å, b = 9.4062(8) Å, c = 8.9570(7) Å, β = 93.320(5)°, V = 701.58(11) Å³ for Cd(BF₄)(BiF₆). Eight fluorine atoms (4 BF₄⁻ + 4 AF₆⁻) form a surrounding around the cadmium atom in the shape of distorted square antiprism. These compounds are not isostructural with mixed-anion analogues of Ca, Sr, Ba and Pb studied earlier.     

Synthesis and structural characterization of (H4APPIP)[V3(C2O4)2(HPO4)3(PO4)(H2O)]·6H2O (APPIP=1,4-bis(3-aminopropyl)piperazine), a layered vanadium oxalatophosphate containing double 6-ring units

A new vanadium(III) oxalatophosphate has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. It crystallizes in the triclinic space group with a=11.604(2) Å, b=12.391(2) Å, c=15.220(3) Å, α=71.090(3)°, β=82.630(3)°, γ=62.979(3)°, V=1843.8(5) Å³ and Z=2. The structure consists of V₆(HPO₄)₆ double 6-ring (D6R) units connected by coordinating C₂O₄²⁻ and PO₄³⁻ anions to form anionic sheets in the ab plane with charge-compensating quadruply protonated 1,4-bis(3-aminopropyl)piperazinium cations and water molecules between the sheets. It is one of the few compounds with 2D layer structures and the second example containing D6R units in the system of metal oxalatophosphates. The iron analogue was also synthesized.     

Hydrothermal synthesis, crystal structure, and magnetic property of a three-dimensional inorganic-organic hybrid material: Mn(H2O)[HO3PCH2NH(CH2CO2)2]

A novel three-dimensional inorganic-organic hybrid compound, Mn(H₂O)[HO₃PCH₂NH(CH₂CO₂)₂] from a hydrothermal reaction of Mn (II) ion with N-(phosphonomethyl)iminodiacetic acid (H₄PMIDA) was reported. The compound crystallizes in the monoclinic P2₁/n with cell dimensions of a=5.215(5) Å, b=14.111(15) Å, c=12.727(12) Å, β=93.646(16)°, V=934.6(16) Å³ and Z=4. In this structure each Mn atom is six-coordinated with the carboxylic groups and phosphonic groups to form layers along the bc plane. These layers are further connected with the organic moieties of H₂PMIDA, resulting in a complicated three-dimensional network structure. Thermogravimetric analysis, IR spectrum and magnetic susceptibility of this compound are given.     

Hexatungstate subunit as building block in the hydrothermal synthesis of organic-inorganic hybrid materials: synthesis, structure and optical properties of Co2(bpy)6 (W6O19)2 (bpy=4,4′-bipyridine)

A hydrothermal reaction of WO₃, CoCl₂ and 4,4′-bipyridine, yields a novel organic-inorganic hybrid compound, Co₂(bpy)₆(W₆O₁₉)₂, at 170°C. X-ray single crystal structure determination reveals a two-dimensional covalent structure belonging to monoclinic crystal system, space group C2/c, with cell parameters a=19.971(4) Å, b=11.523(2) Å, c=16.138(3) Å, β=96.49(3)°, V=3690.0 Å³ and Z=2. The hexatungstate, [W₆O₁₉]²⁻, acts as a building block in bidentate fashion to bridge the Co(II) centers in the crystal structure. The title compound is found to have an optical energy gap of 2.2 eV from UV-Vis-NIR reflectance spectra.