Bridging Bidentate Carboxylate Groups Research Articles

An intramolecular antiferromagnetically coupled pentanuclear Mn(II) cluster containing acetate and tetracarboxylate linkers: Synthesis, structure and magnetism

A new Mn(II) complex {[Mn5(CH3COO)2(L)2(DMF)8](DMF)}n (1), (H4L = 3,5-bis(3′,5′-dicarboxylphenyl)-1H-1,2,3-triazole), has been synthesized and structurally characterized. The complex 1 have pentanuclear Mn(II) core, where the two sides of metal centers (Mn2 and Mn3) have trigonal bipyramidal arrangement and the middle metal center (Mn1) have octahedral environment utilizing two O atoms from adjacent bridging bidentate carboxylate groups and four O atoms from four coordinated DMF molecules. The planar arrangement of pentanuclear Mn(II) atoms are linked by L linkage to generate two dimensional sheet. The magnetic property of the compound indicates χMT value for the five Mn(II) unit to be 21.3 cm3 K mol−1 at 300 K, which is close to the spin-only value (21.9 cm3 K mol−1) for the pentamer having S = 5/2. Also, the Hirshfeld surface analyses have been performed which indicated the absence of weak Mn···Mn interaction thereby corroborating the results of observed magnetic properties.

A series of lanthanide complexes with 2,3-dichlorobenzoic acid and 2,2:6′,2″-terpyridine: Crystal structures, spectroscopic and thermal properties

Three new binuclear solid lanthanide complexes with the general formula [Ln(2,3-DClBA)3(terpy)(H2O)]2(Ln=Pr(1), Sm(2), Eu(3); 2,3-DClBA=2,3-dichlorobenzoate; terpy=2,2′:6′2″-terpyridine), have been synthesized and characterized. The powder XRD and single-crystal structures of the title complexes indicate that all the complexes are isomorphous. The two lanthanide ions in each complex are linked by two bridging bidentate carboxylate groups. Under ultraviolet light excitation, the europium complex exhibited characteristic red fluorescence of Eu3+(5D0→7F1–4). The thermal decomposition mechanism is investigated by TG/DSC–FTIR technology. The 3D stacked plots for the FTIR spectra of the evolved gases were recorded and the gaseous products were identified by the typical IR spectra obtained at different temperatures from the 3D stacked plots.

Molecular and Polymeric Uranyl and Thorium Complexes with Sulfonate‐Containing Ligands

AbstractSix uranyl and one thorium(IV) cation complexes with ligands involving either only sulfonate or both sulfonate and carboxylate groups as complexing sites were obtained, mainly under hydrothermal conditions, and their crystal structures were determined. The uranyl ion complex with the 2‐sulfobenzoate (2‐SB2–) anion synthesized in the presence of pyridine, [pyH]4[(UO2)2(2‐SB)2O]2·4H2O (1), is a molecular, tetranuclear complex in which 2‐SB2– is chelating through its two functional groups, while [Th(2‐SB)2(H2O)3]·2H2O (2) is a 1D polymer with monodentate sulfonate and bridging bidentate carboxylate groups. Complex [(UO2)3K(4‐SB)O(OH)3(H2O)1.5]·0.5H2O (3), with the 4‐sulfobenzoate ligand, crystallizes as a 3D framework in which uranyl oxo/hydroxo 1D subunits are connected to one another by 4‐SB2– and potassium cation bridges, the latter being involved in as much as five bonds with uranyl oxo groups (“cation–cation” bonds). Complex [UO2(5‐SSH2)(H2O)3]2·2(5‐SSH2)·3H2O (4), with 5‐sulfosalicylic acid (5‐SSH3), is a dinuclear species in which the ligand is only coordinated through its bridging bidentate sulfonate group, an unusual occurrence. 5‐Sulfosalicylic acid undergoes partial desulfonation and carboxylation under hydrothermal conditions, yielding the heterometallic, tetranuclear complex [UO2Ni(5‐SHIPH)(4‐HIPH2)(bipy)2(H2O)]2·(4‐HIPH3) (5), 5‐sulfonato‐2‐hydroxyisophthalic acid (5‐SHIPH4) and 4‐hydroxyisophthalic acid (4‐HIPH3) being generated in situ. The all‐sulfonate ligand 1,2‐ethanedisulfonate (EDS2–) acts as a divergent linker in both [UO2(EDS)(H2O)3] (6) and [(UO2)2(EDS)(OH)2(phen)2]·4H2O (7). 1D polymers are formed in both cases, the doubly monodentate EDS2– ligand bridging isolated uranyl ions in 6 or hydroxo‐bridged uranyl dimers in 7. Sulfonate coordination to the 5f cation is present in all these complexes but 5, even in the absence of synergistic effects exerted by the stronger carboxylate ligating groups, and the variety of structures obtained in this as well as in previous work demonstrates that, together with the more investigated phosphonates, sulfonates are anions of great potential for the synthesis of actinide–organic coordination polymers and frameworks.

Synthesis, crystal structure, and luminescence properties of new binuclear europium and terbium complexes with tubular morphology

The two dinuclear rare earth complexes Eu2(PBa)6(Phen)2 and Tb2(PBa)6(Phen)2, (where PBa=4-pentylbenzoate group and Phen=1, 10-phenanthroline), were synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Both of them crystallize in space group P-1 with similar cell parameters. Each Eu or Tb ion is nine-coordinated with one 1, 10-phenanthroline molecule, one bidentate chelating carboxylate group, two bidentate bridging carboxylate groups, and two tridentate bridging carboxylate groups. The fluorescent properties of the europium and terbium complexes were also investigated. Under the UV excitation, the two complexes exhibit extensive characteristic emissions of europium and terbium ions, respectively.

Tetrakis(μ-3-azaniumylbenzoato)-κ3O:O,O′;κ3O,O′:O;κ4O:O′-bis[tetraaquaneodymium(III)] hexachloride tetrahydrate

The structure of the title compound, [Nd2(C7H7NO2)4(H2O)8]Cl6·4H2O, consists of dimeric cationic units related by an inversion centre. The two NdIII atoms are linked by two bridging bidentate carboxyl­ate groups and two bidentate chelating bridging carboxyl­ate groups, with an Nd⋯Nd separation of 4.1259 (4) Å. Each NdIII atom is nine-coordin­ated by five O atoms from the carboxyl­ate groups of the zwitterionic azaniumylbenzoate ligands and four from water mol­ecules. They adopt a distorted tricapped trigonal–prismatic arrangement. The dihedral angle between the mean planes of the benzene ring and the carboxlate groups are 7.7 (6) and 24.4 (5)°. The two carboxyl­ate groups are almost perpendicular to one another with a dihedral angle of 84.0 (7)°, while the two benzene rings are inclined to one another by 81.8 (2)°. The mol­ecular packing is stabilized by O—Hwater⋯Cl, O—Hwater⋯N, N—H⋯Cl, N—H⋯O, and O—Hwater⋯O hydrogen bonds and π–π stacking inter­actions [centroid–centroid distance = 3.500 (3) Å] between symmetry-related benzene rings. All of the Cl− anions and the uncoordinated water molecules are disordered over two sets of sites with different occupancy ratios.

Tetrakis(μ-3-azaniumylbenzoato)-κ3O:O,O′;κ3O,O′:O;κ4O:O′-bis[triaquachloridolanthanum(III)] tetrachloride dihydrate

The tiltle complex, [La2(C7H7NO2)4Cl2(H2O)6]Cl4·2H2O, is a centrosymmetric dimer formed by edge-sharing LaO5(H2O)3Cl polyhedra linked together by a carboxyl­ate ligand. The two LaIII metal ions are linked by two bidentate bridging carboxyl­ate groups with a κ2 O:O′ coordination mode and two bidentate chelating bridging carboxyl­ate groups with a κ3 O:O,O′ coordination mode. The coordination sphere of lanthanum, completed by a terminal chloride and three water mol­ecules, adopts a distorted tricapped trigonal–prismatic arrangement. N—H⋯Cl, N—H⋯O and O—Hwater⋯Cl hydrogen bonds, and slipped π–π inter­actions between parallel benzene rings [centroid–centroid distance of 3.647 (3) Å] are observed in the structure. These combine to stabilize a three-dimensional network.

Synthesis, Crystal Structure, and Thermal Properties of a Holmium(III) Benzoate Complex with 1,10-Phenanthroline

A binuclear holmium(III) benzoate 1,10-phenanthroline ternary complex, [Ho(BA)3phen]2, was synthesized and characterized by elemental analysis, IR and UV spectroscopy, molar conductance, single crystal X-ray diffraction, and thermogravimetric/differential thermogravimetric (TG-DTG) techniques. The crystal of the complex is in a triclinic crystal system, space group p1̅ with a = 10.7162(18) Å, b = 11.845(3) Å, c = 12.227(2) Å, α = 105.141(11)°, β = 93.845(8)°, γ = 112.880(5)°, and Z = 1. Each Ho(III) cation in the crystal is eight-coordinated including two O atoms of one chelating bidentate carboxylate group, four O atoms of four bridging bidentate carboxylate groups, and two N atoms of one 1,10-phenanthroline molecule, yielding a distorted square antiprismatic comformation. The thermal analysis of [Ho(BA)3phen]2 has been performed by simultaneous TG/DSC-FTIR techniques. By the Malek method, SB(m,n) was defined as a kinetic model for the second-step thermal decomposition. The activation energy E of this step is 296.99 kJ·mol−1, and the pre-exponential factor ln A is 39.99 s−1. The thermodynamic parameters, Gibbs energy (ΔG≠), enthalpy (ΔH≠), and entropy (ΔS≠) of activation, at the peak temperatures were also calculated. The heat capacity of [Ho(BA)3phen]2 was measured by differential scanning calorimetry (DSC) over the temperature range from (254 to 470) K. In addition, the values of the experimental heat capacities were fitted to a polynomial equation with the least-squares method.

Syntheses, structures and luminescence properties of five lanthanide–isonicotinate coordination polymers

Five isostructural compounds of lanthanide with isonicotinate ligand, formula as [Ln(IN) 2(H 2O) 4](NO 3) (Ln = La, Nd, Eu, Tb and Er, 1− 5, IN = isonicotinate), were synthesized under hydrothermal conditions by tuning the pH level and the ratio of lanthanide with isonicotinic acid. These compounds were characterized by single-crystal X-ray structure analysis, elemental analysis, IR and TG-DTA. In five compounds, the adjacent eight-coordination lanthanide centers were linked together through the bidentate bridging carboxylate groups of isonicotinate ligands to generate infinite chain structures which were further interconnected to form 3D supramolecular networks via the OW–H···N (nitrogen atom came from isonicotinate ligands) and OW–H···O (oxygen atom came from nitrate) hydrogen bonds. Compounds 3 and 4 show strong red and green emission, corresponds to 5D 0→ 7F 2 transition of Eu 3+ ions and 5D 4→ 7F 5 transition of Tb 3+ ions, respectively.

Synthesis, structures and properties of ternary rare earth complexes with m-methoxybenzoic acid and 1,10-phenanthroline

Two dimeric rare earth complexes [Eu( m-MOBA) 3(phen)] 2 ( I) and [Tb( m-MOBA) 3(phen)] 2·2C 2H 5OH ( II) (where m-MOBA = m-methoxybenzoate, phen = 1,10-phenanthroline) were synthesized and structurally characterized. Both complexes consist of neutral dimeric molecules. Complex I crystallizes in triclinic system, space group P 1 ¯ . Each Eu(III) ion is nine-coordinated with one 1,10-phenanthroline molecule, one bidentate chelating carboxylate group, two bridging bidentate carboxylate groups and two bridging tridentate chelating carboxylate groups. Complex II crystallizes in triclinic system, space group P 1 ¯ . Each Tb(III) is eight-coordinated with one 1,10-phenanthroline molecule, one bidentate chelating carboxylate group and four bridging bidentate carboxylate groups. Complex I shows bright red luminescence, II shows green luminescence under UV light at room temperature, respectively. The thermal analysis indicates that they are all quite stable to heat.

Synthesis, crystal structure and properties of two ternary rare earth complexes with aromatic acid and 1,10-phenanthroline

Abstract Two dimeric rare-earth complexes [Eu(o-MOBA)3phen]2·2H2O (1), [Tb(o-MOBA)3phen]2·2H2O (2), (where o-MOBA = o-methoxybenzoate, phen = 1,10-phenanthroline) were synthesized and structurally characterized. Both of them consist of neutral dimeric molecules, crystallize in triclinic system, space group P 1 ¯ . Each RE(III) ion is nine-coordinated with one 1,10-phenanthroline molecule, one bidentate chelating carboxylate group, two bidentate bridging carboxylate groups and two tridentate bridging carboxylate groups. Complex 1 shows bright red luminescence, 2 shows green luminescence under UV light at room temperature, respectively. The thermal analysis indicates that they are all quite stable to heat.

Sb(III) fluoride complexes with DL-valine. Crystal structure of molecular complex SbF3{(CH3)2CHCH(+NH3)COO?}

Preparative method in combination with X-ray diffraction and IR spectroscopy is used to study reaction of Sb(III) fluoride with α-aminoisovaleric acid (DL-valine) in an aqueous solution in the range of the molar ratios of components (0.25–2) : 1 in the presence of hydrofluoric acid. The molecular complex of Sb(III) fluoride with valine (1 : 1) of the composition SbF3{(CH3)2CHCH(+NH3)COO−}(I) and valinium tetrafluoro-antimonate(III) monohydrate {(CH3)2CHCH(+NH3)COOH}SbF4· H2O (II) are synthesized for the first time. Crystal structure was determined for the molecular complex I consisting of SbF3 groups and valine molecules united into polymer chains through bidentate bridging carboxylate groups of amino acid molecules.

Synthesis, Structural Characterization and Properties of Copper(II) and Zinc(II) Coordination Polymers with a New Bridging Chelating Ligand

AbstractTwo new coordination polymers [Cu3(cpida)2(H2O)4]n·4nH2O (1) and [Zn(Hcpida)]n·nH2O (2) have been synthesized with a new bridging chelating ligand N‐(4‐carboxyphenyl)iminodiacetic acid (H3cpida). X‐ray diffraction analysis reveals that complex 1 consists of 1D parallelogram‐shaped molecular‐box chains constructed from unusual linear trinuclear CuII secondary building units (SBUs), which further extend into 2D layers by perfect parallel AA stacking. Complex 2 adopts a 2D framework comprised of tetrahedral ZnII centres isolated from each other by the bridging bidentate carboxylate groups of the Hcpida2− ligands. Compound 2 possesses alternate open and closed channels along the a direction. The dehydation and rehydration experiments showed that compound 2 undergoes a reversible inclusion process to some extent. However, the removal of guest water molecules from 1 results in the collapse of the polymeric networks owing to the loss of the coordinated water molecules. Compound 2 also shows strong photoluminescence and may be a good candidate for a photoactive or porous material. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Synthesis, structure and luminescent property of a binuclear terbium complex [Tb 2(Hsal) 8(H 2O) 2][(Hphen) 2]·2H 2O

A binuclear terbium complex [Tb 2(Hsal) 8(H 2O) 2][(Hphen) 2]·2H 2O 1 (Hsal= o-HOC 6H 4CO 2 −, phen=1,10-phenanthroline) was synthesized and characterized by elemental analysis, molar conductance, IR, UV–VIS, X-ray powder diffraction, Thermogravimetric analysis and fluorescence. Its structure was determined by X-ray single crystal diffraction. In the dimeric anion [Tb 2(Hsal) 8(H 2O) 2] 2−, two terbium atoms are connected by four bidentate bridging carboxylate groups. Each Tb atom is eight-coordinated to four bidentate bridging carboxylate groups, one bidentate chelating carboxylate groups, one monodentate carboxylate group as well as one water molecule. The mono-protonated phen does not coordinate to the Tb atom directly. Hydrogen bonds, π–π stacking interactions and electrostatic attractions result in the formation of a two-dimensional supramolecular structure. The solid-state luminescence behavior of 1 was studied. Compared with binary terbium salicylate Tb(Hsal) 3(H 2O) 2·2H 2O, it emits a relatively weak green light under the excitation of UV light, which may be attributed to the formation of extensive π-electron conjugation systems in the structure.

Crystal Structure and Luminescence of a Europium Coordination Polymer { [Eu(p‐MOBA)3 · 2H2O] · 0.5H2O · 0.5 (4, 4′‐bipy) } ∞

AbstractThe structure of the complex { [Eu (p‐MOBA)3 · 2H2O] · 0.5H2O·0.5(4,4′‐bipy)}∞ (p‐MOBA: p‐methoxybenzoate, 4,4′‐bipy: 4,4′‐bipyridine) was determined by single crystal X‐ray diffraction study. Each europium atom is coordinated with two oxygen atoms of the chelated carboxyl group, four oxygen atoms of the four bidentate bridging carboxylate groups and two oxygen atoms of two water molecules, forming an infinite polymeric chain structure. Excitation and luminescence spectra were observed at 77 K. The high resolution spectrum of the complex shows that the europium ion site in the crystal has low symmetry. The complex displays intense luminescence which may be related to the p‐MOBA ligand and the polymeric coordination.

Structure and mesomorphism of neodymium(III) alkanoates.

The structural and thermal behavior of all members of the homologous series of neodymium(III) alkanoates, ranging from neodymium(III) butyrate to neodymium(III) eicosanoate are described. Neodymium(III) butyrate monohydrate, Nd(C3H7COO)3.H2O crystallizes in space group P1 (No. 2), Z = 2. The lattice parameters are a = 9.824(2) A, b = 11.974(2) A, c = 14.633(2) A, alpha = 86.21(2) degrees, beta = 75.92(2) degrees, gamma = 77.97(2) degrees. The crystal structure consists of ionic layers of neodymium ions, separated by bilayers of butyrate anions. In the ionic layers, the neodymium ions are connected by bridging tridentate carboxylate groups to zigzag chains, whereas the chains are connected among themselves by bridging bidentate carboxylate groups. The two crystallographically different neodymium ions are both having coordination number 9, with a geometry close to a monocapped square antiprism. The structure of the higher homologues can be derived from the structure of neodymium butyrate by extending the alkyl chains. These compounds have a lamellar bilayer structure with planes of neodymium(III) ions coordinated to the carboxylate groups and with the alkyl chains in an all-trans conformation. All homologous compounds from neodymium(III) pentanoate to neodymium(III) pentadecanoate display a thermotropic mesophase, which was identified by high-temperature X-ray diffraction as a smectic A phase. For the series from neodymium(III) pentanoate to neodymium(III) undecanoate an additional high viscosity mesophase is present between the crystalline state and the smectic A mesophase.

Crystal structure and luminescence of a europium 3-methoxybenzoate complex with 2,2′-bipyridine

The structure of the dimer [Eu( m-MOBA) 3·2,2′-bipy] 2 ( m-MOBA: m-methoxybenzoate, 2,2′-bipy: 2,2′-bipyridine) was determined by single crystal X-ray diffraction. Each europium atom is coordinated with two oxygen atoms of the chelated carboxyl group, four oxygen atoms of the bidentate bridging carboxylate groups and two nitrogen atoms from a 2,2′-bipyridine molecule forming a dimeric structure with coordination number 8. The luminescence behaviour of the Eu 3+ ion in [Eu( m-MOBA) 3·2,2′-bipy] 2 was observed at 77 K. The emission spectra of 5 D 1→ 7 F J (J=1–3) and 5 D 0→ 7 F J (J=0–4) transitions were measured. The complex displays intense luminescence and the Eu 3+ ions in the dimer occur in slightly different chemical environments.

Crystal structure and luminescence of a europium coordination polymer {[Eu( m-MOBA) 3·2H 2O]1/2(4,4′-bpy)} ∞

The structure of the complex [Eu( m-MOBA) 3·2H 2O]1/2(4,4′-bpy) ( m-MOBA: m-methoxybenzoate, 4,4′-bpy: 4,4′-bipyridine) was determined by single crystal X-ray diffraction. The bonding around each europium consists of two oxygen atoms of the chelated carboxyl group, two oxygen atoms of two water molecules and four oxygen atoms of the bidentate bridging carboxylate groups, forming an infinite polymeric chain structure. The luminescence behaviour of Eu 3+ in {[Eu( m-MOBA) 3·2H 2O]1/2(4,4′-bpy)} ∞ was observed at 77 K. The emission spectra of 5D 1→ 7F J ( J=1–3) and 5D 0→ 7F J ( J=0–4) transitions were recorded. The complex displays intense luminescence which may be related to the m-MOBA ligand and the polymeric coordination.

Infrared, 119Sn, 13C and 1H NMR, 119Sn and 13C CP/MAS NMR and Mössbauer Spectral Study of Some Tributylstannyl Citrates and Propane-1,2,3-tricarboxylates

Six tributylstannyl citrates and three tributylstannyl propane-1,2,3-tricarboxylates of the formula R1C(CH2COOR2)(COOR3)(CH2COOR4) (R1 = OH or H, R2, R3, R4 = H, Bu3Sn, C6H11NH3, (C6H11)2NH2 or (CH2)5NH2) have been synthesised, and their solution and solid-state structures studied by infrared, 1H, 13C and 119Sn NMR, 13C and 119Sn CP/MAS NMR and 119Sn Mössbauer spectroscopies. In non-coordinating solvents, the compounds exist as isolated molecules or ionic-pairs with their tin atoms in pseudotetrahedral environments. In coordinating solvents, the tin atoms in the compounds are five-coordinate owing to the participation of the solvent in bonding; and their trans-trigonal bipyramidal coordination spheres consist of the ipso-carbon atoms of the butyl substituents in equatorial plane, and the solvent molecule and the oxygen atom of the monodentate carboxyl group in axial positions. A part of tributylstannyl groups together with some bidentate bridging carboxylate groups form polymeric chains in the solid state of citrates and propane-1,2,3-tricarboxylates. Also dioxastanna-rings with the participation α-hydroxycarboxylate fragments and one of the tributylstannyl groups occur probably in some citrates in the solid state. The spectroscopic assignment for the citrate has been confirmed by crystal structure analysis.

Complexation of tin with amide ligands: two cases of mixed oxidation state tin complexes

The reaction of SnCl 2 with the sodium salts of orotic and 2-thioorotic acids under aerobic conditions leads to the formation of compounds with empirical formulae Sn(H 2or)·0.5H 2O and Sn(H 2thor) 3, where H 3ororotic acid and H 3thor2-thioorotic acid. Variable temperature 119mSn Mössbauer spectroscopy shows that these compounds contain tin in both the II and IV oxidation states. The Mössbauer data taken together with the vibrational and 1H NMR data lead to the conclusion that the two complexes are best formulated as [Sn 2 IISn 2 IVL 12] where L −H 2or − or H 2thor −. The central cluster of two Sn(II) and two Sn(IV) atoms is proposed to be held together by eight bidentate bridging carboxylate groups, each of which bridges one Sn(II) and one Sn(IV) atom, while the remaining four ligands appear to form links among the clusters via bridging carboxylate groups.

Organolanthanoids. XV. The Preparation of Carboxylatobis(cyclopentadienyl)ytterbium(III) Complexes by Oxidation of Bis(cyclopentadienyl)ytterbium(II)

The complexes, Cp2Yb(O2CR) [Cp = cyclopentadienyl; R = Me, CF3, Ph, C6F5, C6Br5, o- MeO2CC6F4 (tmcp), 2,4,6-Me3C6H2 (tmp), pyridin-2-yl (pyr), or quinolin-2-yl (quin)] have been prepared in good yield by oxidation of bis(cyclopentadienyl)(1,2-dimethoxyethane)ytterbium(II) with the appropriate mercury(ll) or thallium(I) carboxylate, generally in tetrahydrofuran. Structural data suggest that four complexes (R=Me, CF3, Ph or C6F5) are dimeric with bridging bidentate carboxylate groups, three (R = tmp, pyr or quin) are monomeric with chelating carboxylates, but the structure is less clear for R = C6Br5 or tmcp. Unit cell dimensions have been determined for bis(cyclopentadienyl)(2,4,6-trimethyibenzoato)ytterbium(III), but the structure could not be solved owing to decomposition of single crystals in the X-ray beam.