Speciation studies of mono- and binuclear Pd(II) complexes involving mixed nitrogen–sulfur donor ligand and 4,4′-bipiperidine as a linker

Pd(MME)Cl₂ complex, where MME = methionine methyl ester, was synthesized and characterized by elemental analysis and spectroscopic techniques. [Pd(MME)(H₂O)₂]²⁺ interacts with some DNA constituents giving 1 : 1 and 1 : 2 complexes. The binuclear complexes having 4,4′-bipiperidine as a linker and involving [Pd(MME)(H₂O)₂]²⁺ and DNA constituents were investigated. The results show formation of [(H₂O)(MME)Pd(Bip)Pd(MME)(H₂O)]⁴⁺. Inosine, uracil, and thymine interact with the previously mentioned complex by substitution of the two coordinated water molecules. Formation constants of all possible mono- and binuclear complexes were determined and their speciation diagrams were evaluated.     

Synthesis,X-ray structure,DFT and thermodynamic studies of mono- and binuclear palladium(II) complexes involving 1,4-bis(2-hydroxyethyl)piperazine,bio-relevant ligands and 4,4′-bipiperidine

[Pd(BHEP)Cl₂] (BHEp = 1,4-bis(2-hydroxyethyl)piperazine) was synthesized and characterized. The palladium center has a typical square-planar geometry with a tetrahedral distortion. The alcohol groups of the ligand do not participate in binding to Pd(II). The DFT/B3LYP method was used for geometric optimization of the ligand and the complex using the Gaussian 09 program and compared with experimental results. The stoichiometry and stability constants of the complexes formed between [Pd(BHEP)(H₂O)₂]²⁺ and some selected amino acids, peptides, and DNA constituents were investigated at 25 °C and 0.1 M ionic strength. The binuclear complex [(H₂O)(BHEP)Pd(Bip)Pd(BHEP)(H₂O)]⁴⁺ was detected, where Bip = 4,4′-bipiperidine. Inosine, uracil, and thymine interact with the binuclear complex via substitution of both coordinated water molecules. The potentiometric results were complimented by spectroscopic measurements. The concentration distribution diagrams of the various species formed were evaluated.     

[Ni(bpy)(mal)(H2O)3]·H2O and [Ni(4,4′-dmbpy)(mal)(H2O)3]·1.5H2O: syntheses,crystal structures,magnetic properties,and computational study of stacking interactions

[Ni(bpy)(mal)(H₂O)₃]·H₂O and [Ni(4,4′-dmbpy)(mal)(H₂O)₃]·1.5H₂O (mal = maleato; bpy = 2,2′-bipyridine; 4,4′-dmbpy = 4,4′-dimethyl-2,2′-bipyridine) exhibit molecular crystal structures. The Ni(II) central ions in both complexes are six-coordinate by one chelate bonded L–L ligand, three aqua ligands, and one position is occupied by a maleato oxygen donor atom. Hydrogen bonded ribbon-like supramolecular structural motifs are present in both studied complexes; these are linked by weaker C–H?O hydrogen bonds in [Ni(bpy)(mal)(H₂O)₃]·H₂O, whereas in [Ni(4,4′-dmbpy)(mal)(H₂O)₃]·1,5H₂O the hydrogen bonded ribbons are linked by O?H-O-H?O hydrogen bonds with the participation of the additional water solvate molecule positioned on the twofold axis. In both structures, π–π stacking interactions with different patterns in respective structures were found. The role of dispersion energy and many-body effects in the stabilization of bpy and 4,4′-dmbpy stacking interactions were investigated using methods of computational chemistry. Those confirm the dispersion-dominated stabilization of the 4,4′-dmbpy supramolecular chain-like structure, with only marginal impact of cooperativity effects. Thermal decompositions of both complexes start with dehydration. Magnetic susceptibility studies performed from 2 to 300 K revealed a dominant effect of the zero-field splitting of the Ni(II) ion, governing the low-temperature magnetic properties of both compounds.     

Synthesis,spectroscopic, and biological activities of two binuclear complexes [Cu(II)(1-phenylamidino-O-methylurea)2(H2O)]2(Cl2)2 and [Cu(II)(1-phenylamidino-O-i-butylurea)tmen]2(Cl2)2·2H2O

EPR spectra of two copper(II) binuclear complexes, [Cu(II)(1-phenylamidino-O-methylurea)₂(H₂O)]₂(Cl₂)₂ (1) and [Cu(II)(1-phenylamidino-O-i-butylurea)tmen]₂(Cl₂)₂?·?2H₂O (2), at room temperature showed fine structure transitions (ΔM _s?=?±1) and a very weak half-field signal corresponding to forbidden transitions (ΔM _s?=?±2). The spectrum of 1 showed disappearance of normal and half-field transitions when cooled to 77?K, suggesting antiferromagnetical coupling dicopper complex which is also supported by the low magnetic moments (µ _eff?=?1.64?B.M.). The isotropic exchange interaction constant J (41?cm^?1) for 2 indicated that interaction between the two spins of the binuclear complex is ferromagnetic, confirmed from the high magnetic moment value (µ _eff?=?2.25?B.M.). The binding of these complexes with calf thymus DNA suggested that these complexes interact with DNA by electrostatic or groove binding, not by intercalation. The two complexes have good antibacterial activity against tested bacteria responsible for urinary tract infection.     

Mono- and dinuclear palladium(II) compounds containing nitrogen ligands. Crystal and molecular structure of [Pd(N,C-dmba)(NCO)(2,3-lut)] and [Pd(H2CCOMe)Cl(2,2′-bipy)]

The cyanate-bridged cyclopalladated compound [Pd(N,C-dmba)(-NCO)]₂ (1)(dmba = PhCH₂NMe₂) reacts in CH₂Cl₂ with 2,3-lutidine (2,3-lut), 3,4-lutidine (3,4-lut), 2,2-bipyridine (2,2-bipy) and 4,4-bipyridine (4,4-bipy), to give [Pd(N,C-dmba)(NCO)(2,3-lut)](2), [Pd(N,C-dmba)(NCO)(3,4-lut)](3), [{Pd(N,C-dmba)(NCO)}₂(-2,2-bipy)]· CH₂Cl₂ (4) and [{Pd(N,C-dmba)(NCO)}₂(-4,4-bipy)]· CH₂Cl₂ (5), respectively. The compounds were characterized by elemental analysis, i.r. and n.m.r. spectroscopy and also by t.g.a. The i.r. spectra of (2–5) display typical bands of monodentate N-bonded cyanate groups, whereas the n.m.r. data of (4) are consistent with the presence of a bridging 2,2-bipyridine ligand. Complex (4) decomposes slowly in acetone. One of the products formed, [Pd(H₂CCOMe)Cl(2,2-bipy)](6), was characterized by X-ray diffraction. As inferred from the t.g.a., the thermal stability decreases in the order:[{Pd(N,C-dmba)(NCO)}₂(-4,4-bipy)].CH₂Cl₂ (5) > [Pd(N,C-dmba)(2,3-lut)(NCO)](2)=[Pd(N,C-dmba)(3,4-lut)(NCO)](3) > [{Pd(N,C-dmba)(NCO)}₂(-2,2-bipy)]· CH₂Cl₂ (4). According to thermal analysis and X-ray diffraction patterns compounds (2–3) decompose into metallic palladium Pd(0), whereas (4–5) decompose with the formation of PdO. The X-ray crystal and molecular structure of [Pd(N,C-dmba)(NCO)(2,3-lut)](2) was determined. The lutidine unit is perpendicular to the coordination plane.     

Fluorine-substituted β-diketonate PbII complexes, [Pb(phen)(TFPB)2] and [Pb(2,2′-bipy)(TFPB)2]

Lead(II) 4,4,4-trifluoro-1-phenyl-1,3-butandionate (TFPB^?) complexes with 1,10-phenanthroline (phen) and 2,2′-bipyridine (2,2′-bipy), [Pb(L)(TFPB)₂], have been synthesized and characterized by elemental analysis, IR-, ¹H NMR spectroscopy and studied by X-ray crystallography. The self-assembly of [Pb(L)(TFPB)₂] complexes, (L?=?phen or 2,2′-bipy) is caused by C–H?···?F–C, C–H?···?O–C and π–π stacking interactions. The thermal stabilities of compounds were studied by thermal gravimetric (TG) and differential thermal analyses (DTA).     

Synthesis,structure and photoluminescent properties of a new coordination polymer [Cd2(pzdc)2(4,4′-bpy)(H2O)2] n (H2pzdc = pyrazine-2,3-dicarboxylic acid, 4,4′-bpy = 4,4′-bipyridine)

A new 2D coordination polymer, [Cd₂(pzdc)₂(4,4′-bpy)(H₂O)₂] _n (1) (pzdc = pyrazine-2,3-dicarboxylic acid, 4,4′-bpy = 4,4′-bipyridine), has been hydrothermally synthesized and characterized by elemental analyses, IR spectra and single crystal X-ray diffraction. X-ray diffraction analysis reveals that 1 features an interesting 2D stair-like layer with linear [Cd₂(pzdc)₂(H₂O)₂] _n ribbons linked by 4,4′-bpy bridges. Furthermore, these layers are packed in an ABAB arrangement to give a 3D supramolecular network via hydrogen bonding and π–π packing interactions. Compound 1 displays strong fluorescent emission in the solid state at room temperature.     

A new ZnII two-dimensional coordination polymer, {[Zn(μ-4,4′-bipy)(1,4-ndc)(H2O)2] · (H2O)} n (4,4′-bipy= 4,4′-bipyridine and 1,4-ndc=1,4-naphthalenedicarboxylate)

A 2D Zn^II(μ-4,4′-bipy) coordination polymer with 1,4-naphthalenedicarboxylate, {[Zn(μ-4,4′-bipy)(1,4-ndc)(H₂O)₂] · (H₂O)} _n , has been synthesized, characterized and studied by X-ray crystallography. The structural studies show the Zn atoms have six-coordinate geometry with a distorted octahedral environment. The 2D structure is grown by hydrogen bonds into a hybrid three-dimensional network.     

Crystal Structure and Interaction with DNA of [Ni(phen)(mal)(H2O)2]·3H2O

A new complex [Ni(phen)(mal)(H2O)2]·3H2O (phen = 1,10-phenanthroline,mal2-= malonic acid) has been synthesized by the reaction of nickel nitrate,phen and malonic acid.EA,IR spectra and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure of the title complex.Crystal data:monoclinic system,space group P2/c,a =8.937(3),b = 12.163(5),c = 9.725(3)(A),β = 119.36°,C15H19N2O9Ni,Mr= 430.03,Z = 2,F(000) =446,V = 921.3 (A)3,Dc = 1.550 g/cm3,μ = 1.104 mm-1,-10≤h≤ 10,-12≤k≤ 14,-11 ≤l≤7,R =0.0261 and wR = 0.0609 for 4376 (Rint = 0.0203) independent reflections and 1631 observed ones (I＞ 2σ(I)).Ni(Ⅱ) exhibits an octahedral coordination geometry,with hydrogen bonds and π-π interactions stabilizing the whole structure.UV spectrum of the complex interacting with protamine DNA indicates that the title compound interacts with DNA via insertion mode with bonding constant Kb of 1.11 × 104.     

Diaqua[N,N-di(2-carboxyethyl)-o-anisidinato]copper(II) Dihydrate [Cu(o-Andp)(H2O)2] · 2H2O: Synthesis and Crystal Structure

Crystals of [Cu(o-Andp)(H₂O)₂] · 2H₂O (where o-Andp^2–is -anisidine-N,N-di-3-propionate) were synthesized and studied using X-ray diffraction analysis. The crystals are triclinic: a= 12.063(1) Å, b= 12.483(3) Å, c= 13.586(2) Å, = 91.29(1)°, = 111.67(1)°, = 104.00(1)°, V= 1830.5(5) ų, space group P , Z= 2, and R= 0.0528 for 5965 reflections with I2(I). The two crystallographically independent complexes are isostructural. The tetragonal–bipyramidal coordination of copper(III) involves three O atoms, the N atom of the tetradentate ligand o-Andp^2–, and two O atoms from water. The aminodipropionate group of the ligand (average Cu–O 1.939 Å and Cu–N 2.051 Å) and one of the coordinated water molecules (Cu–O(w) 1.991 Å) lie in the equatorial plane. The second water molecule (Cu–O(w) 2.32 Å) and the methoxy O atom of o-Andp^2–(Cu–O 2.37 Å) are in the apical positions of the bipyramid.     

Syntheses and structural determination of eight-coordinate Na[YbIII(Cydta)(H2O)2] · 5H2O and [YbIII(Hegta)] · 2H2O complexes

Na[Yb^III(Cydta)(H₂O)₂] · 5H₂O (1) (H₄Cydta = trans-1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid) and [Yb^III(Hegta)] · 2H₂O (2) (H₄egta = ethyleneglycol-bis-(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) were prepared and their composition and structures were determined by elemental analyses and single-crystal X-ray diffraction techniques. Complex 1 crystallized in the triclinic crystal system with space group P 1; the Yb^III is eight-coordinate by a hexadentate Cydta and two water molecules. Complex 2 is a protonated egta complex, crystallized in the monoclinic crystal system with space group P 2 ₁ /c; Yb^III is coordinated only by the octadentate Hegta ligand. Both these complexes adopt a pseudo-square antiprismatic conformation.     

Synthesis,characterization and crystal structure of a 1D heteropolytungstate [4,4′-bipyH2]2[4,4′-bipyH][PCoW11O39]·H2O

A chain-like structure compound [4,4′-bipyH₂]₂[4,4′-bipyH][PCoW₁₁O₃₉]?·?H₂O, in which lacunary polyoxoanions are joined by a Co–O–W bridge, was prepared through the hydrothermal method and characterized by IR, and X-ray crystallography. The title compound crystallizes in a monoclinic lattice, P2₁/n space group, with a?=?13.643 (3), b?=?27.052(5), c?=?15.180(3)?Å, β?=?100.63(3)°, V?=?5506.2(19)?ų, Z?=?4, R ₁?=?0.0792, wR ₂?=?0.1532. Cobalt-substituted Keggin-type subunits are connected via Co–O–W bridges to form a 1D, chainlike, polymolecular Keggin POM. TG-DTA analysis indicates the title compound decomposes at 553°C.     

Preparative chemistry with [Ru(η6-arene)(H2O)3]2+: bis-arene and monobenzene complexes with O,N and S donors

The preparation, and electronic, ¹H and ¹³C NMR spectra of the complex ions [Ru(η⁶-C₆H₆)L₃]²⁺ (L = acetonitrile, dimethylsulphoxide, dimethylsulphide or tetrahydrothiophene) from [Ru(η⁶-C₆H₆)(H₂O)₃]²⁺ are reported. The NMR data of coordinated benzene are discussed in terms of the π-backbonding capacity of the monodentate ligand.     

Syntheses and structural determination of the nine-coordinate rare earth metal complexes: [TbIII(Eg3a)(H2O)2] · 4.5H2O and K[TbIII(Edta)(H2O)3] · 5H2O

Two title complexes, [Tb^III(Eg3a)(H₂O)₂] · 4.5H₂O (I) (H₃Eg3a = 3-carboxymethyl-6, 9-dioxa-3,12-diazatetradecanedioic acid) and K[Tb^III(Edta)(H₂O)₃] · 5H₂O(II) (H₄Edta = ethylenediamine-N,N,N′,N′-tetraaceti acid), were prepared and characterized by FT-IR, elemental analyses, TGA-DTA-DTG, and single-crystal X-ray diffraction technique. For I, the Tb³⁺ ion is nine-coordinated by an Eg3a ligand and two coordination water molecules, yielding a monocapped square-antiprismatic (MCSAP) conformation. Complex I crystallizes in the monoclinic system with P2₁/c space group. The crystal data are as follows: a = 9.237(3), b = 10.018(3), c = 23.580(7) Å, β = 99.021(5)°, V = 2155.2(11) ų, Z = 4, ρ = 1.822 Mg m^?3, μ = 3.353 mm^?1, F(000) = 1180, R ₁ = 0.0445 and wR ₂ = 0.1034 for 4262 observed reflections with I ≥ 2σ(I). For II, the Tb³⁺ ion is nine-coordinated by an Edta ligand and three coordinate water molecules also yielding a MCSAP conformation. Complex II crystallizes in the orthorhombic system with Fdd2 space group. The crystal data are as follows: a = 19.373(5), b = 35.429(10), c = 12.114(3) Å, V = 8315(4) ų, Z = 16, ρ = 2.014 Mg m^?3, μ = 2.014 mm^?1, F(000) = 5024, R ₁ = 0.0224 and wR ₂ = 0.0557 for 3189 observed reflections with I ≥ 2σ(I). The potassium cations bridge the coordination spheres yielding many infinite long 1-D zigzag-type chains. The molecular structure of I is more stable than that of II. According to thermal analyses, the collapsing temperatures of crystal structure are 314°C for I and 348°C for II, which indicates that the crystal structure of II is more stable.     

Syntheses and structures of mononuclear eight-coordinate Na[ErIII(Cydta)(H2O2]·5H2O (Cydta = trans-1,2-cyclohexanediaminetetraacetic acid) and binuclear nine-coordinate Na2[SmIII(Cydta)][SmIII(Cydta)(H2O)3] · 11H2O

The title complexes, Na[Er^III(Cydta)(H₂O)₂] · 5H₂O (I) and Na₂[Sm^III(Cydta)][Sm^III(Cydta)(H₂O)₃] · 11H₂O (II) (Cydta is trans-1,2-cyclohexanediaminetetraacetic acid), are prepared and characterized using IR, elemental analyses, and single-crystal X-ray diffraction techniques. Crystal I belongs to triclinic system (space group P1), which has a mononuclear eight-coordinate slightly distorted square antiprismatic conformation. The crystal data are as follows: a = 8.371(12) Å, b = 9.952(14) Å, c = 14.74(2) Å, α = 88.32(2)°, β = 76.30(2)°, γ = 87.87(2)°, V = 1192(3) ų, Z = 1, ρ = 1.835 g/cm³, μ = 3.612 mm^?1, F(000) = 658, R = 0.0194, and wR = 0.0520 for 4130 observed reflections with I≥2σ(I). Crystal II belongs to monoclinic system (space group P2₁/n), which has the binuclear nine-coordinate structure with tricapped trigonal prismatic conformation for Sm(1) and the pseudomonocapped square antiprismatic conformation for Sm(2). The crystal data are as follows: a = 12.283(6) Å, b = 15.626(7) Å, c = 25.875(12) Å, β = 97.962(7)°, V = 4919(4) ų, Z = 4, ρ = 1.717 g/cm³, μ = 2.476 mm^?1, F(000) = 2536, R = 0.0781, and wR = 0.1745 for 8554 observed reflections with I ≥ 2σ(I).     

Synthesis, crystal structure, and fluorescence properties of a novel coordination polymer [Zn(L)(4,4′-bipyridine)(H2O)] n · (H2O)4

In this work, a novel and rare coordination polymer, [Zn(L)(Bipy)(H₂O)] _n · (H₂O)₄ (H₂L??sphenylpropylmalonate acid, Bipy??4,4??-bipyridine), has been synthesized and characterized by elemental analysis, FT-IR spectroscopy, and solid fluorimetry studies. In the crystal, the Zn²⁺ ion of the complex is hexacoordinated in a slightly distorted octahedral configuration forming the unit structure, 2D structure, and 3D framework. The supramolecular architecture was constructed by a unit of (H₂O)₄ discrete water cluster. Besides, the coordination polymer displays strong emission spectra due to the metal-to-ligand charge-transfer transition, having potential applications as fluorescent materials.     

Syntheses and structures of nine-coordinate NH4[HoIII(Edta)(H2O)3] · 1.5H2O, (NH4)4[Ho 2 III (Dtpa)2] · 9H2O, and (NH4)3[HoIII(Ttha)] · 5H2O complexes

The three title complexes, NH₄[Ho^III(Edta)(H₂O)₃] · 1.5H₂O (I) (H₄Edta = ethylenedianine-N,N,N′,N′-tetraacetic acid), (NH₄)₄[Ho ₂ ^III (Dtpa)₂] · 9H₂O (II) (H₅Dtpa = diethylenetriamine-N,N,N′,N″,N″-entaacetic acid), and (NH₄)₃[Ho^III(Ttha)] · 5H₂O (III) (H₆ Ttha = triethylenetetramine-N,N,N′,N″,N?,N?-hexaacetic acid), have been prepared and characterized by FT-IR, elemental analyses, and single-crystal X-ray diffraction technique. Complex I has a nine-coordinate mononuclear structure with distorted monocapped square antiprismatic conformation and its crystal structure belongs to orthorhombic system and Fdd2 space group. The crystal data are as follows: a = 19.343(9), b = 35.125(17), c = 12.364(6) Å, V = 8400(7) ų, Z = 16, M = 552.26, ρ_calcd = 1.747 g cm^?3 μ = 3.828 mm^?1, and F(000) = 4368. Complex II has a binuclear nine-coordinate pseudomonocapped square antiprismatic conformation and its crystal structure belongs to triclinic system and space P1 group. The crystal data are as follows: a = 9.7637(16), b = 9.9722(16), c = 12.945(2) Å, α= 85.853(2)°, β = 77. 140(2)°, γ = 77.140(2)°, V = 1198.4(3) ų, Z = 1, M = 1340.80, ρ_calcd = 1.858 g cm^?3, μ = 3.380 mm^?1, and F(000) = 674. As for complex III, it also has nine-coordinate mononuclear structure with distorted tricapped trigonal prism and its crystal structure belongs to monoclinic system andP2₁/c space group. The crystal data are as follows: a = 10.349(3), b = 12.760(4), c = 23.142(7) Å, β = 91.020(6)°, V = 3055.6(16) ų, Z = 2, M = 797.55, ρ_calcd = 1.734 g cm^?3, μ = 2.674 mm^?1, and F(000) = 1624. The results showed that although the ligands are different from one another in the shape and the numbers of coordination atoms, they all have nine-coordinate structures. However, one of them has binuclear structure and the other two have mononuclear structures because of the difference of the ligands.     

Spectral, thermal and electrochemical characterization of novel homo-dinuclear complexes [M2(H3DTPA)(H2O)6]Cl2·xH2O (M=Cr2+, Mn2+, Co2+, Ni2+ or Cu2+)

The title complexes were prepared and characterized employing spectral (FAB-Mass, IR, electronic, (1)H and (13)C NMR), thermal and electrochemical techniques. Analytical and FAB-Mass data suggested a homo-dinuclear stoichiometry. IR and electronic ligand field spectral studies coupled with molecular model computations have indicated a distorted octahedral geometry where the ligand coordinates as a hexadentate dianionic [H(3)DTPA](2-)(H(5)DTPA=diethylenetriaminepentaacetic acid) moiety. The electrochemical redox properties and the antibacterial activities of the compounds were also investigated.     

Light-induced cis/trans isomerization of cis-[Pd(L-S,O)2] and cis-[Pt(L-S,O)2] complexes of chelating N,N-dialkyl-N′-acylthioureas: key to the formation and isolation of trans isomers

Irradiation cis-[M(Lⁿ-S,O)₂] complexes (M = Pt^II, Pd^II) derived from N,N-dialkyl-N′-benzoylthioureas (HLⁿ) with various sources of intense visible polychromatic or monochromatic light with λ < 500 nm leads to light-induced cis?→?trans isomerization in organic solvents. In all cases, white light derived from several sources or monochromatic blue-violet laser 405 nm light, efficiently results in substantial amounts of the trans isomer appearing in solution, as shown by ¹H NMR and/or reversed-phase HPLC separation in dilute solutions at room temperature. The extent and relative rates of cis/trans isomerization induced by in situ laser light (λ = 405 nm) of cis-[Pd(L²-S,O)₂] was directly monitored by ¹H NMR and ¹⁹⁵Pt NMR spectroscopy of selected cis-[Pt(L-S,O)₂] compounds in chloroform-d; both with and without light irradiation allows the δ(¹⁹⁵Pt) chemical shifts cis/trans isomer pairs to be recorded. The cis/trans isomers appear to be in a photo-thermal equilibrium between the thermodynamically favored cis isomer and its trans counterpart. In the dark, the trans isomer reverts back to the cis complex in what is probably a thermal process. The light-induced cis/trans process is the key to preparing and isolating the rare trans complexes which cannot be prepared by conventional synthesis as confirmed by the first example of trans-[Pd(L-S,O)₂] characterized by single-crystal X-ray diffraction, deliberately prepared after photo-induced isomerization in acetonitrile solution.