Synthesis and Crystal Structures of Nickel(II) and Copper(II) Complexes of Meso-3,6,6,9-Tetramethyl-4,8-Diazaundecane-2,10-Dione Dioxime

The nickel(II) and copper(II) complexes of meso-3,6,6,9-tetramethyl-4,8-diazaundecane-2,10-dione dioxime (meso-HM-PAO) have an intramolecular hydrogen bond between cis oxime groups. [Cu(meso-HM-PAO-H)(H₂O)](NCS) crystallizes in space group P2₁/n with a = 7.692(1), b = 12.028(2), c=20.235(3) Å, β=93.03(1)°, Z = 4 and Dc=1.46 g/cm³. The final R value for this complex was 0.034 for 2223 observed reflections with I ≥ 2.5σ (I). The Cu(II) coordination is a distorted square pyramid. The Cu(II) ion is five-coorinated with the diazadioxime N atoms equatorial and water O atom axial. The Cu(II) is 0.12 Å from the equatorial plane towards the hydrate. The equatorial Cu-N distances span a narrow range, 1.953(3)-1.999(3) Å. The axial Cu-O distance is 2.314(3) Å. The thiocyanate group is almost linear. The intramolecular O ?O hydrogen bond length is 2.479(4) Å. [Ni(meso-HM-PAO-H)](ClO₄) crystallizes in space group P2₁/c with a = 14.774(3), b = 12.752(3), c = 20.035(4) Å, β = 92.94(3)°, Z = 8 and Dc = 1.51 g/cm³. The final R value for the complex was 0.053 for 4794 observed reflections with F ≥ 4σ (F). The coordination about Ni(II) is a slightly distorted square plane. The Ni(II) ion is 0.0673(7) Å from the best plane of the four donor nitrogen atoms away from the perchlorate ion. The Ni-N distances span a narrow range 1.863(4)-1.927(4) Å. There are two molecules per asymmetrical unit resulting in eight molecules being packed in an unit cell; they are bound together by van der Waals interactions. The O-H ?O bonds of these complexes give characteristic infrared absorptions as well as chemical shift of the ¹H NMR signal (Ni complex).     

Synthesis of ditopic ligands for the selective extraction of copper(II) nitrate and crystal structures of their Cu(II) complexes

We have synthesized two ditopic ligands for selective extraction of copper(II) nitrate. We also synthesized one cation-only binding analog for comparison. All three ligands were characterized by conventional techniques. Competitive two-phase metal ion solvent extraction experiments were performed at 25 °C over a period of 24 h. These ligands showed significant selectivity for Cu(II) ions, having the ditopic ligands extract 81 and 73% of the Cu(II) ions in a solution of different metal ions {Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Pb(II)} at pH 5.09. Competitive transport experiments (water/chloroform/water) were undertaken employing each ligand separately as the ionophore in the membrane (chloroform) phase. No metal ion transport was observed, but a large concentration of Cu(II) was present in the membrane phase. Competitive anion extraction and transport were carried out with the ditopic ligands, yielding selective extraction and transport of nitrate. Furthermore, a pH isotherm of the best ditopic ligand (H₂L²) with Cu(II) was determined from pH 1.0 to 6.0, producing a pH_½ value of approximately 2.6. Finally, crystal structures of the ditopic ligands complexed with Cu(II) were determined and refined. The coordination geometry around the metal centers are distorted square planar and the Cu(II)-donor bond lengths fall within the normal range.     

Structure of the nitrosoguanidine complexes of nickel(II) and copper(II) by X-ray crystallography and computational analysis

Using the X-ray structure of solid nitrosoguanidine (ngH), potential structures of its complex with aqueous nickel(II) were surmised. A single-crystal X-ray diffraction determination of the Ni(II) complex confirmed one of these configurations. The X-ray structural parameters were compared with the most stable gaseous configurations derived from ab initio-MO calculations. The lowest energy calculated configuration of the nickel(II) complex and the X-ray crystal structure are in excellent agreement. The neutral diamagnetic, planar, red-colored [bis(nitrosoguanidate)nickel(II)] complex, [Ni(ng)₂]°, is nitrogen coordinated in the trans configuration. It is highly insoluble in all solvents investigated, and has essentially the same crystal symmetry and unit-cell dimensions as the free ligand. In ligand crystals, two molecules have four nitrogen atoms aligned in a plane such that they are suitable for coordination to a nickel ion (1.945, 2.064?Å), when it is at the 1/2,?1/2,?1/2 unit-cell position. Furthermore, the complexes stack, as in [Ni(dmg)₂]°, placing the nickel ions in nearly perfect positions for weak metal–metal bonding between adjacent layers at the near optimum distance of 3.65(1)?Å. This results in a tight, linear macromolecule having low volatility and the extremely low solubility observed. As far as we are aware this is the first instance in which a ligand crystal structure is essentially the same as the complex it forms, with minor differences in bond distances, angles and torsion angles, and suggests some potentially unique properties and applications for this material.     

Synthesis and characterization of novel Cd(II), Zn(II) and Ni(II) complexes with 2-quinolinecarboxaldehyde selenosemicarbazone. Crystal structure of bis(2-quinolinecarboxaldehyde selenosemicarbazonato)nickel(II)

New complexes of Cd(II), Zn(II) and Ni(II) with 2-quinolinecarboxaldehyde selenosemicarbazone (Hqasesc) were synthesized and structurally characterized. The structure of the ligand, Cd(II) and Zn(II) complexes was determined by NMR and IR spectroscopy, elemental microanalysis and molar conductivity measurements. Both complexes occur in solution in two forms, the major tetrahedral and minor octahedral. In the major Cd(II) complex one qasesc⁻ ligand is coordinated as a tridentate, the fourth coordination site being occupied by acetate, while in the major Zn(II) complex two qasesc⁻ ligands are coordinated as bidentates. In both minor complexes two qasesc⁻ ligands are coordinated as tridentates forming the octahedral geometry around the central metal ion. The only paramagnetic complex in the series is Ni(II) complex for which X-ray structure analysis was performed. The complex has the angularly distorted octahedral geometry with two qasesc⁻ ligands coordinated as tridentates, in a similar way as in the minor complexes of Cd(II) and Zn(II).     

Mononitrosated and phenylamido substituted chelate linkage isomers of quadridentate Schiff base copper(II) complexes

The nitrosation of monophenylamido substituted quadridentate Schiff base complexes of copper(II) are observed to adopt N-bonded isonitroso coordination whereas the phenylisocyanation of the corresponding mononitrosated quadridentate complexes are found to prefer O-bonded isonitroso coordination.     

Study of amino- and pyridyl-containing zinc(II) and cadmium(II) complexes by molecular mechanics using a force field based on the Gillespie-Kepert model

A new approach combining the molecular mechanics (MM) method and the Gillespie-Kepert model was applied to calculate the geometry and strain energy of zinc(II) and cadmium(II) complexes with amino- and pyridyl-containing ligands. High accuracy of calculations of the geometry was demonstrated for more than 20 complexes of these metals. Typical r.m.s. deviations between the calculated and experimental values (X-ray diffraction analysis) were 0.02 Å for bond lengths, 2° for bond angles, and 4° for torsion angles. The size-match selectivity of several macrocycles and polydentate open-chain ligands was studied. Correlations between the calculated strain energies of metal complexes and the experimental values of their stability constants and enthalpies of formation are discussed.     

大环金属铜(II)、镍(II)配合物的模板合成与晶体结构

用模板法合成了1个大环金属铜(II)配合物[CuLCl₂]·3H₂O (1)和3个大环金属镍(II)配合物[NiLCl₂] (2)，[NiL](ClO₄)₂ (3)和[NiLH₂](ClO₄)₄ (4)(L=3,10-二乙基-1，3，5，8，10，12-六氮杂十四烷)，通过X-射线衍射单晶结构分析测定了它们的晶体结构。晶体结构显示：配合物1和2的金属离子与大环配体的4个氮原子及大环平面轴向的2个氯离子以八面体配位方式配位；配合物3和4的金属离子与大环配体的4个氮原子以平面正方形配位方式配位，配合物4的侧链氮原子的质子化导致侧链结构翻转，使得其侧链与大环平面共面。     

Influence of steric strain of S,N-heterocycles derivative ligands on the coordination geometry in cadmium(II) nitrato complexes

The new ligands 2-(3,5-dimethyl-1-pyrazolyl)-2-thiazoline (DMPyTn) and 2-(3,5-diphenyl-1-pyrazolyl)-2-thiazoline (DPhPyTn) have been synthesized and characterized, and six cadmium(II) nitrato complexes with these two ligands and four other pyrazole/S,N-heterocyclic derivative ligands with different steric features, previously reported, have been prepared and structurally characterized by means of elemental analysis, single crystal X-ray diffraction and IR spectra, with the objective of determining the role played by the steric strains of the ligands on the metal ion coordination index and geometry. The effect of two factors has been analyzed: the bulk of the pyrazole ring substituents and the size of the S,N-heterocycle. The data indicate that there is a clear influence of the size of the organic ligands on the coordination environment of the Cd(II) ion.     

Cobalt(II), nickel(II), and copper(II) complexes of 14-membered hexaazamacrocycles: synthesis and characterization

Cobalt(II), nickel(II), and copper(II) complexes containing 5,12-di(4-bromophenyl)-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L¹) and 5,12-diphenyl-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L²) have been synthesized. All complexes were characterized by elemental analysis, MALDI TOF-MS spectrometry, and electronic absorption spectroscopy. The crystal structures of two compounds, [Cu₂(H₂L¹)Cl₄]_n and [NiL²], were determined by X-ray powder diffraction. In the polymeric [Cu₂(H₂L¹)Cl₄]_n, the Cu₂Cl₄ units and H₂L¹ molecules are situated on inversion centers. Each Cu(II) has a distorted trigonal-bipyramidal coordination environment formed by N and O from H₂L¹ [Cu–N 2.340(14)?Å, Cu–O 1.952(11)?Å], two bridging chlorides [Cu–Cl 2.332(5), 2.279(5)?Å] and one terminal chloride [Cu–Cl 2.320(6)?Å]. In the [NiL²] complex, the Ni(II) situated on inversion center has a distorted square-planar coordination environment formed by four nitrogens from L² [Ni–N 1.860(11), 1.900(11)?Å].     

Metal String Complexes: Synthesis,Crystal Structures and Magnetic Properties of Heptanuclear Nickel(II) Complexes, [Ni7(μ7-teptra)4X2] (teptra = tetrapyridyltriamido,X = Cl−, NCS−)

The synthesis, crystal structures and magnetic properties of linear heptanuclear nickel(II) complexes [Ni₇(μ₇-teptra)₄X₂], (teptra = tetrapyridyltriamido), with the axial ligand X = Cl^? ( 1 ), NCS^? ( 2 ), are reported. The hepta-nuclear metal chain is helically wrapped by four syn-syn-syn-syn-syn-syn teptra^3? ligands. Both of the [Ni₇(μ₇-teptra)₄]²⁺ moiety are isostructural involving a Ni₇ linear chain unit with all of the ∠Ni-Ni-Ni being 180°, terminated by two axial ligands. Three types of Ni? Ni distances are found in these complexes. The longest ones bonded with the axial ligands are 2.383(1), 2.374(2) and 2.375(2), 2.354(2), and the intermediate ones are 2.310(1), 2.304(1) and 2.300(2), 2.303(2) Å for ( 1 ) and ( 2 ), respectively. The innermost Ni? Ni distances are the shortest ones with the distances of 2.226(2), 2.214(2) and 2.194(2), 2.206(2) Å for ( 1 ) and ( 2 ), respectively. Two terminal Ni(II) ions bonded with the axial ligands are in a square-pyramidal (NiN₄X) environment and exhibit long Ni? N bonds (?2.10 Å) which are consistent with a high-spin Ni(II) configuration. The inner five Ni(II) ions displayed short Ni? N (～1.90 Å) bond distances which are consistent with a square-planar (NiN₄), diamagnetic arrangement of a low-spin Ni(II) configuration. The magnetic measurement of ( 1 ) shows an antiferromagnetic interaction of two terminal high-spin Ni(II) ions with the coupling constant J = ?3.8 cm^?1. The Ni? Ni, Ni? N distances and magnetic behavior among tri-, penta-, and hepta-nickel(II) complexes are compared and discussed.     

Syntheses and characterization of nickel(II), zinc(II) and palladium(II) complexes derived from three pyrazole-based polydentate ligands

Two pyrazole-based polydentate ligands, 1,3-bis(5-methyl-3-phenylpyrazol-1-yl)-propan-2-ol (Hmppzpo) and 1,3-bis(5-methyl-3-p-isopropylphenylpyrazol-1-yl)-propan-2-ol (Hmcpzpo), have been synthesized. A third ligand, 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-2-ol (Hdmpzpo), has been synthetically modified. Seven new M(II) coordination compounds of general formula M₂L₂X₂ (M?=?Zn, Ni; X?=?NO₃ or ClO₄; L?=?dmpzpo, mppzpo or mcpzpo) or MLX (M?=?Pd; L?=?dmpzpo; X?=?Cl) were synthesized and structurally characterized by elemental analysis and FT-IR analysis. The crystal structures of [Zn₂(μ-dmpzpo-O,N,N′)₂(NO₃)₂]?·?2H₂O (1?·?2H₂O), [Ni₂(μ-dmpzpo-O,N,N′)₂(CH₃CN)₂](ClO₄)₂ (2) and Pd(μ-dmpzpo-N,N′)Cl₂ (4) were determined by single-crystal X-ray crystallography. The crystal structures show that complexes 1?·?2H₂O and 2 are center-symmetric dinuclear compounds, with two metal ions bridged by two alkoxo groups and each metal ion with a distorted square-pyramidal environment. The palladium complex, 4, displayed square-planar coordination geometry around the Pd(II) ion with trans arrangement.     

Preparation and spectral characterization of new macrocyclic Ni(II) and Co(II) complexes derived from 1,4- bis (2-carboxyaldehydephenoxy)butane and various diamines

Six new macrocyclic complexes were synthesized by the template effect from reaction of 1,4-bis(2-carboxyaldehydephenoxy)butane, Ni(NO₃)₂ · 6H₂O or Co(NO₃)₂ · 6H₂O and various diamines. The metal-to-ligand ratios of Ni(II) or Co(II) metal complexes were found to be 1 : 1. Coordination of the Schiff base to Ni(II) and Co(II) through the two nitrogen and two oxygen atom (ONNO) are expected to reduce the electron density in the azomethine link and hydroxyl group. The Ni(II) and Co(II) complexes are proposed to be tetrahedral and are 1 : 2 electrolytes as shown by their molar conductivities (Λ_M) in DMF (dimethyl formamide) at 10^?3 M. The structures are proposed from elemental analysis, FT-IR, UV-VIS, magnetic susceptibility measurements, molar conductivity measurements, and mass spectra.     

Design,synthesis, characterization and antibacterial properties of copper(II) complexes with chromone‐derived compounds

A new series of six chromone‐derived compounds and their Cu(II) complexes was synthesized and characterized by their physical, spectral and analytical data The elemental analysis data of the complexes agree well with the proposed composition of the compounds, which were found to be dimeric in nature with two hydrazine molecules bridging the two copper atoms through coordination. The ligands and their Cu(II) complexes were screened for their in‐vitro antibacterial activity against four Gram‐negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri) and two Gram‐positive (Bacillus subtilis, Staphylococcus aureus) bacterial strains by the agar‐well diffusion method. The ligands were found to exhibit either no or low to moderate activities against one or more of the bacterial species, whereas all the metal complexes exhibited moderate to high activities against different bacterial species. The ligands which were inactive before complexation turned active and less active ones became more active upon coordination with copper ions. Overall, the complexes 7–12 showed comparatively much higher activities than the ligands. Copyright © 2009 John Wiley & Sons, Ltd.     

Coordination ability of 3-pyridinyl coumarins with palladium(II) and platinum(II)

The coordination ability of two 3-pyridinyl coumarins with Pd(II) and Pt(II) both in solution and in solid state is elucidated by conventional and linear-polarized IR-spectroscopy of oriented colloid suspensions in nematic liquid crystal, ¹H- and ¹³C-NMR, UV-Vis spectroscopy, positive and negative ion mass spectrometry (ESI), HPLC tandem mass spectrometry (HPLC ESI MS/MS), TGV, and DSC methods. The four metal complexes are compared with free ligands. Density functional theory calculations are performed to obtain the electronic structure and vibrational properties of the compounds to support the experimental data.     

Some neutral three-coordinate complexes of mercury(II) halides and pseudohalides with N-methylnicotinamide

Coordination compounds of mercury(II) chloride, bromide, cyanide and thiocyanate with N-methylnicotinamide, a potentially bidentate ligand, have been prepared. The complexesisolated have 1∶1 (metal:ligand)stoichiometry. Molecular weight measurements in molten camphor indicate that the mercury (II) chloride and bromide complexes are monomeric. Based on conductance values, molecular weight determinations and infrared spectral data, it is inferred that in the solid state in all these complexes the metal ion has a coordination number three and is bonded to the N-methylnicotinamide via its pyridine ring nitrogen, and is terminally bonded to the halogen/pseudohalogens.     

Synthesis, Structure, Magnetism and Electrochemical Properties of Linear Pentanuclear Complex: Ni5(μ-dmpzda)4(NCS)2

吡啶修饰的线性五核金属化合物[Ni5(μ-dmpzda)4(NCS)2][ dmpzda-H2=N,N’-Di(4-methyl pyrydin-2-yl)pyrazine-2,6-diamine]被合成并表征,其电化学和磁性被报告。 化合物含有接近180º的 Ni-Ni-Ni角,末端含有两个轴配体的Ni5 线性链。这个五核线性金属链被四个顺式的dmpzda2-配体螺旋包裹。化合物中存在两种类型的Ni-Ni键长：末端连接有轴配体的Ni-Ni键长被配体影响,其键长为2.3821 Å;内部的Ni-Ni距离比较短,为2.2959 Å。两末端的Ni(II)离子由于连接轴配体构成四方锥形(NiN4NCS)并存在较长的Ni-N 键长（2.103 Å),这个键长符合高自旋Ni(II)构型。内部的三个Ni-N 距离为1.886-1.906 Å,这样构成正方形平面(NiN4)并呈低自旋的顺磁构型。化合物显示了同[Ni5(μ-tpda)4(NCS)2]类似的磁性,即在化合物中两末端Ni(II)仍存在反铁磁性的作用。     

Crystal structure of (5,14-methyl-7,12-dimethyl-1,4,8,11-tetraazadiiminecyclotetradecylene-N,N',N',N')nickel(II) bis(diisopropyldithiophosphate) complex.

The macrocyclic tetradentate Ni(II) compound was obtained in a reaction and determined by X-ray diffraction. The crystal structure shows that the molecule is centrosymmetric, and Ni atom located in a square planar coordination environment. The two [(iPrO)2PS2]- anions are outside the macrocycle complex to balance. The Ni-N bond lengths are in the range of 1.906(2) to 1.950(2)A.     

Structural Relationships between the Hemiporphyrazine Macrocyclic Ligand and its Metal Complexes. II.: Planar Neutral Ligand,C26H16N8, and Four Isomorphous Metal Complexes, [M(C26H16N8)(H2O)], M=Mn(II), Co(II), Cu(II), Zn(II)

Crystal and molecular structures of the planar neutral ligand, C₂₆H₁₆N₈, and the four isomorphous five-coordinated metal complexes, [M(C₂₆H₁₆N₈)(H₂O)], M = Mn(II), Co(II), Cu(II), Zn(II), have been determined from three-dimensional X-ray diffraction data. The free ligand hpH₂, C₂₆H₁₆N₈, belongs to the P 2₁/c space group with Z=2, a=4.142(3), b=23.736(6), c=10.338(3) Ä, β=94.66(6)°. The metal complexes monohydrate Mhp-H₂O all belong to the orthorhombic Pcab space group with Z=8. The dimensions are roughly 8.8×19.3×23.7 ų. In each structure, the macrocyclic ligand has an almost planar conformation which differs from the saddle shaped ligand hydrate (hpH₂·H₂O) and the nickel complex [Nihp]⁵. The distances from the center of the macrocyclic ring to the nitrogen atom of the free ligand are 1.907(6) and 2.245(6)Å. The coordination geometry in these four complexes is square pyramidal with a water molecule as an axial ligand. The bond distances of M(II)-O(H₂O), M(II)-N1 (imine), M(II)-N3 (pyridine) are: 2.19(1), 2.00(2), 2.27(2)Å respectively for the manganese complex; 2.08(1), 1.97(1), 2.23(1)Å for the cobalt complex; 2.33(1), 1.92(3), 2.18(1)Å for the copper complex; 2.110(5), 1.964(6), 2.252(6)Å for the zinc complex. The variation of metal-ligand distances can be correlated to the metal d orbital occupancy. A comparison with similar ligands will be presented.     

Synthesis,spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

New metal based triazoles (1–12) have been synthesized by the interaction of novel Schiff base ligands (L¹–L³) with the Co(II), Ni(II), Cu(II) and Zn(II) metal ions. The Schiff base ligands and their all metal(II) complexes have been thoroughly characterized using various physical, analytical and spectroscopic techniques. In vitro bacterial and fungal inhibition studies were carried out to examine the antibacterial and antifungal profile of the Schiff bases in comparison to their metal(II) complexes against two Gram‐positive, four Gram‐negative and six fungal strains. The bioactivity data showed the metal(II) complexes to have more potent antibacterial and antifungal activity than their uncomplexed parent Schiff bases against one or more bacterial and fungal species. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural Relationships obtained from the Coordination of α‐Picolinamide to the (Iminodiacetato)copper(II) Chelate: Synthesis,Crystal Structure,and Properties of (α‐Picolinamide)(iminodiacetato)copper(II) Dihydrate

The stoichiometric reaction of copper(II) hydroxycarbonate, iminodiacetic acid (H₂IDA = HN(CH₂CO₂H)₂) and α‐picolinamide (pya) in water yields crystalline samples of (α‐picolinamide)(iminodiacetato)copper(II) dihydrate, [Cu(IDA)(pya)] · 2 H₂O ( 1 ). The compound was characterised by thermal (TG analysis with FT‐IR study of the evolved gasses), spectral (IR, electronic and ESR spectra), magnetic and single crystal X‐ray diffraction methods. It crystallises in the triclinic system, space group P1, a = 8.8737(4), b = 10.23203(5), c = 15.7167(11) Å, α = 77.61(1)°, β = 103.89(1)°, γ = 80.32(1)°, Z = 4, final R1 = 0.056. The asymmetric unit contains two crystallographic independent molecules but chemically very similar ones. The Cu^II atom exhibits a square base pyramidal coordination (type 4 + 1). pya acts as N,O‐bidentate ligand supplying two among the four closest donor atoms of the metal [averaged bond distances (Å): Cu–N = 1.982(2), Cu–O(amide) = 1.972(2)]. IDA plays a N,O,O′‐terdentate chelating role [averaged bond distances (Å): Cu–N = 2.004(3), Cu–O = 1.941(2) and Cu–O = 2.242(2)]. The coordinating behaviour of pya in 1 is discussed on the basis of its N,O‐bidentate chelating role and the preference of the ‘Cu‐iminodiacetato' moiety [Cu(IDA)] to link the N‐heterocyclic donor of pya in trans versus the Cu–N(IDA) bond. Consistently the ligand pya is able to impose a fac‐chelating configuration to IDA one around the copper(II) as previously has been reported to mixed‐ligand complexes having a 1/1/2 Cu^II/IDA/N(heterocyclic) donor ratio or a closely related 1/1/1/1 Cu^II/IDA/N(heterocyclic)/N(aliphatic) one.