Solid and Solution Structural Studies of Dimeric and Tetrameric Molybdenum(Ⅵ) Malate Complexes

Reactions of potassium molybdate with racemic malic acid (H3mal = C4H6O5) result in the isolation of two mesomeric molybdenum malate complexes Ks[(MoO2)2O(R-mal)2][(MoO2)2O(S- mal)2]·4H2O 1 and (Him)2K6[(MoO2)4O3(R-mal)2][(MoO2)4O3(S-mal)2]·8H2O 2. Complex 1 belongs to the monoclinic system, space group C2/c with a = 14.8637(3), b = 6.9544(1), c = 19.6783(5) A, β = 100.081(2)°, V= 2002.70(7)A3, Mr = 1452.88, Z= 2, F(000) = 1416, T= 173 K, Dc = 2.409 g/cm3, μ(MoKa) = 2.167, R = 0.0283 and wR = 0.0733.2 is of triclinic system, space group P1 with a = 8.7707(2), b = 9.3310(3), c = 17.9093(7) A, α = 83.781(3), β = 85.626(2), γ= 84.822(2)°, V = 1447.84(8) A3, Mr = 2160.68, Z = 1, F(000) = 1048, T= 173 K, Dc = 2.478 g/cm3, μ(MoKα) = 2.230, R = 0.0234 and wR = 0.0584.1 is the first isolated dinuclear molybdenum(Ⅵ) malato complex in 1:1 molar ratio. The molybdenum atoms in the two complexes are six-coordinated in an approximately octahedral geometry. Two malates coordinate tridentately with the Mo atom via their α-alkoxy, α-carboxy and α-carboxy groups in 1 and 2. β-Carboxy group in 2 further links with the other two Mo atoms to give a tetrameric unit. The solution 1H and 13C NMR spectra indicate that dimeric malate molybdenum in 1 dissociates partly in solution and exists in an equilibrium with tetrameric species, while 2 is stable and retains its tetrameric structure without any dissociation.     

Synthesis, Characterization and Properties of Organotin Complexes Dibutyltin（Ⅳ） Bis（heteroaromatic carboxylate） and Crystal Structure of Dibutyltin（Ⅳ） Bis（2-thiazolylcarboxylate）

The six organotin complexes dibutyltin(IV) bis(heteroaromatic carboxylate) were synthesized by the reaction of (n‐Bu)2SnO with heteroaromatic carboxylic acid in 1:2 molar ratio. These complexes have been characterized by elemental analysis, IR, ¹H, ¹³C and ¹¹⁹Sn NMR. The crystal structure of dibutyltin(IV) bis(2‐thiazolylcarboxylate) was determined by X‐ray single crystal diffraction. This compound is a weakly bridged dimer through weak interaction Sn···O between molecules. The tin atoms took six‐coordinate skew‐trapezoidal bipyramidal geometry. The crystal of complex 3 belongs to monoclinic symmetry with space group P2₁/c, a=1.863(2) nm, b=2.220(3) nm, c=1.0395(10) nm, β=90.275(16)°, Z=8, V=4.292(8) nm³, D_c=1.514 Mg/m³, μ=1.406 mm^‐1, F(000)=1968, S=0.999, R=0.0549, wR=0.1011.     

Synthesis, Crystal Structure and Thermal Stability of a Saturated Dimeric Ce（III）-chelated Complex Based on Benzoate and 1,10-Phenanthroline Ligands

The title complex, [Ce（BA）3phen]2 （BA = benzoate, phen = 1,10-phenanthroline）, was prepared by the reaction of Ce（NO3）3.6H2O, benzoic acid and 1,10-phenanthroline. The complex was characterized by single-crystal X-ray diffraction, elemental analysis, IR spectra and TG-DTG techniques. The results show that the crystal is of triclinic, space group P1 with a = 10.912（2）, b = 11.962（3）, c = 12.474（3） A, α = 104.889（3）, β = 93.523（3）, γ = 113.332（3）^o, C66H46Ce2N4O12, Mr = 1366.90, V= 1420.2（6） ,A^3, Z = 1, Dc = 1.598 g/cm^3, μ = 1.652 mm^-1, S = 1.024 and F（000） = 682. The final R = 0.0391 and wR = 0.0947 for 4878 observed reflections with I 〉 2σ（I）. The structure of the title complex consists of two Ce（C6HsCOO）3（C12H8N2） units, forming a binuclear molecule. Each Ce（Ⅲ） is coordinated by two O atoms of one bidentate chelating carboxylate group, five O atoms of two bidentate bridging and two tridentate chelating-bridging carboxylate groups, and two N atoms of one 1,10-phenanthroline molecule to complete a distorted monocapped square antiprism geometry. Its thermogravimetric analysis was determined by TG-DTG techniques.     

Reaction of Molybdenum Hexa-carbonyl with Mercapto-pyridine （PySH） or Mercapto-pyridine Oxide （PyS→O） and Crystal Structure of [Et4N][Mo2（PyS）3（CO）5]

Introduction Mercapto-pyridine, C5H4NS-(PyS), containing two active atoms, S and N, is a bidentate ligand, which may act as a 3-electron donor or a 5-electron donor and may be a bridging ligand to link two metal atoms to form polynuclear metal clusters or a chelating agent to coor-dinate to a metal atom by S and N atoms. So the mer-capto-pyridine is a very important reagent and its reac-tion with metal compound is very useful for simulating the active center in metal enzymes and syntheses …     

Syntheses, Structural Characterization of Fe and Ni Complexes with Polypyrazolyl Borate Ligand ： Fe [ HB （pz） 3 ] 2 and Ni [ HB （pz） 3 ] 2

Fe(Ⅱ) complex Fe[HB(pz)3]2(compound 1, pz=pyrazole) and Ni(Ⅱ) complex Ni[HB(pz)3]2(compound 2) have been obtained by the reaction of MCI2(M=Fe and Ni) with NaHB(pz)3 in MeOH. The two complexes(compounds 1 and 2) were characterized by IR, NMR, elemental analysis and X-ray diffraction. Compound 1 crystallizes in space group P21/c with a=1.224(3) nm, b=1.161(2) nm, c=1.648(3) nm, β=107.62(15)°, V=2.233(8) nm3, Z=2. Compound 2 crystallizes in space group P21/c with a=0.97926(18) nm, b=1.7423(3) nm, c=1.3156(2) nm, β=97.055(16)°, V=2.2277(7) nm3, Z=4. The results of X-ray structural analyses show that both compounds 1 and 2 are monomeric neutral, possessing a similar coordination mode and a similar structure around the metal centers. The related spectral characterizations, steric effects and binding properties are discussed.     

Synthesis and Characterization of a One- dimensional Molybdenum Oxide （H2enMe）[Mo3O10]

A hybrid organic-inorganic material (H2enMe)[Mo3O10] (C3H12Mo3N2O10, Mr = 523.97) has been synthesized under hydrothermal conditions and its crystal structure was determined by X-ray diffraction. It crystallizes in the orthorhombic system, space group Pnma with a = 12.430(2), b = 7.6089(12), c = 11.9553(19) , V = 1130.7(3) 3, Dc = 3.078 g/cm3, Z = 4, μ(MoKa) = 3.328 mm1, F(000) = 1000, the final R = 0.0256 and wR = 0.0716 for 1314 observed reflections with I > 2σ(I). A total of 11780 reflections were measured and 1325 were unique (Rint = 0.0244). It consists of infinite one-dimensional edge-sharing MoO6 octahedral chains with [Mo3O10]2 moieties. The protonated diaminopropane cations are located between the chains and linked to the oxygen atoms of the inorganic skeletal backbones by hydrogen bonds. It is indicated that the as-synthesized compound displays photochromic property in the solid state.     

A Series of New Molybdenum(VI) Complexes with the ONS Donor Thiosemicarbazone Ligands

New dioxomolybdenum(VI) complexes were obtained by the reaction of [MoO₂(acac)₂] with 4‐phenylthiosemicarbazone ligands derived from salicylaldehyde, 2‐hydroxy‐1‐naphthaldehyde, 2‐hydroxy‐3‐methoxybenzaldehyde or from 4‐(diethylamino)salicylaldehyde. In all complexes the ligands are coordinated to molybdenum as tridentate ONS‐donors through phenolic‐oxygen, imine‐nitrogen and thiol‐sulphur. Octahedral coordination of each Mo atom is completed either by one neutral donor molecule (D) or by the oxygen atom of the Mo=O unit from the neighbouring molecule. All compounds were characterized by means of chemical analysis, IR spectroscopy, TG and in some cases by DSC measurements, some of them by X‐ray crystallography, and by one and two‐dimensional NMR method.     

Synthesis, Spectroscopic Properties and Structural Characterization of Sodium Potassium Citrato Oxotungstate(VI) Dimer

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｅｓｓｅｎｔｉａｌｒｏｌｅｏｆＭｏｉｎｖａｒｉｏｕｓｆｕｎｄａｍｅｎｔａｌｂｉｏｌｏｇｉｃａｌｃｏｎｖｅｒｓｉｏｎｓｃａｒｒｉｅｄｏｕｔｂｙｂｏｔｈｍｉｃｒｏｏｒｇａｎｉｓｍｓａｎｄｈｉｇｈｅｒｌｉｆｅｆｏｒｍｓｈａｓｂｅｅｎｋｎｏｗｎｆｏｒｄｅｃａｄｅｓ〔1〕.ＲｅｃｅｎｔｓｔｕｄｉｅｓｏｎｔｈｅｎｉｔｒｏｇｅｎａｓｅｅｎｚｙｍｅｈａｓｒｅｖｅａｌｅｄｉｔｓａｃｔｉｖｅｓｉｔｅｏｆＦｅＭｏ ｃｏ (ＦｅＭｏ ｃｏ ｆａｃｔｏｒ)ａｓａｃａｇｅ ｌｉｋｅＭｏＦｅ7Ｓ9ｈｏｍ…     

Copper(II) Complexes with Chiral Diaminodiamido Ligands: Solution and Structural Studies

Abstract

Three diaminodiamido ligands (S,S)-N,N′-bis(prolyl)ethanediamine (ProNN-2), (S,S)-N,N′-bis(N-methylvalyl)ethanediamine (Me₂ValNN-2), and (S,S)-N,N′-bis(N-methylphenylalanyl)-ethanediamine (Me₂PheNN-2) were synthesised and their complex formation equilibria with copper(II) investigated in aqueous solution by potentiometry and, for ProNN-2, by electronic spectrophotometry. ProNN-2 forms the species [CuLH]³⁺, [Cu₂L₂]⁴⁺, [Cu₂L₂H_?2]²⁺ and [CuLH_?2], Me₂PheNN-2 forms the complexes [CuLH]³⁺, [Cu₂L₂H_?2]²⁺ and [CuLH_?2], whereas Me₂ValNN-2 forms the monomer [CuLH_?1]⁺ but not the dimer. The dimeric cation [Cu₂L₂H_?2]²⁺, of Me₂PheNN-2 has severe steric requirements, as demonstrated by the X-ray crystal structure of the complex [Cu₂L₂H_?2]Cl₂· 12H₂O, of the corresponding non-methylated ligand. Since copper(II) complexes of the ligands examined are used as additives to the mobile phase to perform chiral resolution of D,L-amino acids in RP-HPLC, the present results provide valuable clues to an understanding of the mechanism of the enantiomeric separation.     

Molybdenum(VI) Bis(imido) Complexes: From Frustrated Lewis Pairs to Weakly Coordinating Cations

Molybdenum(VI) bis(imido) complexes [Mo(NtBu)₂(L^R)₂] (R=H 1 a ; R=CF₃ 1 b ) combined with B(C₆F₅)₃ ( 1 a /B(C₆F₅)₃, 1 b /B(C₆F₅)₃) exhibit a frustrated Lewis pair (FLP) character that can heterolytically split H−H, Si−H and O−H bonds. Cleavage of H₂ and Et₃SiH affords ion pairs [Mo(NtBu)(NHtBu)(L^R)₂][HB(C₆F₅)₃] (R=H 2 a ; R=CF₃ 2 b ) composed of a Mo(VI) amido imido cation and a hydridoborate anion, while reaction with H₂O leads to [Mo(NtBu)(NHtBu)(L^R)₂][(HO)B(C₆F₅)₃] (R=H 3 a ; R=CF₃ 3 b ). Ion pairs 2 a and 2 b are catalysts for the hydrosilylation of aldehydes with triethylsilane, with 2 b being more active than 2 a . Mechanistic elucidation revealed insertion of the aldehyde into the B−H bond of [HB(C₆F₅)₃]⁻. We were able to isolate and fully characterize, including by single-crystal X-ray diffraction analysis, the inserted products Mo(NtBu)(NHtBu)(L^R)₂][{PhCH₂O}B(C₆F₅)₃] (R=H 4 a ; R=CF₃ 4 b ). Catalysis occurs at [HB(C₆F₅)₃]⁻ while [Mo(NtBu)(NHtBu)(L^R)₂]⁺ (R=H or CF₃) act as the cationic counterions. However, the striking difference in reactivity gives ample evidence that molybdenum cations behave as weakly coordinating cations (WCC).     

Structural analysis of several W(VI) and Mo(VI) complex perovskites prepared by the polymeric precursors method

We describe in this work the synthesis by the Pechini method of five Mo(VI)- and W(VI)-containing complex perovskites and their structural characterisation by HREM and XRD. The compounds studied, Ba(B_2/3′B_1/3″)O₃ (B′=In and Y; B″=W and Mo) and Sr(In_2/3W_1/3)O₃, were obtained after firing the precursor powders for 8 h at 1200°C. Thermal analysis showed that the formation mechanism of the five perovskites is similar and implies the formation of barium carbonate and barium tungstates or molybdates of different stoichiometries as intermediate phases. Interesting enough, these similar mechanisms yield to materials of a quite different structure. Indeed, Ba(In_2/3Mo_1/3)O₃ and Sr(In_2/3W_1/3)O₃ were found to be disordered perovskites (unit cells: a_p×a_p×a_p and , respectively); on the other hand, two phases coexist in the sample Ba(In_2/3W_1/3)O₃ at the synthesis conditions: an ordered predominant phase (unit cell: 2a_p×2a_p×2a_p) and, as a minor phase, a disordered perovskite (unit cell: a_p×a_p×a_p). Finally, the two yttrium-containing compounds were found to be ordered perovskites (2a_p×2a_p×2a_p).     

Synthesis and Crystal Structure of Ammonium cis-Dioxo Dibenzilato Tungstate （VI） Dihydrate

1 INTRODUCTION Tungsten and molybdenum are chemically analogous elements. Because of their great similari- ties in properties, it was reasonable that the insight into catalytic role of Mo in various enzymes may be provided by replacing Mo with W. In order to un- derstand the chemistry and oxo-transfer properties of these enzymes, numerous dioxo-Mo(VI) and di- oxo-W(VI) complexes with a wide range of ligands have been prepared and structurally characteriz- ed[1～5]. Moreover, hydroxyca…     

Thermodynamic and Kinetic Studies on Oxidation of Pyrogallol Red by Hydrogen Peroxide in the Absence and Presence of Molybdenum(VI)

Abstract

The oxidation of pyrogallol red (PGR) by hydrogen peroxide has been studied both in the absence and presence of molybdenum(VI) at pH of 7.0 by spectrophotometric detection. The reaction rate was studied with a fix-time method from 0.5 to 4.5 min. The effect of reagents concentration, ionic strength and temperature was studied to give the optimum conditions. At the optimizing conditions the rate constant, energy and entropy of activation and frequency factor have been calculated using the Arrhenius and Eyring plots.     

1−去氧巴卡亭Ⅵ衍生物的合成和结构的研究

本文以1−去氧巴卡亭Ⅵ为原料合成系列衍生物,用X−射线单晶衍射方法研究了这些衍生物的精细立体结构。研究了母环上不同取代基对分子构象的影响,晶体学数据分析的结果证明C(2)和C(4)取代基对分子母环中A环构象起决定性作用,C(10)、C(13)位去乙酰基或C(9)和C(10)位羟基形成缩酮对分子构象无显著的影响,但对母环上不同环的构象产生细微的变化。研究结果还表明：C(2)位苯甲酰基的构象呈现揉曲性,此特性与紫杉烷类化合物的生物活性有关。     

Synthesis and Crystal Structure of Binuclear Oxomolybdenum(VI) Complex with Both o-Mercaptophenolate

1INTRoDUCTIONMolybdenumintheVandVIoxidationstatesformsaconsiderablenumberofoxocomplexes.Someofthemareactivecatalystsfortheoxidationoforganicsub-stracts[li'Allthesefactshavewidelyarousedchemists'interest.lnordertoobservetheeffectofthedonorgroupsonthedegreeofcomplexaggregationandonthecoor-dinationgeometry,thetitlecompoundwaspreparedbythereactionof(n-Bu'N)'-[Mo,O,,jwitho-mercaptophenolandthesinglecrystalswereobtained.Itcontainsa[Mo,O,j' core.Somereleventreportscanbefoundinthepreviousliter…     

Natriumoxonitridometallate(VI) von Molybdän und Wolfram,Na4MO2N2 (M = Mo,W)

Sodium Oxonitridometallates(VI) of Molybdenum and Tungsten, Na₄MO₂N₂ (M = Mo, W) MoO₃ as well as WO₃ react with an excess of NaNH₂ in autoclaves at temperatures ranging from 250°C to 750°C to yield – in contrast to Ta₂O₅ [1] – oxonitridometallates of general composition Na₄MX₄ and other products like Na₅WO₄N [2]. The compounds decompose in moist air within minutes to Na₂WO₄, Na₂MoO₄ and Na₂MoO₄ · xH₂O, respectively. The structures of the Na₄MX₄ phases were determined from single crystal X-ray diffraction data. They crystallize triclinic in the Na₄CoO₄-type structure [3] P1 , Z = 2 with the following cell constants: