Two new cyano-bridged Cu(II)-Fe(II) complexes: Synthesis and crystal structures

Two new cyano-bridged Cu(II)-Fe(II) binuclear complexes, [Cu(L¹)Fe(CN)₅(NO)] (I) [L¹ = 1,3,6,8,11,14-hexaazatricyclo[12.2.1.1^8,11]octadecane and [Cu(L²)Fe(CN)₅(NO)] · 2H₂O (II) L² = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]octadecane, have been assembled and structurally characterized by spectroscopy and X-ray crystallography. Complex I crystallizes in the monoclinic crystalline system of space group P2₁/c, while complex II crystallizes in the monoclinic crystalline system of space group P2₁/n. These two complexes assume a binuclear structure in which the Fe²⁺ ion is in an octahedron environment and the Cu²⁺ ion is in a square-prism geometry environment.     

Synthesis,Properties and X-ray Crystal Structures of Nickel(II) Complexes of a Hexaazamacrotetracyclic Ligand

The complexes [N₂(L²)₂(H₂O)₄]Cl₄(1) and [Ni(L²)](ClO₄)₂ [sdot]2H₂O (2) (L = 1,3,10,12,16,19-hexaazatetracyclo [17,3,1,1 ^12.16,0^4.9]tetracosane) have been synthesized and structurally characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. The crystal structure of 1 has a distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two water molecules. In 2, the coordination geometry around the nickel atom is square-planar with four nitrogen atoms of the macrocycle. The equilibrium [Ni(L²)]²⁺ + 2H₂O &rlhar2; [Ni(L²)(H₂O)₂]²⁺ has been studied in aqueous solution over a temperature range, yielding Δ H° = -19.0 ± 0.2 kJ mol^-1 and Δ S° = - 56.0 ± 0.4 JK^-1 mol^-1. Cyclic voltammetry of the complexes give two one-electron waves corresponding to Ni(II)/Ni(III) and Ni(II)/Ni(I) processes. The electronic spectra and redox potentials of the complexes are influenced significantly by the geometry.     

Ni(II) complexes with optically active bis(menthane), pinano-para-menthane ethylenediaminodioximes and pinano-para-menthane, bis(pinane) propylenediaminodioximes: Synthesis, structures, and properties

Reactions of Ni(NO₃)₂ · 6H₂O) in EtOH(iso-PrOH) with optically active bis(menthane) ethylene-diaminodioxime (H₂L¹), pinano-para-menthane ethylenediaminodioxime (H₂L²), pinano-para-menthane propylenediaminodioxime (H₂L³) and bis(pinane) propylenediaminodioxime (H₂L⁴) were used to synthesize [Ni(H₂L¹)NO₃[NO₃ · 2H₂O (I), [Ni(HL²)]NO₃ (II), [Ni(HL³)]NO₃ (III), and [Ni(HL⁴)]NO₃ (IV). X-ray diffraction study of paramagnetic complex I (μ_eff = 3.04 μB and diamagnetic complexes II and III revealed their ionic structures. A distorted octahedral polyhedron N₄O₂ in the cation of complex I is formed by the N atoms of tetradentate cycle-forming ligand, i.e., the H₂L¹ molecule, and the O atoms of the NO ₃ ^? anion acting as a bidentate cyclic ligand. In the cations of complexes II and III, containing a pinane fragment, the coordination core NiN₄ has the shape of a distorted square formed on coordination of tetradentate cycle-forming ligands, i.e., anions of the starting dioximes. The structure of diamagnetic complex IV is likely to be similar to the structures of complexes II and III.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Synthesis, spectral characterization and in vitro microbiological evaluation of novel glyoxal, biacetyl and benzil bis-hydrazone macrocyclic Schiff bases and their Co(II), Ni(II) and Cu(II) complexes

A series of binuclear Co(II), Ni(II) and Cu(II) complexes were synthesized by the template condensation of glyoxal, biacetyl or benzil bis-hydrazide, 2,6-diformyl-4-methylphenol and Co(II), Ni(II) or Cu(II) chloride in a 2:2:2 M ratio in ethanol. These 22-membered macrocyclic complexes were characterized by elemental analyses, magnetic, molar conductance, spectral, thermal and fluorescence studies. Elemental analyses suggest the complexes have a 2:1 stoichiometry of the type [M₂LX₂]·nH₂O and [Ni₂LX₂2H₂O]·nH₂O (where M = Co(II) and Cu(II); L = H₂L¹, H₂L² and H₂L³; X = Cl; n = 2). From the spectroscopic and magnetic studies, it has been concluded that the Co(II) and Cu(II) complexes display a five coordinated square pyramidal geometry and the Ni(II) complexes have a six coordinated octahedral geometry. The Schiff bases and their metal complexes have also been screened for their antibacterial and antifungal activities by the MIC method.     

Synthesis, characterization, and X-ray crystal structures of copper(II) and nickel(II) complexes with Schiff base

New copper(II) complexes, [Cu₂L¹L²] · ClO₄ (I) and [Ni(L³)₂] (II), where L¹ is the monoanionic form of 2-[1-(2-emthylaminoethylimino)ethyl]phenol, L² is the dianionic form of N,N′-ethylene-bis(2-hydroxyacetophenonylideneimine), L³ is the mono-anionic form of 2-(1-iminoethyl)phenol, were prepared and characterized using elemental analysis, FT-IR spectroscopy, and X-ray single-crystal diffraction. In complex I, the Cu(1) atom is coordinated by the NNO tridentate ligand L¹ and the two phenolate O atoms of L², forming a square pyramidal geometry. The Cu(2) atom in complex I is coordinated by the NNOO tetradenate ligand L², forming a square planar geometry. The Ni atom in complex II is coordinated by two phenolate O and two imine N atoms from two ligands L³, forming a square planar geometry. In the crystal structure of I, the perchlorate anions are linked to the dinuclear copper(II) complex cations through intermolecular N-H...O hydrogen bonds. In the crystal structure of II, the mononuclear nickel complex molecules are linked through intermolecular N-H...O hydrogen bonds, forming a trimer.     

Complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole

Novel oligonuclear complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-triazole (L) of the composition [M₃L₁₀(H₂O)₂](NO₃)₆ (M = Co(II), Ni(II)), [Ni₃L₆(H₂O)₆]Hal₆ (Hal = Cl^?, Br^?), and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O were synthesized and studied by magnetic susceptibility, electronic and IR spectroscopy, and powder X-ray diffraction methods. All the above complexes are X-ray amorphous. Antifer-romagnetic exchange interactions between the M²⁺ ions were discovered in the [Co₃L₁₀(H₂O)₂](NO₃)₆ and [Ni₃L₁₀(H₂O)₂](NO₃)₆ complexes, whereas ferromagnetic exchange interactions were observed in the complexes [Ni₃L₆(H₂O)₆]Cl₆, [Ni₃L₆(H₂O)₆]Br₆, and [Cu₅L₁₆(H₂O)₂](NO₃)₁₀ · 2H₂O.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Cyanide-bridged complexes based on dinuclear Cu(II)-M(II) [M = Pb and Cu] building blocks: Synthesis, crystal structures and magnetic properties

Four cyanide-bridged heterometallic complexes {[CuPb(L 1 )][Fe III (bpb)(CN) 2 ]} 2 ·(ClO 4 ) 2 ·2H 2 O·2CH 3 CN (1), {[CuPb(L 1 )] 2 [Fe II (CN) 6 ](H 2 O) 2 }·10H 2 O (2), {[Cu 2 (L 2 )][Fe III (bpb)(CN) 2 ] 2 }·2H 2 O·2CH 3 OH (3) and {[Cu 2 (L 2 )] 3 [Fe III (CN) 6 ] 2 (H 2 O) 2 }·10H 2 O (4) have been synthesized by treating K[Fe III (bpb)(CN) 2 ] [bpb 2-=1,2-bis(pyridine-2-carboxamido)benzenate] and K 3 [Fe III (CN)] 6 with dinuclear compartmental macrocyclic Schiff-base complexes [CuPb(L 1 )] (ClO 4 ) 2 or [Cu 2 (L 2 )]·(ClO 4 ) 2 , in which H 2 L 1 was derived from 2,6-diformyl-4-methyl-phenol, ethylenediamine, and diethylenetriamine in the molar ratio of 2:1:1 and H 2 L 2 from 2,6-diformyl-4-methyl-phenol and propylenediamine in the molar ratio of 1:1. Single crystal X-ray diffraction analysis reveals that compound 1 displays a cyclic hexanuclear heterotrimetallic molecular structure with alternating [FeⅢ (bpb)(CN) 2 ]- and [CuPb(L 1 )] 2+ units. Complex 2 is of a neutral dumb-bell-type pentanuclear molecular configuration consisting of one [Fe(CN)6] 4- anion sandwiched in two [CuPu(L 1 )] 2+ cations, and the pentanuclear moieties are further connected by the hydrogen bonding to give a 2D supramolecular framework. Heterobimetallic complex 3 is a tetranuclear molecule composed of a centrosymmetric [Cu 2 (L2)] 2+ segment and two terminal cyanide-containing blocks [FeⅢ (bpb)(CN)2 ]- . Octanuclear compound 4 is built from two [Fe(CN)6]3- anions sandwiched in the three [Cu 2 L 2 ] 2+ cations. Investigation of their magnetic properties reveals the overall antiferromagnetic behavior in the series of complexes except 2.     

Binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff-bases derived from crown ether platforms: Rare examples of ether oxygen atoms bridging metal centers

Bibracchial lariat ethers L³ and L⁴, derived from the condensation of N,N′-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 or N,N′-bis(2-aminobenzyl)-4,13-diaza-18-crown-6 with salicylaldehyde, form binuclear complexes with Co(II), Ni(II), Cu(II) and Zn(II). Our studies show that the different denticity and crown moiety size of the two related receptors give rise to important differences on the structures of the corresponding complexes. Single crystal X-ray diffraction analysis shows that the [Ni₂(L³)(H₂O)₂]²⁺ and [Cu₂(L³)(NO₃)]⁺ complexes constitute a rare example in which an oxygen atom of the crown moiety is bridging the two six coordinate metal ions. In contrast, none of the oxygen atoms of the crown moiety is acting as a bridging donor atom in the [Co₂(L⁴)(CH₃CN)₂]²⁺, [Cu₂(L⁴)]²⁺ and [Zn₂(L⁴)]²⁺ complexes. This is attributed to the larger size the crown moiety and the higher denticity of L⁴ compared to L³. In [Co₂(L⁴)(CH₃CN)₂]²⁺ the metal ions show a distorted octahedral coordination, while in the Cu(II) and Zn(II) analogues the metal ions are five-coordinated in a distorted trigonal bipyramidal environment. In [Cu₂(L³)(NO₃)]⁺ the coordinated nitrate anion acts as a bidentate bridging ligand, which results in the formation of a 1D coordination polymer.     

Synthesis, spectroscopic, structural and electrochemical studies of nickel(II) and copper(II) complexes derived from 2-hydroxy-4-methacryloyloxybenzaldehyde

The free Schiff bases H₂MABCE, H₂MABCP, and H₂MABCT and their complexes [Ni(MABCE)], [Ni(MABCP)], [Ni(MABCT)], [Cu(MABCE)], [Cu(MABCP)], and [Cu(MABCT)] have been synthesized and characterized by spectroscopic, cyclic voltammetric, and thermal studies. The geometry around nickel is square planar with N₂O₂ donor atoms. Cyclic voltammetric studies of the Ni(II) complexes show one-electron quasi-reversible waves corresponding to Ni(II)/Ni(I) and Ni(II)/Ni(III) processes. The Cu(II) complexes exhibit an irreversible well defined one electron transfer reduction peak in the range of ?0.34 to ?1.08 V. The electronic spectra of the complexes suggest a four-coordinate geometry. The crystal structure of the ligand H₂MABCT and the complex [Ni(MABCP)] have also been reported. The mean Ni–N and Ni–O bond distances are Ni–N = 1.849(4) and Ni–O = 1.837(4) Å.     

Synthesis and properties of nickel(II) and copper(II) complexes of a di-N-acetamide tetraaza macrocycle

The syntheses of the hexadentate ligand 2,13-bis(acetamido)-5,16-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane (L²) and its complexes with Ni(II) and Cu(II) are described. Crystal structures of H₂L²·2HClO₄ (1), [Ni(L²)](ClO₄)₂ (2) and [Cu(L²)](ClO₄)₂ (3) are reported. The two pendant acetamide groups of the macrocyclic ligand 1 are trans to each other and the absolute configuration is a trans-IV in the solid state. The crystal structures of 2 and 3 revealed an axially elongated octahedral geometry with four nitrogen atoms of the macrocycle and two oxygen atoms of the pendant acetamide groups at the axial positions. The nickel(II) and copper(II) ions are located at an inversion center. The electronic spectra and electrochemical behaviors of the complexes are significantly affected by the presence of the pendant arms.     

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].     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Versatility of copper(II) coordination compounds with 2,3-bis(2-pyridyl)pyrazine mediated by temperature,solvents and anions choice

Tuning reaction temperatures as well as the variation in starting copper salts and solvents led to the formation of a new series of Cu(II) coordination compounds with 2,3-bis(2-pyridyl)pyrazine (dpp): a mononuclear [Cu(acac)(dpp)(NO₃)] (1) complex, two dinuclear [Cu₂(acac)₂(dpp)(NO₃)(H₂O)]NO₃ (2) and [Cu₂(Hdpp)₂(ox)(Cl)₂(H₂O)₂]Cl₂·6(H₂O) (4) complexes, and four coordination polymers {[Cu₄(dpp)₂(ox)(Cl)₆]}_n (3), {[Cu₄(dpp)₂(ox)(NO₃)₆(H₂O)₂]∙1.2(H₂O)}_n (5), {[Cu(dpp)(NO₃)](NO₃)·(H₂O)}_n (6) and {[Cu(dpp)(SO₄)(H₂O)₂]}_n (7), where acac⁻ = acetylacetonate, ox²⁻ = oxalate. Remarkably, the treatment of Cu(II) chloride dihydrate with dpp in methanol solution led to an unusual in situ condensation of dpp with acac⁻ to produce [Cu₂(acdpp)₂(Cl)₄]·2(MeOH) (8). The structure of 1 consists of neutral, mononuclear [Cu(acac)(dpp)(NO₃)] units with acac⁻ and dpp acting as bidentate ligands. In 2, the dpp ligand coordinates in a bis-chelating mode to two Cu(II) ions and bridges them into a dimeric entity, whereas an oxalate linker joins [Cu(Hdpp)(Cl)₂(H₂O)]⁺ units into a dimer in 4. Compounds 3, 5, 6 and 7 are 1D chain coordination polymers, which incorporate two symmetry independent metal centers and different bridging ligands: Hdpp⁺ as a protonated cationic or dpp as a neutral chelating ligand and oxalate, Cl⁻ anions or sulfate di-anions as bridging ligands. Magnetic studies were performed on samples 1 and 2, and the analysis reveals a very weak magnetic exchange coupling mediated via the dpp ligand.     

Structural Study of Nickel(II), Copper(II), and Palladium(II) Complexes of 2‐Pyridineformamide 3‐Hexamethyleneiminylthiosemicarbazone

Reduction of 2‐cyanopyridine by sodium in the presence of 3‐hexamethyleneiminylthiosemicarbazide produces 2‐pyridineformamide 3‐hexamethyleneiminylthiosemicarbazone, HAmhexim. Complexes with nickel(II), copper(II) and palladium(II) have been prepared and the following complexes structurally characterized: [Ni(Amhexim)OAc], [{Cu(Amhexim)}₂C₄H₄O₄]·2DMSO·H₂O, [Cu(HAmhexim)Cl₂] and [Pd(Amhexim)Cl]. Coordination is via the pyridyl nitrogen, imine nitrogen and thiolato or thione sulfur atom when coordinating as the anionic or neutral ligand, respectively. [{Cu(Amhexim)}₂C₄H₄O₄] is a binuclear complex with the two copper(II) ions bridged by the succinato group in [Cu‐(HAmhexim)Cl₂] the Cu atom is 5‐coordinate and close to a square pyramid structure and in [Ni(Amhexim)OAc] and [Pd(Amhexim)Cl] the metal atoms are planar, 4‐coordinate.     

Heterobinuclear and Heterotrinuclear complexes of Oxorhenium(V) with Cu(II), Ni(II), Fe(III), UO2(VI) and Th(IV) in the solid state

New heteronuclear complexes containing oxorhenium(V), Cu(II), Ni(II), Fe(III), UO₂(VI) and Th(IV) ions were prepared by the reaction of the complex ligand, [ReO(H₄L)Cl]Cl₂, where H₄L = 8,17-dimethyl-6,15-dioxo-5,7,14,16-tetrahydrodibenzo[a,h][14]annulene-2,11-dicarboxylic acid, with the previous transition and actinide salts. Three heteronuclear Cu(II) complexes were isolated depending on the ratio of [ReO(H₄L)Cl]Cl₂?:?Cu(II) ion. When the ratios were 1?:?0.5, 1?:?1 and 1?:?2, the heteronuclear complexes {[ReO(H₃L)Cl]₂CuCl₂(OH₂)₂}SO₄ · H₂O (I), [ReO(H₃L)Cl₂Cu(OH₂)₂(SO₄)] (II) and {ReO(H₂L)Cl[Cu(OH₂)₃ SO₄]₂} (III) were obtained, respectively. Heteronuclear complexes of the other metal cations were obtained by mixing [ReO(H₄L)Cl]Cl₂ with the metal salt in the ratio 1?:?1 to obtain the heteronuclear complexes [ReO(H₃L)Cl₂Ni(OH₂)₂](NO₃)₂ (IV), [ReO(H₃L)Cl₃Fe(OH₂)₃](NO₃)₂ (V), [ReO(H₃L)ClUO₂(NO₃)₂ (OH₂)]Cl (VI) and [ReO(H₃L)Cl₃Th(NO₃)₂(OH₂)]NO₃ · 2H₂O (VII). The complex ligand coordinates with the heterometal ion via the carboxylate group, and the infrared bands ν_as COO and ν_s COO indicate that the carboxylate acts as a unidentate ligand to the heterometal cations. Cu(II) and Fe(III) cations in the heteronuclear complexes have octahedral geometry, while Ni(II) is square planar. Thermal studies explored the possibility of obtaining new heteronuclear complexes pyrolytically in the solid state from the corresponding mother complexes. The structures of the complexes were elucidated by conductance, IR and electronic spectra, magnetic moments, ¹H NMR and TG-DSC measurements as well as by mass spectroscopy.     

Synthesis,crystal structures,and properties of copper(II) dicarboxylate complexes with [bis(2-pyridylcarbonyl)amido]

Four new complexes, [Cu₂(Bpca)₂(L¹)(H₂O)₂] · 3H₂O (I), [Cu₂(Bpca)₂(L²)(H₂O)₂] (II), [Cu₂(Bpca)₂(L³)] · 2H₂O (III), [Cu₂(Bpca)₂(L¹)(H₂O)] · 2H₂O (IV) (Bpca = bis(2-pyridylcarbonyl)amido, H₂L¹ = glutaric acid, H₂L² = adipic acid, H₂L³ = suberic acid, H₂L⁴ = azelaic acid) have been synthesized and characterized by single-crystal X-ray diffraction methods (CIF files CCDC nos. 1432836 (I), 1432835 (II), 817411 (III), and 817412 (IV)), elemental analyses, IR spectra. Structural analyses reveal that compounds I, II, and IV have similar structures [Cu(Bpca)]⁺ units bridged by dicarboxylate forming dinuclear units, whereas the dinuclear of compound III are edge-shared through two carboxylate oxygen atoms of different suberate anions. Hydrogen bonds are response for the supramolecular assembly of compounds I to IV. The temperature-dependent magnetic property of III was also investigated in the temperature range of 2 to 300 K, and the magnetic behaviour suggests weak antiferromagnetic coupling exchange.     

Complexes of 4- and 5-bromo derivatives of 2-(hydroxymethyl)pyridine with copper(II) and cobalt(II) salts. Synthesis and X-ray crystal structures

Four copper(II) complexes (1–4) and a cobalt(II) complex (5) derived from 4-bromo-2-(hydroxymethyl)pyridine (L¹) or 5-bromo-2-hydroxymethyl)pyridine (L²) with Cu(NO₃)₂·3H₂O, CuCl₂·2H₂O and CoCl₂·6H₂O have been synthesized and their respective crystal structures studied. They show specific influences owing to the different kind of metal cations and counter anions, the hydration as well as the different position of the bromine substitution on both the coordination of the complex unit and the network structure of the crystal lattice. The Cu(II) complexes of L¹ are five-coordinate [Cu(L¹)₂NO₃]NO₃·H₂O (1) and [Cu(L¹)₂Cl]Cl·H₂O (2) species with distorted quadratic pyramidal and trigonal bipyramidal coordination geometries of the N₂O₃ and N₂O₂Cl donor atoms around the Cu(II), respectively. The Cu(II) complexes of L² are six-coordinate [Cu(L²)₂(NO₃)₂] (3) and [Cu(L²)₂Cl(H₂O)]Cl·H₂O (4) species with distorted octahedral coordination geometries of the N₄O₂ and N₂O₃Cl donor atoms. A distorted octahedral coordination geometry of the N₂O₂Cl₂ donor atoms is also found in the complex unit [Co(L²)₂Cl₂] of the Co(II) complex 5 but showing the oxygen atoms of the chelating ligand as well as the chloride ions in a cis-position. Depending on the complex, water molecules and chloride anions are shown to act as stabilizing components of the crystal structure. The comparative structural investigation includes also known structures of the bromine-free ligand analogue 2-(hydroxymethyl)pyridine, illustrating the basic implication of the bromine substitution, mostly perceptible in the different modes of crystal packing.     

Novel platinum(II) and (IV) complexes of naphthaldimine schiff bases

Naphthaldimines containing N₂O₂ donor centers react with platinum(II) and (IV) chlorides to give two types of complexes depending on the valence of the platinum ion. For [Pt(II)], the ligand is neutral, [(H₂L¹)PtCl₂]·3H₂O (1) and [(H₂L³)₂Pt₂Cl₄]·5H₂O (3), or monobasic [(HL²)₂Pt₂Cl₂]·2H₂O (2) and [(HL⁴)₂Pt]·2H₂O (4). These complexes are all diamagnetic having square-planar geometry. For [Pt(IV)], the ligand is dibasic, [(L¹)Pt₂Cl₄(OH)₂]·2H₂O (5), [(L²)Pt₃Cl₁₀]·3H₂O (6), [(L³)Pt₂Cl₄(OH)₂]·C₂H₅OH (7) and [(L⁴)Pt₂Cl₆]·H₂O (8). The Pt(IV) complexes are diamagnetic and exhibit octahedral configuration around the platinum ion. The complexes were characterized by elemental analysis, UV-Vis and IR spectra, electrical conductivity and thermal analyses (DTA and TGA). The molar conductances in DMF solutions indicate that the complexes are non-ionic. The complexes were tested for their catalytic activities towards cathodic reduction of oxygen.