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ABSTRACT: The reaction of MoO3, 2,2'-bipyridine-5,5-dicarboxylic acid (H2bpdc), water, and dimethylformamide in the mole ratio 1:1:1730:130 at 150 °C for 3 days in a rotating Teflon-lined digestion bomb leads to the isolation of the molybdenum oxide/bipyridinedicarboxylate hybrid material (DMA)[MoO3(Hbpdc)]·nH2O (1) (DMA = dimethylammonium). Compound 1 was characterized by scanning electron microscopy, FT-IR and (13)C{(1)H} CP MAS NMR spectroscopies, and elemental and thermogravimetric analyses. The solid state structure of 1 was solved and refined through Rietveld analysis of high resolution synchrotron X-ray powder diffraction data in conjunction with information derived from the above techniques. The material, crystallizing in the noncentrosymmetric monoclinic space group Pc, is composed of an anionic one-dimensional organic-inorganic hybrid polymer, ∞(1)[MoO3(Hbpdc)](-), formed by corner-sharing distorted {MoO4N2} octahedra, which cocrystallizes with charge-balancing DMA(+) cations and one water molecule per metal center. In the crystal structure of 1, the close packing of individual anionic polymers, DMA(+) cations, and water molecules is mediated by a series of supramolecular contacts, namely strong (O-H···O, N(+)-H···O(-)) and weak (C-H···O) hydrogen bonding interactions, and π-π contacts involving adjacent coordinated Hbpdc(-) ligands. The catalytic potential of 1 was investigated in the epoxidation reactions of the bioderived olefins methyl oleate (Ole) and dl-limonene (Lim) using tert-butylhydroperoxide (TBHP) as the oxygen donor and 1,2-dichloroethane (DCE) or (trifluoromethyl)benzene (BTF) as cosolvent, at 55 or 75 °C. Under these conditions, 1 acts as a source of active soluble species, leading to epoxide yields of up to 98% for methyl 9,10-epoxystearate (BTF, 75 °C, 100% conversion of Ole) and 89% for 1,2-epoxy-p-menth-8-ene (DCE, 55 °C, 95% conversion of Lim). Catalytic systems employing the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide as solvent could be effectively recycled.
Inorganic Chemistry 03/2013; · 4.60 Impact Factor
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ABSTRACT: The reaction of [MoO(2)Cl(2)(pypzEA)] (1) (pypzEA = ethyl[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate) with water in a Teflon-lined stainless steel autoclave (100 °C) or in an open reflux system leads to the isolation of the molybdenum oxide/pyrazolylpyridine composite material [Mo(2)O(6)(HpypzA)] (2; HpypzA = [3-(pyridinium-2-yl)-1H-pyrazol-1-yl]acetate). The solid state structure of 2 was solved through single crystal and powder X-ray diffraction analyses in conjunction with information derived from FT-IR and (13)C CP MAS NMR spectroscopies and elemental analyses. In the asymmetric unit of 2, two crystallographically distinct Mo(6+) centers are bridged by a syn,syn-carboxylate group of HpypzA. The periodic repetition of these units along the a axis of the unit cell leads to the formation of a one-dimensional composite polymer, (∞)(1)[Mo(2)O(6)(HpypzA)]. The outstretched pyrazolylpyridine groups of adjacent polymers interdigitate to form a zipper-like motif, generating strong onset π-π contacts between adjacent rings of coordinated HpypzA molecules. The composite oxide 2 is a stable heterogeneous catalyst for liquid-phase olefin epoxidation.
Inorganic Chemistry 07/2012; 51(15):8629-35. · 4.60 Impact Factor
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ABSTRACT: The reaction of [MoO(2)Cl(2)(di-tBu-bipy)] (1) (di-tBu-bipy = 4,4'-di-tert-butyl-2,2'-bipyridine) with water at 100-120 °C in a Teflon-lined stainless steel autoclave, in an open reflux system, or in a microwave synthesis system gave the octanuclear complex [Mo(8)O(22)(OH)(4)(di-tBu-bipy)(4)] (2) as a microcrystalline powder in good yields. Single crystals of 2 suitable for X-ray diffraction were obtained by the reaction of MoO(3) and di-tBu-bipy in water at 160 °C for 3 days. The molecular structure of 2 comprises a purely inorganic core, Mo(4)O(8)(μ(3)-OH)(2)(μ(2)-O)(2), attached to two peripheral oxo-bridged binuclear units, Mo(2)O(4)(μ(2)-O)(2)(OH)(di-tBu-bipy)(2). The inorganic core is composed of a unique assembly of four {MoO(5)} distorted square pyramids connected to each other via edge-sharing. Overall, the octanuclear complex adopts a highly distorted form strongly resembling an "S"-shaped molecular unit. Complex 2 was applied in the catalytic epoxidation of the biorenewable olefins DL-limonene (Lim) and methyl oleate (Ole), using tert-butylhydroperoxide (TBHP) as an oxygen donor, under mild reaction conditions (55 °C, air). The reactions of Lim and Ole gave the respective epoxide monomers in fairly high selectivities at high conversions (89% 1,2-epoxy-p-menth-8-ene selectivity at 96% Lim conversion; 99% methyl 9,10-epoxystearate selectivity at 94% Ole conversion, reached within 24 h reaction). Iodometric titrations revealed no measurable "non-productive" decomposition of TBHP.
Inorganic Chemistry 02/2012; 51(6):3666-76. · 4.60 Impact Factor
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ABSTRACT: The asymmetric unit of the title compound, [Mo(C(18)H(24)N(2))(3)][Mo(6)O(19)]·4CH(3)CN, comprises an [Mo(di-t-Bu-bipy)(3)](2+) cation (di-t-Bu-bipy is 4,4'-di-tert-butyl-2,2'-bipyridine), two halves of Lindqvist-type [Mo(6)O(19)](2-) anions (with each anion completed by the application of a center of inversion) and four acetonitrile solvent mol-ecules. The geometry around the metal atom of the cation resembles a distorted octa-hedron, with each of the three di-t-Bu-bipy ligands being almost planar [deviation from planarity < 6.3 (2)°]. Supra-molecular inter-actions, namely Mo=O⋯π, C N⋯π, C-H⋯O and C-H⋯N, along with electrostatic forces, mediate the crystal packing. Two of the tert-butyl groups are affected by rotational disorder which was modeled over two distinct positions with major site occupancies of 0.707 (9) and 0.769 (8).
Acta Crystallographica Section E Structure Reports Online 12/2011; 67(Pt 12):m1828-9. · 0.35 Impact Factor
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ABSTRACT: In the title compound, C(18)H(26)N(2) (2+)·2Cl(-), the complete dication is generated by crystallographic inversion symmetry; both N atoms are protonated and engaged in strong and highly directional N-H⋯Cl hydrogen bonds. Additional weak C-H⋯Cl contacts promote the formation of a tape along ca. [110]. The crystal structure can be described by the parallel packing of these tapes. The crystal studied was a non-merohedral twin with twin law [-1 0 0, 0 -1 0, -0.887 0.179 1] and the final BASF parameter refining to 0.026 (2) .
Acta Crystallographica Section E Structure Reports Online 08/2011; 67(Pt 8):o1903-4. · 0.35 Impact Factor
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ABSTRACT: The reaction of [MoO(2)Cl(2)(bipy)] (1) (bipy = 2,2'-bipyridine) with water in a Teflon-lined stainless steel autoclave (100 degrees C, 19 h), in an open reflux system with oil bath heating (12 h) or in a microwave synthesis system (120 degrees C, 4 h), gave the molybdenum oxide/bipyridine hybrid material {[MoO(3)(bipy)][MoO(3)(H(2)O)]}(n) (2) as a microcrystalline powder in yields of 72-92%. The crystal structure of 2 determined from synchrotron X-ray powder diffraction data is composed of two distinct neutral one-dimensional polymers: an organic-inorganic polymer, [MoO(3)(bipy)](n), and a purely inorganic chain, [MoO(3)(H(2)O)](n), which are interconnected by O-H...O hydrogen bonding interactions. Compound 2 is a moderately active, stable, and selective catalyst for the epoxidation of cis-cyclooctene at 55 degrees C with tert-butylhydroperoxide (tBuOOH, 5.5 M in decane or 70% aqueous) as the oxidant. Biphasic solid-liquid or triphasic solid-organic-aqueous mixtures are formed, and 1,2-epoxycyclooctane is the only reaction product. When n-hexane is employed as a cosolvent and tBuOOH(decane) is the oxidant, the catalytic reaction is heterogeneous in nature, and the solid catalyst can be recycled and reused without a loss of activity. For comparison, the catalytic performance of the precursor 1 was also investigated. The IR spectra of solids recovered after catalysis indicate that 1 transforms into the organic-inorganic polymer [MoO(3)(bipy)] when the oxidant is tBuOOH(decane) and compound 2 when the oxidant is 70% aqueous tBuOOH.
Inorganic Chemistry 08/2010; 49(15):6865-73. · 4.60 Impact Factor
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ABSTRACT: The one-dimensional organic−inorganic hybrid material [MoO3(bipy)] (3) (bipy = 2,2′-bipyridine) is obtained rapidly and in quantitative yield by the reaction of the complex cis-[Mo(CO)4(bipy)] (1) with excess tert-butylhydroperoxide (TBHP) in n-decane/dichloromethane at room temperature. A similar oxidative decarbonylation of the complex cis-[Mo(CO)4(di-t-Bu-bipy)] (2) (di-t-Bu-bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) leads to the isolation of the polynuclear complex [Mo8O24(di-t-Bu-bipy)4] (4). The structure of 4, as the CH2Cl2 solvate, was determined by X-ray crystallography. The unit cell contains two crystallographically independent octameric windmill-type complexes, formulated as [Mo8O24(di-t-Bu-bipy)4], both of which contain a central cubane-type Mo4(μ3-O)4 core. Four peripheral [MoO2(di-t-Bu-bipy)]2+ units cap the long edges of the Mo4 tetrahedron of the central cubane. The close packing of these complexes via weak offset π−π contacts involving the organic ligands leads to a structure having large channels (occupied by solvent molecules) running in various directions of the unit cell. Compounds 3 and 4 can be used as the basis for active catalytic systems for the liquid-phase epoxidation of cis-cyclooctene with TBHP as the oxidant, giving the corresponding epoxide as the only product. Notably higher activities, with no change in selectivity, are possible by using microwave-assisted heating instead of conventional oil bath heating and/or by increasing the reaction temperature from 55 °C to 75 °C. The excellent stability of these MoVI catalytic systems was confirmed by carrying out six consecutive reaction runs at 75 °C under microwave-assisted heating. The stable parent carbonyls (1 and 2) can be used as catalyst precursors since they are transformed into 3 and 4 under the operating catalytic conditions.
Organometallics 01/2010; 29:883-892. · 3.96 Impact Factor
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ABSTRACT: The reaction of FeI(2) with two equivalents of AgReO(4) in acetonitrile leads to yellow, crystalline Fe(ReO(4))(2)(CH(3)CN)(3) (1), and the treatment of 1 with four equivalents of CpFe(CO)(2)CN gives orange, crystalline Fe(ReO(4))(2)[CpFe(CO)(2)(CN)](4) (2). Compound 2 can also be prepared in one step by the reaction of FeI(2), AgReO(4) and CpFe(CO)(2)CN in dichloromethane. The structure of 1 consists of infinite chains in which alternating {Fe(CH(3)CN)(4)} and {Fe(ReO(4))(2)(CH(3)CN)(2)} units are linked by perrhenate anions to form a (-ReO(2)-O-Fe(ReO(4))(2)(CH(3)CN)(2)-O-ReO(2)-O-Fe(CH(3)CN)(4)-O-)(n) molecular wire. The structure of 2 shows a monomeric iron complex with a slightly distorted octahedral coordination environment consisting of four organometallic complexes coordinated in the equatorial plane via the cyanide groups and two monodentate perrhenates in the corresponding apical positions. Both compounds were further characterised in the solid state by IR spectroscopy, thermogravimetric analysis and magnetic susceptibility measurements. The magnetic data indicate that 1 behaves as a ferrimagnetic chain with 3D ordering below 8 K due to inter-chain interactions. Compound 2 has antiferromagnetic interactions within the Fe(ReO(4))(2)[CpFe(CO)(2)(CN)](4) clusters.
Dalton Transactions 12/2009; · 3.84 Impact Factor
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ABSTRACT: The reaction between fluorenyllithium and Mo(eta(3)-C(3)H(5))Cl(NCMe)(2)(CO)(2) led to the isolation of di-mu(3)-chlorido-di-mu(3)-hydroxido-tetrakis[(eta(3)-allyl)dicarbonylmolybdenum(II)]-9-fluorenone-tetrahydrofuran (1/1/1), [Mo(4)(C(3)H(5))(4)Cl(2)(OH)(2)(CO)(8)].C(4)H(8)O.C(13)H(8)O. The tetrametallic Mo(4) unit constitutes the first example of a complex containing simultaneously two mu(3)-OH groups and two mu(3)-Cl anions capping the metallic trigonal prism. The four crystallographically independent Mo(2+) centres exhibit distorted octahedral geometry with the eta(3)-allyl groups being trans-coordinated to a mu(3)-OH group and the carbonyl groups occupying the equatorial plane. Space-filling tetrahydrofuran and 9-fluorenone molecules are engaged in strong O-H...O hydrogen-bonding interactions with Mo(4)(eta(3)-allyl)(4)Cl(2)(OH)(2)(CO)(8) complexes.
Acta crystallographica. Section C, Crystal structure communications 05/2009; 65(Pt 4):m168-70. · 0.78 Impact Factor
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ABSTRACT: The oxodiperoxo complex MoO(O2)(2)(tbbpy) (tbbpy = 4,4'-di-tert-butyl-2,2'- bipyridine) was isolated from the reaction of MoO2Cl(2)(tbbpy) in water under microwaveassisted heating at 120 masculineC for 4 h. The structure of the oxodiperoxo complex was determined by single crystal X-ray diffraction. The Mo(VI) centre is seven-coordinated with a geometry which strongly resembles a highly distorted bipyramid. Individual MoO(O2)(2)(tbbpy) complexes are interdigitated along the [010] direction to form a column. The crystal structure is formed by the close packing of the columnar-stacked complexes. Interactions between neighbouring columns are essentially of van der Waals type mediated by the need to effectively fill the available space.
Molecules 01/2009; 14(9):3610-20. · 2.39 Impact Factor
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ABSTRACT: In the title compound, C(18)H(24)N(2), the mol-ecular unit adopts a trans conformation around the central C-C bond [N-C-C-N torsion angle of 179.2 (3)°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4)°]. The crystal packing is driven by co-operative contacts involving weak C-H⋯N and C-H⋯π inter-actions, and also the need to fill effectively the available space.
Acta Crystallographica Section E Structure Reports Online 01/2009; 65(Pt 8):o2047. · 0.35 Impact Factor
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ABSTRACT: The title organic salt, C(8)H(8)N(3) (+)·Cl(-)·H(2)O, exhibits a rich hydrogen-bonding network involving all constituent species. The water mol-ecules are engaged in strong O-H⋯Cl inter-actions with the chloride anions, two neighboring protonated 2-(1H-pyrazol-3-yl)pyridinium species inter-act via N-H⋯N bonds with two pyrazole rings. Further, a short and highly directional C-H⋯O inter-action is observed connecting the pyridinium ring to the water mol-ecule of crystallization. Weak C-H⋯Cl and N-H⋯Cl inter-actions contribute to the stabilization of the crystal structure.
Acta Crystallographica Section E Structure Reports Online 01/2009; 65(Pt 8):o1962-3. · 0.35 Impact Factor
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ABSTRACT: In the title compound, C18H24N2, the molecular unit adopts a trans conformation around the central C—C bond [N—C—C—N torsion angle of 179.2 (3)°], with the two aromatic rings almost coplanar [dihedral angle of only 0.70 (4)°]. The crystal packing is driven by co-operative contacts involving weak C—H...N and C—H...π interactions, and also the need to fill effectively the available space.
Acta Crystallographica Section E. 01/2009;
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ABSTRACT: In the crystal structure of the title compound, C30H26O2Si2, one Si(Ph)3 residue is bound to another Si(OH)(Ph)2 residue via a non-linear Si—O—Si bridge. The asymmetric unit is composed of two such molecules which interact, on the one hand, via a strong and highly directional O—H...O hydrogen bond involving the two neighbouring Si—OH units and, on the other, via an O—H...π contact connecting the second hydroxyl group with an adjacent phenyl group.
Acta Crystallographica Section E. 01/2008;
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ABSTRACT: In the crystal structure of the title compound, C30H26O2Si2, one Si(Ph)3 residue is bound to another Si(OH)(Ph)2 residue via a nonlinear Si—O—Si bridge. The asymmetric unit is composed of four [Si2O(OH)(Ph)5] molecules. Each pair of adjacent molecules interacts via strong and highly directional O—H...O hydrogen bonds connecting neighbouring Si—OH units, and via inter-unit O—H...π contacts connecting the second hydroxyl groups with adjacent phenyl groups.
Acta Crystallographica Section E. 01/2008;
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ABSTRACT: In the crystal structure of the title compound, C(30)H(26)O(2)Si(2), one Si(Ph)(3) residue is bound to another Si(OH)(Ph)(2) residue via a non-linear Si-O-Si bridge. The asymmetric unit is composed of two such molecules which inter-act, on the one hand, via a strong and highly directional O-H⋯O hydrogen bond involving the two neighbouring Si-OH units and, on the other, via an O-H⋯π contact connecting the second hydroxyl group with an adjacent phenyl group.
Acta Crystallographica Section E Structure Reports Online 01/2007; 64(Pt 1):o237-8. · 0.35 Impact Factor
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ABSTRACT: In the crystal structure of the title compound, C(30)H(26)O(2)Si(2), one Si(Ph)(3) residue is bound to another Si(OH)(Ph)(2) residue via a nonlinear Si-O-Si bridge. The asymmetric unit is composed of four [Si(2)O(OH)(Ph)(5)] molecules. Each pair of adjacent molecules inter-acts via strong and highly directional O-H⋯O hydrogen bonds connecting neighbouring Si-OH units, and via inter-unit O-H⋯π contacts connecting the second hydroxyl groups with adjacent phenyl groups.
Acta Crystallographica Section E Structure Reports Online 01/2007; 64(Pt 1):o239. · 0.35 Impact Factor
