Fumarate Dianion Research Articles

Carboxylato-bridged 3D polymeric networks of Gd(III): Synthesis, crystal structure, magnetic property and thermal behavior

Two novel polymeric carboxylato-bridged gadolinium(III) complexes of formulae, [Gd 2(fum) 3(H 2O) 4] · 2H 2O ( 1) and [Gd 2(tart) 3(H 2O) 2] · 3H 2O ( 2) (fum, fumarate dianion; tart, tartrate dianion) have been synthesized and characterized by single crystal X-ray diffraction studies, low-temperature magnetic measurements and thermal studies. The structure determination reveals a 3D network containing nine coordinated Gd(III) ions: for complex 1, the coordination sphere of gadolinium(III) comprises of two water molecules and seven oxygen atoms from fumarate dianions and for complex 2, a water molecule and eight oxygen donors from tartrate dianions. Variable-temperature magnetic susceptibility measurement reveals the existence of a weak antiferromagnetic coupling through the gadolinium ions. The best-fit parameters for complex 1, assuming a simplified structural model led to J = −0.0076 cm −1, g = 2.0, R = 2 × 10 −5 whereas for complex 2 the double-layered structure inside the 3D network impedes the possibility to calculate the J value(s).

Catena-Poly[[diaqua(1,10-phenanthroline-κ2N,N′)cadmium(II)]-μ-fumarato-κ2O:O′

In the title polymeric complex, [Cd(C4H2O4)(C12H8N2)(H2O)2]n, the CdII ions are bridged by fumarate dianions to form zigzag complex chains. π–π stacking is observed between the parallel phenanthroline ligands of neighboring complex chains. The Cd ion is located on a twofold axis and has a distorted octa­hedral coordination geometry, while the fumarate dianion lies on an inversion center.

Synthesis and Crystal Structures of Two Cadmium Coordination Chain Polymers

AbstractHydrothermal reactions of cadmium precursors with 2, 2′‐bipyridine, fumaric acid or NaN3 in basified aqueous solutions gave rise to two cadmium complexes [Cd(bipy)(fum)(H2O)]n (1), and [Cd(bipy)(μ1, 1‐N3)2]n (2) (fum = fumarate dianion), which were characterized by X‐ray crystallography. Complex [Cd(bipy)(fum)(H2O)]n (1) crystallizes in the orthorhombic system, space group Pbca, with a = 9.0488(8), b = 16.246(3), c = 19.810(4) Å, and Z = 8 while complex [Cd(bipy)(μ1, 1‐N3)2]n (2) in the monoclinic system, space group C2/c, with a = 12.378(3), b = 14.788(3), c = 6.6139(13) Å, β = 91.49(3)°, and Z = 4. The photoluminescence spectra for compounds 1 and 2 have also been studied.

Use of Different Unsaturated Dicarboxylates Toward the Design of New 3D and 2D Networks of Copper(II)

AbstractTwo new polymeric complexes of copper(II), [Cu(L1)(μ‐fum)(μ‐H2O)]n (1) (fum = fumarate dianion; L1 = N,N′‐dimethylethane‐1,2‐diamine) and [Cu(L2)(μ‐tp)]n (2) [tp = terephthalate dianion; L2 = N‐(2‐aminoethyl)‐3‐amino‐1‐propanol], have been synthesized. The molecular structures are determined by X‐ray crystallography. Complex 1 is a fumarato‐bridged zig‐zag 1D chain of CuII−L1, which is extended to a 3D coordination polymer through bridging water molecules. Complex 2 is a chain of CuII in which the terephthalate anions bridge in alternate bis(bidentate) and bis(monodentate) fashions. The coexistence of such types of bridging modes of terephthalate ions in a single molecule is unprecedented. The chelating terephthalate ion is linked to an equatorial and an axial site of consecutive metal ions, while the other terephthalate ion is axially linked to CuII centers. Both the complexes are characterized by variable‐temperature susceptibility measurements at room temperature down to 4 K. Fitting of the magnetic data reveals the existence of weak antiferromagnetic interactions through the bridging dicarboxylate pathways. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Catena-Poly[[diaquabis(1H-benzimidazole-κN3)nickel(II)]-μ-fumarato-κ2O:O′

The title compound, [Ni(μ-C4H2O4)(C7H6N2)2(H2O)2]n, is a one-dimensional polymeric complex bridged by fumarate dianions. The Ni atom lies on one inversion centre and the fumarate on another. The molecular chains are linked by hydrogen bonding. π–π stacking between parallel benz­imidazole rings exists in the crystal structure.

Hydrothermal Synthesis of Two Mixed‐Valence Copper Complexes with Mixed Ligands

AbstractHydrothermal reactions of copper salts with fumaric acid, 1, 10‐phenanthroline or 2, 2‐bipyridine in basic aqueous solution gave rise to two mixed‐valence copper complexes [Cu4(ophen)4(fum)] (1) and [Cu4(obipy)4(fum)]·6H2O (2) (fum = fumarate dianion, Hophen = 2‐hydroxy‐1, 10‐phenanthroline and Hobpy = 6‐hydroxy‐2, 2′‐bipyridine), which were characterized by single crystal X‐ray analysis. [Cu4(ophen)4(fum)] (1) crystallizes in the monoclinic space group P21/n, with a = 10.4749(8), b = 13.4210(9), c = 15.1090(10)Å, β = 103.811(3)° Z = 2; [Cu4(obipy)4(fum)]·6H2O (2) has the triclinic space group P1¯, with a = 10.1302(11), b = 10.4406(12), c = 11.4450(13)Å, α = 84.384(2)°, β = 79.064(2)°, g = 67.734(2)° and Z = 1. The fumaric acid ligand acts as a multi‐dentate bridging ligand in both compounds, 1 and 2, to link copper atoms into dumbbell structure. During the reactions, 1, 10‐phenanthroline and 2, 2′‐bipyridine ligands are all hydroxylated into ophen and obipy, which provide useful structural evidence for the study on the Gillard mechanism.

Hydrothermal synthesis and structural characterization of three novel lanthanide coordination polymers with fumarate and 1,10-phenanthroline

Three novel lanthanide complexes, [Ln 2(fum) 3(phen) 2(H 2O) 2] n (Ln=La, 1; Pr, 2. fum=fumarate dianion; phen=1,10-phenanthroline) and [Er 2(fum) 3(phen) 2] n ( 3), were synthesized hydrothermally and characterized by X-ray crystallography. Single crystal X-ray diffraction analysis shows that complex 1 is isostructural with 2. Ln(III) centers are nine-coordinated in 1 and 2 but eight-coordinated in 3 duo to lanthanide contraction. The coordination modes of fumarate and phen ligands are identical in three complexes. So structures of three complexes are very similar. In three structures, Ln(III) ions are bridged by fumarate anions in two modes, forming polymeric sheets. These sheets are further assembled into 3D supramolecular network by different intermolecular hydrogen bonding and π–π stacking interactions duo to the lack of coordinated water in 3. IR spectra are assigned based on the molecular structures.

Catena-Poly[[diaquabis(benzimidazole-κN)cobalt(II)]-μ-fumarato-κ2O1:O4

The title polymeric complex, [Co(μ-C4H2O4)(C7H6N2)2(H2O)2]n, displays a one-dimensional chain structure bridged by fumarate dianions. In the crystal structure, the polymeric chains are linked to each other by hydrogen bonds. The overlapped arrangement and the short separation of 3.35 (2) Å suggest the existence of π–π stacking between parallel benz­imidazole rings. The CoII atom exists in a centrosymmetric octahedral geometry.

Cyclic Water Hexamers and Decamers in a Porous Lanthanide−Organic Framework: Correlation between Some Physical Properties and Crystal Structure

Erbium fumarate [Er2(fum)3(H2O)4]·8H2O, 1, (fum = fumarate dianion) crystallizes at room temperature in a silica gel column. The structure is three-dimensional and consists of layers of erbium fumarate pillared by fumarate dianions acting in the bis-chelating mode. The layers contain arrays of erbium cations bridged by fumarate dianions acting in the bis-bidentate bridging mode. The relatively large channels formed in the direction of the a and c axes are filled by water molecules that form a hydrogen bonded layer, comprising cyclic hexamers with both boat and chair conformations and cyclic decamers with boat−chair−boat conformation. The water molecules are reversibly removed at 90 °C. The evacuated metal−organic framework, 2, is stable up to 400 °C. Both compounds 1 and 2 exhibit weak antiferromagnetic interactions.

Tris(phenanthroline-κ2N,N′)cobalt(II) fumarate fumaric acid tetrahydrate

The title compound, [Co(C12H8N2)3](C4H2O4)0.5(C4H3O4)·1.5C4H4O4·4H2O, consists of the cobalt(II) complex cation with phenanthroline (phen), half a fumarate dianion, a fumarate monoanion, one and a half fumaric acid mol­ecule and uncoordinated water mol­ecules. The separations of 3.342 (8) and 3.493 (15) Å between the phen rings related by inversion centers indicate the existence of π–π-stacking interactions between the neighboring complex ions. These complex mol­ecules assemble as hydro­phobic layers via π–π stacking. Fumarate, fumaric acid and water are linked to each other to form hydro­philic layers by hydrogen bonding in the crystal structure.

Synthesis, Crystal Structures, and Magnetic Properties of Two New 1D Copper(II) Coordination Polymers Containing Fumarate(−2) and Chelating N,N′-Donor as Ligands

Two new polynuclear complexes of CuII, [Cu2(fum)(μ-OH)(bpy)2(H2O)](NO3)·2H2O (1) (fum = fumarate dianion, bpy = 2,2′-bipyridine) and [Cu(fum)(tmen)]·2H2O (2) (tmen = N,N,N′,N′-tetramethylethane-1,2-diamine), have been synthesized and structurally characterized by X-ray crystallography. Complex 1, C24H27Cu2N5O12, crystallizes in a triclinic system, space group P , with a = 10.168(14), b = 11.347(14), c = 14.74(2) A, and Z = 2; complex 2, C10H22CuN2O6, crystallizes in an orthorhombic system, space group Pbca, with a = 14.701(19), b = 14.899(19), c = 26.90(3) A, and Z = 16. Compound 1 is an alternating chain compound, with alternate repetition of bis(monodentate) (μ2) and bis(bidentate) (μ4) bridging modes of fumarate, showing ferromagnetic interaction between CuII ions through hydroxo bridges with a Cu−O−Cu angle of 108.5°. Compound 2 is a linear 1D zig-zag polymer. There are two copper(II) ions with equivalent coordination and geometry in the asymmetric unit, each of them bonded to a bidentate tmen ligand and to two different fumarate moieties. Magnetic susceptibility data were measured in the 300−2 K temperature range. The magnetic data for 1 were fitted by use of a ferromagnetic/antiferromagnetic alternating S = 1/2 chain system and show the following results: JF = +5.4 cm−1, JAF = −0.25 cm−1, g = 1.96. The susceptibility data of 2 were fitted by use of the Bonner−Fisher expression for antiferromagnetically coupled S = 1/2 local spins, giving the parameters J = −1.81 cm−1, g = 2.03.

Self-assembly directed by NH–O hydrogen bonding: new molecular assemblies derived from N, N-tetramethyl-1,2-diaminoethane and malonic or fumaric acid incorporating ‘proton transfered’ hydrogen bonds

Co-crystallisation of N, N-tetramethyl-1,2-diaminoethane (TMEN) and malonic or fumaric acid from water in a 1:1 ratio results in crystalline products whose X-ray structures show that they contain hydrogen-bonded motifs in self-assembled arrays. The stoichiometry of the malonate-containing assembly is 1:2, [TMENH 2(hydrogen malonate) 2], while that of the fumarate-containing assembly is 1:1:1 (TMENH 2, fumarate, fumaric acid). In each structure, protons from individual carboxylic acids have been transferred onto the nitrogens of N, N-tetramethyl-1,2-diaminoethane (TMEN) to yield diammonium cations; the ammonium protons hydrogen bond to carboxylate oxygens of hydrogen malonate in one case or to fumarate anions in the other. The hydrogen malonate-containing structure has layers of aligned diprotonated TMEN separated by layers of hydrogen malonate anions. Successive hydrogen malonate ions are hydrogen bound in an 'alternate’ manner between adjacent protonated TMEN layers. Each [TMENH 2(hydrogen malonate) 2] moiety describes an approximate 'Z’ configuration which are in turn stacked at an oblique angle; adjacent ‘columns of Zs’ are partially interlaced to form the overall array. The fumarate-containing structure consists of parallel ribbons of alternating, hydrogen bonded, fumarate dianions and fumaric acid molecules. These form layers alternating with layers of diammonium ions which lie essentially in the xy plane. The diammonium ions form parallel staggered head-to-tail chains along the y axis and so run at an angle across the fumarate-fumaric acid ribbons.

A three component fully interlocked 3-D network: crystal structure and magnetic properties

A one-pot reaction of three different components [Cu(II), fumarate dianion and piperazine] leads to the self assembly of a magnetic molecular fully interlocked 3D structure with (4,4) nets formed by equal 2D sheets.

Mononuclear and binuclear complexes of iron(III) with the tetradentate Schiff base derived from salicylaldehyde and 1,2 diaminopropane

The complexes of type [Fe(salpn)L]ClO 4 [L = bpy (2,2′-bipyridyl) or phen ( o-phenanthroline), H 2salpn = N, N′-bis(salicylidene)propylenediamine] and type [(Fe (salpn)) 2L] (L = terephthalate or fumarate dianion) have been prepared and studied by elemental analyses, IR and electronic spectroscopies and magnetochemical measurements. An octahedral arrangement of iron(III) ( S = 5/2) is proposed. The complexes with dicarboxylic acids are probably binuclear and magnetically diluted at room temperature. The compounds with bpy or phen are probably mononuclear. Regarding their anomalous μ eff values (5.52 or 4.25 B.M.), the temperature dependence of magnetic susceptibility was measured, but antiferromagnetic exchange interaction or spin equilibrium were not found.

Dinuclear, diuranyl-containing metallomacrocycles: neutral receptors for dicarboxylates

Dinuclear UO2-sal(oph)en metallomacrocycles 1 and 2, containing flexible and rigid cavities, respectively, have been found linearly to recognise and form strong solution complexes with terephthalate, succinate and fumarate dianions in (CD3)2SO; weaker interactions between these hosts and the shorter malonate and monoanionic benzoate were observed.

The effect of carboxylic acids on the dissolution of calcite in aqueous solution. Part 1.—Maleic and fumaric acids

The effects of maleic and fumaric acids and their mono- and di-anions on the dissolution of calcite in aqueous solution have been studied over a wide pH range (3–8.5) by (i) the channel flow cell method, (ii) etch pit morphology measurements and (iii) the determination of adsorption isotherms. It is established that the mono-anion of maleic acid reacts with CaCO3via a first order heterogeneous process of rate constant 0.014 cm s–1 indicating a significant inhibition of the dissolution reaction as compared to dissolution in HCl of comparable pH. The inhibition is attributed to adsorption of the dianion and the shapes of the etch pits are used to infer the crystallographic environment of the adsorption sites on the (100) surface. In contrast the monoanion of fumaric acid shows no such inhibition. Under conditions where both maleic mono- and di-anions are present it is demonstrated that a Langmuirian adsorption of the latter occurs at dislocations greatly reducing the rate of dissolution. Again the fumaric acid system is impotent. Around pH 8 where the dissolution reaction is controlled by a process involving H2O, rather than a proton source, strong inhibition is observed in the presence of Langmuirian adsorption of trace amounts of the maleate dianion (10–6 mol dm–3). Much higher levels (10–3 mol dm–3) of fumarate dianion are required for a comparable effect.