Dicyanamide Bridges Research Articles

Synthesis, characterization and study of magnetic property of two isomorphic Cu(II) coordination polymers (CP) with chromone based ligand systems

Synthesis, characterization and magnetic properties of two Cu(II)-based coordination polymers (CPs, [{Cu(L1)(N(CN)2)}(ClO4)]n L1 = 3-(((2-(diethylamino)ethyl)imino)methyl)-4H-chromen-4-one (1) and [{Cu(L2)(N(CN)2)}(ClO4)]n L2 = 3-(((2-(dimethylamino)ethyl)imino)methyl)-4H-chromen-4-one (2)) involving chromone based chelating ligands and dicyanamide bridging ligands are reported. Both compounds have been characterized by physicochemical methods and the crystal structures have been determined by X-ray diffraction analysis, disclosing that they are isostructural and isomorphous compounds of polymeric linear chains where the central metal has adopted distorted square pyramidal coordination geometry. The magnetic studies reveal that the synthesized compounds show a prevailing paramagnetic behavior. Only below 15 K does a weak antiferromagnetic interaction become effective in these systems, and they have been further analyzed and interpreted.

Synthesis, Structure, and Magnetic and Biological Properties of Copper(II) Complexes with 1,3,4-Thiadiazole Derivatives.

New coordination compounds of copper(II) with 2,5-bis(ethylthio)-1,3,4-thiadiazole (L1) and 2,5-bis(pyridylmethylthio)-1,3,4-thiadiazole (L2) with compositions Cu(L1)2Br2, Cu(L1)(C2N3)2, Cu(L2)Cl2, and Cu(L2)Br2 were prepared. The complexes were identified and studied by CHN analysis, infrared (IR) spectroscopy, powder X-Ray diffraction (XRD), and static magnetic susceptibility. The crystal structures of Cu(II) complexes with L1 were determined. The structures of the coordination core of complexes Cu(L2)Cl2 and Cu(L2)Br2 were determined by Extended X-ray absorption fine structure (EXAFS) spectroscopy. Magnetization measurements have revealed various magnetic states in the studied complexes, ranging from an almost ideal paramagnet in Cu(L1)2Br2 to alternating-exchange antiferromagnetic chains in Cu(L1)(C2N3)2, where double dicyanamide bridges provide an unusually strong exchange interaction (J1/kB ≈ -23.5 K; J2/kB ≈ -20.2 K) between Cu(II) ions. The cytotoxic activity of copper(II) complexes with L2 was estimated on the human cell lines of breast adenocarcinoma (MCF-7) and hepatocellular carcinoma (HepG2).

Cu(II) coordination polymers containing dicyanamide and 2,2’-bipyridine: structural and antibacterial properties

From reaction mixture containing the same reagents, the two Cu(II) complexes, with dicyanamide (dca) bridges, [Cu(bpy)(dca)2]n (1) and [Cu(bpy)Cl(dca)]n.H2O (2) (bpy= 2,2’-bipyridine) were prepared. The complexes were characterized by elemental analysis, FT-IR spectroscopy and X-ray single crystal techniques. In both complexes, the geometry of the Cu(II) atom is best described as a slightly distorted square pyramidal. A zigzag chain structure is formed in both structures by dca units serving as an end-to end bridging ligand. In addition, studies on antibacterial activity of the compounds against Gram(+) (Staphylococcus aureus ATCC-6538) and Gram(-) (Escherichia coli ATTC-8739, Pseudomonas aeruginosa ATCC-27853 and Enterobacter aerogenes ATCC-13048) bacteria have been performed using disc-diffusion and microdilution broth techniques. Both complexes were found to be significantly more effective against Gram(-) bacteria E. Coli than against the other bacteria.

Energetic isostructural metal imidazolate frameworks with a bridging dicyanamide linker towards high-performance hypergolic fuels

High energy anions N(CN)2− were successfully introduced into two isostructural HMOFs by molecular design toward enhanced hypergolicity.

Two new Co(II) coordination polymers based on redox-active ligands: Structure, Chromism and Magnetism

By utilizing redox-active ligands [monoquaternized 4,4′-bipyridines (monoquats) and naphthalene diimide derivatives] and dicyanamide (dca) bridges, two new Co(II) complexes, [Co(dca)2(DPNDI)]n⋅2nDMF⋅nH2O (1) and [Co(EQ)2(dca)2]nI2n⋅4nH2O (2), have been synthesized (DPNDI = N,N'-di(3-pyridyl)-1,4,5,8-naphthalene tetracarboxydiimide, EQI = 1-ethyl-4-(4-pyridyl) pyridinium iodide). Complex 1 is a 2D network where 1D chains of [Co(dca)2]n are linked by DPNDI ligands to form 2D layers. In complex 2, 1D chains of [Co(EQ)2(dca)2]n cross vertically. Interestingly, complex 1 is photochromic while complex 2 is both photo- and thermochromic. Moreover, their magnetic properties have also been investigated.

Low-dimensional compounds containing cyanido groups. Part XXXV. Structure, spectral, thermal and magnetic properties of a binuclear CuII-biquinoline complex with bridging and terminal dicyanamide ligands.

From the system CuCl2-biq-NaN(CN)2 (biq is 2,2'-biquinoline), the binuclear molecular complex bis(μ-dicyanamido-κ2N1:N5)bis[(2,2'-biquinoline-κ2N,N')(dicyanamido-κN1)copper(II)], [Cu2(C2N3)4(C18H12N2)2] or [Cu2(biq)2(dca)2(μ1,5-dca)2] (1) [dca is dicyanamide, N(CN)2-] was isolated and characterized by crystal structure analysis, and spectral, thermal and magnetic measurements. IR spectroscopy confirmed the presence of the biq and dca ligands in 1. Its solid-state structure consists of discrete centrosymmetric binuclear copper(II) units with double end-to-end dca bridges. Each CuII atom is in a distorted square-pyramidal environment with the equatorial plane formed by two nitrile N atoms from bridging dca groups, one of the two N atoms of the chelate biq molecule and one nitrile N atom from a terminal dca ligand, whereas the second biq N atom occupies the axial position. Thermal decomposition of 1 in an air atmosphere proceeds gradually, with copper(I) cyanide being the final decomposition product. Magnetic measurements revealed the formation of alternating spin chains and a relatively strong exchange interaction within the binuclear units was also confirmed by Broken Symmetry DFT (density functional theory) calculations.

A new two-dimensional polymeric cadmium(II) complex containing dicyanamide bridging ligands.

As part of an exploration of new coordination polymers, a cadmium-dicyanamide complex, namely poly[benzyltriethylammonium [tri-μ-dicyanamido-κ6N1:N5-cadmium(II)]], {(C13H22N)[Cd(C2N3)3]}n, has been synthesized by the reaction of benzyltriethylammonium bromide, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution, and characterized by single-crystal X-ray diffraction at room temperature. In the crystal structure, each CdII cation is coordinated by six nitrile N atoms from six anionic dicyanamide (dca) ligands to furnish a slightly distorted octahedral geometry. Neighbouring CdII cations are linked by dicyanamide bridges to construct a two-dimensional anionic layer coordination polymer. One amide N atom in the bridging dca ligand is disordered over two sites. The cations lie between the anionic frameworks and there are no hydrogen-bond interactions between the cations and anions. The organic cations are not involved in the formation of the supramolecular network.

Crystal structure of catena-poly[bis-(tetra-ethyl-ammonium) [tetra-aqua-tris(μ-dicyanamido-κ2N1:N5)bis(dicyanamido-κN1)di-cobaltate(II)] dicyanamide

The structure of the title compound, [N(C2H5)4]2[Co2(C2N3)5(H2O)4](C2N3), is a new example of a metal-dicyanamide coordination polymer which exhibits a unique three-dimensional framework of covalently linked CoII chains. All bridging dicyanamide ligands in the title structure are in the μ1,5-bridging mode. The anionic CoII-dicyanamide network is templated by tetra-ethyl-ammonium cations residing in a series of channels extending along the b axis where additional non-coordinating dicyanamidate anions are also located. The framework structure is further stabilized by O-H⋯N hydrogen bonding between aqua ligands and dicyanamido ligands or the dicyanamide anion. In addition, C-H⋯N inter-actions are present between the tetra-ethyl-ammonium cations and dicyanamide amide nitro-gen atoms.

Syntheses, crystal structures and magnetic studies of new manganese(II) coordination polymers with ditopic N-pyridinylisonicotinohydrazide ligand and dicyanamide

Two new coordination polymers of Mn(II) with dicyanamide anion (dca) and isonicotinohydrazone based ligands, {[Mn2(L1)2(dca)2(CH3OH)2]·H2O}n (1) and [Mn2(L2)2(μ-dca)2]n (2), were synthesized and characterized by elemental analyses and spectroscopic methods where HL1=(E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide and HL2=(E)-N′-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide. The IR spectra of 1 and 2 show the characteristic stretching vibration bands of a dicyanamide ligand as three bands. Structures of the compounds were characterized by X-ray diffraction analysis which indicates that the isonicotinohydrazone ligands act as a ditopic ligand and coordinate to manganese ions via the N2O-donor set and pyridine group of the isonicotine part. The magnetic susceptibility measurements studies indicated the presence of an antiferromagnetic coupling between high spin Mn(II) ions. Antiferromagnetic coupling for 2 is stronger than that of 1 which is due to connection of Mn(II) ions through dicyanamide bridges in the former.

A two-dimensional anionic CdII polymer constructed through dicyanamide coordination bridges.

In the search for potential ferroelectric materials, molecular-based one-, two- and three-dimensional cadmium(II) organic-inorganic compounds have been of interest as they often display solid-solid phase transitions induced by a variation in temperature. A new cadmium dicyanamide complex, poly[4-dimethylamino-1-ethylpyridin-1-ium [tri-μ-dicyanamido-κ(6)N(1):N(5)-cadmium(II)]], {(C9H15N2)[Cd(C2N3)3]}n, was synthesized by the reaction of 4-dimethylamino-1-ethylpyridin-1-ium bromide, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each Cd(II) cation is octahedrally coordinated by six terminal N atoms from six anionic dicyanamide (dca) ligands. Neighbouring Cd(II) cations are linked together by dicyanamide bridges to form a two-dimensional coordination polymer. The organic cations are not involved in the formation of the supramolecular network.

Assembly of dinuclear copper(ii) secondary building units into polymeric complexes: crystal structures and magnetic properties

Four Cu(II) complexes, the one-dimensional [Cu(HL1)2(CuCl4)]n (1), {[Cu2(L1)2(N(CN)2)(CH3OH)](ClO4)}n (2), dinuclear [Cu2(L2)2Cl2] (3), and two-dimensional layered [Cu2(L2)2(N(CN)2)2]n (4) were synthesized by Cu(II) salts (CuCl2·2H2O or Cu(ClO4)2·6H2O), alkanol bidentate ligands trans-2-(1-pyrazolyl)cyclohexanol (HL1) or 3,5-dimethyl-N-hydroxyethyl-pyrazolyl (HL2) together with sodium dicyanamide. For complex 1, the bridging chlorine atoms of the tetrahedral [CuCl4]2− moieties are located at the Jahn–Teller axis of the elongated octahedral Cu(II), forming an alternate elongated-octahedral-tetrahedral Cu(II) chain complex. For complexes 2, 3 and 4, the alkyl oxygen atoms of the deprotonated ligands HL1 and HL2 bridge two Cu(II) ions, yielding a dinuclear Cu(II) unit [Cu2(Lx)2]2+ (x = 1, 2), and one- or two-dimensional complexes via bridging dicyanamide ligands. Complex 1 shows weak ferromagnetic coupling, whilst complexes 2–4 display strong antiferromagnetic coupling or are even nearly diamagnetic due to the large Cu–O–Cu bond angles.

Synthesis, structure and magnetic properties of a 1D coordination polymer of Cu(II) containing phenoxido and dicyanamido bridging groups

A new CuII 1D coordination polymer, {[Cu2(L)(μ1,5-dca)]2·2(CH3OH)}n (1), containing the carbohydrazide based ligand (H3L=bis-[(E)-N′-(2-hydroxybenzylidene)]carbohydrazide) and the dicyanamide (dca) bridging group has been synthesized and characterized by magnetic measurements, single crystal X-ray diffraction and other spectroscopic methods. X-ray analysis reveals that the ligand coordinates to the CuII ion as a hexadentate trinegative N3O3-donor ligand. Tetranuclear copper(II) units with double phenoxido bridges are formed, connected and extended by two μ1,5-dca anions, forming a 1D polymeric structure. The magnetic measurements showed global antiferromagnetic interactions with two coupling constants between “outer” (J=−87±2cm−1) and “inner” (J′=−129±2cm−1) copper pairs in tetranuclear units. The dicyanamide, adopting the end-to-end bridging mode (metal–metal separation of ca. 8.062(5)Å), has presented poor efficiency in mediating magnetic interactions.

Synthesis, crystal structure, spectroscopic study, and magnetic behavior of the first dinuclear Mn(II) complex of hydrazone-based ligand-containing dicyanamide bridging groups

A new dinuclear complex of manganese(II), [Mn(L)(μ1,5-dca)(CH3OH)]2 (1), with dicyanamide anion and (E)-3-hydroxy-N′-(pyridin-2-ylmethylene)-2-naphthohydrazide (HL) was synthesized. The complex was characterized by elemental analyzes, spectroscopic methods, X-ray diffraction, and magnetic susceptibility studies. Two manganese ions in the complex were connected by two bridging dicyanamide ligands in a symmetric end-to-end (μ1,5-dca) fashion. The presence of intramolecular hydrogen bonding in the mononegative naphthohydrazone (L−) affects keto-enol tautomerism and the ligand coordinates to manganese(II) in the keto-form. Magnetic measurements showed an antiferromagnetic interaction between adjacent manganese ions in the dimer.

Synthesis, structures and magnetic properties of dissymmetrical Schiff-base copper(II) complexes: [(Cu2L)2(H2O)4]·(CuL)2·4H2O and [Cu2L(dca)

Abstract Two new dissymmetrical Schiff-base copper(II) complexes, [(Cu2L)2(H2O)4]·(CuL)2·4H2O (1) and [Cu2L(dca)]n (2) (H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane), have been synthesized and characterized by IR, elemental analysis, X-ray crystal diffraction and magnetic properties. Single-crystal structural analysis shows that complex 1 contains a tetranuclear [Cu4L2(H2O)4]2 + cation, two [CuL]− anions and four uncoordinated water molecules. Complex 2 is an infinite two-dimensional network structure in which the tetranuclear [Cu4L2] cations are interlinked by dicyanamide (dca−) bridges in the end-to-end (μ1,5) fashion. The magnetic properties of two complexes have been determined in the temperature range of 2.7–300 K.

Manganese(III) complexes with tetradentate (N2O2) Schiff bases and dicyanamide

New Mn(III) complexes with Schiff bases and dicyanamide are synthesized: [Mn(Salpn)N(CN)2]n (two polymorphous modifications, Ia and Ib), {[Mn(5-BrSalen)N(CN)2] · CH3OH}n (II), and [Mn(3-MeOSalen)N(CN)2(H2O)] (III), where SalpnH2 = N,N′-bis(salicylidene)-1,3-diaminopropane, 5-BrSalenH2 = N,N′-bis(5-bromosalicylidene)-1,2-diaminoethane, and 3-MeOSalenH2 = N,N′-bis(3-methoxysalicylidene)-1,2-diaminoethane. Complexes Ia, Ib, and II have the polymer structure in which the dicyanamide anion binds the paramagnetic Mn(III) complexes with the Schiff bases into one-dimensional chains. Unlike them, in complex III the monomer units containing water and the dicyanamide anion as terminal ligands form dimers due to hydrogen bonds. The study of the magnetic properties of complexes Ia and II shows a weak antiferromagnetic interaction between the Mn3+ ions through the dicyanamide bridges in these complexes.

Catena-Poly[[bis(4-methylpyridine-κN)cobalt(II)]-di-μ-dicyanamido-κ2N1:N5

Cobalt(II) nitrate hexa­hydrate and sodium dicyanamide self-assembled in dimethyl­formamide (DMF) and 4-methyl­pyridine solutions to form the title compound, [Co(C2N3)2(C6H7N)2]n. The Co2+ ion lies on an inversion center and adopts an octa­hedral coordination geometry in which four N atoms from four different dicyanamide ligands lie in the equatorial plane and two 4-methyl­pyridine N atoms occupy the axial positions. The CoII atoms are connected by two bridging dicyanamide ligands, resulting in a chain parallel to the c axis. The chains are connected into a three-dimensional network by C—H⋯N hydrogen bonds.

A triclinic polymorph ofcatena-poly[[bis(N,N-dimethylformamide-κO)cobalt(II)]-di-μ-1,5-dicyanamido-κ4N1:N5

The title compound, [Co(C2N3)2(C3H7NO)2]n, is a triclinic polymorph of the previously reported monoclinic structure [Tong et al. (2003 ▶). Acta Cryst. E59, m405–m407]. The CoII ion lies on an inversion centre and adopts an almost regular octa­hedral N4O2 coordination geometry. Adjacent CoII atoms are connected by two bridging dicyanamide ligands, resulting in the formation of neutral chains parallel to the b axis. The title complex is isotypic with the MnII analogue but not with the NiII analogue.

Syntheses, Crystal Structure and Properties of Two 1-D Coordination Polymers Bridged by Dicyanamides

Two new 1-D coordination polymers [M II (3-Bzpy)2(N(CN)2)2] (M = Cd (1), Cu (2), 3-Bzpy = 3-benzoylpyridine) have been synthesized and structurally characterized by single-crystal X-ray diffraction and IR. Single-crystal X-ray diffraction reveals that the complexes 1 and 2 are isostructural and all crystallize in monoclinic P21/c space group with cell dimensions: a = 6.3889(16) A, b = 7.6496(12) A, c = 26.767(6) A, β = 99.131(19)°, V = 1291.6(5) A3, Z = 2 for 1 and a = 6.4483(9) A, b = 7.5449(10) A, c = 25.965(4) A, β = 98.559(10)°, V = 1249.2(3) A3, Z = 2 for 2. Structure analysis manifest that 1 and 2 are all 1-D chains structures which parallel to the crystallographic b axis through end-to-end coordination by bidentate bridging dicyanamide ligands. Magnetic property of complex 2 was further investigated. The paper is about synthesis, crystal structure and magnetic property of two new 1-D coordination polymers. Perspective view down the a-axis of complex 1 with thermal ellipsoids drawn at the 50% probability level .

A new polymeric Cu(II) compound with double bridging dicyanamide. Synthesis, X-ray structure and spectroscopy of catena-[poly-trans-bis(4-methyl-pyrimidine-κN1)copper(II)-bis(μ-dicyanamido-κ2N1,N5)

The synthesis, spectral and magnetic characterization and the molecular and 3D structure of a double dicyanamide-bridged Cu(II) chain compound are described. The axial ligands are 4-Mepyrimidine. The Jahn–Teller axis of the Cu(II) ion is directed towards one dicyanamide pair (Cu-N = 2.393 Å); the short Cu-N distances are around 2.00 Å. Magnetic exchange interactions between the Cu(II) ions are weak, as deduced from EPR, and can be explained by the different orientations of the Jahn–Teller axes of the molecular units, resulting in no overlap between the magnetic orbitals.

Assembly of two cluster-based coordination polymers with good NLO performance from one NLO-inactive precursor cluster [Et4N][Tp*W(μ3–S)3(CuCl)3

Reactions of the precursor cluster [Et4N][Tp*W(μ3–S)3(CuCl)3] (Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate) (1) with 2 equiv of AgSCN produced one 1D [Tp*W(μ3–S)3Cu3]-based coordination polymer [Tp*W(μ3–S)3Cu2Cu(μ–SCN)(μ3–SCN)]2·Et2O (2·Et2O) while analogous reactions of 1 with Nadca (dca = dicyanamide) formed one 2D [Tp*W(μ3–S)3Cu3]-based coordination polymer [Tp*W(μ3–S)3Cu3(μ1,5–dca)(μ1(3),5–dca)]2·CH2Cl2 (3·CH2Cl2). Compounds 2–3 were characterized by elemental analysis, IR spectra, UV-vis spectra, 1H NMR spectra, and the crystal structures of 2·Et2O and 3·CH2Cl2 were determined by single-crystal X-ray crystallography. The structure of 2 consists of the incomplete cubanelike [Tp*W(μ3–S)3Cu3] cores which are interlinked by SCN bridges. Compound 3 contains repeating dimeric [Tp*W(μ3–S)3Cu3(μ1(3),5–dca)]2 units, which are further interconnected by four Cu–μ–dca–Cu bridges to form a 2D layer with a 63 topology. The third-order nonlinear optical (NLO) properties of 1–3 in DMF were also investigated using femtosecond a degenerate four-wave mixing DFWM technique. The two assemblies 2 and 3 exhibited good third-order NLO performances through connecting the cluster [Tp*W(μ3–S)3Cu3] cores of 1 bearing no NLO properties via thiocyanate or dicyanamide bridges.