Three 2,2′-biimidazole transition metal complex-supported octamolybdates derived from hexamolybdochromate

Three octamolybdate compounds, namely [Cu(H₂biim)₂]₂[β-Mo₈O₂₆{Cu(H₂biim)₂}₂][β-Mo₈O₂₆] (1), [{Fe(H₂biim)₂(Hbiim)}₂(γ-Mo₈O₂₆)]·5H₂O (2), and [{Co(H₂biim)₂(Hbiim)}₂(γ-H₂Mo₈O₂₆)]·5 H₂O (3) (H₂biim = 2,2′-biimidazole) have been hydrothermally synthesized from the reaction of mixtures of hexamolybdochromate ({CrMo₆}), transition metal, and H₂biim in acetate buffer solution, and characterized by physico-chemical and spectroscopic methods. They represent the first examples of the conversion of hexamolybdochromate to octamolybdate. Single-crystal X-ray diffraction analysis reveals that compound 1 is composed of a β-[Mo₈O₂₆]⁴⁻ polyoxoanion bi-supported by two [Cu(H₂biim)₂]²⁺ complex cations, an isolated β-[Mo₈O₂₆]⁴⁻ anion, and two [Cu(H₂biim)₂]²⁺ complex cations. The copper complex cations are situated at two different sites and associate with β-[Mo₈O₂₆]⁴⁻ anions to give 2D layers, which are further packed into a 3D framework via strong hydrogen bonding interactions. Compounds 2 and 3 are isostructural, and contain a γ-[Mo₈O₂₆N₂] unit and two symmetrical {M(H₂biim)₂(Hbiim)} (M=Fe or Co) fragments grafted onto the polyoxoanion through Mo–N bonds. The two compounds also exhibit 3D supramolecular frameworks involving hydrogen bonding interactions.     

Synthesis and crystal structure determination of Cl-substituted iridium(III) acetylacetonate

γ-Halogen-substituted iridium(III) acetylacetonates of general formula Ir(acacX)₃,where acacX = CH₃ -CO-CX-CO- CH₃,X =Br, I, were synthesized. The compounds are characterized by melting points and chemical analysis data for C, H, Br, and I. An X-ray diffraction analysis was performed for iridium(III) acetylacetonate and its y-substituted analogs, crystal data were obtained, and crystal structures were determined. The crystals are monoclinic;the structures are molecular. Crystal data: Ir(acac)3 _- IrO₆C₁₅H₂₁,a = 13.900(2), b = 16.440(3), c = 7.494(2) ?, γ =98.63(2)‡, V= 1693.2 ?³,space group P2₁/b,Z = 4, d_calc =1.92 g/cm³,sin θ/λ_max = 0.703, F_hkl = 2841, R = 0.044. Ir(acacBr)_3- IrBr₃O₆C₁₅H₁₈,a = 12.794(2), b = 15.753(2), c = 9.990(2) ? Β = 105.76(2)‡, V= 1937.6 ?³,space group P2₁/n,Z =4, d_calc =2.49 g/cm³, sinθ/λ_max = 0.702, F_hkl = 1748, R = 0.048. Ir(acacI)3- M₃O₆C₁₅H₁₈,a = 12.855(2), b = 10.136(2), c =16.338(3)?, Β = 104.6(2)‡, V=2059.8?³,space group P2₁/n, Z =4, d_calc = 2.79g/cm³, θ_max =25‡, F_hkl = 2817, R =0.032. The Ir..Ir distances were estimated to be > 7.49 ? for Ir(acac)3 and > 8.10 ? for Ir(acacBr)3 and Ir(acacl)₃.If the estimate is limited to 10 ?, the intermolecular coordination number (ICN) in the structures is 10. Translated fromZhurnal Struktumoi Khimii, Vol. 40, No. 2, pp. 331–339, March–April, 1999     

Hydrothermal syntheses and crystal structures of two organic–inorganic hybrid molybdovanadates based on [V2Mo6(OH)2O24]4− and [VMo12O40]3− polyoxoanions

Two new organic–inorganic hybrid cobalt-molybdovanadates [Co(phen)₃]H₂[H₂V₂Mo₆O₂₆] · 7H₂O (1) and [Co(2,2′-bipy)₃][Na(H₂O)₇][VMo₁₂O₄₀] (2) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV, XPS spectroscopy, thermogravimetric (TG) analyses, and X-ray single crystal diffraction. The molecular structure of 1 consists of a [V₂Mo₆(OH)₂O₂₄]^4? polyoxoanion, a [Co(phen)₃]²⁺, two H⁺ and seven lattice water molecules. The structure of [V₂Mo₆(OH)₂O₂₄]^4? consists of six MoO₆ octahedra and two VO₄ tetrahedra; six MoO₆ octahedra are linked by edge-sharing oxygens forming a {Mo₆} ring, and two VO₄ tetrahedra cap opposite sides of the {Mo₆} ring. The molecular structural unit of 2 is constructed from a typical Keggin-type [VMo₁₂O₄₀]^3? polyoxoanion and a [Co(2,2′-bipy)₃]²⁺ cation and a Na⁺ countercation; Co²⁺ is coordinated by six nitrogens from three 2,2′-bipyridines forming a distorted octahedron.     

A new hybrid material constructed from octamolybdate anion and neutral dinuclear copper units

A new organic–inorganic hybrid material constructed from octamolybdate anion and neutral dinuclear copper(I) units, H₄{[Cu₂(ophen)₂]₂[Mo₈O₂₆]}[Cu₂(ophen)₂] · H₂O (1) (Hophen =2-hydroxy-1,10-phenanthroline), has been prepared under hydrothermal condition and characterized by elemental analysis, IR, XPS, TGA and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P 1, with a = 9.9091(8), b = 13.3981(8), c = 14.8266(10) Å, α = 84.6310(10), β = 83.0620(10)°, γ = 77.7800(10), V = 1905.0(2) ų, Z = 1. Compound 1 contains a centrosymmetric polyoxoanion {[Cu₂(ophen)₂]₂[Mo₈O₂₆]}^4?, in which the β-[Mo₈O₂₆]^4? is bisupported by two copper(I) coordination groups through the terminal oxygen atoms. The discrete molecules of 1 are extended into a 3-D supramolecular array through C–H ··· O hydrogen bonds and strong aromatic π–π stacking contacts.     

Hydrothermal Synthesis and Crystal Structure of Two New α-Keggin Derivatives Decorated by Transition Metal Complexes

Two new neutral Keggin-polyoxometalate derivatives: [{Co(2,2′-bipy)₂(H₂O)}₂]–[PMo^VI₇Mo^V₅O₄₀(V^IVO)₂] (1) and [{Ni(phen)₂(H₂O)}₂](H₃O) [PMo^VI₁₀Mo^V₂O₄₀] · 4H₂O (2) have been synthesized under hydrothermal conditions and characterized by i.r., t.g. analysis, x.p.s. spectra and single-crystal X-ray diffraction. In the case of (1), the polyoxoanion cluster [PMo₁₂O₄₀]⁸⁻ is capped by two vanadium atoms via four bridging oxo groups on two opposite {Mo₄O₄} pits of the Keggin polyoxoanion. Two {Co (2,2′-bipy)₂(H₂O)} fragments are supported on the two vanadium atoms through two terminal oxygen atoms from two vanadium atoms. In (2), two {Ni(phen)₂(H₂O)}²⁺ moieties are linked to the molybdophosphate cluster [PMo₁₂O₄₀] core to form a neutral bimetallic cluster. Furthermore, through the linkages of π – π stacking interactions and hydrogen bond contacts, extended three-dimensional supramolecular networks in the solid of (1) and (2) were formed.     

Heteropoly Complexes Na0.5Cs2 ? x[H0.5 ? xM

Crystals of novel heterepoly complexes (HPC) Na_0.5Cs_{2 − x} [H_{0.5 − x} M _x ^II X^III(OH)₆Mo₆O₁₈] · 7−8H₂O (M^II = Fe, Mn; X^III = Cr, Al) are synthesized. Crystal structures of the complexes Na_0.5Cs_{2 − x} [H_{0.5 − x} Fe_xCr(OH)₆Mo₆O₁₈] · 7H₂O (I) (x = 0.19) and Na_0.5Cs_{2 − x} [H_{0.5 − x} Mn_xAl(OH)₆Mo₆O₁₈] · 8H₂O (II) (x = 0.22) are determined (space group Pbcn, Z = 8, a = 23.023(4) Å, b = 22.064(4) Å, c = 11.606(3) Å, V = 5895.66 ų for I and a = 22.972(9) Å, b = 22.002(8) Å, c = 11.543(5) Å, V = 5834.18 ų for II, respectively). The [X^III(OH)₆Mo₆O₁₈]³⁻ ligands were found to be coordinated in monodentate fashion to M atoms due to the participation of a terminal O atom of the cis-MoO₂ group in coordination with the Fe and Mn atoms, which was confirmed by IR data. __________ Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 9, 2005, pp. 663–676. Original Russian Text Copyright ? 2005 by Gavrilova, Molchanov.     

Synthesis and Structure of the Alkoxido-Titanium Pentamolybdate (nBu4N)3[(iPrO)TiMo5O18]: An Entry into Systematic TiMo5 Reactivity

The alkoxido-titanium pentamolybdate [(ⁱPrO)TiMo₅O₁₈]³⁻ (1) has been obtained as its tetrabutylammonium (TBA) salt by hydrolysis of a mixture containing (TBA)₂[Mo₂O₇], (TBA)₄[Mo₈O₂₆] and Ti(OⁱPr)₄ in MeCN and has been characterised by ¹H, ¹³C, ¹⁷O, ⁴⁹Ti and ⁹⁵Mo NMR and FTIR spectroscopy, electrospray ionisation mass spectrometry, elemental microanalysis and single-crystal X-ray crystallography. The Lindqvist-type structure is derived from [Mo₆O₁₉]²⁻ by replacement of {Mo=O}⁴⁺ by {(ⁱPrO)Ti}³⁺ and shows bond alternation in the TiMo₃O₄ rings, with average bond distances of 1.956(8) ? for Ti–O(Mo), 1.832(7) ? for Mo–O(Ti), 1.943(7) ? for Mo_eq–O(Mo_ax) and 1.910(6) ? for Mo_ax–O(Mo_eq), while the increase in charge results in a decrease in ¹⁷O NMR chemical shift for terminal Mo=O groups from δ 933 for [Mo₆O₁₉]²⁻ to δ 875 and 857 for 1 and a shift in ν_Mo=O from 951 cm⁻¹ for [Mo₆O₁₉]²⁻ to 930 cm⁻¹ for 1. The main peaks in the negative-ion electrospray ionisation mass spectrum of (TBA)₃ 1 could be assigned to ion aggregates containing 1 or fragments derived from 1, including {(TBA)₂[(ⁱPrO)TiMo₅O₁₈]}⁻, {(TBA)[(ⁱPrO)TiMo₅O₁₈]}²⁻, {(ⁱPrO)TiMo₂O₈}⁻, {TiMo₅O₁₈}²⁻, {TiMo₄O₁₅}²⁻ and {Mo₃O₁₀}²⁻.     

Hydrothermal synthesis, structure and quantum chemistry of transition metal complex supported by metal-oxo cluster [(Ni(phen)22 (ξ-Mo8O26)]

A nickel-1,10-phenanthroline complex supported on an octamolybdate, [(Ni(phen)_{2 2}(ξ-Mo₈O₂₆)], has been hydrothermally synthesized with MoO₃, H₂MoO₄, Ni(OAc)₂ 6H₃O and 1,10-phenathroline (1,10-phen) as raw materials. The crystals of the compound belong to monoclinic P2₁/n space group,a = 1.2952(2),b = 1.6659(10),c = 1.3956(12) nm, β =106.273(8)°,V = 2.8906(5) nm³,Z = 2. 5604 observable reflections (I >2σ(I)) were used for structure resolution and refinements to converge to finalR ₁ = 0.0414,wR ₂ = 0.0815. The result of structure determination shows that the compound contains octamolybdate possessing a novel structure type (named as ξ-isomer). The feature of ξ-[Mo₈O₂₆]^4- is that it is composed of Mo₆O₆ ring and two MoO₆ octahedral located at cap positions on opposite faces. The Mo₆O₆ ring contains two octahedral and four trigonal-bipyramidal Mo^VI atoms. Each ξ-[Mo₈O₂₆]^4- unit is bonded with two [Ni(phen)₂]²⁺ through terminal oxygen atoms of octahedral and neighbouring trigonal-bipyramidal Mo atom in the Mo₆O₆ ring. IR and UV-Vis spectra of the compound were measured and its electronic structure was studied by EHMO method.     

Polyoxomolybdates functionalized with aminomethylene phosphonate

A new organic-inorganic hybrid Strandberg-type polyoxomolybdate derivative [(n-C₄H₉)₄N]₂[(NH₂CH₂PO₃)₂Mo₅O₁₅] · (CH₃NHCH₃)₂ · H₂O (I) has been synthesized and structurally characterized by elemental analysis, IR spectrum, UV spectrum, TG analysis, cyclic voltammetry, and single-crystal X-ray diffraction. The hybrid polyoxoanion [(NH₂CH₂PO₃)₂Mo₅O₁₅]²⁻ consists of a ring-shaped {Mo₅O₂₁} cluster with two [NH₂CH₂PO₃]⁻ groups incorporating into the opposite sides of the ring. The UV spectrum studied at different times reveals that I remains stable in CH₃CN-H₂O solvents (volume ratio = 1 : 2) for one day, and the electrochemical measurement indicates that I can exist in a pH range of 4.12–4.72.     

Assembly of four copper(II)–2,2′-biimidazole complex-supported Strandberg-type phosphomolybdates

Four Strandberg-type phosphomolybdate-based Cu(II) complexes of 2,2′-biimidazole (C₆H₆N₄, H₂biim) and H₂O molecules, namely [Cu(H₂biim)₂(H₂O)][Cu(H₂biim)₂(HPO₄)₂(Mo₅O₁₅)]·2H₂O (1), [{Cu(H₂biim)(H₂O)}₂{μ-Cu(H₂biim)(H₂O)}(P₂Mo₅O₂₃)]₂·20H₂O (2), [Cu(H₂biim)₂][{Cu(H₂biim)(H₂O)₂}{Cu(H₂biim)₂}(HPO₄)(PO₄)(Mo₅ O₁₅)]₂·20H₂O (3), and [Cu(H₂biim)₂(H₂O)][Cu(H₂biim)₂(HPO₄)₂(Mo₅O₁₅)]·6H₂O (4) have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray diffraction analysis reveals that compound 1 consists of a mono-supporting heteropolyoxoanion [Cu(H₂biim)₂(H₂P₂Mo₅O₂₃)]²⁻and an isolated [Cu(H₂biim)₂(H₂O)]²⁺ cation. Compound 2 is composed of two tetra-supporting heteropolyoxoanions linked via two Cu(II) complex fragments. In compound 3, there exist two symmetrical bi-supported polyoxoanion clusters and an isolated [Cu(H₂biim)₂]²⁺ fragment lying in the center of the clusters. Compound 4 is also constructed from a [Cu(H₂biim)₂(H₂P₂Mo₅O₂₃)]²⁻ polyoxoanion and a [Cu(H₂biim)₂(H₂O)]²⁺ cation, but it has a different space group and packing interactions compared with compound 1.