Malonate Dianion Research Articles

Diaqua(2,2′-diamino-4,4′-bi-1,3-thiazole)(malonato)nickel(II)

The title complex, [Ni(C6H6N4S2)(C3H2O4)(H2O)2], has a distorted octahedral coordination geometry with the malonate dianion and di­amino­bi­thia­zole chelating to the NiII atom in the equatorial plane, and two water mol­ecules in the axial positions. Both the malonate and di­amino­bi­thia­zole are planar, and are tilted out of the equatorial plane, with dihedral angles of 9.87 (5) and 11.65 (5)°, respectively.

Malonic Acid: A Multi-Modal Bridging Ligand for New Architectures and Properties on Molecule-Based Magnets

Abstract In this work, we show how the design of one-, two- and three-dimensional materials can strongly benefit from the use of crystal engineering techniques, which can give rise to structures of different shapes, and how these differences can give rise to different properties. We will focus on the networks constructed by assembling malonate ligands and metal centres. The idea of using malonate (dianion of propanedioic acid, H 2 mal) is that they can give rise to different coordination modes with the metal ions bind. Extended magnetic networks of dimensionalities 1 (1D), 2 (2D) and 3 (3D) can be chemically constructed from malonato-bridged metallic complexes. These coordination polymers behave as ferro-, ferri- or canted antiferromagnets. The control of the spatial arrangement of the magnetic building blocks is of paramount importance in determining the strength of the magnetic interaction. It depends on the coordination bond between the metal ion and the ligands, and on supramolecular interactions such as stacking interactions or hydrogen bonds.

Aqua(malonato-κ2O,O′)(pyridine-2-carboxamide-κ2N1,O)copper(II) monohydrate

The title compound, [Cu(mal)(pca)(H2O)]·H2O [mal is the malonate dianion, CH2(COO)22−, and pca is pyridine-2-carbox­amide, C6H6N2O), has a five-coordinated Cu atom in a distorted square-pyramidal environment, coordinated by two O atoms of the malonate ion, an O atom and an N atom of pca, and an O atom of water. An uncoordinated water mol­ecule stabilizes the complex by participation in a hydrogen-bonding system. The crystal structure is built from layers parallel to the (111) plane.

Poly[disodium bis(μ-malonato)zincate(II) dihydrate

The title compound, {Na2[Zn(C3H2O4)2]·2H2O}n, is a three-dimensional polymeric complex bridged by malonate dianions. The malonate ligand exhibits versatile coordination modes and links two ZnII and four NaI atoms. The Zn atom occupies a special position in an inversion centre and is chelated by two malonate ligands [Zn—O = 2.0230 (10) and 2.0875 (11) A]; two other malonates are involved in monodentate coordin­ation of the Zn atom [Zn—O = 2.2789 (12) A], thus completing its octahedral coordination environment. The Na atom also has a distorted octahedral coordination, formed by four carboxyl­ate O atoms of four malonate ligands [2.4328 (15)–2.5493 (13) A] and two water mol­ecules [2.3749 (15) and 2.4144 (14) A].

Tetrakis(benzimidazole-κN)(malonato-κ2O,O′)cobalt(II)

The title cobalt(II) compound, [Co(C3H2O4)(C7H6N2)4], displays an octahedral coordination geometry formed by four benz­imidazole ligands and one malonate dianion. The malonate chelates to the CoII atom with both terminal carboxyl groups in a boat configuration. The uncoordinated carboxyl O atoms of the malonate are hydrogen bonded to the neighboring benz­imidazole ligands.

Design of high-dimensional copper(II) malonate complexes with exo-polydentate N-donor ligands.

Two polymeric malonato-bridged copper(II) complexes of formulas [(H(2)bpe)[Cu(mal)2]]n.4nH2O (1) and [Cu(4")(mal)(4)(bpe)(3)]n.6nH(2)O (2) [mal = malonate dianion; bpe = 1,2-bis(4-pyridyl)ethylene] have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in triclinic space group P(-)1, Z = 1, with unit cell parameters a = 4.8831(10) A, b = 9.585(2) A, c = 11.813(2) A, alpha = 77.29(3) degrees, beta = 82.18(3) degrees, and gamma = 84.92(3) degrees, whereas complex 2 crystallizes in the monoclinic space group P2(1)/n, Z = 4, with unit cell parameters a = 13.462(3) A, b = 10.275(5) A, c = 19.579(4) A, and beta = 105.21(3) degrees. The structure of 1 consists of anionic malonato-bridged uniform copper(II) chains which are connected through hydrogen bonds involving malonate-oxygen atoms, noncoordinated water molecules, and H(2)bpe(2+) cations. The intrachain copper-copper separation through carboxylate-malonate bridge in the anti-syn conformation is 4.8831(10) A. Complex 2 possesses a three-dimensional structure made up of neutral corrugated malonated-bridged copper(II) layers linked through bis-monodentate bpe molecules. The copper(II) atoms within each layer are bridged by a double mu-oxo and four carboxylato-malonate bridges with copper-copper separations of 3.4095(7) A (through oxo) and 4.9488(11)-6.5268(13) A (through carboxylato). The shortest interlayer copper-copper separation across bridging bpe is 13.434(3) A. Variable-temperature magnetic measurements (2-290 K) show an overall ferromagnetic behavior for both compounds. The magnetic pathway of complex 1 is through a single carboxylate-malonate bridge connecting apical and equatorial positions of adjacent copper(II) atoms, and the value of the magnetic coupling (J) for 1 through a numerical expression for a ferromagnetic uniform chain of interacting local doublets is J = +0.049(1) cm(-1). The values for the magnetic couplings through the main intralayer exchange pathways in 2 which correspond to carboxylate-malonate bridges connecting equatorial-equatorial (J(1)) and equatorial-apical (J(2)) coordination sites and to the double mu-oxo bridge linking equatorial-apical (J(5)) positions have been determined through a simplified model. The three magnetic couplings are weak, two of them being ferromagnetic (J(1) = +23(1) cm(-1) and J(2) = +6.5(1) cm(-1)) and the other one antiferromagnetic [zJ' = -1.0(1) cm(-1)]. The values of the magnetic couplings in 1 and 2 compare well with those previously reported for similar malonato-bridged copper(II) complexes of different dimensionalities.

Polymeric aqua(benzimidazole-κN)(μ-malonato)cobalt(II)

The crystal structure of the title compound, [Co(C3H2O4)(C7H6N2)(H2O)]n, consists of two-dimensional polymeric CoII complex layers. The octahedral coordination around a CoII atom is composed of a chelate malonate, two monodentate malonate anions from the adjacent asymmetric unit, a bez­imidazole ligand and a coordinated water molecule. Each malonate dianion links three CoII atoms related by an n-glide plane to form polymeric layers in the (010) plane. π–π stacking of the benz­imidazole ligands occurs between adjacent polymeric layers, the separation between parallel benz­imidazole rings being 3.42 (2) A.

Two new supramolecular malonato complexes of manganese(II): synthesis, crystal structure and magnetic property

A mononuclear [Mn(mal)(bipy)(H 2O) 2] ( 1) and a dinuclear [Mn 2(mal)(phen) 3(H 2O) 2(Cl)]Cl ( 2) (mal=malonate dianion; bipy=2,2′-bipyridine and phen=1,10-phenanthroline) have been synthesised and structurally characterized by X-ray crystallography. The structure of complex 1 shows that each Mn(II) is linked with one bipy, two water molecules and a malonate ligand forming distorted octahedral environment and each mononuclear fragment through H-bonding interactions form 2D supramolecular network. The structure of complex 2 comprises to an asymmetric dinuclear cation which is bridged by a single anti–anti malonate ligand and chloride anions. The two distorted Mn(II) centres are separated by large distance 6.256(3) Å due to the anti–anti bridging mode. The magnetic behavior of complex 2 studied in the temperature range 300–2 K corresponds to a weak antiferromagnetic coupling through the MnOCOMn anti–anti conformation. The magnetic data were fitted based on H=−2 JS 1·S 2, yielding the intramolecular coupling constant J=−0.35 cm −1 with g=1.92 and R=1.255×10 −4.

Diaqua(2,2'-bipyridine)malonatomanganese(II).

In the crystal structure of the title compound, [Mn(C(3)H(2)O(4))(C(10)H(8)N(2))(H(2)O)(2)], the Mn(II) atom demonstrates a distorted octahedral geometry, being coordinated by two N atoms of a 2,2'-bipyridine ligand, two O atoms from the carboxylate groups of the chelating malonate dianion and two O atoms of two cis water molecules. The complex molecules are linked to form a three-dimensional supramolecular array by both hydrogen-bonding interactions between coordinated water and the carboxylate groups of neighboring molecules and aromatic pi-pi-stacking interactions of the bipyridine rings.

Magneto-structural xorrelations in 2D and 3D extended structures of manganese(II)-malonate systems.

Two polymeric malonato-bridged manganese(II) complexes of formula [Mn(mal)(H(2)O)(2)](n)() (1) and [Mn(2)(mal)(2)(4,4'-bipy)(H(2)O)(2)](n)() (2) have been synthesized and characterized (mal = malonate dianion; 4,4'-bipy = 4,4'-bipyridine). The crystal structure of complex 1 was already known. Complex 2 crystallizes in monoclinic space group P2(1)/n, Z = 2, with unit cell parameters of a = 7.2974(10) A, b = 18.7715(10) A, c = 7.514(3) A, and beta = 91.743(12) degrees. The structure determination reveals that the complex [Mn(2)(mal)(2)(4,4'-bipy)(H(2)O)(2)](n)() (2) is a 3D network being composed of Mn-malonate sheets which are pillared by bidentate 4,4'-bipy spacer forming small voids. The Mn-Mn distances through Mn-mu-(O3-C8-O4)-Mn, Mn-mu(O1-C6-O2)-Mn, and Mn-mu-4,4'-bipy-Mn bridges are 5.561, 5.410, and 11.723 A, respectively. The magnetic behaviors of complexes 1 and 2 in the temperature range 300-2 K are very close, corresponding to a weak antiferromagnetic coupling. The magnetic pathways of complex 1 are through two Mn-O-C-O-Mn with anti-anti conformation and two Mn-O-C-O-Mn with syn-anti conformations and in complex 2 through all Mn-O-C-O-Mn with syn-anti conformations. Both syn-anti and anti-anti conformations create weak antiferromagnetic coupling, and the susceptibility data are fitted by the expansion series of Lines and the Curély formula for an S = 5/2 antiferromagnetic quadratic layer, based on the exchange Hamiltonian H = -Sigma(nn)()JS(i)()S(j)(). The best fit is given by the superexchange parameters J = -0.32 cm(-)(1) and g = 2.00 for complex 1 and J = -0.14 cm(-)(1), J(inter) = -0.031 cm(-)(1), and g = 2.00 for complex 2. Finally, in both the complexes there is a magnetic pathway Mn-O-C-C-C-O-Mn, and this pathway through the three carbon atoms of the malonato-bridging ligand could be considered negligible.

Ferromagnetic coupling in the malonato-bridged copper(ii) chains [Cu(Im)2(mal)]nand [Cu(2-MeIm)2(mal)]n(H2mal = malonic acid, Im = imidazole and 2-MeIm = 2-methylimidazole)

Two new malonato-bridged copper(II) complexes of formula [Cu(Im)2(mal)]n (1) and [Cu(2-MeIm)2(mal)]n (2) (Im = imidazole, 2-MeIm = 2-methylimidazole and mal = malonate dianion) have been prepared and their structures solved by X-ray diffraction methods. The [Cu(Im)2(mal)] and [Cu(2-MeIm)2(mal)] neutral entities act as monodentate ligands towards the adjacent copper(II) units through one of the two carboxylate groups, the OCO bridge exhibiting an anti-anti conformation. The environment of each copper atom in 1 and 2 is distorted square pyramidal: two carboxylate oxygen atoms from a bidentate malonate and two nitrogen atoms from two imidazole (1) or 2-methylimidazole (2) ligands form the equatorial plane whereas the apical position is occupied by a carboxylate oxygen from the malonate group of the neighbouring complex unit. The intrachain copper-copper separation is 6.036(2) (1) and 6.099(2) Å (2). The magnetic properties of 1 and 2 have been investigated in the temperature range 1.9–290 K. Overall, ferromagnetic behaviour is observed in both cases and the intrachain magnetic coupling (J) between the copper(II) ions through the carboxylato group is found to be 1.64 (1) and 0.39 cm−1 (2) (the Hamiltonian being H = −JΣiSi·Si+1).

Thermodynamics of dioxoneptunium(V) complexation by dicarboxylic acids

The free energy and enthalpy changes associated with complexation of NpO2+by oxydiacetic acid, iminodiacetic acid, and malonic acid have been measured in 1 M NaClO4at 25 °C using spectrophotometric, potentiometric, and calorimetric titrations. Only 1:1 complexes were observed with the oxydiacetate and iminodiacetate dianions, while both 1:1 and 1:2 complexes were observed with the malonate dianion. The free energies indicate that all of the potential donor groups are bound to the neptunium center. The favorable complexation entropies are unusually large for the NpO2+-oxydiacetate complex, suggesting a unique interaction of the metal-ligand complex with the solvent molecules. Relationships between the free energies of complexation of UO22+and NpO2+and between the dicarboxylate complexation entropies of NpO2+and a variety of metal cations are developed and discussed.

Magnetic coupling through the carbon skeleton of malonate in two polymorphs of ([Cu(bpy)(H2O)][Cu(bpy)(mal)(H2O)])(ClO4)2 (H2mal = malonic acid; bpy = 2,2'-bipyridine).

Two polymorphic malonato-bridged copper(II) complexes of formula ([Cu(bpy)(H2O)][Cu(bpy)(mal)(H2O)])-(ClO4)2 (1 and 2) (bpy = 2,2'-bipyridine and mal = malonate dianion) have been prepared and their structures solved by X-ray diffraction methods. Compound 1 crystallizes in the monoclinic space group P2(1)/a, with a = 23.743(3) A, b = 9.7522(5) A, c = 27.731(2) A, beta = 114.580(10) degrees, and Z = 4. Compound 2 crystallizes in the orthorhombic space group Pbcn, with a = 23.700(5) A, b = 25.162(5) A, c = 9.693(5) A, and Z = 4. The structures of 1 and 2 are made up of uncoordinated perchlorate anions and malonate-bridged zigzag copper(II) chains grouped in an isosceles triangle running parallel to the b (1) and c (2) axes. These chains are built by a [Cu(bpy)(mal)(H2O)] unit acting as bis-monodentate ligand toward two [Cu(bpy)(H2O)] adjacent units through its OCCCO skeleton in an anti-anti conformation, whereas the OCO carboxylate bridges exhibit the anti-syn conformation. Compounds 1 and 2 contain four crystallographically independent copper(II) atoms, but the environment of all of them is distorted square pyramidal: the axial position is occupied by a water molecule, whereas the equatorial plane is formed by a chelating bpy and either a bidentate malonate or two carboxylate oxygens from two malonate groups. The equatorial Cu-O(mal) (1.911(4)-1.978(4) (1) and 1.897(5)-1.991(4) A (2)) and Cu-N(bpy) (1.983(4)-2.008(5) (1) and 1.971(6)-2.007(6) A (2)) bonds are somewhat shorter than the axial Cu-O(w) one (2.257(5)-2.524(5) (1) and 2.236(5)-2.505(6) A (2)). The angles subtended at the copper atom by the chelating bpy vary in the ranges 80.9(2)-81.8(2) degrees (1) and 80.4(2)-82.1(2) degrees (2), values which are somewhat smaller than those of the chelating malonate (80.4(2)-82.1(2) degrees (1) and 93.0(2)-93.6(2) degrees (2)). The intrachain copper-copper separations through the OCCCO fragment are 8.227(1) (1) and 8.206(2) A (2), whereas those through the OCO bridging unit are 4.579(1)-5.043(1) (1) and 4.572(2)-5.040(2) A (2). The magnetic behavior of 1 and 2 in the temperature range 2.0-290 K is very close, and it corresponds to an overall ferromagnetic coupling, the chi MT versus T curve exhibiting a maximum at 18 K. The analysis of the magnetic data through a numerical expression derived for the real topology of 1 and 2, that is, chains of isosceles triangles with two intrachain exchange pathways J1 (exchange coupling through the OCO carboxylate) and J2 (exchange coupling through the OCCCO malonate), indicates the occurrence of ferro- (J1 = +4.6 cm-1) and antiferromagnetic couplings (J2 = -4.2 cm-1). The magnetic coupling through these exchange pathways is further analyzed and substantiated by density functional theory calculations on a malonate-bridged trinuclear copper(II) model system.

A novel alpha-helix-liked metallohelicate series and their structural adjustments for the isomorphous substitution.

A novel metallohelical motif is well designed and synthesized by mimicking the alpha-helical fold structure of protein. The 1D helical structures of [Cd(CH2(COO)2)(SC(NH2)2)2]n (I) and [Zn(CH2(COO)2) (SC(NH2)2)2]n (II) are primarily induced and stabilized by the multiple long-range intrahelix hydrogen bonds. Malonate dianion acts as a bidentate ligand coordinated with metal ions to form the backbone of the helix, and thiourea molecules that bend into the helical turn are involved in the intrahelix hydrogen-bond system. The metal ion occupations in the helix of I and II can be freely substituted by simply controlling the initial ratio of those two metal ions. Single crystals of three mixed metal ion complexes of [Cd0.77Zn0.23(CH2(COO)2)(SC(NH2)2)2]n (III), [Cd0.50Zn0.50(CH2(COO)2)(SC(NH2)2)2]n (IV), and [Cd0.21Zn0.79(CH2(COO)2)(SC(NH2)2)2]n (V) were synthesized from systems with an initial Cd/Zn mole ratio of 1:1 for III, 1:2 for IV, and 1:8 for V. They are isomorphous as confirmed by X-ray characterization. When the metal ion is substituted, the multiple intrahelix hydrogen interaction motifs of the coordination polymer structure are self-adjusted to sustain their 1D helical motifs.

Supramolecular Catalysis of H/D Exchange in Malonate Ions by Macrocyclic Polyamines: A Model Enzyme with Enolase Activity

In three ways at once the macrocyclic polyamine [24]aneN6O2 promotes the H/D exchange at the α position in malonate ions: The quadruply protonated species in neutral pH range forms a quite stable dicationic complex (1) with the malonate dianion, which facilitates the approach of a base and assists the enolization through the acidic NH+ centers. The acceleration factor for the fourfold protonated polyamine [24]aneN6O2 is kcat/kuncat ≈ 1.4 × 103.

Rational Synthesis of Dinuclear Mixed-Valence Cu(I)/Cu(II)Carboxylate Derivatives. Steric Influence of Phosphine Ligands on the Structures of the Complexes

The mixed-valence Cu(I)/Cu(II) complexes (Ph 3 P) 4 Cu I 2 Cu II (O 2 CCH 2 CO 2 ) 2 (1) and (Cy 3 P) 4 Cu I 2 Cu II (O 2 CCH 2 -CO 2 ) 2 (2), have been prepared from the acid-base reaction of Cu II (acac) 2 or Cu II (butyrate) 2 with the respective copper(I) hydrogen dicarboxylate derivative and their solid-state structures determined crystallographically. The Cu(II) center in both derivatives is chelated by two malonate dianions in a squate-planar geometry

Anion‐receptor molecules: Macrocyclic and macrobicyclic effects on anion binding by polyammonium receptor molecules

AbstractThe stability constants for anion binding by the acyclic hexaamine 1, its macrocyclic analogue 2, and the bicyclic compound 3 in their protonated forms are reported. Compound 3 forms stable and selective complexes with halide ions, the stability sequence being I− > Br− > Cl−. Compound 2 forms more stable complexes with sulfate, oxalate, and malonate dianions than its acyclic analogue 1 and shows a better selectivity pattern. Compound 3 forms stronger complexes with oxalate2− than 2 and shows a remarkably high binding selectivity between oxalate2− and malonate2−. The comparison of the ability of 1–3 to complex anions demonstrates the macrocyclic and macrobicyclic effects on anion binding stability and selectivity.

Ternary Coordination Complexes Formed by Copper(II) with Thio-or Dithiodialkanoic Acids and Some Selected Ethyl-substituted Malonic Acids

Abstract Binary and ternary complexes formed by copper(II) with thio- or dithiodialkanoic acids and ethyl-substituted malonic acids have been investigated potentiometrically in an aqueous solution and the relevant stability constants have been evaluated using computer technique. Thio- and dithiodialkanoic acids were thiodiacetic, dithiodiacetic, 3,3′-thiodipropionic, and 3,3′-dithiodipropionic acids. The results are discussed in terms of substituent influences upon the chelation of the malonate dianions to the systems copper(II)-thiodialkanoic acids. It is suggested that in the mixed copper chelates containing thiodiacetic acid, the geometrical characteristics of the more basic ligand, governs the coordination of the other ligand.

Deuteration Reaction of Malonate Hydrogens in Some Monomalonatocobalt(III) Compounds

Abstract The rate of deuteration at malonate hydrogens has been measured for [Co(mal)(N)4]+ and [Co(malH)(NH3)5]2+ ions in aqueous solution over the pD range of 2 to 8, where mal=malonate dianion, malH=malonate monoanion, and (N)4=(NH3)4, (ethylenediamine)2, (1,3-propanediamine)2, (1,10-phenanthroline)2, or (2,2′-bipyridine)2. For the tetraamine type complexes with a chelated malonate ligand, the deuteration process is acid-catalysed up to pD=about 4 and base-catalysed at higher pD values. This contrasts with the behavior of the unidentate malonate ligand, for which the deuteration is base-catalysed up to pD=3.5, whereupon the deprotonation of the carboxylate group takes place and the deuteration rate steps down to a constant, pH-independent value. The deuteration mechanisms are discussed.

KINETICS AND MECHANISM OF ANATION OF AQUOPENTAAMMINECOBALT(III) BY CARBOXYLATE LIGANDS : STUDY OF THE MECHANISM OF FORMATION OF MALONATOPENTAAMINECOBALT (III) COMPLEX

Abstract Anation of aquopentaamminecobalt(III) by malonic acid, Hmalonate and malonate dianion has been studied in a medium of 0.3 M ionic strength adjusted with sodium perchlorate and at 55–70°. Ion pairing is not significant between the complex ion and malonic acid but is kinetically identifiable with Hmalonate and malonate dianion. The observed pseudo-first-order rate constants fit the equation: k obsd=k 0[H2 mal] + k 1 Q 1[Hmal−] + k 2 Q 2[mal2- / 1+ Q 1 [Hmal− + Q 2[mal2- where, k 0 is the second order rate constant of anation of(NH)3)5 CoOH2 3+ by malonic acid; k 2,Q 1 and k 2, Q 2 are the rate and stability constants of Hmalonate and malonate dianion ion-pairs respectively. At 60° and I=0.3 M, k 0=3.62(±0.26)×10−5 M−1 sec−1, k 1=39.3(±1.2)×10−5 sec−1, k 2=24.9(±1.6)×10−5 sec−1, and the essentially temperature independent parameters Q 1 Q 2 are 1.0 M−1 and 19.0 M−1 respectively. The activation parameters for k 0, k 1 and k 2 paths are: δH‡=23.1(±0.7), 27.1(±0.8), 29.0(±1.2) kcal mol−1 and δS ‡=-9.7(...