Synthesis,structural characterization,and properties of two new polyoxovanadates based on decavanadate [V10O28]6−

Two new decavanadate metal compounds, [Co(pyim)₃]₂[V₁₀O₂₈]·7H₂O (1) and [Ni(pyim)₃]₂[H₂V₁₀O₂₈]·4H₂O (2) (pyim?=?2-(2-pyridyl)-imidazole), have been synthesized under hydrothermal conditions and characterized by elemental analysis, single-crystal X-ray diffraction analysis, infrared spectra, powder X-ray diffraction analysis, and thermogravimetric analysis. Crystallographic analysis reveals that 1 is constructed from [V₁₀O₂₈]^6?, metal cation [Co(pyim)₃]³⁺, and water. [V₁₀O₂₈]^6? clusters are connected by waters through O–H?O hydrogen bonds to form a sheet structure which is further connected by N–H?O hydrogen bonds to form a 3-D supermolecular framework. In 2, although [Ni(pyim)₃]²⁺ is similar to [Co(pyim)₃]³⁺ in 1, the M?O cluster anion is protonated [H₂V₁₀O₂₈]^4?.     

Synthesis,structures, catalytic,and anticancer activities of some coordination compounds involving two new triazole derivatives

Five N-heterocyclic carboxylate-based coordination complexes, [Co(L¹)₂(H₂O)₂]·2H₂O (1), [Cd(L¹)₂(H₂O)₂]·2H₂O (2), [Co(L²)(H₂O)₃] (3), [Ni(L²)(H₂O)₃] (4), and [Cu₂(L²)₂(H₂O)₂] (5), have been synthesized and characterized by elemental analysis, IR spectroscopy, Powder X-ray diffraction, thermogravimetric analyses, and single-crystal X-ray crystallography, where HL¹ is 2-((5-amino-1H-1,2,4-triazol-3-yl)thio)acetic acid and H₂L² is 2-((5-amino-1-(carboxymethyl)-1H-1,2,4-triazol-3-yl)thio)acetic acid. In these complexes, the hydrogen bonds (H-bonds) play an important role in their packing structures. Complex 1 has nine H-bonds showing a 3-D sqc38 topology. Complex 2 has 17 H-bonds exhibiting a 3-D hxl network. Complexes 3 and 4 are isomorphic, both of which possess ten H-bonds to present a 3-D btc topology. Complex 5 with eight H-bonds forms a 2-D sq1 structure. In addition, complex 3 catalyzes the decolorization of methyl orange. Meanwhile, 1, 3, and 5 show certain anticancer activities to inhibit the growth of HepG2 cells.     

Three New d~(10) Coordination Polymers with Arenedisulfonates:Syntheses,Crystal Structures and Luminescent Properties

Three new cadmium or zinc arenedisulfonate complexes [Zn（bpp）2（L）]n 1, { [Cd（bpp）2（1,5-NDS）（H2O）2]·4H2O }n 2 and { [Cd（bpp）2（H2O2）2]·（1,5-NDS） } n 3 （L = 4,4′-bis（2-sulfonatostyryl）biphenyl, bpp = 1,3-di（4-pyd-dyl）propane and 1,5-NDS = 1,5-Naphthalenedisulfonate） have been synthesized from aqueous solution and structurally characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. Crystal data for complex 1： space group P21/n, a = 10.559（3）, b = 13.138（4）, c = 17.623（5）A^°, β = 100.852（3）°, V = 2400.9（12） A^°^3 Z = 2, Dc= 1.351 g/cm^3, F（000） = 1016, μ = 0.654 mm^-1, the final R = 0.0412 and wR = 0.0994; Crystal data for complex 2： space group P^-1, a = 8.5642（19）, b = 10.076（3）, c = 12.114（3） A^°, α = 81.623（7）, β = 77.149（8）, γ = 82.787（7）°, V = 1003.6（4） A^°^3 Z = 1, Dc= 1.495 g/cm^3, F（000） = 466,μ = 0.713 mm^3, the final R = 0.0241 and wR = 0.0713; Crystal data for complex 3： space group C2/c, a = 21.6024（15）, b = 9.4608（5）, c = 18.4656（11）A^°, β = 107.359（3）°, V= 3602.0（4）A^°^3 Z = 4, Dc= 1.533 g/cm^3, F（000） = 1704,μ = 0.780 mm^-1, the final R = 0.0229 and wR = 0.0572. The X-ray single diffraction reveals that 1 exhibits a 3D metal-organic framework formed from 2D Zn（bpp）2^2＋ networks connected by L in the third dimension; 2 and 3 possess 3D and 2D architectures constructed from 1D polymeric chains through H-bond. Complexes 1-3 display photoluminescent emissions at 452 and 335 nm, respectively.     

Origin of the Correlation of the Rate Constant of Substrate Hydroxylation by Nonheme Iron(IV)–oxo Complexes with the Bond‐Dissociation Energy of the C?H Bond of the Substrate

A series of hydrogen‐abstraction barriers of a nonheme iron(IV)–oxo oxidant mimicking the active species of taurine/α‐ketoglutarate dioxygenase (TauD) are rationalized by using a valence‐bond curve‐crossing diagram (see figure). It is shown that the barriers correlate with the strength of the C? H bond. Furthermore, electronic differences explain the differences between nonheme and heme iron(IV)–oxo hydrogen‐abstraction barriers.

     

The Si?Sn Chemical Bond: An Integrated Thermochemical and Quantum Mechanical Study of the SiSn Diatomic Molecule and Small Si–Sn Clusters

The silicon–tin chemical bond has been investigated by a study of the SiSn diatomic molecule and a number of new polyatomic Si_xSn_y molecules. These species, formed in the vapor produced from silicon–tin mixtures at high temperature, were experimentally studied by using a Knudsen effusion mass spectrometric technique. The heteronuclear diatomic SiSn, together with the triatomic Si₂Sn and SiSn₂ and tetratomic Si₃Sn, Si₂Sn₂, and SiSn₃ species, were identified in the vapor and studied in the overall temperature range 1474–1944 K. The atomization energy of all the above molecules was determined for the first time (values in kJ mol^?1): 233.0±7.8 (SiSn), 625.6±11.6 (Si₂Sn), 550.2±10.7 (SiSn₂), 1046.1±19.9 (Si₃Sn), 955.2±26.8 (Si₂Sn₂), and 860.2±19.0 (SiSn₃). In addition, a computational study of the ground and low‐lying excited electronic states of the newly identified molecules has been made. These electronic‐structure calculations were performed at the DFT‐B3LYP/cc‐pVTZ and CCSD(T)/cc‐pVTZ levels, and allowed the estimation of reliable molecular parameters and hence the thermal functions of the species under study. Computed atomization energies were also derived by taking into account spin–orbit corrections and extrapolation to the complete basis‐set limit. A comparison between experimental and theoretical results is presented. Revised values of (716.5±16) kJ mol^?1 (Si₃) and (440±20) kJ mol^?1 (Sn₃) are also proposed for the atomization energies of the Si₃ and Sn₃ molecules.     

Syntheses and crystal structures of butterfly M2Te2 complexes of molybdenum and tungsten with functionalized cyclopentadienyl ligands

Reactions of singly-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₆] (I, M?=?Mo; II, M?=?W) with the diarenylditelluride [4-CH₃C₆H₄Te]₂ in refluxing toluene for 4–6?h afforded dinuclear complexes 1 and 2 trans/ae-[(η⁵-RC₅H₄)₂M₂(CO)₄(μ-ArTe)₂] (Ar?=?4-CH₃C₆H₄Te). Complexes 1 and 2 were also synthesized by reactions of triply-bonded dinuclear complexes [(η⁵-CH₃O₂CC₅H₄)₂M₂(CO)₄] (III, M?=?Mo; IV, M?=?W) with [4-CH₃C₆H₄Te]₂ in refluxing toluene for 1?h. Both complexes have been characterized by elemental analysis, ¹H NMR, ¹³C NMR and IR spectroscopy and X-ray diffraction. Preliminary low-temperature NMR experiments on complexes 1 and 2 have revealed that in solution each complex goes through a rapid inversion of the butterfly four-membered ring M₂Te₂.