Malonate Dianion Research Articles

Synthesis, Thermal, Structural Analyses, and Photoluminescent Properties of a New Family of Malonate-Containing Lanthanide(III) Coordination Polymers.

Five new Lanthanide(III) complexes of malonic acid (HOOC-CH2-COOH); {[Gd(C3H2O4)(H2O)4]·NO3}n (1), {[Tb(C3H2O4)(H2O)4]·NO3}n (2), {[Ho(C3H2O4)(H2O)4]·NO3}n (3), [Er(C3H2O4)(C3H3O4)(H2O)2]n (4), and {[Eu2(C3H2O4)2(C3H3O4)2(H2O)6]·4H2O}n (5) were synthesized and characterized by elemental, infrared spectral, and thermal analyses. The structures of compounds 1–5 were determined by single crystal X-ray diffraction technique. The X-ray analysis reveals that compounds 1, 2, and 3 are isostructural and crystallized in the orthorhombic space group Pmn21. The lanthanide(III) ions are coordinated by four carboxylate and four water oxygen atoms adopting a distorted square antiprism geometry. The LnO8 square antiprisms are linked into infinite layers by malonate (C3H2) dianions sandwiching sheets of nitrate counter ions. Compound 4 contains ErO8 square antiprisms linked into a two-dimensional network by hydrogen malonate (C3H3) anions and malonate dianions. The europium complex, 5 is dinuclear having the two europium(III) ions (Eu1 and Eu2) bridged by carboxylate groups of hydrogen malonate ligands. The europium ions in 5 are nine-coordinate and exhibit a distorted monocapped square antiprism geometry. All the structures are consolidated by O–H⋯ O hydrogen bonds. The photoluminescence spectra of 1–5 exhibit characteristic emissions in the visible region. The IR spectra and thermal data are consistent with the structural results. The room-temperature effective magnetic moments for 1–4 are in good agreement with those expected for the free ions, while the data for 5 indicates that low-lying excited states contribute to the observed moment. The compound 1 was further subjected to quantum computational calculations to explore its optoelectronic properties including; density of states (DOS), dielectric function, refractive index, extinction coefficient, and absorption spectrum, to highlight the possible applications of such materials in the optoelectronics.

Mechanistic Studies on the Copper-Catalyzed N-Arylation of Alkylamines Promoted by Organic Soluble Ionic Bases

Experimental studies on the mechanism of copper-catalyzed amination of aryl halides have been undertaken for the coupling of piperidine with iodobenzene using a Cu(I) catalyst and the organic base tetrabutylphosphonium malonate (TBPM). The use of TBPM led to high reactivity and high conversion rates in the coupling reaction, as well as obviating any mass transfer effects. The often commonly employed O,O-chelating ligand 2-acetylcyclohexanone was surprisingly found to have a negligible effect on the reaction rate, and on the basis of NMR, calorimetric, and kinetic modeling studies, the malonate dianion in TBPM is instead postulated to act as an ancillary ligand in this system. Kinetic profiling using reaction progress kinetic analysis (RPKA) methods show the reaction rate to have a dependence on all of the reaction components in the concentration range studied, with first-order kinetics with respect to [amine], [aryl halide], and [Cu]total. Unexpectedly, negative first-order kinetics in [TBPM] was observed...

A combined experimental and theoretical study of the supramolecular self-assembly of Cu(II) malonate complex assisted by various weak forces and water dimer

A Cu(II) malonate complex with formula [Cu(C3H2O4)(C6H8N2)(H2O)]2·4H2O (1) [C6H8N2=2-picolylamine, C3H2O42−=malonate dianion] has been synthesized by mixing the reactants in their stoichiometric proportion and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, monomeric neutral metal malonate units [Cu(C3H2O4)(C6H8N2)(H2O)] are interlinked with each other through hydrogen bonds, weak lone pair⋯π and cuprophilic interactions to generate supramolecular dimers, which in turn further associated through hydrogen bonding to form infinite 1D chains. Water dimers, through series of hydrogen bonds and weak π–stacking forces are found to be responsible for interconnection of 1D chains, which resulted in a 3D network. A density functional (DFT) study of the energetic features of several noncovalent interactions observed in the solid state have been analyzed and characterized using Bader׳s theory of “atoms-in-molecules”. We also present here Hirshfeld surface analysis to investigate the close intermolecular contacts.

The crystallochemical role of malonate ions in coordination polymers

All compounds that contain malonate dianions C3H2O42-(mal2-) and atoms of d- or f-metals were analyzed. Dianions mal2-in structures of examined compounds reveal 17 topological types of coordination against metal atoms. Available data shows that mal2-more often form six-membered metal cycles which is the most abundant case for all 570 crystallographic sorts of analyzed mal2-(80%). For those mal2-which form six-membered metal cycles the average observed valence angle SSS is equal to 1200. Results of regression analysis of all mal2-showed linear dependence of ∠SSS on dihedral angel (φ) between planes which go through oxygen and carbon atoms of different carboxyl groups of one anion. For the equation ∠SSS = 124.9 – 0.207φ, correlation coefficient is -0.90. Discovered that in structures of crystals when φ < 600mal2-necessarily form six-membered metal cycles. Structural slackness of mal2-influence on characteristics of six-membered metal cycles formed by them. Those metal cycles usually have bath conformation. Coordination polymers with fixed type of metal atom and identical type of coordination of mal2-can have different dimension even in the absence of other linkers. This effect is evident on the example of [UO2(mal)(L)]·nH2O compounds. Reportedly [1], change of composition and structure of ligand L lead to changes in the system of intramolecular hydrogen bonds which influence on conformation of six-membered metal cycles. The change of conformation of this cycles lead to different relative spatial distribution of the three uranium atoms, connected with one mal2-. Although of the same stoichiometric composition and crystallochemical role of uranium atoms and coordinated ligand resulting polymeric groups [UO2(mal)(L)] in crystals have different dimension: 3D, 2D or 1D respectively for L – carbamide, water or dimethylacetamide. This work was supported by the base part of the government mandate of the Ministry of Education and Science of the Russian Federation.

Tetranuclear Copper(II) Complex with N,N′-bis(2-N-Tosylaminobenzylidene)-1,3-Diaminopropan-2-ol: Crystal structure and magnetic properties

Tetranuclear copper(II) complex, [Cu4L2(OOCCH2COO)], where L is triply deprotonated bis-N,N′-(2-N-tosylaminobenzylidene)-1,3-diaminopropan-2-ol, in which two binuclear fragments are linked by the malonate dianion, is synthesized. The exchange interaction in the binuclear clusters is shown to be antiferromagnetic (2J = −59 cm−1), whereas the intercluster interaction is ferromagnetic (zJ’ = 7.5 cm−1). The structure of the DMSO solvate of the complex is determined by X-ray diffraction analysis.

Malonato(2−)-κ2O,O′]bis(1,10-phenanthroline-κ2N,N′)zinc(II) pentahydrate

In the title complex, [Zn(C3H2O4)(C12H8N2)2]·5H2O, the ZnII cation displays a distorted octa­hedral geometry, being coordinated by four N atoms from two 1,10-phenanthroline ligands and two O atoms from different carboxyl­ate groups of the chelating malonate dianion. In the crystal, the complexes are linked into a three-dimensional supra­molecular network by both O—H⋯O hydrogen-bonding inter­actions between water mol­ecules and the uncoordinated carboxyl­ate O atoms of neighboring mol­ecules, and aromatic π–π stacking inter­actions between neighboring phenanthroline rings with centroid–centroid distances of 3.4654 (17) and 3.697 (2) Å.

Poly[[μ2-aqua-tetraaquadi-μ3-malonato-nickel(II)strontium(II)] dihydrate

The unit-cell parameters for the title mixed-metal coordination polymer, {[NiSr(C3H2O4)2(H2O)5]·2H2O}n, which is isostructural with its Co-containing analogue, were reported previously [Gil de Muro et al. (1999 ▶). Eur. J. Inorg. Chem. pp. 935–943]; the full crystal structure including a description of the hydrogen bonding is reported here. The Sr2+ ion is bonded to five O atoms from three different malonate dianions and four water mol­ecules, displaying a distorted tricapped trigonal–prismatic coordination geometry. Two malonate dianions, two water mol­ecules and one Ni2+ ion build up a dianionic [Ni(C3H2O4)2(H2O)2]2− unit incorporating a slightly distorted NiO6 octa­hedron, which coordinates to three nearby Sr2+ ions. This arrangement creates a metal-organic framework having a 20-membered ring with four Ni and six Sr atoms lying in the bc plane. The coordinated and uncoordinated water mol­ecules are responsible for the formation of two D5 hydrogen-bonded water chains within the 20-membered ring and they are linked into an R4 water cluster via two bifurcated O—H⋯(O,O) links.

Poly[tetra-aqua-di-μ(4)-malonato-barium(II)cadmium(II)

In the title complex, [BaCd(C3H2O4)2(H2O)4]n, the BaII atoms, located on crystallographic twofold axes, adopt slightly distorted square-anti­prismatic coordination geometries, while the CdII atoms, which lie on crystallographic centres of symmetry, have a distorted octa­hedral coordination. Each malonate dianion binds two different CdII atoms and two different BaII atoms. This connectivity generates alternating layers along [100] in the structure, with one type containing CdII cations and malonate dianions, while the other is primarily composed of BaII ions and coordinated water mol­ecules. The water mol­ecules also participate in extensive O—H⋯O hydrogen bonding.

Poly[diaquabis(μ3-2,2-dimethylpropanedioato)calcium(II)copper(II)

The title complex, [CaCu(C(5)H(6)O(4))(2)(H(2)O)(2)](n), is the first heterobimetallic complex based on a substituted malonate dianion. The Cu(II) cation and two independent 2,2-dimethylmalonate (or 2,2-dimethylpropanedioate) dianions build up a robust dianionic [Cu(C(5)H(6)O(4))(2)](2-) complex, which acts as a building block to coordinate to four Ca(2+) cations. Each Cu(II) centre is in a four-coordinate square plane of dimethylmalonate O atoms, while each Ca(II) atom is in an eight-coordinate distorted bicapped trigonal-prismatic environment of six O atoms from four different dimethylmalonate groups and two water molecules. This arrangement creates a two-dimensional layer connectivity of the structure. The dianionic [Cu(C(5)H(6)O(4))(2)](2-) units are involved in different intermolecular hydrogen-bonding interactions with water molecules via the formation of hydrogen-bonded rings of graph sets R(1)(2)(8) and R(6) within this layer. The crystal was nonmerohedrally twinned by rotation about [011] with a major twin volume fraction of 0.513 (3).

X-ray structure and properties of a dinuclear palladium(II) complex [Pd2(μ-L)4] with four adenine-based bridges in a paddle wheel-like arrangement

A unique dinuclear palladium(II) complex of the general composition [Pd 2 (μ-L) 4 ]· x DMF (DMF = N,N′-dimethylformamide, x = 2 for 1a , x = 4 for 1b ) was prepared by a reaction of K 2 [Pd(mal) 2 ] and two molar equivalents of 2-chloro-N6-benzyl-9-isopropyladenine (HL); mal stands for the malonate dianion. The prepared complex was fully characterized by elemental analysis, molar conductivity measurements, IR, Raman and NMR spectroscopies, ESI + mass spectrometry, TG/DTA thermal studies (for 1a ), and by a single crystal X-ray analysis (for 1b ). The results revealed that both metal centres are bridged by four N6-deprotonated 2-chloro-N6-benzyl-9-isopropyladenine molecules (L) in a paddle wheel-like arrangement with the Pd1⋯Pd1A separation of 2.7532(4) Å. Each of the L molecules is coordinated to the Pd(II) ions through its N6 and N7 atoms. The geometry around each of the central atoms can be described as distorted square-planar formed by two N6 and two N7 atoms. The [Pd 2 (μ-L) 4 ]· x DMF complex represents the first dinuclear transition metal complex with two central ions bridged by four adenine derivatives coordinated through their N6 and N7 atoms. The [Pd 2 ( μ -L)4]· x DMF complex (L=a deprotonated form of 2-chloro-N6-benzyl-9-isopropyladenine) represents the first dinuclear transition metal complex with two central Pd(II) atoms [Pd1···Pd1A separation of 2.7532(4)] connected by four adenine-based ligands in a paddle wheel-like arrangement coordinated through their N6 and N7 atoms.

Structure, spectroscopy, and theory calculations of mononuclear mixed-ligand copper(II) complex with malonate and 2-propylimidazole, [Cu(mal)(PIM) 2(H 2O)

A mononuclear copper(II) complex, [Cu(mal)(PIM) 2(H 2O)] (1) [mal = malonate dianion, PIM = 2-propylimidazole] has been synthesized and characterized by elemental analysis, IR, UV–Vis, TG-DTA, and single crystal X-ray diffraction. The center Cu(II) atom in the complex has a distorted square-pyramidal geometry, being coordinated by two nitrogen atoms and three oxygen atoms. Density Functional Theory (DFT) with the B3LYP method and time-dependent DFT calculations were performed to provide insight into the structural, electronic, and electronic spectroscopic properties of the complex 1, and the UV–Vis spectrum of the title compound has been discussed on this basis. All the absorption bands in UV–Vis spectrum are mostly π/( P, σ) → d x 2– y 2 ligand-to-metal charge transfer (LMCT) transition, together with partial d → d ligand field (LF) transition.

Dibridged Bis(Zn2+–cyclen): A Novel Host Molecule of Malonate Dianion in Aqueous Solution

Abstract A dinuclear zinc(II) complex, m,m-bis(Zn2+–cyclen) was synthesized as a novel host molecule for a malonate dianion. The dizinc(II) complex has two zinc(II)–cyclen moieties (cyclen = 1,4,7,10-tetraazacyclododecane) connected through two m-xylene bridges. The 1:1 association constant of log K (K = {[malonate-bound m,m-bis(Zn2+–cyclen)]/[m,m-bis(Zn2+–cyclen)][malonate]}/M−1) was determined to be 3.6 by potentiometric pH titration at 25 °C with I = 0.10 M (NaNO3) in aqueous solution. The H/D exchange reaction of methylene hydrogen atoms of malonate dianion was accelerated by m,m-bis(Zn2+–cyclen) in D2O. The half-life was determined to be 80 min for a 1:1 mixture (2 mM) of malonate and m,m-bis(Zn2+–cyclen) at 25 °C and pD 7. From an aqueous solution of equimolar malonate and m,m-bis(Zn2+–cyclen) however, a cyclic 2:2 malonate/m,m-bis(Zn2+–cyclen) complex was isolated. The structure was confirmed by X-ray crystallography.

Rate constants for decarboxylation reactions calculated using no barrier theory

No barrier theory (NBT) provides both a qualitative way of thinking about what makes a reaction fast or slow and a quantitative way of calculating the rate constant (free energy of activation) corresponding to a particular mechanism. The origin and development of this idea are reviewed and examples of its use for qualitative understanding are presented before applying it to a set of decarboxylations. From the literature, a set of best values for rate constants for decarboxylation was picked. Detailed mechanistic models were developed for reactions leading to delocalized “anions” or to localized anions. It was necessary to have pKa values for ionizaion of the carbon acids corresponding to all of these species and these were selected from the literature or estimated by linear free energy relations (or occasionally calculated from proton exchange data). Over the entire range of measured decarboxylation rate constants, a range of 1025 in rate constant, the calculated values were in good agreement with experiment, with two exceptions: malonate dianion, which has been reported but probably not measured, and glycine, where it is possible that a different mechanism is being followed, unfortunately, one which we do not yet know how to treat by NBT. NBT is both a qualitatively and quantitatively useful tool for understanding chemistry.

Analysis of the Interaction between Adenine Nucleobase and Metal‐Malonato Complexes

AbstractThe synthesis, crystal structure and variable‐temperature magnetic measurements of compounds [M2(μ‐Hade)2(μ‐mal)2(H2O)2]·2H2O [M = Ni (1), Co (2)], [Co2(μ‐Hade)2(μ‐mal)2(H2O)2] (3), {(H2ade)2[Cu(μ‐mal)2]·2H2O}n (4) and (H2ade)2[Cu(mmal)2(H2O)] (5; H2ade = adeninium, Hade = adenine, mal = malonato, mmal = methylmalonato) are reported. Compounds 1–3 contain neutral paddle‐wheel [M2(μ‐Hade)2(μ‐mal)2(H2O)2] [M = Ni (1), Co (2 and 3)] units where the 7H‐tautomeric form of the nucleobase and the malonate dianion act as μ‐κN3:κN9 and μ‐κ2O1,O2:κO1 bridging ligands, respectively. The supramolecular crystal structures of 1–3 are essentially maintained by hydrogen‐bonding interactions involving the nucleobases, the carboxylate groups and crystallisation water molecules (in compounds 1 and 2). Compounds 4 and 5 show a hybrid inorganic‐organic lamellar structure containing layers of anionic metal‐malonato complexes and supramolecular aggregates of the 1H,9H‐adeninium cation. Their overall three‐dimensional architectures are controlled, in addition to electrostatic forces, by supramolecular recognition processes between the inorganic and organic frameworks. Compound 4 contains one‐dimensional anionic copper‐malonato chains in which the copper atoms are doubly bridged by μ‐κ2O1,O2:κO2′ malonato ligands and the cationic nucleobases form dimeric entities sustained by Hoogsteen‐Hoogsteen hydrogen‐bonding interactions. Compound 5 is built up of anionic [Cu(mmal)2(H2O)]2– monomeric entities and planar, hydrogen‐bonded, one‐dimensional, ribbon‐like aggregates of protonated adenine. Variable‐temperature magnetic susceptibility measurements of compounds 1–4 show the preponderance of ferromagnetic interactions between the paramagnetic centres. DFT calculations have been performed to evaluate the magnetic behaviour of these compounds and to analyze the interaction between two adeninium cations in compound 4. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Three-fold-Interpenetrated Diamondoid Coordination Frameworks with Torus Links Constructed by Tetranuclear Building Blocks

Two new isostructural coordination polymers, namely, [M(malo)(HFlu)]n (M = Zn for 1 and Cu for 2, malo = malonate dianion, HFlu = fluconazole), have been prepared by a solution diffusion method. The polymers show rare three-dimensional 3-fold interpenetrated dia-f coordination frameworks with (2.2.1) Hopf links and (6.3.3) Torus links. The tetranuclear M4(malo)4 cluster as a secondary building unit becomes the decorated vertex in the dia-f net. Polymer 1 shows an intense fluorescent emission, while polymer 2 shows a quenching phenomenon in the solid state at room temperature. Magnetic susceptibility studies for 2 reveal a ferromagnetic coupling interaction in the anti-syn carboxylate-bridged Cu(II) clusters. Comparable experiments with Ni(II) and Cd(II) resulting in discrete dinuclear structures are also reported.

Robust recognition of malonate and 2-amino-4-picolinium in conjunction with M(ii) as a triad (M = Ni/Co/Mn): role of this highly stable hydrogen-bonded motif in driving supramolecular self-assembly

The crystal lattice of the three isostructural compounds , (C(6)H(8)N(2)H)(2)[M(C(3)H(2)O(4))(2)(H(2)O)(2)].4H(2)O (C(6)H(8)N(2)H = protonated 2-amino-4-picoline, M = Ni/Co/Mn, C(3)H(4)O(4) = malonate dianion; hereafter, malonate) is formed by supramolecular 2D layers. Hydrogen-bonding, pi...pi and lone pair...pi interactions play crucial role in organizing monomeric [M(II)(mal)(2)(H(2)O)(2)] units into 2D sheets along the ab plane, through the self-association between two different supramolecular building blocks, namely a tetrameric water cluster including metal-coordinated water molecules, and R(2)(2)(8) and R(2)(2)(7) hydrogen-bonded recognition synthons between 2-amino-4-picolinium and malonate. DFT calculations clearly show that the robust 2-amino-4-picolinium/malonate hydrogen-bonded motif drives the self-assembly of the supramolecular network observed.

Mechanism of electron transfer reaction of ternary nitrilotriacetatocobalt(II) complexes involving succinate and malonate as secondary ligands

AbstractThe mechanism of oxidation of ternary complexes, [CoII(nta)(S)(H2O)2]3− and [CoII(nta)(M)(H2O)]3− (nta = nitrilotriacetate acid, S = succinate dianion, and M = malonate dianion), by periodate in aqueous medium has been studied spectrophotometrically over the (20.0–40.0) ± 0.1°C range. The reaction is first order with respect to both [IO4−] and the complex, and the rate decreases over the [H+] range (2.69–56.20) × 10−6 mol dm−3 in both cases. The experimental rate law is consistent with a mechanism in which both the hydroxy complexes [CoII(nta)(S)(H2O)(OH)]4− and [CoII(nta)(M)(OH)]4− are significantly more reactive than their conjugate acids. The value of the intramolecular electron transfer rate constant for the oxidation of the [CoII(nta)(S)(H2O)2]3−, k1 (3.60 × 10−3 s−1), is greater than the value of k6 (1.54 × 10−3 s−1) for the oxidation of [CoII(nta)(M)(H2O)]3− at 30.0 ± 0.1°C and I = 0.20 mol dm−3. The thermodynamic activation parameters have been calculated. It is assumed that electron transfer takes place via an inner‐sphere mechanism. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 103–113, 2008

Poly[μ-aqua-diaqua-μ4-malonato-μ3-malonato-barium(II)nickel(II)

The title complex, [BaNi(C3H2O4)2(H2O)3]n, is polymeric, with two non-equivalent malonate dianions bridging one Ni atom and five different Ba atoms. The Ni atoms have a distorted octahedral (NiO6) environment, and are coordinated by four malonate O atoms in a planar arrangement and two water molecules in axial positions. The Ba atom may be described as a BaO9 polyhedron in a monocapped square-antiprismatic environment, which involves two water molecules and seven O atoms from different malonate ligands. The three-dimensional structure is further maintained and stabilized by hydrogen bonds.

Diaqua[(Z)-4,4′-ethylenedipyridineN,N′-dioxide-κO](malonato-κ2O:O)copper(II) trihydrate

In the title compound, [Cu(C3H2O4)(C12H10N2O2)(H2O)2]·3H2O, a CuII center with `4+1' Jahn–Teller-distorted square-pyramidal coordination is bound by a chelating malonate dianion, two aqua ligands and a monodentate Z-4,4′-ethyl­ene­dipyridine N,N′-dioxide ligand. Three uncoordinated water mol­ecules cocrystallize with each complex mol­ecule. Individual mol­ecules are connected into one-dimensional ribbons and two-dimensional sheets through extensive hydrogen-bonding patterns mediated by both aqua ligands and water mol­ecules of crystallization.

Aqua(2,2′-diamino-4,4′-bi-1,3-thiazole-κ2N,N′)(malonato-κ2O,O′)zinc(II) monohydrate

In the asymmetric unit of the crystal structure of the title compound, [Zn(C3H2O4)(C6H6N4S2)(H2O)]·H2O, there are two independent ZnII complex mol­ecules. Each ZnII ion assumes a distorted square-pyramidal coordination geometry formed by a diamino­bithia­zole (DABT) ligand, a malonate dianion and a water mol­ecule. Within the chelating DABT ligand, the two thia­zole rings are twisted with respect to each other, with dihedral angles of 3.23 (19) and 2.54 (18)°. O—H⋯O and N—H⋯O hydrogen bonding occurs in the crystal structure.