Hydrothermal Synthesis and Structure of a Novel Binuclear Molybdenum Complex with Oxalate Ligand, (enH_2){NH_4[Co(en)_3][Mo_2O_7(C_2O_4)] }_2·2H_2O

The title complex (enH2){NH4[Co(en)3][Mo2O7(C2O4)]}22H2O (C18H70Co2Mo4- N16O24, Mr = 1396.52) was obtained under hydrothermal conditions and its crystal structure has been determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/c with a = 17.8023(8), b = 7.7527(4), c = 16.9781(4) ? b = 103.878(7), V = 2274.8(2) 3, Dc = 2.039 g/cm3, Z = 2, m(MoKa) = 1.878 mm-1 and F(000) = 1408. The final R = 0.0410 and wR = 0.1070 for 4065 observed reflections with I≥2s(I). The crystal structure is composed of bi- nuclear [Mo2O7(C2O4)]4- anions, complex [Co(en)3]2+ cations, protonated ethylenediamine cations, ammonium cations and crystal water molecules, which are held together into a three-dimensional network via hydrogen-bonding interactions. The binuclear structure of [Mo2O7(C2O4)]4- consist of one MoO4 and one MoO6 octahedra through sharing a bridging oxygen atom, where the oxalate ligand acts as a bidentate ligand coordinating to the octahedral molybdenum atom though two deprotonated corboxylate groups.

Thermodynamic simulation of metal behaviors in Cu_(2+)−Ni_(2+)−NH_(3)−NH_(4)+−C_(2)O_(4)^(2-)−H_(2)O system

To investigate the behaviors of Cu^(2+)and Ni^(2+)with the change of conditions in Cu_(2+)−Ni_(2+)−NH_(3)−NH_(4)+−C_(2)O_(4)^(2-)−H_(2)O reaction system,mathematical models of thermodynamics based on the principle of mass conservation were established.The simulation results indicate that the precipitation of metal ions from the aqueous phase is a complicated dynamic equilibrium process,during which the coordination reactions of Cu^(2+)and Ni^(2+)with NH3 forming[Cu(NH3)n]^(2+)(n=3−5)and[Ni(NH3)m]^(2+)(m=3−6)are predominant under high pH conditions,respectively.The pH ranges for the simultaneous precipitation of Cu^(2+)and Ni^(2+)are 2.0−6.5 and 2.0−5.5 when[NH3]T equals 0.6 and 4.2 mol/L,respectively,with the prefixed[C_(2)O_(4)^(2-)]T of 0.6 mol/L.Due to the fractional precipitation of Cu^(2+)and Ni^(2+),Cu−Ni composite is obtained after the thermal decomposition of Cu−Ni oxalate complex salts prepared in a pure water system when pH>7.0.By applying the mixed solvent(water/ethanol)as the precipitation medium,the Cu−Ni alloy rods can be finally fabricated with high purity and crystallinity.

A Novel Chromium(III) Hybrid Salt, Triethylammonium <i>Trans</i>-Diaquabis(Oxalato-<i>κ</i>²O¹,O²) Chromate(III), (C<SUB>6</SUB>H<SUB>16</SUB>N)[Cr(C<SUB>2</SUB>O<SUB>4</SUB>)<SUB>2</SUB>(H<SUB>2</SUB>O) <SUB>2</SUB>]: Synthesis, Spectroscopic Studies, Thermal Behavior and Crystal Structure

A novel organic-inorganic chromium(III) hybrid salt, triethylammonium trans-diaquabis(oxalato-κ2O1,O2)chromate(III), (C6H16N)[Cr(C2O4)2(H2O)2] (1), has been synthesized in aqueous solution and characterized by elemental and thermal analyses, FTIR and UV-Vis spectroscopies, and by single crystal X-ray structure determination. Compound 1 crystallizes in the orthorhombic system, Pbcn space group with the unit cell parameters a = 11.1776(10), b = 7.6105(10), c = 17.5654(2) Å, α = β = γ = 90°, V = 1494.24(3) Å3, Z = 4 and Z’ = 1/2. The structure of 1 consists of [Cr(C2O4)2(H2O)2]− mononuclear anions and triethylammonium [(C2H5)3NH]+ cations. In the anionic unit, the CrIII ion is six coordinated, in a distorted octahedral geometry, by four equatorial O atoms of two oxalate anions acting as chelating ligands and two O atoms from trans-coordinated water molecules occupying the apical positions with longer metal-oxygen distances. In the solid, O-H … O and N-H … O intra and inter molecular hydrogen bonding interactions connect the components into a 3D network. The triethylammonium cations are disordered among two possible orientations with occupancies rates around 50% for C4, N1, C1a, C1b, C4ii, N1ii, C1aii, C1bii (ii = −x + 1, y, − z + 1/2). The IR spectrum of 1 is consistent with the presence of the various molecular building constituents. The UV-Vis spectrum shows two absorption bands around 564 and 416 nm which are compatible with an anionic chromium (III) complex in an octahedral environment. Thermal studies carried out in air between 25°C and 700°C confirm the anhydrous character of 1 and show that it is stable up to 210°C.

[Co(NH_3)_6]_2[Cd_8(C_2O_4)_(11)(H_2O)_4]·8H_2O: A 5-connected sqp topological metal-organic framework co-templated by Co(NH_3)_6^(3+) cation and (H_2O)_4 cluster

In our efforts to construct new metal-organic frameworks （MOFs） by template-directing method, a new cadmium oxalate, [Co（NH3）612[Cds（C204）ll（H20）4].8H20 （denoted HNU-1 ）, has been synthesized under hydrothermal condition in the presence of C0（NH3）6C13, The crystal structure of HNU-1 was determined by single-crystal X-ray diffraction （monoclinic, C2/c）, a = 11.126（2）A, b = 17.361 （4）,A, c = 16.119（3）A, fi = 102.40（3）, V = 3040.8（10） A and Z = 8. The open framework of HNU-1 contains 12-ring channels and exhibits a 5-connected sqp topological network with dinuclear Cd（ll） clusters acting as nodes. The Co（NH3）63＋ cations and unusual hydrogen-bonded （H20）4 clusters are found in the 12-ring channels with an alternative arrangement. It is believed that the （H20）4 clusters play a co-templating role in the crystallization of HNU-1.