RESUMO
3-(1,2,4-Triazol-4-yl)adamantane-1-carboxylic acid (tradcH), a heterobifunctional organic ligand in which carboxylic acid and 1,2,4-triazole groups are united through a rigid 1,3-adamantanediyl spacer, was employed for the synthesis of a MoVI oxide organic hybrid. The ligand crystallized from water as tradcH·H2O (1), possessing a two-dimensional hydrogen-bonding network, and from ethanol as a cyclic molecular solvate with the composition (tradcH)3·2EtOH (2). Treatment of tradcH with MoO3 under hydrothermal conditions afforded a new Mo trioxide hybrid, [MoO3(tradcH)]·H2O (3), which was structurally characterized. In 3, the molybdenum atoms form a polymeric zigzag chain of {µ2-O-MoO2}n which is supported by double triazole bridges, while the carboxylic acid termini are left uncoordinated. The coordination environment of the Mo centers appears as distorted cis-{MoN2O4} octahedra. The hybrid exhibits high thermal stability (up to 270 °C) and was employed for a relatively broad scope of catalytic oxidation reactions in the liquid phase. Its catalytic behavior may be compared to a reversible mutation, featuring the best sides of homogeneous and heterogeneous catalysis. The original solid material converts into soluble active species, and the latter revert to the original material upon completion of the catalytic reaction, precipitating and allowing straightforward catalyst separation/reuse (like a heterogeneous catalyst). This catalyst was explored for a chemical reaction scope covering sulfoxidation, oxidative alcohol dehydrogenation, aldehyde oxidation, and olefin epoxidation, using hydrogen peroxide as an eco-friendly oxidant that gives water as a coproduct.
RESUMO
A pentanuclear CuII5-hydroxo cluster possessing an unusual linear-shaped configuration was formed and crystallized under hydrothermal conditions as a result of the unique cooperation of bridging 1,2,4-triazole ligand ( trans-1,4-cyclohexanediyl-4,4'-bi(1,2,4-triazole) ( tr2 cy)), MoVI-oxide, and CuSO4. This structural motif can be rationalized by assuming in situ generation of {Cu2Mo6O22}4- anions, which represent heteroleptic derivatives of γ-type [Mo8O26]4- further interlinked by [Cu3(OH)2]4+ cations through [ N- N] bridges. The framework structure of the resulting compound [Cu5(OH)2( tr2 cy)2Mo6O22]·6H2O (1) is thus built up from neutral heterometallic {Cu5(OH)2Mo6O22} n layers pillared with tetradentate tr2 cy. Quantum-chemical calculations demonstrate that the exclusive site of the parent γ-[Mo8O26]4- cluster into which CuII inserts corresponds with the site that has the lowest defect ("MoO2 vacancy") formation energy, demonstrating how the local metal-polyoxomolybdate chemistry can express itself in the final crystal structure. Magnetic susceptibility measurements of 1 show strong antiferromagnetic coupling within the Cu5 chain with exchange parameters J1 = -500(40) K (-348(28) cm-1), J2 = -350(10) K (-243(7) cm-1) and g = 2.32(2), χ2 = 6.5 × 10-4. Periodic quantum-chemical calculations reproduce the antiferromagnetic character of 1 and connect it with an effective ligand-mediated spin coupling mechanism that comes about from the favorable structural arrangement between the Cu centers and the OH-, O2-, and tr2 cy bridging ligands.
RESUMO
Three organic ligands bearing 1,2,4-triazolyl donor moieties, (S)-4-(1-phenylpropyl)-1,2,4-triazole (trethbz), 4-(1,2,4-triazol-4-yl)benzoic acid (trPhCO2H), and 3-(1H-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)propionic acid (trhis), were prepared to evaluate their coordination behavior in the development of molybdenum(VI) oxide organic hybrids. Four compounds, [Mo2O6(trethbz)2]·H2O (1), [Mo4O12(trPhCO2H)2]·0.5H2O (2a), [Mo4O12(trPhCO2H)2]·H2O (2b), and [Mo8O25(trhis)2(trhisH)2]·2H2O (3), were synthesized and characterized. The monofunctional tr-ligand resulted in the formation of a zigzag chain [Mo2O6(trethbz)2] built up from cis-{MoO4N2} octahedra united through common µ2-O vertices. Employing the heterodonor ligand with tr/-CO2H functions afforded either layer or ribbon structures of corner- or edge-sharing {MoO5N} polyhedra (2a or 2b) stapled by tr-links in axial positions, whereas -CO2H groups remained uncoordinated. The presence of the im-heterocycle as an extra function in trhis facilitated formation of zwitterionic molecules with a protonated imidazolium group (imH+) and a negatively charged -CO2- group, whereas the tr-fragment was left neutral. Under the acidic hydrothermal conditions used, the organic ligand binds to molybdenum atoms either through [N-N]-tr or through both [N-N]-tr and µ2-CO2- units, which occur in protonated bidentate or zwitterionic tetradentate forms (trhisH+ and trhis, respectively). This leads to a new zigzag subtopological motif (3) of negatively charged polyoxomolybdate {Mo8O25}n2n- consisting of corner- and edge-sharing cis-{MoO4N2} and {MoO6} octahedra, while the tetradentate zwitterrionic trhis species connect these chains into a 2D net. Electronic spectra of the compounds showed optical gaps consistent with semiconducting behavior. The compounds were investigated as epoxidation catalysts via the model reactions of achiral and prochiral olefins (cis-cyclooctene and trans-ß-methylstyrene) with tert-butylhydroperoxide. The best-performing catalyst (1) was explored for the epoxidation of other olefins, including biomass-derived methyl oleate, methyl linoleate, and prochiral dl-limonene.
RESUMO
We investigated the coordination ability of the bis(1,2,4-triazolyl) module, tr2pr = 1,3-bis(1,2,4-triazol-4-yl)propane, toward the engineering of solid-state structures of copper polyoxomolybdates utilizing a composition space diagram approach. Different binding modes of the ligand including [N-N]-bridging and N-terminal coordination and the existence of favorable conformation forms (anti/anti, gauche/anti, and gauche/gauche) resulted in varieties of mixed metal CuI/MoVI and CuII/MoVI coordination polymers prepared under hydrothermal conditions. The composition space analysis employed was aimed at both the development of new coordination solids and their crystallization fields through systematic changes of the reagent ratios [copper(II) and molybdenum(VI) oxide precursors and the tr2pr ligand]. Nine coordination compounds were synthesized and structurally characterized. The diverse coordination architectures of the compounds are composed of cationic fragments such as [CuII3(µ2-OH)2(µ2-tr)2]4+, [CuII3(µ2-tr)6]6+, [CuII2(µ2-tr)3]4+, etc., connected to polymeric arrays by anionic species (molybdate MoO42-, isomeric α-, δ-, and ß-octamolybdates {Mo8O26}4- or {Mo8O28H2}6-). The inorganic copper(I,II)/molybdenum(VI) oxide matrix itself forms discrete or low-dimensional subtopological motifs (0D, 1D, or 2D), while the organic spacers interconnect them into higher-dimensional networks. The 3D coordination hybrids show moderate thermal stability up to 230-250 °C, while for the 2D compounds, the stability of the framework is distinctly lower (â¼190 °C). The magnetic properties of the most representative samples were investigated. The magnetic interactions were rationalized in terms of analyzing the planes of the magnetic orbitals.
Assuntos
Complexos de Coordenação/química , Cobre/química , Molibdênio/química , Polímeros/química , Triazóis/química , Complexos de Coordenação/síntese química , Ligantes , Fenômenos Magnéticos , Modelos Químicos , Conformação Molecular , Estrutura Molecular , Polímeros/síntese químicaRESUMO
A bitopic ligand, 4-(3,5-dimethylpyrazol-4-yl)-1,2,4-triazole (Hpz-tr) (1), containing two different heterocyclic moieties was employed for the design of copper(II)-molybdate solids under hydrothermal conditions. In the multicomponent Cu(II)/Hpz-tr/Mo(VI) system, a diverse set of coordination hybrids, [Cu(Hpz-tr)2SO4]·3H2O (2), [Cu(Hpz-tr)Mo3O10] (3), [Cu4(OH)4(Hpz-tr)4Mo8O26]·6H2O (4), [Cu(Hpz-tr)2Mo4O13] (5), and [Mo2O6(Hpz-tr)]·H2O (6), was prepared and characterized. A systematic investigation of these systems in the form of a ternary crystallization diagram approach was utilized to show the influence of the molar ratios of starting reagents, the metal (Cu(II) and Mo(VI)) sources, the temperature, etc., on the reaction products outcome. Complexes 2-4 dominate throughout a wide crystallization range of the composition triangle, while the other two compounds 5 and 6 crystallize as minor phases in a narrow concentration range. In the crystal structures of 2-6, the organic ligand behaves as a short [N-N]-triazole linker between metal centers Cu···Cu in 2-4, Cu···Mo in 5, and Mo···Mo in 6, while the pyrazolyl function remains uncoordinated. This is the reason for the exceptional formation of low-dimensional coordination motifs: 1D for 2, 4, and 6 and 2D for 3 and 5. In all cases, the pyrazolyl group is involved in H bonding (H-donor/H-acceptor) and is responsible for π-π stacking, thus connecting the chain and layer structures in more complicated H-bonding architectures. These compounds possess moderate thermal stability up to 250-300 °C. The magnetic measurements were performed for 2-4, revealing in all three cases antiferromagnetic exchange interactions between neighboring Cu(II) centers and long-range order with a net moment below Tc of 13 K for compound 4.
RESUMO
A large family of bifunctional 1,2,4-triazole molecular tectons (tr) has been explored for engineering molybdenum(VI) oxide hybrid solids. Specifically, tr ligands bearing auxiliary basic or acidic groups were of the type amine, pyrazole, 1H-tetrazole, and 1,2,4-triazole. The organically templated molybdenum(VI) oxide solids with the general compositions [MoO3(tr)], [Mo2O6(tr)], and [Mo2O6(tr)(H2O)2] were prepared under mild hydrothermal conditions or by refluxing in water. Their crystal structures consist of zigzag chains, ribbons, or helixes of alternating cis-{MoO4N2} or {MoO5N} polyhedra stapled by short [N-N]-tr bridges that for bitriazole ligands convert the motifs into 2D or 3D frameworks. The high thermal (235-350 °C) and chemical stability observed for the materials makes them promising for catalytic applications. The molybdenum(VI) oxide hybrids were successfully explored as versatile oxidation catalysts with tert-butyl hydroperoxide (TBHP) or aqueous H2O2 as an oxygen source, at 70 °C. Catalytic performances were influenced by the different acidic-basic properties and steric hindrances of coordinating organic ligands as well as the structural dimensionality of the hybrid.
RESUMO
Bifunctional 1,2,4-triazole-carboxylate ligands, an achiral 1,2,4-triazol-4-yl-acetic acid (trgly-H) and a chiral (d)-2-(1,2,4-triazol-4-yl)-propionic acid (d-trala-H), derived from the corresponding α-amino acid precursors revealed unique binding abilities in the construction of Cu(II)-coordination polymers composing discrete triangular [Cu3(µ3-OH)] clusters. A related series of MOFs, [Cu3(µ3-OH)(trgly)3(SO4)]·2H2O (1a), [Cu3(µ3-OH)(trgly)3(H2O)3]SO4·16H2O (1b), Cu3(µ3-OH)(d-trala)3(ClO4)0.5](ClO4)1.5·1.5H2O (2), was prepared, and their crystal structures were determined by means of X-ray diffraction. Being singly deprotonated, the organic ligands act as multidentate µ3- or µ4-donors using tr and -COO(-) moieties. The generated [Cu3(µ3-OH)(tr)3] cluster core is primarily supported by three [-N-N-] triazole heterocycles in a basal plane and tripodal-assisted µ3-anions (SO4(2-): 1a; ClO4(-): 2) capping the axial faces. The carboxylate groups join the units into either two-dimensional (2D) layer (1a, 2) or 3D zeolite-like networks (1b). Compound 1b represents the topology of α-Po (pcu: 4(12).6(3)) and crystallizes in the noncentrosymmetric space group I4Ì 3m, in which the six-connected [Cu3(µ3-OH)] clusters and trgly self-assemble in an open-channel cubic array possessing â¼56% solvent-accessible volume. Upon slight thermal treatment (â¼60 °C), the structure irreversibly shrinks to the nonporous 2D motif 1a that belongs to a uninodal (3,6) network type. In structure 2 (space group R32), due to the [-N-N-] triazole and 1,3-bidentate carboxylate binding mode, each organic ligand bridges three metal clusters affording cross-linking of two adjacent layers with the same (3,6) topology. The resultant 3,9-c net is novel and can be categorized as two-nodal with point symbol {4(18).6(18)}{4(2).6}3. Spin frustration and antisymmetric exchange effects, resulting in abnormally low g values in the S = 1/2 states, were observed in the magnetic properties and the EPR spectra.
RESUMO
The multicomponent mixed-metal Cu(II)/Mo(VI) oxides/1,3-bis(1,2,4-triazol-4-yl)adamantane (tr2ad) system was thoroughly studied employing a compositional diagram approach. The concept allowed us to prepare three layered copper-molybdate hybrid solids [Cu(II)2(tr2ad)4](Mo8O26) (1), [Cu4(II)(µ4-O)(tr2ad)2(MoO4)3]·7.5H2O (2), and [Cu(I)2(tr2ad)2](Mo2O7)·H2O (3), and to elucidate the relationship between initial reagent concentration/stoichiometry and the stability of the resultant structural motifs. Compounds 1 and 2 were found to dominate throughout a wide crystallization range of the concentration triangle, whereas compound 3 was formed by redox processes in the narrow crystallization area having a high excess of Cu(OAc)2·H2O. Independent experiments carried out with Cu(OAc)2 and (NH4)6Mo7O24 in the absence of tr2ad, under the same conditions, revealed the formation of low-valent and bimetallic oxides, including Cu2O, MoO2, Cu(Mo3O10)·H2O, and Cu3(MoO4)2(OH)2. Compounds 1 and 2 show high thermal and chemical stability as examined as catalysts in the epoxidation of cis-cyclooctene and the oxidation of benzyl alcohol (BzOH) with different types of oxidants. The oxidation reaction of BzOH using tert-butyl hydroperoxide (TBHP) as the oxidant, in the presence of 1 or 2, led to benzaldehyde and benzoic acid (PhCO2H), with the latter being formed in up to 90% yield at 24 h. The results suggest that 1 and 2 may be favorable heterogeneous catalysts for the synthesis of PhCO2H. Whereas compound 1 only reveals a weak ferromagnetic coupling between neighboring Cu(II) centers (J = 0.41 cm(-1)), compound 2 shows distinct intracluster antiferromagnetic exchange interactions (J = -29.9 cm(-1), J' = -25.7 cm(-1)), which consequently results in a diamagnetic ground state.
RESUMO
In the structure of the title co-crystal, C3H3N3O2·C5H8N2, the components are linked by a set of directional O-Hâ¯N, N-Hâ¯O, N-Hâ¯N and C-Hâ¯O hydrogen bonds to yield a two-dimensional mono-periodic arrangement. The structure propagates in the third dimension by extensive π-π stacking inter-actions of nearly parallel mol-ecules of the two components, following an alternating sequence. The primary structure-defining inter-action is very strong oxime-OH donor to pyrazole-N acceptor hydrogen bond [Oâ¯N = 2.587â (2)â Å], while the significance of weaker hydrogen bonds and π-π stacking inter-actions is comparable. The distinct structural roles of different kinds of inter-actions agree with the results of a Hirshfeld surface analysis and calculated inter-action energies. The title compound provides insights into co-crystals of active agrochemical mol-ecules and features the rational integration in one structure of a fungicide, C3H3N3O2, and a second active component, C5H8N2, known for alleviation the toxic effects of fungicides on plants. The material appears to be well suited for practical uses, being non-volatile, air-stable, water-soluble, but neither hygroscopic nor efflorescent.
RESUMO
Bistriazoles, 1,3-bis(1,2,4-triazol-4-yl)propane (tr(2)pr) and 1,3-bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad), were examined in combination with the rigid tetratopic 1,3,5,7-adamantanetetracarboxylic acid (H(4)-adtc) platform for the construction of neutral heteroleptic copper(II) metal-organic frameworks. Two coordination polymers, [{Cu(4)(OH)(2)(H(2)O)(2)}{Cu(4)(OH)(2)}(tr(2)pr)(2)(H-adtc)(4)]·2H(2)O (1) and [Cu(4)(OH)(2)(tr(2)ad)(2)(H-adtc)(2)(H(2)O)(2)]·3H(2)O (2), were synthesized and structurally characterized. In complexes 1 and 2, the N(1),N(2)-1,2,4-triazolyl (tr) and µ(3)-OH(-) groups serve as complementary bridges between adjacent metal centers supporting the tetranuclear dihydroxo clusters. The structure of 1 represents a unique association of two different kinds of centrosymmetrical {Cu(4)(OH)(2)} units in a tight 3D framework, while in compound 2, another configuration type of acentric tetranuclear metal clusters is organized in a layered 3,6-hexagonal motif. In both cases, the {Cu(4)(OH)(2)} secondary building block and trideprotonated carboxylate H-adtc(3-) can be viewed as covalently bound six- and three-connected nodes that define the net topology. The tr ligands, showing µ(3)- or µ(4)-binding patterns, introduce additional integrating links between the neighboring {Cu(4)(OH)(2)} fragments. A variable-temperature magnetic susceptibility study of 2 demonstrates strong antiferromagnetic intracluster coupling (J(1) = -109 cm(-1) and J(2) = -21 cm(-1)), which combines for the bulk phase with a weak antiferromagnetic intercluster interaction (zj = -2.5 cm(-1)).
RESUMO
New fluorinated hybrid solids [Mo2F2O5(tr2pr)] (1), [Co3(tr2pr)2(MoO4)2F2]·7H2O (2), and [Co3(H2O)2(tr2pr)3(Mo8O26F2)]·3H2O (3) (tr2pr = 1,3-bis(1,2,4-triazol-4-yl)propane) were prepared from the reaction systems consisting of Co(OAc)2/CoF2 and MoO3/(NH4)6Mo7O24, as Co(II) and Mo(VI) sources, in water (2) or in aqueous HF (1, 3) employing mild hydrothermal conditions. The tr2pr ligand serves as a conformationally flexible tetradentate donor. In complex 1, the octahedrally coordinated Mo atoms are linked in the discrete corner-sharing {Mo2(µ2-O)F2O4N4} unit in which a pair of tr-heterocycles (tr = 1,2,4-triazole) is arranged in cis-positions opposite to "molybdenyl" oxygen atoms. The anti-anti conformation type of tr2pr facilitates the tight zigzag chain packing motif. The crystal structure of the mixed-anion complex salt 2 consists of trinuclear [Co3(µ3-MoO4)2(µ2-F)2] units self-assembling in Co(II)-undulating chains (Co···Co 3.0709(15) and 3.3596(7) Å), which are cross-linked by tr2pr in layers. In 3, containing condensed oxyfluoromolybdate species, linear centrosymmetric [Co3(µ2-tr)6](6+) SBUs are organized at distances of 10.72-12.45 Å in an α-Po-like network using bitopic tr-linkers. The octahedral {N6} and {N3O3} environments of the central and peripheral cobalt atoms, respectively, are filled by triazole N atoms, water molecules, and coordinating [Mo8O26F2](6-) anions. Acting as a tetradentate O-donor, each difluorooctamolybdate anion anchors four [Co3(µ2-tr)6](6+) units through their peripheral Co-sites, which consequently leads to a novel type of a two-nodal 4,10-c net with the Schläfli symbol {3(2).4(3).5}{3(4).4(20).5(16).6(5)}. The 2D and 3D coordination networks of 2 and 3, respectively, are characterized by significant overall antiferromagnetic exchange interactions (J/k) between the Co(II) spin centers on the order of -8 and -4 K. The [Mo8O26F2](6-) anion is investigated in detail by quantum chemical calculations.
RESUMO
Developing the structures of organic materials that rely on the hydrogen bonding of multifunctional substrates is often complicated due to a competition between various possible motifs. In this context, the illustrative case of the carbamoylcyanonitrosomethanide anion, [ONC(CN)-C(O)NH2]-, suggests sufficient control over the crystal lattice with a set of supramolecular synthons, which are specific to all the present nitroso, carbamoyl and cyano groups. The structures of the carbamoylcyanonitrosomethanide salts of ethane-1,2-diammonium, C2H10N22+·2C3H2N3O2-, (1), piperazine-1,4-diium, C4H12N22+·2C3H2N3O2-, (2), butane-1,4-diammonium, C4H14N22+·2C3H2N3O2-, (3), and hexane-1,6-diammonium, C6H18N22+·2C3H2N3O2-, (4), reveal two- and three-dimensional hydrogen-bonded frameworks governed by a set of site-selective interactions. The strongest N-H...O hydrogen bonds [N...O = 2.6842â (17)-2.8718â (17)â Å, mean 2.776â (2)â Å] are associated with the polarized ammonium N-H donors and nitroso O-atom acceptors, which sustain invariant motifs in the form of nitroso/ammonium dimers. Subtle structural changes within this series of compounds concern the rupture of some weaker interactions, i.e. mutual hydrogen bonds of the carbamoyl groups in (1)-(3) [N...O = 2.910â (2)-2.9909â (18)â Å; mean 2.950â (2)â Å] and carbamoyl/nitrile hydrogen bonds in (1), (2) and (4) [N...N = 2.936â (2)-3.003â (3)â Å, mean 2.977â (2)â Å], providing a gradual evolution of the hydrogen-bonding pattern. A hierarchy of the synthons involving three different groups could be applicable to supramolecular synthesis with polyfunctional methanide species, suggesting also a degree of control over layered and interpenetrated hydrogen-bonded networks.
RESUMO
Here we present a novel three-dimensional iron(II) spin-crossover porous coordination polymer based on the bis(1,2,4-triazol-4-yl)adamantane (tr(2)ad) ligand and the [Au(CN)(2)](-) metalloligand anions with the formula {Fe(3)(tr(2)ad)(4)[Au(CN)(2))](2)}[Au(CN)(2)](4)·G. The sorption/desorption of guest molecules, water, and five/six-membered-ring organic molecules is easily detectable because the guest-free and -loaded frameworks present drastically distinct coloration and spin-state configurations.
RESUMO
A series of new silver(I)-containing MOFs [Ag(2)(tr(2)ad)(2)](ClO(4))(2) (1), [Ag(2)(VO(2)F(2))(2)(tr(2)ad)(2)]·H(2)O (2), [Ag(2)(VO(2)F(2))(2)(tr(2)eth)(2)(H(2)O)(2)] (3), and [Ag(2)(VO(2)F(2))(2)(tr(2)cy)(2)]·4H(2)O (4) supported by 4-substituted bifunctional 1,2,4-triazole ligands (tr(2)ad = 1,3-bis(1,2,4-triazol-4-yl)adamantane, tr(2)eth = 1,2-bis(1,2,4-triazol-4-yl)ethane, tr(2)cy = trans-1,4-bis(1,2,4-triazol-4-yl)cyclohexane) were hydrothermally synthesized and structurally characterized. In these complexes, the triazole heterocycle as an N(1),N(2)-bridge links either two adjacent Ag-Ag or Ag-V centers at short distances forming polynuclear clusters. The crystal structure of compound 1 is based on cationic {Ag(2)(tr)(4)}(2+) fragments connected in a 2D rhombohedral grid network with (4,4) topology. The neighboring layers are tightly packed into a 3D array by means of argentophilic interactions (Ag···Ag 3.28 Å). Bridging between different metal atoms through the triazole groups assists formation of heterobimetallic Ag(I)/V(V) secondary building blocks in a linear V-Ag-Ag-V sequence that is observed in complexes 2-4. These unprecedented tetranuclear {Ag(2)(VO(2)F(2))(2)(tr)(4)} units (the intermetal Ag-Ag and Ag-V distances are 4.24-4.36 and 3.74-3.81 Å, respectively), in which vanadium(V) oxofluoride units possess distorted trigonal bipyramidal environment {VO(2)F(2)N}¯, are incorporated into 1D ribbon (2) or 2D square nets (3, 4) using bitopic µ(4)-triazole ligands. The valence bond calculation for vanadium atoms shows +V oxidation state in the corresponding compounds. Thermal stability and photoluminescence properties were studied for all reported coordination polymers.
RESUMO
5-[4-(1,2,4-Triazol-4-yl)phenyl]-1H-tetrazole, C(9)H(7)N(7), (I), an asymmetric heterobifunctional organic ligand containing triazole (tr) and tetrazole (tz) termini linked directly through a 1,4-phenylene spacer, crystallizes in the polar space group Pc. The heterocyclic functions, serving as single hydrogen-bond donor (tz) or acceptor (tr) units, afford hydrogen-bonded zigzag chains with no crystallographic centre of inversion. In the structure of catena-poly[[diaquacadmium(II)]bis{µ(2)-5-[4-(1,2,4-triazol-4-yl)phenyl]tetrazol-1-ido-κ(2)N(1):N(1')}], [Cd(C(9)H(6)N(7))(2)(H(2)O)(2)](n), (II), the Cd(II) dication resides on a centre of inversion in an octahedral {N(4)O(2)} environment. In the equatorial plane, the Cd(II) polyhedron is built up from four N atoms of two kinds, namely of trans-coordinating tr and tz fragments [Cd-N = 2.2926 (17) and 2.3603 (18) Å], and the coordinating aqua ligands occupy the two apical sites. The metal centres are separated at a distance of 11.1006 (7) Å by means of the double-bridging tetrazolate anion, L(-), forming a chain structure. The water ligands and tz fragments interact with one another, like a double hydrogen-bond donor-acceptor synthon, leading to a hydrogen-bonded three-dimensional array.
RESUMO
The crystal structure of the title compound, [Ag2(VO2F2)2(C9H9N3)4], is presented. The mol-ecular complex is based on the heterobimetallic AgI-VV fragment {AgI 2(VVO2F2)2(tr)4} supported by four 1,2,4-triazole ligands [4-benzyl-(4H-1,2,4-triazol-4-yl)]. The triazole functional group demonstrates homo- and heterometallic connectivity (Ag-Ag and Ag-V) of the metal centers through the [-NN-] double and single bridges, respectively. The vanadium atom possesses a distorted trigonal-bipyramidal coordination environment [VO2F2N] with the Reedijk structural parameter τ = 0.59. In the crystal, C-Hâ¯O and C-Hâ¯F hydrogen bonds as well as C-Hâ¯π contacts are observed involving the organic ligands and the vanadium oxofluoride anions. A Hirshfeld surface analysis of the hydrogen-bonding inter-actions is also described.
RESUMO
Poly[bis(3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium) γ-octamolybdate(VI) dihydrate], {(C(10)H(16)N(4))(2)[Mo(8)O(26)]·2H(2)O}(n), (I), and bis(3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium) α-dodecamolybdo(VI)silicate tetrahydrate, (C(10)H(16)N(4))(2)[SiMo(12)O(40)]·4H(2)O, (II), display intense hydrogen bonding between the cationic pyrazolium species and the metal oxide anions. In (I), the asymmetric unit contains half a centrosymmetric γ-type [Mo(8)O(26)](4-) anion, which produces a one-dimensional polymeric chain by corner-sharing, one cation and one water molecule. Three-centre bonding with 3,3',5,5'-tetramethyl-4,4'-bi-1H-pyrazole-2,2'-diium, denoted [H(2)Me(4)bpz](2+) [N···O = 2.770 (4)-3.146 (4) Å], generates two-dimensional layers that are further linked by hydrogen bonds involving water molecules [O...O = 2.902 (4) and 3.010 (4) Å]. In (II), each of the four independent [H(2)Me(4)bpz](2+) cations lies across a twofold axis. They link layers of [SiMo(12)O(40)](4-) anions into a three-dimensional framework, and the preferred sites for pyrazolium/anion hydrogen bonding are the terminal oxide atoms [N···O = 2.866 (6)-2.999 (6) Å], while anion/aqua interactions occur preferentially via µ(2)-O sites [O···O = 2.910 (6)-3.151 (6) Å].
RESUMO
The structure of the title salt, ammonium carbamoyl-cyano-nitro-somethanide, NH4 +·C3H2N3O2 -, features the co-existence of different hydrogen-bonding patterns, which are specific to each of the three functional groups (nitroso, carbamoyl and cyano) of the methanide anion. The nitroso O-atoms accept as many as three N-Hâ¯O bonds from the ammonium cations [Nâ¯O = 2.688â (3)-3.000â (3)â Å] to form chains of fused rhombs [(NH4)(O)2]. The most prominent bonds of the carbamoyl groups are mutual and they yield 21 helices [Nâ¯O = 2.903â (2)â Å], whereas the cyano N-atoms accept hydrogen bonds from sterically less accessible carbamoyl H-atoms [Nâ¯N = 3.004â (3)â Å]. Two weaker NH4 +â¯O=C bonds [Nâ¯O = 3.021â (2), 3.017â (2)â Å] complete the hydrogen-bonded environment of the carbamoyl groups. A Hirshfeld surface analysis indicates that the most important inter-actions are overwhelmingly Oâ¯H/Hâ¯O and Nâ¯H/Hâ¯N, in total accounting for 64.1% of the contacts for the individual anions. The relatively simple scheme of these inter-actions allows the delineation of the supra-molecular synthons, which may be applicable to crystal engineering of hydrogen-bonded solids containing polyfunctional methanide anions.
RESUMO
The bitopic ligand 1,2-bis(1,2,4-triazol-4-yl)ethane (tr(2)eth) provides an unprecedented short-distance N(1):N(2)-triazole bridging of Cu(I) and V(IV) ions in poly[bis[mu(4)-1,2-bis(1,2,4-triazol-4-yl)ethane]di-mu(2)-fluorido-tetrafluoridodi-mu(2)-oxido-dicopper(I)divanadium(IV)], [Cu(2)V(2)F(6)O(2)(C(6)H(8)N(6))(2)](n). The Cu(I) ions and tr(2)eth linkers afford a two-dimensional square-grid topology involving centrosymmetric (tr)Cu(mu-tr)(2)Cu(tr) [tr is triazole; Cu-N = 1.9525 (16)-2.0768 (18) A] binuclear net nodes, which are expanded in a third dimension by centrosymmetric [V(2)O(2)F(6)](2-) pillars. The concerted mu-tr and mu-O bridging between the Cu(I) and V(IV) ions allows a multi-centre accommodation of the vanadium oxyfluoride moiety on a cationic Cu/tr(2)eth matrix [Cu-O = 2.1979 (15) A and V-N = 2.1929 (17) A]. The distorted octahedral coordination of [VONF(4)] is completed by two terminal and two bridging F(-) ions [V-F = 1.8874 (14)-1.8928 (13) and 2.0017 (13)-2.1192 (12) A, respectively]. The resulting three-dimensional framework has a primitive cubic net topology and adopts a threefold interpenetration.
RESUMO
In the structures of the Cd(II) pseudohalide coordination polymer poly[[diaquabis[mu(2)-3,3'-bis(1,2,4-triazol-4-yl)-1,1'-biadamantane-kappa(2)N(1):N(1')]cadmium(II)] dithiocyanate dihydrate], {[Cd(C(24)H(32)N(6))(2)(H(2)O)(2)](NCS)(2).2H(2)O}(n), (I), and the isomorphous selenocyanate analogue, {[Cd(C(24)H(32)N(6))(2)(H(2)O)(2)](NCSe)(2).2H(2)O}(n), (II), the Cd(II) cations occupy inversion centres and have octahedral CdN(4)O(2) environments, completed by four N atoms of the organic ligands [Cd-N = 2.316 (2) and 2.361 (2) A for (I), and 2.313 (3) and 2.372 (3) A for (II)] and two trans-coordinated aqua ligands [Cd-O = 2.3189 (15) A for (I) and 2.323 (2) A for (II)]. In each compound, the ligand displays a bidentate N(1):N(1')-bridging mode, connecting the metal centres at a distance of 14.66 A into two-dimensional nets of (4,4)-topology, while the uncoordinated thio(seleno)cyanate anions reside inside the net cavities. Hydrogen bonding between the water molecules, anions and 1,2,4-triazole N atoms supports the tight packing, with an interlayer distance of 6.09 A.