Quantum-chemical calculations of molybdenum chloride clusters Mo13C24, Mo13Cl26, and Mo13Cl30

Quantum-chemical calculations of the structures and thermodynamic stabilities of isomers of molecular clusters of lower Mo chlorides Mo₁₃Cl₂₄, Mo₁₃Cl₂₆, and Mo₁₃Cl₃₀, as well as of the Mo₁₃Cl ₂₆ ^? anion of cuboctahedral or icosahedral structure, have been performed by the DFT B3LYP method with the use of the Lanl2dz basis set for the Mo atoms and the 631G(d) basis set for the Cl atoms. The highest symmetry polyhedra are considered: Mo₁₃Cl₃₀ and Mo₁₃Cl₂₄ have a structure of centered icosahedron and cuboctahedron with bridging Cl atoms sitting atop the midpoints of 30 and 24 edges, respectively. In both cases, calculations lead to a rapid increase in the Mo-Mo distance to the values that are evidence of the absence of metal-metal bonds; hence, the cluster structure, in its classical meaning, is not retained. Both the neutral cluster Mo₁₃Cl₂₆ and the Mo₁₃Cl ₂₆ ^? anion—a symmetric icosahedron, in which Cl ions sit atop the centers of 20 faces and 6 Cl atoms are terminal, and a cuboctahedron, in which 14 Cl atoms are located on the three- and fourfold axes over the centers of molybdenum faces and 12 terminal Cl atoms are located on twofold axes. For both the neutral cluster and the anion, stable structures have been obtained. In both cases, the total energies are lower for the initial icosahedral configuration.     

Missing link in the ligand-field photolysis of [Mo(CN)8]4-: synthesis, X-ray crystal structure, and physicochemical properties of [Mo(CN)6]2-

Photoinduced dissociation of two Mo-CN bonds in [Mo(CN)8]4- affords the octahedral complex anion [Mo(CN)6]2-. This hexacyanomolybdate(IV) ion is also obtainable from tetracyanooxomolybdate via a thermal substitutional synthetic route. The anion represents the missing link in the ligand-field photolysis of octacyanomolybdate(IV); it is characterized by means of single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility measurements as well as IR, Raman, 1H and 13C NMR, and electronic spectroscopy.     

Removal of185W,99Mo and125Sb radioisotopes from aqueous solutions using polyamine incorporated polysaccharides

Polyamino group-containing resins act both as chelating ion exchangers and weakly basic anion exchangers depending upon the species in contact in the solution. In the present work, ion exchangers based on polyamine incorporated polysaccharides (cellulose and galactomannan or guaran) have been used for removal of radioisotopes of¹⁸⁵W as WO ₄ ^2– ,⁹⁹Mo as MoO ₄ ^2– and¹²⁵Sb as Sb³⁺ from their separate aqueous solutions. These chelating anion exchangers have been synthesized by reaction of polysaccharides with epichlorohydrin followed by the respective polyamines as nucleophiles in a strongly alkaline medium. WO ₄ ^2– and MoO ₄ ^2– are adsorbed from their aqueous solutions through anion exchange process by chloride form of cellulose-triethylenetetraamine (cellulose-trien), cellulose-tetraethylenepentaamine (cellulose-tetren), guaran-triethylenetetraamine (guar-trien) and guar-tetraethylenepentaamine (guar-tetren) weakly basic anion exchangers. Guar-tetren chelating polymer has been found to be highly selective for¹²⁵Sb isotopes presumably due to the presence of chelating cis-hydroxy and tetren groups in the galactomannan matrix.     

Supramolecular squares with Mo2(4+) corners

Seven complexes obtained by reacting the quadruply bonded complex [Mo2(cis-DAniF)2(CH3CN)4](BF4)2 (DAniF = N,N'-di-p-anisylformamidinate) and (Bun4N+)2(Carb2-), where Carb2- is a dicarboxylate anion, have been found to have a ratio of dimetal unit to dicarboxylate of 1:1. As noted by the carboxylate linker, the compounds are oxalate, 1, fumarate, 2, ferrocene dicarboxylate, 3, 4,4'-biphenyldicarboxylate, 4, acetylenedicarboxylate, 5, tetrafluorophthalate, 6, and carborane dicarboxylate, 7. Structural characterization of 1-4 revealed a square of dimolybdenum units linked by the dicarboxylate anions, each having an interstice capable of accommodating specific solvent molecules. Results of NMR studies of all seven compounds are consistent with the presence of a highly symmetrical structure. These compounds display a rich electrochemical behavior that is affected by the nature of the carboxylate group.     

Synthesis and characterization of the face-sharing bioctahedral [Mo2O6F3]3- anion

The face-sharing bioctahedral molybdenum(VI) oxide fluoride anion [Mo2O6F3]3- has been isolated in the new compound [Cu(3-apy)4]3(Mo2O6F3)2 (3-apy = 3-aminopyridine) and has been characterized by experimental and computational techniques. Single-crystal X-ray diffraction studies show that the structure of the [Mo2O6F3]3- anion resembles two distorted face-sharing octahedra, each with three short terminal metal-ligand bonds and three long metal-ligand-metal bridging interactions. Aspects of the electronic structure, as well as geometric comparisons of the bond lengths and angles in [Mo2O6F3]3- with those in the similarly distorted [MoO3F3]3- anion, suggest that the six terminal ligand positions of the confacial bioctahedra are occupied exclusively by oxide ligands and that the three bridging sites are occupied by fluorides. Crystal data for [Cu(3-apy)4]3(Mo2O6F3)2: trigonal space group R3 (No. 148) with hexagonal axes of a = 13.881(1) A and c = 31.783(3) A (Z = 3).     

Systematic preparation of Mo 2 4+ building blocks for supramolecular assemblies

The preparation of additional and useful building blocks for the construction of supramolecular entities with quadruply bonded Mo(2)(4+) units has been explored, and five new mixed-ligand complexes with three types of ligands and various basicities are reported. The ligands used were the DAniF (N,N'-di-p-anisylformamidinate) anion, the acetate anion, and neutral acetonitrile molecules. The formamidinate ligands are the least labile, and the acetonitrile molecules are the most labile. This difference as well as a relatively strong trans directing influence by the formamidinate anions in ligand substitution reactions allows designed synthesis of various mixed-ligand building blocks, including rare pairs of cis and trans isomers. The new compounds are cis-Mo(2)(DAniF)(2)(O(2)CCH(3))(2) (1), trans-Mo(2)(DAniF)(2)(O(2)CCH(3))(2) (2), trans-[Mo(2)(DAniF)(2)(O(2)CCH(3))(CH(3)CN(eq)())(2)]BF(4) (3), trans-[Mo(2)(DAniF)(2)(CH(3)CN(eq)())(4)](BF(4))(2) (4), and [Mo(2)(O(2)CH(3))(CH(3)CN(eq)())(6)(CH(3)CN(ax)())](BF(4))(3) (5), where eq and ax designate equatorial and axial ligands, respectively. A comparison with some previously synthesized complexes is given along with a discussion of the overall reactivity of all compounds.     

Single-component magnetic conductors based on Mo3S7 trinuclear clusters with outer dithiolate ligands

A trinuclear cluster complex containing the Mo(3)S(7) central unit coordinated to dithiolate ligands, in particular the organic dmit (1,3-dithia-2-thione-4,5-dithiolate) anion, has been used to prepare a single-component molecular conductor formed by the threefold symmetry magnetic building block Mo(3)S(7)(dmit)(3) (1). The [Mo(3)S(7)(dmit)(3)](2)(-) ([1](2)(-)) diamagnetic anion forms dimers by interaction between the electrophilic cluster axial sulfur atoms and the sulfur atoms of the outer dithiolate ligand. Additional contacts between adjacent dmit ligands result in chain formation. The two-electron oxidation of [1](2)(-) yields to a three-dimensional molecular solid formed by neutral Mo(3)S(7)(dmit)(3) (1) units with partially filled molecular orbitals, which exhibits sizable intermolecular electronic interactions together with a significant electron delocalization. It also contains large open channels. The interactions responsible for the conducting properties have been identified using a first-principle DFT approach and the calculated electronic structure has allowed us to model the magnetic behavior of the material with two competing antiferromagnetic interactions to produce a spin-frustrated extended network. The potential of this Mo(3)S(7) cluster complex to be modified together with the capability of filling the open channels with doping species paves the way to an entirely new set of molecular conductors and/or magnets.     

{AsW9O33}-{Mo3S4} based polyoxometalates including a metal-metal bond with Pd or Ni. Synthesis, structure and studies in solution

Heterometallic cuboidal clusters [Mo(3)S(4)M(H(2)O)(9)Cl](3+) M = Pd or Ni react with the trivacant [AsW(9)O(33)](9-) anion to give tetramodular complexes [(H(2)AsW(9)O(33))(4){Mo(3)S(4)M(H(2)O)(5)}(2)](20-) (M = Pd for anion 2 and M = Ni for anion 3) in good yield. Both anions crystallized as single crystals of potassium salts to give K-2 and K-3 salts which have been characterized structurally by X-ray diffraction. Both compounds are isomorphous and the anions 2 and 3 are described as two dimeric moeties, associated by internal hydrogen bonds, electrostatic interactions involving four outer potassium ion and coordination bonds within a central {M(2)S(2)} unit containing a M-M metallic bond. Studies in solution reveal that the dimeric association is maintained in solution in the 2 × 10(-4)-2 × 10(-3) mol L(-1) range. Conversely, in the presence of exogeneous ligands, such as iodide or pyridine the UV-vis data are consistent with the dissociation of the anion 2 into monomer through a Pd-L coordination bond (L = I(-) or Py). Furthermore, (183)W NMR spectrum of 2 shows that molecular structure of 2 is retained in solution. Elemental analysis and IR are also supplied. Electrochemical behavior of 2 and 3 are given and compared with the Pd or Ni free parent anion. The CVs are dominated mainly by irreversible reduction or oxidation processes, where the peak potentials appear dependent upon the ionic charge of the complex. However, the CV of the Pd-containing anion (2) is consistent with the deposition of Pd metal at the electrode, which gives rise to an oxidation process into palladium oxide.     

Synthese und Kristallstruktur von (PPh4)2[Mo2Cl10]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂Cl₁₀] The title compound is obtained in the reaction of [MoCl₄(Ph? C?C? Ph)]₂ with tetraphenylphosphonium chloride in dichloro methane, forming brown crystals. It is characterized by the i.r. spectrum and a crystal structure analysis by the aid of X-ray diffraction data. The complex crystallizes triclinic in the space group P1 with one formula unit per unit cell. The cell dimensions are a = 1122 pm, b = 1137 pm, c = 1283 pm; α = 63.4°, β = 69.1°, γ = 86.5°. The crystal structure determination (2959 observed, independent reflexions, R = 4.5%) shows the constants of the unit cell to consist of on centrosymmetric anion, two cations and one disordered molecule of dichloro methane. The distance Mo? Mo in the anion is 380 pm, which excludes direct magnetic interaction between the molybdenum atoms.     

Increasing the solubility of strong reducing agents containing Mo(2)(4+) units and alkyl-substituted guanidinate ligands

Six very soluble paddlewheel compounds containing Mo(2)(n+) units, n = 4, 5, 6, and two alkyl-substituted bicyclic guanidinate ligands have been synthesized. The quadruply bonded complexes with n = 4, Mo(2)(TMhpp)(4) and Mo(2)(TEhpp)(4), (TMhpp = the anion of 3,3,9,9-tetramethyl-1,5,7-triazabicyclo[4.4.0]dec-4-ene and TEhpp = the anion of 3,3,9,9-tetraethyl-1,5,7-triazabicyclo[4.4.0]dec-4-ene) are easily oxidized. The electrode potentials in THF are -1.08 and -1.17 V vs. Ag/AgCl, respectively, for the Mo(2)(5+/4+) couple. These potentials are in accord with the low ionization potentials for the quadruply bonded compounds. Because of the high solubility of the Mo(2)(4+) compounds in most common organic solvents they are attractive candidates for use as strong reducing agents in homogeneous systems.     

Ligand-field photolysis of [Mo(CN)8]4- in aqueous hydrazine: trapped Mo(II) intermediate and catalytic disproportionation of hydrazine by cyano-ligated Mo(III,IV) complexes

The substitutional photolysis of K4[Mo(CN)8].2H2O in 98% N2H4.H2O has been investigated in detail. A molybdenum(II) intermediate, K5[Mo(CN)7].N2H4, is isolated in the primary stage of the reaction that involves the oxidation of N2H4 to N2, as evidenced by the analysis of evolving gases. The powder X-ray crystal structure of K5[Mo(CN)7].N2H4 indicates the pentagonal bipiramidal geometry of the anion and the presence of N2H4 in proximity to the CN(-) ligands. The salt is characterized by means of EDS, IR, UV-vis, and EPR spectroscopy as well as cyclic voltammetry measurements. The secondary stages of photolysis, involving the catalytic decomposition of N2H4 into NH3 and N2, lead to the formation of a molybdenum(IV) complex, [Mo(CN)4O(NH3)]2-. The monitoring of the amounts of evolving gases combined with UV-vis and EPR spectroscopic measurements at various stages of photolysis indicate that the molybdenum(III,IV) couple is catalytically active. The scheme of the catalytic decomposition of hydrazine is presented and discussed.     

一维锯齿状化合物[(en)2(Mo6O20H4)]n的水热合成及晶体结构

利用Na2MoO4·2H2O,MoO3,乙二胺,和H2O通过水热合成法合成了一维锯齿状化合物[(en)2(Mo6O20H4)]n.晶体解析表明,该化合物属于单斜晶系,P21/n空间群,a=0.80680(16)nm,b=1.4371(3)nm,c=0.88874(18)nm,β=97.89(3)°,V=1.0207(4)nm3,Z=2,Dc=3.305Mg·m-3,μ=3.681mm-1,F(000)=960.该化合物结构单元由二个游离的乙二胺分子和一个阴离子Mo6O4-20阴离子中,六20构成.在Mo6O4-个钼原子和八个相邻的氧原子构成两个八员环,在每个八员环的两侧分别存在着一个与三个钼原子相连的桥氧.     

抗肿瘤多酸药物[Mo7O24]6-的电子结构研究

运用第一原理密度泛涵理论中的离散变分方法（ＤＦＴ－ＤＶＭ）对具有抗肿瘤活性的多酸药物三合水七钼酸异丙基胺的阴离子「Ｍｏ７Ｏ２４」＾６－进行了电子结构，获得了键级、不等价原子的电子占据数、原子净电荷，分子轨道能级以及「Ｍｏ７Ｏ２４」＾６－的ＨＯＭＯ和ＬＵＭＯ组成等数据，并对该药物的活性和作用机理从电子结构的角度进行了讨论。     

Mo(Tm(Me))(O)2Cl]: an alternative functional model of sulfite oxidase

The hydrotris(methimazolyl)borate anion (TmMe) has been used to synthesize an alternative functional model ([Mo(TmMe)(O)2Cl]) of the metalloenzyme sulfite oxidase. It has been shown that the complex undergoes oxygen atom transfer chemistry and that it performs the primary function of the enzyme, sulfite oxidation. A method using ion chromatography has been developed to definitively prove that sulfite is oxidized to sulfate. Employment of a soft tripodal ligand has allowed us to tune the redox potentials of our complex so that they are significantly closer to those reported for sulfite oxidase.     

Reactivity of small Mo(x)Oy- clusters toward methane and ethane

The reactions of Mo2Oy- suboxide clusters with both methane and ethane have been studied with a combination of mass spectrometry, anion photoelectron spectroscopy, and density functional theory calculations. Reactions were carried out under "gentle" and "violent" conditions. For methane, a number of products appeared under the gentler source conditions that were more logically attributed to dissociation of Mo2Oy- clusters upon reacting with methane to form MoCH2-, Mo(O)CH2-, and HMo(O2)CH3-. With ethane, products observed under the same gentle conditions were Mo(O)C2H2-, Mo(O)C2H4-, Mo(O2)C2H4-, and Mo(O2)(C2H5)2-. As expected, more products were observed when the reactions were carried out under violent conditions. The photoelectron spectra obtained for these species were compared to calculated adiabatic and vertical electron affinities and vibrational frequencies, leading to definitive structural assignments for several of the products.     

含有柠檬酸配体的钼硫配合物的合成、光谱及电子结构

含有柠檬酸配体的钼硫配合物的合成、光谱及电子结构;钼硫化合物;柠檬酸;性质;电子结构     

A pseudo-Jahn-Teller distortion in an Mo(2)(mu(2)-O)(2) ring having the shortest Mo(IV)-Mo(IV) double bond

Four structures of edge-sharing bioctahedral compounds of the type Mo(2)(mu(2)-DArF)(2)(eta(2)-L-L)(2)(mu(2)-O)(2), where DArF is an anion of an N,N'-diarylformamidine and L-L is a chelating acetate or DArF group, are reported here. The cores of the ring formed by the Mo(2)(mu(2)-O)(2) are very similar with very short Mo-Mo distances of 2.306[2] A. These are consistent with the presence of a Mo=Mo double bond of the type sigma(2)pi(2). As expected for these electronic configurations, the compounds are diamagnetic. The most striking characteristic is the distortion of the Mo(2)(mu(2)-O)(2) ring where a set of two Mo-O distances are significantly shorter then the other set (by ca. 0.05 A). This D(2)(h)--> C(2)(h) distortion is explained on the basis of a pseudo-Jahn-Teller effect.     

Electronic and magnetic properties of alpha-Keggin anions: A DFT study of [XM12O40](n-), (M = W, Mo; X = Al(III), Si(IV), P(V), Fe(III), Co(II), Co(III)) and [SiM11VO40](m- (M = Mo and W).

Calculations based on density functional theory (DFT) have been carried out to investigate the electronic and magnetic properties of the alpha-Keggin anions mentioned in the title. The atomic populations and the distribution of the electron density computed for the studied clusters support the hypothesis that an oxidized Keggin anion is an XO(4)(n-) clathrate inside a neutral M(12)O(36) cage. The energy gap between the band of occupied orbitals, formally delocalized over the oxo ligands, and the unoccupied d-metal orbitals, delocalized over the addenda, has been found to be independent of the central ion. However, substitution of a W or a Mo by V modifies the relative energy of the LUMO and then induces important changes in the redox properties of the cluster. In agreement with the most recent X-ray determination of [Co(III)W(12)O(40)](5-) and with the simplicity of the (183)W NMR and (17)O NMR spectra observed for this anion the calculations suggest that [Co(III)W(12)O(40)](5-) has a slightly distorted T(d ) geometry. For the parent cluster [CoW(12)O(40)](6-) the quadruplet corresponding to the anion encapsulating a Co(II) was found to be approximately 1 eV more stable than the species formed by a Co(III) and 1 e delocalized over the sphere of tungstens. The one-electron reduction of [Co(II)W(12)O(40)](6-) and [Fe(III)W(12)O(40)](5-) leads to the formation of the 1 e blue species [Co(II)W(12)O(40)](7-) and [Fe(III)W(12)O(40)](6-). The blue-iron cluster is considerably antiferromagnetic, and in full agreement with this behavior the low-spin state computed via a Broken Symmetry approach is 196 cm(-1) lower than the high-spin solution. In contrast, the cobalt blue anion has a low ferromagnetic coupling with an S-T energy gap of +20 cm(-1). This blue species is more stable than the alternative reduction product [Co(I)W(12)O(40)](7-) by more than 0.7 eV.     

SYNTHESIS AND STRUCTURE OF （Me4N）[Mo（OC6H4S—o）3]

<正> (Me_4N)[Mo(OC_6H_4S-o)_3] ,Mr=542. 57,orthorhombic,space group Pnb21 with a = 22. 708(1),b = 9. 737(4),c=10. 486(2) A;V=2318. 6A3;Z=4,Dc = 1. 55g/cm3,final R=0. 064 and Rw=0. 074.μ=8. 3cm-1, F(000) = 1108,The atom Mo( V ) of the anion issix-coordinated to three oxygen and three sulfur atoms in a distorted octahedral geometry.     

Dinuclear and heteropolynuclear complexes containing Mo2(4+) units

The quadruply bonded compound Mo2(DpyF)4 (1), where DpyF- is the anion of N,N'-di(2-pyridyl)formamidine, has been prepared by ligand substitution reactions of Mo2(OOCCF3)4 and either the neutral ligand, HDpyF, at ambient temperature or its lithium salt, LiDpyF, under refluxing conditions. An X-ray structural analysis shows that 1 has a paddlewheel structure with a [symbol: see text] distance of 2.1108(6) A. Reaction of 1 with CoCl2 in methanol produces the paramagnetic compound [Mo2Co(DpyF)4][CoCl4].2MeOH (2). The Co(II) atom in the cation [Mo2Co(DpyF)4]2+ resides on a low-spin hexacoordinate environment (S = 1/2) with a Co...Mo separation of 2.979(6) A, suggesting there is no direct bonding interaction between the Co and Mo atoms. The Mo-Mo distance of 2.1096(5) A is similar to that in 1. Reaction of 1 and CuCl in methanol yields [Mo2Cu4(DpyF)4Cl2][CuCl2]2.2MeOHxEt2O (3). In the cation there are two copper atoms on each side of the Mo2 core. Each is coordinated to two pyridyl nitrogen atoms of the cis DpyF- ligands and loosely bridged to the other by a chloride ion. As a result, the Cu(I) atoms are not aligned with the Mo2 unit. The Cu to Mo separations are in the range 3.003(1)-3.015(1) A, and the Mo-Mo distance of 2.127(1) A is comparable to those in 1 and 2.