Dimethylformamide Ligands Research Articles

Reaction Chemistry of the syn-[Mo2O2(μ-S)2(S2)(DMF)3] Complex with Cyanide and Catalytic Thiocyanate Formation.

Removal of cyanide as nontoxic thiocyanate under physiological conditions may serve as a catalytic detoxification route in vivo. Aqueous catalytic reaction conditions were explored where at the conditions employed the reaction proceeded to exhaustion in 1 h. The complex, syn-[Mo2O2(μ-S)2(S2)(DMF)3] 1, participates in a ligand exchange reaction of the dimethylformamide ligands and cyanide. Simultaneous sulfur abstraction reaction from the terminal disulfide group forms thiocyanate and terminal sulfido ligand. Respective reaction rates for the two reactions appear competitive where different products were isolated solely based on change of reaction temperature. The approach to determine the number of cyanide ligands participating in the ligand exchange reaction by varying the stoichiometry and reaction temperature led to identification and isolation of tetranuclear complexes 2 and 5 and dinuclear complexes 3, 4, and 6. A synthesized and fully characterized thiocyanate analog of 6 (7) supports spectroscopic characterization of 6. The tetranuclear anion, [Mo4O4(μ-S)6(CN)4]4-, 2, was crystallized from a reaction at ambient temperature. The dinuclear anion, [Mo2O2(μ-S)2(S)(CN)3]3-, 3, was crystallized from similar reaction conditions at lower temperature. The reaction yield of thiocyanate obtained at pH of 7.4 and at 9.2 as a function of time, for several ratios of cyanide, favors the sulfur abstraction reaction at elevated pH. The sulfur abstraction reaction is the first step in a proposed mechanism of the reaction of cyanide and thiosulfate to form thiocyanate and sulfite by 1.

Sulfate-bridged dimeric trinuclear copper(II)-pyrazolate complex with three different terminal ligands.

The reaction of CuSO4·5H2O, 4-chloro-pyrazole (4-Cl-pzH) and tri-ethyl-amine (Et3N) in di-methyl-formamide (DMF) produced crystals of di-aqua-hexa-kis-(μ-4-chloro-pyrazolato-κ(2) N:N')bis-(N,N-di-methyl-formamide)di-μ3-hydroxido-bis-(μ4-sulfato-κ(4) O:O':O'':O'')hexa-copper(II) N,N-di-methyl-formamide tetra-solvate dihydrate, [Cu3(OH)(SO4)(C3H2ClN2)3(C3H7NO)(H2O)]2·4C3H7NO·2H2O. The centrosymmetric dimeric molecule consists of two trinuclear copper-pyrazolate units bridged by two sulfate ions. The title compound provides the first example of a trinuclear copper-pyrazolate complex with three different terminal ligands on the Cu atoms, and also the first example of such complex with a strongly binding basal sulfate ion. Within each trinuclear unit, the Cu(II) atoms are bridged by μ-pyrazolate groups and a central μ3-OH group, and are coordinated by terminal sulfate, H2O and DMF ligands, respectively. Moreover, the sulfate O atoms coordinate at the apical position to the Cu atoms of the symmetry-related unit, providing square-pyramidal coordination geometry around each copper cation. The metal complex and solvent mol-ecules are involved in O-H⋯O hydrogen bonds, leading to a two-dimensional network parallel to (10-1).

Crystal structure of hexa-kis-(di-methyl-formamide-κO)manganese(II) deca-kis-(di-methyl-formamide)-1κ(5) O,2κ(5) O-[μ-octa-deca-tungstodiphosphato(V)-κO:κO']dimanganate(II) di-methyl-formamide disolvate.

The crystal structure of the title compound, [Mn(C3H7NO)6][{Mn(C3H7NO)5}2(μ-P2W18O62)]·2C3H7NO, reveals that the Wells-Dawson-type polyanion [P2W18O62](6-), through terminal O atoms from the belts, bridges two Mn(II) octa-hedral complexes. In the complex anion [{Mn(dmf)5}2(μ-P2W18O62)](2-), located around a twofold rotation axis, the Mn(II) ions are coordinated by five O atoms from di-methyl-formamide (dmf) ligands and to a terminal O atom from the [P2W18O62](6-) polyanion. Another Mn(II) ion, located on an inversion centre, is coordinated by six O atoms from the dmf ligands and forms the [Mn(dmf)6](2+) cation. The crystal components are connected through numerous weak C-H⋯O hydrogen bonds to construct a three-dimensional network.

Structural and spectroscopic characterization of two new blue luminescent pyridylbenzimidazole zinc(II) complexes.

Luminescent metal complexes are used in photooptical devices. Zinc(II) complexes are of interest because of the ability to tune their color, their high thermal stability and their favorable carrier transport character. In particular, some zinc(II) complexes with aryl diimine and/or heterocyclic ligands have been shown to emit brightly in the blue region of the spectrum. Zinc(II) complexes bearing derivatized imidazoles have been explored for possible optoelectronic applications. The structures of two zinc(II) complexes of 5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole (L), namely dichlorido(dimethylformamide-κO){5,6-dimethyl-2-(pyridin-2-yl-κN)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole-κN(3)}zinc(II) dimethylformamide monosolvate, [ZnCl2(C20H18N4)(C3H7NO)]·C3H7NO, (I), and bis(acetato-κ(2)O,O'){5,6-dimethyl-2-(pyridin-2-yl-κN)-1-[(pyridin-2-yl)methyl]-1H-benzimidazole-κN(3)}zinc(II) ethanol monosolvate, [Zn(C2H3O2)2(C20H18N4)]·C2H5OH, (II), are reported. Complex (I) crystallized as a dimethylformamide solvate and exhibits a distorted trigonal bipyramidal coordination geometry. The coordination sphere consists of a bidentate L ligand spanning axial to equatorial sites, two chloride ligands in equatorial sites, and an O-bound dimethylformamide ligand in the remaining axial site. The other complex, (II), crystallized as an ethanol solvate. The Zn(II) atom has a distorted trigonal prismatic coordination geometry, with two bidentate acetate ligands occupying two edges and a bidentate L ligand occupying the third edge of the prism. Complexes (I) and (II) emit in the blue region of the spectrum. The results of density functional theory (DFT) calculations suggest that the luminescence of L results from π*←π transitions and that the luminescence of the complexes results from interligand charge-transfer transitions. The orientation of the 2-(pyridin-2-yl) substituent with respect to the benzimidazole system was found to have an impact on the calculated HOMO-LUMO gap (HOMO is highest occupied molecular orbital and LUMO is lowest unoccupied molecular orbital).

A new one-dimensional coordination polymer of 5-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl)isophthalic acid with manganese.

The coordination polymer catena-poly[[(dimethylformamide-κO)[μ3-5-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl)isophthalato-κ(4)O(1),O(1'):O(3):O(3')](methanol-κO)manganese(III)] dimethylformamide monosolvate], {[Mn(C40H23NO6)(CH3OH)(C3H7NO)]·C3H7NO}n, has been synthesized from the reaction of 5-(1,3-dioxo-4,5,6,7-tetraphenylisoindolin-2-yl)isophthalic acid and manganese(II) acetate tetrahydrate in a glass tube at room temperature by solvent diffusion. The Mn(II) centre is hexacoordinated by two O atoms from one chelating carboxylate group, by two O atoms from two monodentate carboxylate groups and by one O atom each from a methanol and a dimethylformamide (DMF) ligand. The single-crystal structure crystallizes in the triclinic space group P\overline{1}. Moreover, the coordination polymer shows one-dimensional 2-connected {0} uninodal chain networks, and free DMF molecules are connected to the chains by O-H···O hydrogen bonds. The thermogravimetric and photoluminescent properties of the compound have also been investigated.

Rhodium(III) cationic methyl complexes containing dimethylformamide ligand, cis-[Rh(β-diket)(PPh3)2(CH3)(DMF)][BPh4] (β-diket = acetylacetonate or benzoylacetonate), in comparison with their acetonitrile analogs

The rhodium(III) cationic methyl complexes, cis-[Rh(Acac)(PPh3)2(CH3)(DMF)][BPh4] (1) and cis-[Rh(BA)(PPh3)2(CH3)(DMF)][BPh4] (2) are formed upon reactions of cis-[Rh(β-diket)(PPh3)2(CH3)(MeCN)][BPh4] (β-diket = acetylacetonate, Acac, or benzoylacetonate, BA) with excess of dimethylformamide (DMF) in CH2Cl2 solution at ambient temperature. Complexes 1 and 2 were characterized by elemental analysis, 31P{1H} and 1H NMR spectra, and single crystal X-ray crystallography. The cations of 1 and 2 have slightly distorted octahedral geometry. The “equatorial” plane contains the β-diketonate and two PPh3 ligands; methyl and DMF ligands occupy the axial positions. Peculiar features of complexes 1 and 2 in solid state are: (i) unusually long Rh–O(DMF) bond and (ii) non-symmetrical orientation of the formyl C–H bond in relation to two oxygen atoms of the β-diketonate ligand. The signals from formyl protons in the 1H NMR spectra of 1 and 2 are shifted significantly upfield relatively to free DMF. The hydrogen bonding between formyl proton and one of the β-diketonate oxygen atoms is considered. In solutions, 1 and 2 show dynamic behavior at ambient temperature and keep their solid-state geometry at −70 °C.

Supramolecular architecture of metal–organic frameworks involving dinuclear copper paddle-wheel complexes

The two centrosymmetric dinuclear copper paddle-wheel complexes tetrakis(μ-4-hydroxybenzoato-κ(2)O:O')bis[aquacopper(II)] dimethylformamide disolvate dihydrate, [Cu2(C7H5O3)4(H2O)2]·2C3H7NO·2H2O, (I), and tetrakis(μ-4-methoxybenzoato-κ(2)O:O')bis[(dimethylformamide-κO)copper(II)], [Cu2(C8H7O3)4(C3H7NO)2], (II), crystallize with half of the dinuclear paddle-wheel cage unit in the asymmetric unit and, in addition, complex (I) has one dimethylformamide (DMF) and one water solvent molecule in the asymmetric unit. In both (I) and (II), two Cu(II) ions are bridged by four syn,syn-η(1):η(1):μ carboxylate groups, showing a paddle-wheel cage-type structure with a square-pyramidal coordination geometry. The equatorial positions of (I) and (II) are occupied by the carboxylate groups of 4-hydroxy- and 4-methoxybenzoate ligands, and the axial positions are occupied by aqua and DMF ligands, respectively. The three-dimensional supramolecular metal-organic framework of (I) consists of three different R2(2)(20) and an R4(4)(36) ring motif formed via O-H···O and OW-HW···O hydrogen bonds. Complex (II) simply packs as molecular species.

A three-dimensional coordination polymer of 3-(3,5-dicarboxybenzyloxy)benzoic acid with zinc

The synthesis is reported of the tricarboxylic acid 3-(3,5-dicarboxybenzyloxy)benzoic acid (H₃L) and the product of its reaction under solvothermal conditions with ZnII cations, namely poly[[μ₆-3-(3,5-dicarboxylatobenzyloxy)benzoato](dimethylformamide)-μ₃-hydroxido-dizinc(II)], [Zn₂(C₁₆H₉O7)(OH)(C₃H₇NO)]n, the formation of which is associated with complete deprotonation of H₃L. Its crystal structure consists of a single-framework coordination polymer of the organic L³⁻ ligand with ZnII cations in a 1:2 ratio, with additional hydroxide and dimethylformamide (DMF) ligands coordinated to the ZnII centres. The ZnII cations are characterized by coordination numbers of 5 and 6, being bridged to each other by hydroxide ligands. In the polymeric framework, the carboxylate- and hydroxy-bridged ZnII cations are arranged in coordination-tessellated columns, which propagate along the a axis of the crystal structure, and each L³⁻ ligand links to seven different ZnII centres via Zn-O bonds of two different columns. The coordination framework, composed of [Zn₂(L)(OH)(DMF)]n units, forms an open architecture, the channel voids within it being filled by the zinc-coordinating DMF ligands. This report provides the first structural evidence for the formation of coordination polymers with H₃L via multiple metal-ligand bonds through its carboxylate groups.

Pentaaqua(dimethylformamide)cobalt(II) sulfate dimethylformamide monosolvate

The title compound, [Co(C3H7NO)(H2O)5]SO4·C3H7NO, contains five aqua ligands, a CoII atom, a sulfate ion and both a coordinating and a non-coordinating di­methyl­formamide (DMF) mol­ecule. The DMF solvent mol­ecule lies between the complex units, which are located along the b axis. The sulfate ion is for charge balance. The CoII atom has distorted octa­hedral coordination geometry, being ligated by five aqua ligands and the O atom of the DMF ligand. O—H⋯O hydrogen bonds between the aqua ligands and the sulfate anion and non-coordinating DMF molecule lead to the formation of a three-dimensional network. Since all constituents lie on a mirror plane, the H atoms of all methyl groups and of one of the aqua ligands are equally disordered over two positions.

A square-pyramidal copper(II) complex with strong intramolecular hydrogen bonds: diaqua(N,N′-dimethylformamide-κO)bis[2-(diphenylphosphoryl)benzoato-κO]copper(II)

In the title Cu(II) complex, [Cu(C19H14O3P)2(C3H7NO)(H2O)2], the molecule is bisected by a twofold axis relating the two 2-(diphenylphosphoryl)benzoate (ODPPB) ligands. The asymmetric unit consists of a Cu(II) metal centre on the symmetry axis, an ODPPB ligand, one water ligand and one dimethylformamide (DMF) ligand (disordered around the twofold axis). The Cu(II) ion has fivefold coordination provided by two carboxylate O atoms from two ODPPB ligands, two O atoms from two coordinated water molecules and another O atom from a (disordered) DMF molecule, giving a CuO5 square-pyramidal coordination geometry. The ODPPB ligand adopts a terminal monocoordinated mode with two free O atoms forming two strong intramolecular hydrogen bonds with the coordinated water molecules, which may play a key role in the stability of the molecular structure, as shown by the higher release temperature for the coordinated water molecules than for the coordinated DMF molecule. The optical absorption properties of powder samples of the title compound have also been studied.

A novel amido–pyrophosphate MnIIchelate complex with the synthetic ligand O{P(O)[NHC(CH3)3]2}2(L): [Mn(L)2{OC(H)N(CH3)2}2]Cl2·2H2O

The title complex, trans-bis(dimethylformamide-κO)bis{N,N'-N'',N'''-tetra-tert-butyl[oxybis(phosphonic diamide-κO)]}manganese(II) dichloride dihydrate, [Mn(C16H40N4O3P2)2(C3H7NO)2]Cl2·2H2O, is the first example of a bis-chelate amido-pyrophosphate (pyrophosphoramide) complex containing an O[P(O)(NH)2]2 fragment. Its asymmetric unit contains half of the complex dication, one chloride anion and one water molecule. The Mn(II) atom, located on an inversion centre, is octahedrally coordinated, with a slight elongation towards the monodentate dimethylformamide ligand. Structural features of the title complex, such as the P=O bond lengths and the planarity of the chelate ring, are compared with those of previously reported complexes with six-membered chelates involving the fragments C(O)NHP(O), (X)NP(O) [X= C(O), C(S), S(O)2 and P(O)] and O[P(O)(N)2]2. This analysis shows that the six-membered chelate rings are less puckered in pyrophosphoramide complexes containing a P(O)OP(O) skeleton, such as the title compound. The extended structure of the title complex involves a linear aggregate mediated by N-H...O and N-H...Cl hydrogen bonds, in which the chloride anion is an acceptor in two additional O-H...Cl hydrogen bonds.

Thermal tuning of advanced Cu sol–gels for mixed oxidation state Cu/CuxOy materials

In this report, we describe new conditions for the formation of copper gels and aerogels via epoxide addition to CuBr2 in dimethylformamide (DMF). These CuBr2-derived sols undergo a rapid gel transition and result in materials that have enhanced mechanical properties when compared with the gels derived from CuCl2. Additionally, upon air-annealing, they convert to nanoscopic CuO at temperatures much lower than the CuCl2 analogues. Moreover, annealing under nitrogen results in copper species with reduced oxidization states including Cu2O and metallic Cu. The ratio of copper oxidation states can be controlled by simple modification of the thermal program used to anneal the materials. The thermal reduction of the copper is attributed to retained DMF ligands in the as-prepared aerogels which was confirmed by FTIR spectroscopy. These aerogel materials were characterized by powder X-ray diffraction (PXRD), physisorption, thermogravimetric analysis (TGA), and temperature programmed reduction (TPR).

(4,4′-Dimethyl-2,2′-bipyridine-κ2N,N′)(dimethylformamide-κO)diiodidocadmium

In the title compound, [CdI2(C12H12N2)(C3H7NO)], the CdII cation is five-coordinated in a distorted trigonal–bipyramidal configuration by two N atoms from a 4,4′-dimethyl-2,2′-bipyridine ligand, one O atom from a dimethyl­formamide ligand and two I− anions. π–π stacking between pyridine rings of adjacent mol­ecules [centroid–centroid distance = 3.666 (3) and 3.709 (4) Å] stabilizes the three-dimensional structure

Trans-Bis[4-amino-N-(pyrimidin-2-yl-κN)benzenesulfonamidato-κN]bis(N,N-dimethylformamide-κO)cobalt(II)

The title complex, [Co(C10H9N4O2S)2(C3H7NO)2], lies across an inversion center. The CoII atom is coordinated in a slightly distorted octa­hedral geometry by four N atoms from two bidentate 4-amino-N-(pyrimidin-2-yl)benzene­sulfonamidate (sulfadiazine) anions and two O atoms from two dimethyl­formamide (DMF) ligands. The dihedral angle between the benzene and pyrimidine rings is 82.37 (13)°. A three-dimensional network is generated by N—H⋯O hydrogen bonds between the amino groups and of the sulfonamidate O atoms of neighbouring mol­ecules. The DMF ligand is disordered over two sets of sites in a 0.559 (4):0.441 (4) ratio.

Controlled radical polymerization of vinyl acetate in presence of mesoporous silica supported TiCl4 heterogeneous catalyst

The heterogeneous TiCl4 catalysts supported on mesoporous mobile composition of matter (MCM-41) and mesoporous silicone particles synthesized from block copolymer of PPG–PEG–PPG (SPB) complexed with dimethyl formamide (DMF) ligand were used in a controlled free radical reaction with benzoyl peroxide (BPO) initiator in bulk polymerization of vinyl acetate (VAc). In this polymerization process, mesoporous particle of SPB increased the reactivity of TiCl4 catalyst with DMF ligand. The active site formed on the surface and the pores of the catalyst produced specific sequences of VAc on the chain with different thermal and microstructural properties and crystallinity.

Tetrakis(μ-naphthalene-1-acetato-κ2O:O′)bis[(N,N-dimethylformamide-κO)copper(II)

The asymmetric unit of the title compound, [Cu2(C12H9O2)4(C3H7NO)2], contains two independent centrosymmetric dinuclear copper(II) complexes. The central paddle-wheel units are formed by four bridging bidentate naphthalene-1-acetate ligands with two dimethyl­formamide ligands in the axial positions. The unique CuII ions have slightly distorted square-pyramidal coordination geometries. One of the naphthalene rings is disordered over two sets of sites, with refined occpancies of 0.535 (4) and 0.465 (4).

High-performance liquid chromatographic analysis of as-synthesised N,N′-dimethylformamide-stabilised gold nanoclusters product

Reverse-phase high-performance liquid chromatographic (RP-HPLC) separation and analysis of polydisperse water-soluble gold nanoclusters (AuNCs) stabilised with N,N'-dimethylformamide (DMF) were investigated. Under optimal elution gradient conditions, the separation of DMF-AuNCs was monitored by absorption and fluorescence spectroscopy. The UV-vis spectral characteristics of the separated DMF-AuNCs have been captured and they do not possess distinct surface plasmon resonance bands, indicating that all DMF-AuNCs are small AuNCs. The photoluminescence emission spectra of the separated DMF-AuNCs are in the blue-light region. Moreover, cationic DMF-AuNCs are for the first time identified by ion chromatography. Our proposed RP-HPLC methodology has been successfully applied to separate AuNCs of various Au atoms as well as DMF-stabilised ligands. Finally, the composition of the separated DMF-AuNCs was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry and electrospray ionisation mass spectrometry, proving that the as-synthesised DMF-AuNCs product consists of Au₁₀⁺, Au₁₀, Au₁₁, Au₁₂, Au₁₃, and Au₁₄ NCs stabilised with various numbers of DMF ligands.

Triaqua-1κ3O-μ-cyanido-1:2κ2N:C-pentacyanido-2κ5C-tetrakis(dimethylformamide-1κO)-1-holmium(III)-2-iron(III) monohydrate

In the bimetallic cyanide-bridged title complex, [Fe0.98HoRu0.02(CN)6(C3H7NO)4(H2O)3]·H2O, the HoIII ion is in a slightly distorted square-anti­prismatic arrangement formed by seven O atoms from four dimethyl­formamide (DMF) mol­ecules and three water mol­ecules, and one N atom from a bridging cyanide group connected with the FeIII atom which is octa­hedrally coordinated by six cyanide groups. In the crystal, mol­ecules are held together through O—H⋯N and O—H⋯O hydrogen-bonding inter­actions to form a three-dimensional framework. Elemental analysis of one of the precursors and the crystal shows that there is a slight contamination of Fe by Ru. The Fe site displays, therefore, small substitutional disorder with site-occupancy factors Fe/Ru = 0.98:0.02. The two methyl groups of two dimethyl­formamide ligands are positionally disordered with site-occupancy factors of 0.44 (3):0.56 (3) and 0.44 (3):0.56 (3).

(Dimethylformamide-κO)(2-hydroxybenzoato-κ2O1,O1′)[tris(1-methyl-1H-benzimidazol-2-ylmethyl-κN3)amine-κN]manganese(II) perchlorate dimethylformamide monosolvate

In the title complex, [Mn(C7H5O3)(C27H27N7)(C3H7NO)]ClO4·C3H7NO, the MnII ion is coordinated in a slightly distorted monocapped trigonal-prismatic geometry. The tris­(1-methyl-1H-benzimidazol-2-ylmeth­yl)amine (Mentb) ligand coordinates in a tetra­dentate mode and the coordination is completed by a bis-chelating salicylate ligand and a dimethyl­formamide ligand. The hy­droxy group and the ortho H atoms of the salicylate ligand were refined as disordered over two sites with occupancies of 0.581 (8) and 0.419 (8). Both disorder components of the hy­droxy group form intra­molecular O—H⋯O hydrogen bonds.

Aqua(dimethylformamide){tris[(1-methyl-1H-benzimidazol-2-yl)methyl]amine}nickel(II) dipicrate

In the title complex, [Ni(C27H27N7)(C3H7NO)(H2O)](C6H2N3O7)2, the NiII ion is coordinated in a slightly distorted octa­hedral coordination evironment by an NiN4O2 ligand set. The tris­(N-methyl­benzimidazol-2-ylmeth­yl)amine ligand is in a tetra­dentate mode while a coordinated water molecule and a dimethyl­formamide ligand complete the coordination. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the cation and one of the pictrate anions into four-component centrosymmetric clusters.