One-dimensional hydrogen-bonded infinite chains composed of nickel(II) and copper(II) tetraaza macrocyclic complexes with cyclopropane-1-carboxylic acid-1-carboxylate ligand

The reaction of [M(L)]Cl₂ · 2H₂O (M = Ni²⁺ and Cu²⁺, L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane) with 1,1-cyclopropanedicarboxylic acid (H₂-cpdc) generates one-dimensional hydrogen-bonded infinite chains [Ni(L)(H-cpdc)₂] (1) and [Cu(L)(H-cpdc)₂] (2) (H-cpdc = cyclopropane-1-carboxylic acid-1-carboxylate). These complexes have been characterized by X-ray crystallography, spectroscopy, and cyclic voltammetry. The crystal structures of (1) and (2) show a distorted octahedral coordination geometry around the metal ion, with four secondary amines and two oxygen atoms of the H-cpdc ligand at the trans position. Complexes (1) and (2) display the one-dimensional hydrogen-bonded infinite chains. The cyclic voltammogram of the complexes display two one-electron waves corresponding to M^II/M^III and M^II/M^I processes. The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature of the axial H-cpdc ligand.     

Synthesis,characterization, and crystal structure of cobalt(II) complex with 2-oximino-3-thiosemicarbazone-2,3-butanedione

The reaction of cobalt(II) chloride with the tridentate ligand 2-oximino-3-thiosemicarbazone-2,3-butanedione [Hotsb (1)] leads to the formation of the novel six-coordinated complex [Co(otsb)₂]·2H₂O (2). This complex has been synthesized and characterized by X-ray crystallography, spectroscopic and cyclic voltammetric measurements. The ligand Hotsb (1) obtained by the condensation of 2,3-butanedione monoxime and thiosemicarbazide is used for the preparation of complex 2. The Hotsb (1) crystallizes into a monoclinic lattice with space group P2₁/c. The crystal structure of 2 shows a distorted mer-octahedral geometry in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the hydrazine nitrogen atoms, the azomethine nitrogen atoms, and the thiolate sulfur atoms. The cyclic voltammogram of 2 undergoes two irreversible one-electron waves corresponding to Co^II/Co^III and Co^II/Co^I processes.     

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.     

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.     

Synthesis,Properties and Crystal Structures of Mononuclear Copper(II) Complexes with Bis(2-Pyridylmethyl)Amino Acids

Tetradentate Schiff-base carboxylate-containing ligands, bis(2-pyridylmethyl)amino-3-propionic acid (Hpmpa) and bis(2-pyridylmethyl)amino-4-butyric acid (Hpmba), react with CuCl₂ to give rise to the mononuclear complexes [Cu(Hpmpa)Cl]Cl · 2H₂O (1) and [Cu(Hpmba)Cl₂]· H₂O (2). These complexes have been characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. Crystal structure of (1) shows that the copper(II) ion has a distorted square-pyramidal geometry with the three nitrogen atoms of the Hpmpa ligand and one chloride anion occupying the basal plane and an oxygen atom from the carboxylate group coordinating the axial position. In (2), the coordination environment around the copper(II) ion reveals a distorted square-pyramids with three nitrogen atoms of the Hpmba ligand and one chloride anion that comprise the basal plane, whereas the apical position is filled by the chloride anion. Cyclic voltammetry of the complexes gives two one-electron waves corresponding to Cu^II/Cu^III and Cu^III/Cu^I processes. The electronic spectra and redox potentials of the complexes are influenced significantly by the N-pendant carboxylate groups.     

Synthesis and characterization of mononuclear copper(II) and dinuclear cadmium(II) complexes with di-(2-picolyl)sulfide

The reaction of CuCl₂ · 2H₂O and CdCl₂ with di-(2-picolyl)sulfide (dps) leads to the formation of mononuclear copper(II) and binuclear cadmium(II) complexes, [Cu(dps)Cl₂] · H₂O (1) and [(dps)(Cl)Cd^II(μ-Cl)₂Cd^II(Cl)(dps)] (2). The copper atom in (1) is coordinated to one sulfur and two nitrogen atoms from the dps ligand and two chlorides in a distorted square-pyramidal environment. Complex (2) has two distorted octahedra sharing the basal edge that contain the bridging chloro ligands, each of which resides at a center of inversion. Cyclic voltammetric data show that (1) undergoes two reversible one-electron waves corresponding to Cu^II/Cu^III and Cu^II/Cu^I processes. However, cyclic voltammetry of (2) gives two irreversible reduced waves.     

Synthesis,Structure and Photoluminescent Properties of Zn(II)/Cd(II)‐Complexes Containing 2,4,6‐Tris‐(benzimidazolyl‐2‐yl)pyridine Ligand

Hydrothermal reactions of tridentate rigid 2,4,6‐tris‐(benzimidazolyl‐2‐yl)pyridine (pytbzim) ligand and Zn(II)/Cd(II) salts generate binuclear complexes {[Cd₂Cl₂(pytbzim)₂(H₂O)₂]·2NO₃}_n ( 1 ) and two isomorphs {[M₂Cl₂(pytbzim)₂(H₂O)₂]Cl₂·2H₂O}_n [M=Cd ( 2 ), Zn ( 3 )]. All complexes include [M₂Cl₂(pytbzim)₂(H₂O)₂] dimers, which are further connected into a three‐dimensional supramolecular networks through ?‐? stacking interaction and hydrogen bonds. The solid state photoluminescent studies reveal good fluorescent properties of the pytbzim ligand and complexes 1 – 2 at room temperature.     

Trinuclear Cobalt(II) and Zinc(II) Salamo‐type Complexes: Syntheses,Crystal Structures,and Fluorescent Properties

Two trinuclear Co^II and Zn^II complexes, [(CoL)₂(OAc)₂Co] and [(ZnL)₂(OAc)₂Zn], with an asymmetric Salen‐type bisoxime ligand [H₂L = 4‐(N,N‐diethylamine)‐2,2′‐[ethylenediyldioxybis(nitrilomethylidyne)]diphenol] were synthesized and characterized by elemental analyses, IR, UV/Vis, and fluorescent spectroscopy. The crystal structures of the Co^II and Zn^II complexes were determined by single‐crystal X‐ray diffraction methods. The Co^II atom is pentacoodinated by N₂O₂ donor atoms from the (L)^2– unit and one oxygen atom from the coordinated acetate ion, resulting in a trigonal bipyramid arrangement. With the help of intermolecular hydrogen bonding C–H ··· O and C–H ··· π interactions, a self‐assembled continual zigzag chain‐like supramolecular structure is formed. The Zn^II atom is pentacoodinated by N₂O₂ donor atoms from the (L)^2– unit and one oxygen atom from the coordinated acetate ion, resulting in an almost regular trigonal bipyramid arrangement. A self‐assembled continual 1D supramolecular chain‐like structure is formed by intermolecular hydrogen bonding C–H ··· O and C–H ··· π interactions. Additionally, the photophysical properties of the Co^II and Zn^II complexes were discussed.     

Synthesis and characterization of cobalt(III) tetraaza macrocyclic complexes containing chloro and azido ligands

The complexes [Co(L)Cl₂]Cl · 4H₂O (1) and [Co(L)(N₃)₂]N₃ · 2H₂O (2) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo [14,4,0^1.18,0^7.12]docosane) have been synthesized, and structurally characterized by X-ray crystallography, spectroscopy and cyclic voltammetry. The crystal structure of (1) is centrosymmetric and the cobalt(III) atom has an axially elongated octahedral geometry with four nitrogen atoms of the macrocycle and two chloride ligands. The cobalt(III) ion in (2) is coordinated to four nitrogen atoms from the macrocycle, and two azide ligands in an octahedral environment, which forms the 1D polymer through hydrogen bonding contacts involving the cation, azide anion and solvent water molecules. Electronic spectra of the complexes also exhibit a low-spin octahedral environment. Cyclic voltammetry of the complexes undergoes a one-electron wave corresponding to Co(III)/Co(II) processes. The electronic spectra and electrochemical behaviors of the complexes are significantly affected by the nature of the axial ligands.     

A 1:1 cocrystal of di‐μ‐chloro‐bis{[N‐(1‐hydroxy­but‐2‐yl)­salicyl­idene­iminato‐N,O,O′]copper(II)} monohydrate and its methanol solvate

The structure consists of two crystallographically independent and differently solvated binuclear complexes, {[Cu₂Cl₂(C₁₁H₁₄NO₂)₂]·CH₄O}·{[Cu₂Cl₂(C₁₁H₁₄NO₂)₂]·H₂O}. The water and methanol solvate mol­ecules are similarly connected with the complex mol­ecules by two hydrogen bonds. The asymmetrical system of hydrogen bonds breaks up the potential centrosymmetricity of both chelate mol­ecules. All copper(II) centres are in a square‐pyramidal environment, with four short bonds in the basal plane formed by two trans O atoms and one N atom of the tridentate ligand, and a bridge chloride ion. The fifth axial long bond is formed by a chloride ligand which lies in the basal plane of the neighbouring copper(II) ion.     

Coordination chemistry of a new tetranucleating 26-membered polyaza macropolycyclic ligand and a novel phenolate/phthalazine-bridged copper(II) and zinc(II) complexes

The novel phenol and phthalazine-based symmetric compartmental 26-membered polyaza macropolycyclic ligand LH₂, was synthesised, incorporating 2,6-diformyl-p-cresol and 1,4-dihydrazinophthalazine via 1:1 condensation. Its coordination behaviour with Cu^II and Zn^II ions was investigated. The tetranuclear complexes [M₄μ(Cl₂)(L)Cl₄]·2H₂O exhibited aremarkably high stability, suggesting that, along with the large number of nitrogen donors available for metal binding, deprotonated phenolic functions were also involved in binding the metal ion. Incorporation of the bridging units into the macrocyclic cavity influenced electronic communications between the metal ions.     

Tetranuclear Complexes with {M4O4} (M = CoII,NiII) Cubane‐Like Core: Synthesis,Crystal Structure,and Magnetic Properties

Two tetranuclear clusters of formula [M₄L₄(HOMe)₄] {H₂L = (E)‐1‐[(2‐(hydroxymethyl)phenylimino)methyl]naphthalen‐2‐ol} [M = Co ( 1 ), Ni ( 2 )] were hydrothermally synthesized by reaction of M(OAc)₂ · 4H₂O with H₂L and NaOH in MeOH. X‐ray crystal structure analysis revealed that complexes 1 and 2 are isostructural. In the core of the structures, four M^II ions and four oxygen atoms occupied alternate vertices of [M₄O₄] cubane. The magnetic property measurements of 1 and 2 revealed that overall ferromagnetic M^II ··· M^II exchange interactions exist in both complexes.     

Synthesis and characterization of binuclear palladium(II) and platinum(II) complexes with a bridging hydroxypyridinate ligand

Summary Binuclear Pd^II and Pt^II complexes of the type [M₂Cl₂(-Opy)₂(PR₃)₂] [M = Pd or Pt; Opy = 2-OC₅H₄N (2-hydroxypyridinate ion); PR₃ = PEt₃, Pn-Bu₃, PMe₂Ph or PMePh₂] were synthesized and characterized by elemental analysis, ¹H- and ³¹P-n.m.r. spectroscopies. The Pd complexes exist in the sym trans form, whereas the corresponding Pt complexes were generated as different isomers.     

Crystal structures of some lanthanide(III) complexes with acylhydrazone and their coordination chemistry

Three new lanthanide(III) complexes with N-(2-propionic acid)-salicyloylhydrazone (H₂L, C₁₀H₁₀N₂O₄) ligand [La(HL)₂(NO₃)(H₂O)₂]₃ ·4H₂O(I), [Gd(HL)₃] · 2(C₂H₅)₃ N(II) and [Er(L)(HL)(H₂O)₂] · 2H₂O(III) has been synthesized and characterized by elemental analyses, IR, UV, and molar conductivity. The crystal structures of three complexes have been determined by X-ray single-crystal diffractometer. In complex I, the La³⁺ ion is ten-coordinated by two tridentate ligands, one bidentate nitrate, and two water molecules. In complex II, the Gd³⁺ ion has a coordination number of nine by three tridentate ligands. In complex III, the Er³⁺ ion is eight-coordinated by two tridentate ligands and two water molecules. In all structures, tridentate ligands are coordinated by carboxyl O and acyl O atoms and azomethine N atom to form two stable five-membered rings sharing one side in the keto mode as indicated by the results of crystal structures and infrared spectral analysis.     

Synthesis, crystal structure and magnetic property of the novel dinuclear nickel(II) complex with 4-(p-methoxyphenyl)-3,5-bis(pyridine-2-yl)-1,2,4-triazole

A novel dinuclear nickel(II) complex, [Ni₂(MOBPT)₂Cl₂(H₂O)₂]Cl₂ · 7H₂O (MOBPT = 4-(p-methoxyphenyl) −3,5-bis(pyridine-2-yl)-1,2,4-triazole), has been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction methods. The crystal structure determination shows that the dinuclear Ni₂N₈ unit is almost planer in which each Ni^II ion is coordinated by four nitrogen atoms from MOBPT equatorially and a water molecule and a chloride ion axially in a distorted octahedral geometry. Magnetic measurements reveal a relatively weak antiferromagnetic exchange in the complex.     

N-Phthaloylglycinate ternary complexes with cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) metal ions and aromatic mono,bi and tridentate amines

Complexes of N-phthaloylglycinate (N-phthgly) and Co^II, Ni^II, Cu^II, Zn^II and Cd^II containing imidazole (imi), N-methylimidazole (mimi), 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen), and tridentate amines such as 2,2,2-terpyridine (terpy) and 2,4,6-(2-pyridyl)s-triazine (tptz), were prepared and characterized by conventional methods, i.r. spectra and by thermogravimetric analysis. For imi and mimi ternary complexes, the general formula [M(imi/mimi)₂(N-phthgly)₂]·nH₂O, where M = Co^II, Ni^II, Cu^II and Zn^II applies. For Cd^II ternary complexes with imi, [Cd(imi)₃(N-phthgly)₂]·2H₂O applies. For the bi and tridentate ligands, ternary complexes of the formula [M(L)(N-phthgly)₂]·nH₂O were obtained, where M = Co^II, Ni^II, Cu^II and Zn^II; L = bipy, phen, tptz and terpy. In all complexes, N-phthgly acts as a monodentate ligand, coordinating metal ions through the carboxylate oxygen, except for the ternary complexes of Co^II, Ni^II and Cu^II with mimi and Cu^II and Zn^II with imi, where the N-phthgly acts as a bidentate ligand, coordinating the metal ions through both carboxylate oxygen atoms.     

Synthesis and Crystal Structures of Manganese(II) and ­Cobalt(II) Complexes with 2, 6‐Dimethoxybenzoic Acid and Additional N‐Donor Ligands

Three coordination compounds [Mn₃(dmb)₆(H₂O)₄(4, 4′‐bpy)₃(EtOH)]_n ( 1 ) and [M(dmb)₂(pyz)₂ (H₂O)₂] [M^II = Co ( 2 ), Mn ( 3 )] (Hdmb = 2, 6‐dimethoxybenzoic acid, 4, 4′‐bpy = 4, 4′‐bipyridine, pyz = pyrazine) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. Compound 1 consists of infinite 1D polymeric chains, in which the metal entities are bridged by 4, 4′‐bpy ligands. There are four crystallographically independent Mn^II atoms in the linear chain with different coordination modes, which is only scarcely reported for linear polymers. The isostructural crystals of 2 and 3 are composed of neutral mononuclear complexes. In crystal the complexes are combined into chains by intermolecular O–H ··· N hydrogen bonds and π–π interactions between antiparallel pyrazine molecules.     

Spectroscopic studies of bridged binuclear complexes of Co(II), Ni(II), Cu(II) and Zn(II)

Binuclear cobalt(II), nickel(II), copper(II) and zinc(II) complexes of general composition [M₂L^1-2(μ-Cl)Cl₂] · nH₂O with the Schiff-base ligands (where L¹H and L²H are the potential pentadentate ligands derived by condensing 2,6-diformyl-4-methylphenol with 4-amino-3-antipyrine and 2-hydroxy-3-hydrazinoquinoxiline, respectively) have been synthesized and characterized. Analytical and spectral studies support the above formulation. ¹H-NMR and IR spectra of the complexes suggest they have an endogenous phenoxide bridge, with chloride as the exogenous bridge atom. The electronic spectra of all the complexes are well characterized by broad d–d and a high intensity charge-transfer transitions. The complexes are chloro-bridged as evidenced by two intense far-IR bands centered around 270–280 cm⁻¹. Magnetic susceptibility measurements show that complexes are antiferromagnetic in nature. The compounds show significant growth inhibitory activity against fungi Aspergillus niger and Candida albicans and moderate activity against bacteria Bacillus cirroflagellosus and Pseudomonas auresenosa.     

Synthesis and electrochemical study of 2-(2-pyridyl)benzothiazole complexes with transition metals (CoII, NiII, and CuII). Molecular structure of aquabis[2-(2-pyridyl)benzothiazole]copper(II) diperchlorate

The reactions of 2-(2-pyridyl)benzothiazole (1) with MX₂·nH₂O salts (M = Ni^II, Co^II, or Cu^II; X = Cl or ClO₄; n = 0–2) in EtOH afforded the corresponding complexes. Depending on the nature of the counterion in the starting metal salt, the reactions give compounds of composition M(1)Cl₂·nH₂O or Cu(1)₂(ClO₄)₂·H₂O. The molecular and crystal structure of the Cu^II(1)₂(ClO₄)₂·H₂O complex was established by X-ray diffraction. The copper atom in this complex has a distorted tetragonal-pyramidal ligand environment and is coordinated by four nitrogen atoms of two ligand molecules and one water molecule. Electrochemical study of the ligand and the resulting complexes by cyclic voltammetry and at a rotating disk electrode demonstrated that ligand 1 stabilizes reduced forms of complexes containing Ni, Co, or Cu atoms in the oxidation state +1. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1738–1744, October, 2006.     

Synthesis,Structure and Characterization of Two Novel Mercury(II) Complexes with N‐(2‐aminoethyl)piperazine

Two novel mercury(II) complexes [Hg^II(μ₂‐LH)Cl₂]₂[Hg^II₂(μ₂‐Cl)₂Cl₄]·2H₂O ( 1 ) and [Hg^II₄(μ₂‐L)₂(μ₂‐Cl)₂Cl₆] ( 2 ) have been synthesized by the reaction of N‐(2‐aminoethyl)piperazine (L) with HgCl₂ under different pH conditions. 1 and 2 were characterized by single‐crystal X‐ray diffraction analysis. The results reveal that in 1 there exist discrete mononuclear [Hg^II(μ₂‐LH)Cl₂]⁺ units and binuclear [Hg^II₂(μ₂‐Cl)₂Cl₄]²⁺ unit while in 2 there exist the rarely reported discrete cylic tetranuclear [Hg^II₄(μ₃‐L)₂(μ₂‐Cl)₂Cl₆] cluster units, which are both assembled into 3D supramolecular structures via extensive hydrogen‐bonding interactions. 1 and 2 were also characterized by element analysis, FT‐IR and luminescence spectra.