Synthesis, structural, spectroscopic characterization, and structural comparison of 3-hydroxybenzoate and nicotinamide/N,N-diethylnicotinamide mixed ligand complexes with Zn(II)

The mixed-ligand 3-hydroxybenzoic acid complex of Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and characterized (colorless single crystals, [Zn(3-hba)₂(H₂O)₂(na)₂] and [Zn(3-hba)₂(H₂O)₂(dena)₂]). The chemical, FT-IR, thermal, mass spectral analyses, and X-ray data results revealed that both of the compounds contain two water molecules, two 3-hydroxybenzoate (3-hba) and two nicotinamide (na) or two N,N-diethylnicotinamide (dena) ligands per formula unit. 3-hba and na or dena ligands bind to the Zn(II) ion monodentately through their acidic oxygen and pyridinic nitrogen atoms, respectively. The coordination of metal atoms are completed by two molecules of aqua ligands. The charge balance of complexes is accommodated by two molecules of 3-hba ions. The unit cell has two molecules coordination molecules and each of them was as settled to four surfaces of unit cell cage in na complex. There is one mole molecule that was occupied to center of unit cell cage in dena complex. The two dimensional network structure of the complex is like a hexagonal for na and square plane for dena complexes. The thermal decomposition takes place in three steps; first, dehydration of the two aqua ligands, second, elimination of the two nicotinamide ligands, finally, burning of the two benzoate ion ligands.     

Processes of dissociative electron capture by 20-hydroxyecdysone molecules

The peculiarities of dissociative electron capture by 20-hydroxyecdysone molecules with the formation of fragment negative ions were studied. In the region of high electron energies (5–10 eV), processes of skeleton bond rupture are accompanied by the elimination of H₂O and H₂ molecules. In the region of thermal energies of electrons (≈0 eV), the mass spectrum is formed mainly by the [M−nH₂O]^.− (n=1–3) and [M−H₂−nH₂O]^.− (n=0−3) ions that are generated exclusively by the rearrangement. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–712, April, 2000.     

Structural and kinetic effects of chloride ions in the palladium-catalyzed allylic substitutions

Addition of ligands to [Pd(η³-RCHCHCH₂)(μ-Cl)]₂ or chloride ions to cationic [(η³-RCHCHCH₂)PdL₂]⁺BF₄⁻ induces the formation of neutral complexes η¹-RCHCHCH₂PdClL₂ (R=H with L=(4-ClC₆H₄)₃P, (4-CH₃C₆H₄)₃P, (4-CF₃C₆H₄)₃P or L₂=1,2-bis(diphenylphosphino)butane (dppb), 1,1′-bis(diphenylphosphino)ferrocene (dppf); R=Ph with L=(4-ClC₆H₄)₃P), instead of the expected cationic complexes [(η³-RCHCHCH₂)PdL₂]⁺Cl⁻. In the presence of chloride ions, the reaction of morpholine with the cationic complexes [(η³-allyl)Pd(PAr₃)₂]⁺BF₄⁻ (Ar=4-ClC₆H₄, 4-CH₃C₆H₄) goes slower and involves both cationic [(η³-allyl)Pd(PAr₃)₂]⁺ and neutral η¹-allyl-PdCl(PAr₃)₂ complexes as reactive species in equilibrium with Cl⁻. The cationic complex is more reactive than the neutral one. However, their relative contribution in the reaction strongly depends on the chloride concentration, which controls their relative concentration. The neutral η¹-allyl-PdCl(PAr₃)₂ may become the major reactive species at high chloride concentration. Consequently, [Pd(η³-allyl)(μ-Cl)]₂ associated with ligands or cationic [(η³-allyl)PdL₂]⁺BF₄⁻, used indifferently as precursors in palladium-catalyzed allylic substitutions, are not equivalent. In both situations, the mechanism of the Pd-catalyzed allylic substitution depends on the concentration of the chloride ions, delivered by the precursor or purposely added, that determines which species, [(η³-allyl)PdL₂]⁺ or/and η¹-allyl-PdClL₂ are involved in the nucleophilic attack with consequences on the rate of the reaction and probably on its regioselectivity. Consequently, the chloride ions of the catalytic precursors [Pd(η³-allyl)(μ-Cl)]₂ must not be considered as ‘innocent’ ligands.     

A Water‐Stable Uranyl Organic Framework as a Highly Selective and Sensitive Bifunctional Luminescent Probe for Fe3+ and Tetracycline Hydrochloride

A new coordination polymer (H₂bpy)_0.5?[(UO₂)_1.5(ipa)₂(H₂O)] ( 1 ) (H₂ipa=isophthalic acid, bpy=4,4′‐bipyridine) was synthesized by hydrothermal condition. It was characterized by IR spectroscopy, elemental analysis, TG‐DTA analysis, and powder X‐ray diffraction. Analysis of single‐crystal X‐ray diffraction results showed that the title compound exhibited a double chain bridged by the different uranyl ions and ipa^2? ligands. Through the hydrogen bond interactions and π???π stacking interactions, the double chains were assembled into the three‐dimensional supramolecular framework. Furthermore, the compound can be used as a promising bifunctional luminescence sensor for detecting and identifying Fe³⁺ and tetracycline hydrochloride antibiotic molecules with high selectivity and sensitivity in aqueous solutions. Moreover, the luminescent sensing mechanisms for different analytes were proposed. Moreover, the electronic properties of title compound were explored by density functional theory (DFT) calculations. The sensor system has been successfully applied for the detection of Fe³⁺ and tetracycline hydrochloride with high recovery percentages and low relative standard deviation in real river water samples.     

catena‐Poly[[[pentaaquathulium(III)]‐μ‐5‐sulfonatobenzene‐1,3‐dicarboxylato] 4,4′‐bipyridyl 1.5‐solvate hemihydrate]

The crystal structure of the title compound, {[Tm(C₈H₃O₇S)(H₂O)₅]·1.5C₁₀H₈N₂·0.5H₂O}_n, is built up from two [Tm(SIP)(H₂O)₅] molecules (SIP³⁻ is 5‐sulfonatobenzene‐1,3‐dicarboxylate), three 4,4′‐bipyridyl (bpy) molecules and one solvent water molecule. One of the bpy molecules and the solvent water molecule are located on an inversion centre and a twofold rotation axis, respectively. The Tm^III ion coordination is composed of four carboxylate O atoms from two trianionic SIP³⁻ ligands and five coordinated water molecules. The Tm³⁺ ions are linked by the SIP³⁻ ligands to form a one‐dimensional zigzag chain propagating along the c axis. The chains are linked by interchain O—H...O hydrogen bonds to generate a two‐dimensional layered structure. The bpy molecules are not involved in coordination but are linked by O—H...N hydrogen bonds to form two‐dimensional layers. The two‐dimensional layers are further bridged by the bpy molecules as pillars and the solvent water molecules through hydrogen bonds, giving a three‐dimensional supramolecular structure. π–π stacking interactions between the parallel aromatic rings, arranged in an offset fashion with a face‐to‐face distance of 3.566 (1) Å, are observed in the crystal packing.     

A new one‐dimensional nickel metal–organic framework: catena‐poly[[[diaquabis(4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoato‐κO)nickel(II)]‐μ‐4,4′‐bipyridine‐κ2N:N′] monohydrate]

The title complex, {[Ni(C₁₅H₁₁N₄O₂S)₂(C₁₀H₈N₂)(H₂O)₂]·H₂O}_n, was synthesized by the reaction of nickel chloride, 4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoic acid (HL) and 4,4′‐bipyridine (bpy) under hydrothermal conditions. The asymmetric unit contains two half Ni^II ions, each located on an inversion centre, two L⁻ ligands, one bpy ligand, two coordinated water molecules and one unligated water molecule. Each Ni^II centre is six‐coordinated by two monodentate carboxylate O atoms from two different L⁻ ligands, two pyridine N atoms from two different bpy ligands and two terminal water molecules, displaying a nearly ideal octahedral geometry. The Ni^II ions are bridged by 4,4′‐bipyridine ligands to afford a linear array, with an Ni...Ni separation of 11.361 (1) Å, which is further decorated by two monodentate L⁻ ligands trans to each other, resulting in a one‐dimensional fishbone‐like chain structure. These one‐dimensional fishbone‐like chains are further linked by O—H...O, O—H...N and C—H...O hydrogen bonds and π–π stacking interactions to form a three‐dimensional supramolecular architecture. The thermal stability of the title complex was investigated via thermogravimetric analysis.     

Poly[[trans‐diaquabis(μ2‐biphenyl‐2,2′‐dicarboxylato)bis(μ2‐4,4′‐bipyridine)dicobalt(II)] biphenyl‐2,2′‐dicarboxylic acid disolvate]

In the title compound, {[Co₂(C₁₄H₈O₄)₂(C₁₀H₈N₂)₂(H₂O)₂]·2C₁₄H₁₀O₄}_n, each Co^II ion is six‐coordinate in a slightly distorted octahedral geometry. Both Co^II ions are located on twofold axes. One is surrounded by two O atoms from two biphenyl‐2,2′‐dicarboxylate (dpa) dianions, two N atoms from two 4,4′‐bipyridine (bpy) ligands and two water molecules, while the second is surrounded by four O atoms from two dpa dianions and two N atoms from two bpy ligands. The coordinated dpa dianion functions as a κ³‐bridge between the two Co^II ions. One carboxylate group of a dpa dianion bridges two adjacent Co^II ions, and one O atom of the other carboxylate group also chelates to a Co^II ion. The Co^II ions are bridged by dpa dianions and bpy ligands to form a chiral sheet. There are several strong intermolecular hydrogen bonds between the H₂dpa solvent molecule and the chiral sheet, which result in a sandwich structure.     

μ‐4,4′‐Bipyridine‐κ2N:N′‐bis[triaqua(4,4′‐bipyridine‐κN)cadmium(II)] bis(3‐aminobenzoate) bis(perchlorate) dihydrate: a novel supramolecular system constructed by π–π and hydrogen‐bonding interactions

The title dicadmium compound, [Cd₂(C₁₀H₈N₂)₅(H₂O)₆](C₇H₆NO₂)₂(ClO₄)₂·2H₂O, is located around an inversion centre. Each Cd^II centre is coordinated by three N atoms from three different 4,4′‐bipyridine ligands and three O atoms from three coordinating water molecules in a distorted octahedral coordination environment. In the dicadmium cation unit, one 4,4′‐bipyridine (4,4′‐bipy) molecule acts as a bidentate bridging ligand between two Cd metal ions, while the other four 4,4′‐bipy molecules act only as monodentate terminal ligands, resulting in a rare `H‐type' [Cd₂(C₁₀H₈N₂)₅(H₂O)₆] host unit. These host units are connected to each other viaπ–π stacking interactions, giving rise to a three‐dimensional supramolecular grid network with large cavities. The 3‐aminobenzoate anions, perchlorate anions and water molecules are encapsulated in the cavities by numerous hydrogen‐bonding interactions. To the best of our knowledge, this is the first example of a coordination compound based on both 4,4′‐bipyridine ligands together with discrete 3‐aminobenzoate anions.     

The two‐dimensional coordination polymer poly[diaqua(μ2‐1H‐imidazo[4,5‐f][1,10]phenanthroline)‐μ4‐sulfato‐μ3‐sulfato‐dicadmium(II)]

In the title coordination polymer, [Cd₂(SO₄)₂(C₁₃H₈N₄)(H₂O)₂]_n, there are two crystallographically independent Cd^II centres with different coordination geometries. The first Cd^II centre is hexacoordinated by four O atoms of four sulfate ligands, one water O atom and one N atom of a 1H‐imidazo[4,5‐f][1,10]phenanthroline (IP) ligand, giving a distorted octahedral coordination environment. The second Cd^II centre is heptacoordinated by four O atoms of three sulfate ligands, one water O atom and two N atoms of one chelating IP ligand, resulting in a distorted monocapped anti‐trigonal prismatic geometry. The symmetry‐independent Cd^II ions are bridged in an alternating fashion by sulfate ligands, forming one‐dimensional ladder‐like chains which are connected through the IP ligands to form two‐dimensional layers. These two‐dimensional layers are linked by interlayer hydrogen bonds, leading to the formation of a three‐dimensional supramolecular network.     

A novel three-dimensional pillared-layer hybrid zinc phosphite featuring double-helical channels

A new zinc phosphite (C₂H₈N₂)_0.5(HPO₃)Zn has been hydrothermally synthesized from a mixture of ZnO, H₃PO₃, 4,4’-bipyridine, ethylenediamine, and H₂O. Single-crystal X-ray diffraction analysis reveals that the Zn ions are first interconnected by HPO₃ ²- ligands to produce a neutrally infinite two-dimensional inorganic layer with four- and eight-membered rings, which is further used as the second building units and helically pillared by bridging ethylenediamine molecules to form the scarcely reported three-dimensional pillared-layer hybrid zinc phosphite with double-helical channels due to the flexibility of the ethylenediamine ligands.     

Nitrosolates and related compounds—IX: Coordination compounds of divalent copper,nickel and cobalt with nitroacetate(2−) ions as chelating ligands. Crystal and molecular structure of potassium bis[nitroacetato(2−)]cuprate(II)-water (1/1)

The syntheses of K₂[Cu(nac)₂]·H₂O (4), [Cu(nac)(N-N)(H₂O)]·H₂O (N-N = bpy, phen; 5,6) and [M(nac)(N-N)₂]·xH₂O (M = Ni, Co; 7–10) with nitroacetate(2?) ions (nac^2?) as chelating ligands are described.The structure of 4 has been determined by single crystal X-ray diffraction and contains square planar [Cu(nac)₂]^2? units in which the nitro and carboxyl groups of the two chelate ligands are in cis positions. Two of the units form a centrosymmetric dimer with a four-membered CuOCu“O”-ring, the dimers being connected by exo-oxygens of the ligands into two-dimensional layers. The water molecules and the potassium ions are arranged between the layers; there are two kinds of potassium ions with distorted (1+4+1) and (2+4+3) coordinations respectively.     

Synthesis,Structure, and Fluorescent Properties of Lanthanide Complexes Based on 8‐Hydroxyquinoline‐7‐carboxylic Acid

The lanthanide complex [Eu₃(8‐HQCA)₃(COOH)(OH)₂(H₂O)₃]_n · nH₂O (8‐HQCA = 8‐hydroxyquinoline‐7‐carboxylic acid) was synthesized and characterized. Single‐crystal X‐ray diffraction shows that the trinuclear structures are linked by ligands to form 2D layers. The results of DFT calculation shows that energy can be transferred effectively from the ligand to Eu^III ions. A series of heteronuclear complexes {[(Eu_1–xY_x)₃(8‐HQCA)₃(COOH) (OH)₂(H₂O)₃]_n · nH₂O (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8)} were synthesized and their luminescent properties were studied. The results showed that the doping of Y^III ions could change the fluorescent intensity of the Eu^III complex, but could not change their positions.     

Crystal structures of some lanthanide(III) complexes with acylhydrazone and their coordination chemistry

Three new lanthanide(III) complexes with N-(2-propionic acid)-salicyloylhydrazone (H₂L, C₁₀H₁₀N₂O₄) ligand [La(HL)₂(NO₃)(H₂O)₂]₃ ·4H₂O(I), [Gd(HL)₃] · 2(C₂H₅)₃ N(II) and [Er(L)(HL)(H₂O)₂] · 2H₂O(III) has been synthesized and characterized by elemental analyses, IR, UV, and molar conductivity. The crystal structures of three complexes have been determined by X-ray single-crystal diffractometer. In complex I, the La³⁺ ion is ten-coordinated by two tridentate ligands, one bidentate nitrate, and two water molecules. In complex II, the Gd³⁺ ion has a coordination number of nine by three tridentate ligands. In complex III, the Er³⁺ ion is eight-coordinated by two tridentate ligands and two water molecules. In all structures, tridentate ligands are coordinated by carboxyl O and acyl O atoms and azomethine N atom to form two stable five-membered rings sharing one side in the keto mode as indicated by the results of crystal structures and infrared spectral analysis.     

A two‐dimensional ZnII coordination polymer constructed by benzotriazole‐5‐carboxylate and 1,4,8,9‐tetraazatriphenylene

Poly[[(μ₃‐benzotriazole‐5‐carboxylato‐κ⁴N¹:N³:O,O′)(1,4,8,9‐tetraazatriphenylene‐κ²N⁸,N⁹)zinc(II)] 0.25‐hydrate], {[Zn(C₇H₃N₃O₂)(C₁₄H₈N₄)]·0.25H₂O}_n, exhibits a two‐dimensional layer structure in which the asymmetric unit contains one Zn^II centre, one 1,4,8,9‐tetraazatriphenylene (TATP) ligand, one benzotriazole‐5‐carboxylate (btca) ligand and 0.25 solvent water molecules. Each Zn^II ion is six‐coordinated and surrounded by four N atoms from two different btca ligands and one chelating TATP ligand, and by two O atoms from a third btca ligand, to furnish a distorted octahedral geometry. The infinite connection of the metal ions and ligands forms a two‐dimensional wave‐like (6,3) layer structure. Adjacent layers are connected by C—H...N hydrogen bonds. The solvent water molecules are located in partially occupied sites between parallel pairs of inversion‐related TATP ligands that belong to two separate layers.     

A novel O–Zn bridging polymer complex of 2,6‐bis[bis(carboxylatomethyl)aminomethyl]‐4‐methylphenolate

A new one‐dimensional coordination polymer, catena‐poly[[acetatohexaaqua{μ₄‐2,6‐bis[bis(carboxylatomethyl)aminomethyl]‐4‐methylphenolato}trizinc(II)] octahydrate], [Zn₃(C₁₇H₁₇N₂O₉)(C₂H₃O₂)(H₂O)₆]·8H₂O, is a trinuclear complex consisting of three zinc centers joined by a phenolate bridge and Zn(H₂O)₄ units. In each complex polymer unit, the three Zn atoms have different coordination modes. Of the two phenolate‐bridged Zn ions, one adopts a distorted octahedral coordination composed of two carboxylate ligands, one tertiary N atom, two water molecules and the bridging phenolate ligand, while the other adopts a pyramidal geometry composed of two carboxylate ligands, one tertiary N atom from another coordination arm, one acetate anion as the counter‐anion and the bridging phenolate ligand. The third type of Zn centre is represented by two independent Zn atoms lying on inversion centres. They both have an octahedral coordination consisting of four O atoms from four water molecules and two acetate carbonyl O atoms from the ligand. The latter Zn atoms join the above‐mentioned binuclear complex units through O atoms of the carboxylate groups into an infinite chain. Neighboring aromatic rings are distributed above and below the chain in an alternating manner. Between the coordination chains, the Zn...Zn separations are 5.750 (4) and 6.806 (4) Å. The whole structure is stabilized by hydrogen bonds formed mainly by solvent water molecules.     

Syntheses,characterization and thermal properties of lanthanide complexes with 2-mercaptonicotinic acid

Fourteen new complexes with the general formula of Ln(Hmna)₃·nH₂O (n=2 for Ln=La-Ho and n=1 for Er-Lu, H₂mna=2-mercaptonicotinic acid) were synthesized and characterized by elemental analyses, IR spectra and thermogravimetric analyses. In addition, molar specific heat capacities were determined by a microcalorimeter at 298.15 K. The IR spectra of the prepared complexes revealed that carboxyl groups of the ligands coordinated with Ln(III) ions in bidentate chelating mode. Hydrated complexes lost water molecules during heating in one step and then the anhydrous complexes decomposed directly to oxides Ln₂O₃, CeO₂, Pr₆O₁₁ and Tb₄O₇. The values of molar specific heat capacities for fourteen solid complexes were plotted against the atomic numbers of lanthanide, which presented as ‘tripartite effect’. It suggested a certain amount of covalent character existed in the bond of Ln³⁺ and ligands, according with nephelauxetic effect of 4f electrons of rare earth ions.     

二甲基取代五元瓜环与钾离子和钆离子的配位结构

利用X-射线单晶衍射技术表征了2个二甲基取代五元瓜环(DMeQ[5])与金属离子形成的配合物的晶体结构,2个配合物分别为{[K2(H2O)3DMeQ[5]}I2.5H2O(1)和{[Gd(H2O)3][K(H2O)][(NO3)@DMeQ[5]]}(NO3)3.5H2O(2)。与DMeQ[5]和钆离子形成的配合物的结构不同的是,配合物1和2中每个DMeQ[5]端口的所有羰基氧原子都和钾离子或钆离子配位,形成全封闭结构。     

Poly[[diaqua(N,N‐dimethylformamide‐κO)manganese(II)]‐μ3‐sulfato]

In the title complex, [Mn(SO₄)(C₃H₇NO)(H₂O)₂]_n, each Mn^II ion has a distorted octahedral geometry formed by three O atoms of three different sulfate groups, one O atom of a dimethylformamide ligand and two water molecules. The sulfate groups act as tridentate bridging ligands connecting the Mn^II ions into a two‐dimensional layer structure which can be regraded as a 4.8² network.     

The Crystal and Molecular Structures of Pb(II) Complexes with Furan-2-Carboxylate and Furan-3-Carboxylate Ligands

The crystals of Pb(II) 2-furancarboxylate (title compound I) contain tetrameric structural units Pb₄(2-FCA)₈(H₂O₂) in which four Pb(II) ions are bridged by carboxylate oxygen atoms forming a circular moiety. In addition, pairs of Pb(II) ions are bridged by carboxylate oxygen atoms inside this moiety. The molecular pattern observed in Pb(II) 3-furancarboxylate (title compound II) is polymeric. It consists of Pb(3-FCA)₂(H₂O) structural units bridged by carboxylate oxygen atoms donated by the furan-3-carboxylate (3-FCA) ligands which are bidentate, using both their carboxylate oxygen atoms for chelation. The coordination around Pb(II) ions is eightfold and ninefold including, apart from carboxylate oxygen atoms, a water oxygen atom and oxygen atoms donated by the furan rings of the ligand molecules. Hydrogen bonds with the water molecule as the donor operate between adjacent ligand molecules. The stereochemical activity of the lone 6s ² electron pair on the Pb(II) is observed in title compound II.     

Infrared Spectrum of the Si3H8+ Cation: Evidence for a Bridged Isomer with an Asymmetric Three‐Center Two‐Electron Si?H?Si Bond

The IR spectrum of Si₃H₈⁺ ions produced in a supersonic plasma molecular beam expansion of SiH₄, He, and Ar is inferred from photodissociation of cold Si₃H₈⁺–Ar complexes. Vibrational analysis of the spectrum is consistent with a Si₃H₈⁺ structure ( 2⁺ ) obtained by a barrierless addition reaction of SiH₄ to the disilene ion (H₂Si?SiH₂⁺) in the silane plasma. In this structure, one of the electronegative H atoms of SiH₄ donates electron density into the partially filled electrophilic π orbital of the disilene cation. The resulting asymmetric Si? H? Si bridge of the 2⁺ isomer with a bond energy of approximately 60 kJ mol^?1 is characteristic for a weak three‐center two‐electron bond, which is identified by its strongly IR active asymmetric Si? H? Si stretching fundamental at about 1765 cm^?1. The observed 2⁺ isomer is calculated to be only a few kJ mol^?1 less stable than the global minimum structure of Si₃H₈⁺ ( 1⁺ ), which is derived from vertical ionization of trisilane. Although more stable, 1⁺ is not detected in the measured IR spectrum of Si₃H₈⁺–Ar, and its lower abundance in the supersonic plasma is rationalized by the production mechanism of Si₃H₈⁺ in the silane plasma, in which a high barrier between 2⁺ and 1⁺ prevents the efficient formation of 1⁺ . The potential energy surface of Si₃H₈⁺ is characterized in some detail by quantum chemical calculations. The structural, vibrational, electronic and energetic properties as well as the chemical bonding mechanism are investigated for a variety of low‐energy Si₃H₈⁺ isomers and their fragments. The weak intermolecular bonds of the Ar ligands in the Si₃H₈⁺–Ar isomers arise from dispersion and induction forces and induce only a minor perturbation of the bare Si₃H₈⁺ ions. Comparison with the potential energy surface of C₃H₈⁺ reveals the differences between the silicon and carbon species.