Synthesis,crystal structures,and characterization of two Co(II) coordination polymers with 3-pyrid-3-ylbenzoic acid

Two pyridinecarboxylato-bridged coordination polymers {[Co(pbc)₂(H₂O)] · H₂O} _n (1) and [Co(pbc)₂] _n (2) (Hpbc = 3-pyrid-3-ylbenzoic acid) have been synthesized by the hydrothermal method and characterized by X-ray single crystal diffraction. In 1, pbc^? ligands link two Co(II) centers as μ₂-N,O and μ₂-N,O,O. Co(II) is six coordinate, octahedral. In 2, Co(II) is coordinated by four oxygens and two nitrogens. The ligands are μ₂-N,O,O and μ₃-N,O,O. Through different pbc^? ligands, 2 generates a 3-D network composed of six-connected nodes. Compound 2 exhibits good photoluminescence, whereas 1 is nonemissive at room temperature.     

Nickel(II), copper(II), and cobalt(II) complexes derived from a new unsymmetrical ONS donor Schiff base ligand: synthesis,characterization, crystal structure,and catalytic activities

Ni(II), Cu(II), and Co(II) complexes, ML₂, with a new thioether containing ONS donors were synthesized, where L = deprotonated Schiff base. The analytical, spectral (FTIR, ¹H NMR, and UV-vis), conductivity, and magnetic studies show that the metal complexes possess octahedral geometry and are non-electrolytes. The coordination mode of ligand, 1, and nickel(II) complex, NiL₂, 2, was determined by single-crystal X-ray diffraction studies. Here, the nickel is coordinated to two oxygens, two nitrogens, and two sulfurs of two tridentate ligands with slightly distorted octahedral environment around nickel. The copper complex shows very good catalytic activities towards oxidation of organic thioethers to the corresponding sulfoxide predominantly using H₂O₂ as the oxidant.     

Semiempirical studies on the interactions of dialkyldi(aquo)tin cations, [R2Sn(H2O)2]2+, with selected nucleotides

Semiempirical calculations have been carried out on the interactions of [R₂Sn(H₂O)₂]²⁺, [R = H(CH₂)_n: n = 1–8], mainly with five nucleotides, 5′‐adenosine monophosphate (5′‐AMP), but also with guanosine 5′‐monophosphate (5′‐GMP), cytidine 5′‐monophosphate (5′‐CMP), uridine‐5′‐monophosphate (5′‐UMP) and inosine 5′‐monophosphate (5′‐IMP). The preferred sites of interaction were calculated to be the ribose O2 and O3 hydroxyl oxygens and/or the phosphate oxygens, with the nitrogen sites in the bases the least attractive to the tin compounds. This is in general agreement with experimental findings. Structures of the 1:1 coordination complexes vary from distorted tetrahedral, to distorted trigonal pyramidal to distorted octahedral geometries. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,structures and properties of cobalt(III) and iron(III) complexes with a new triazamacrocycle, 1,4-diacetate-1,4,7-triazacyclodecane

A new bidisplaced acetate functionalized pendant arm derivative, 1,4-diacetate-1,4,7-triazacyclodecane (L) and its corresponding Co(III), Fe(III) complexes [CoLCl] (1) and [FeLCl]₂ · 3H₂O (2) were synthesized and characterized by elemental analysis, IR spectra,UV–Vis spectra, HNMR, MS, XPRD, TGA and single-crystal X-ray diffraction analysis. The crystal structure shows the metal ions in the complexes have similar coordination six-coordinate, by three nitrogens and two oxygens of the chelate ligand, and a chloride. Through calculation of the twist angle, we discover 1 forms a distorted octahedral geometry while 2 forms a distorted-prismatic geometry. In 2, there are abundant hydrogen bonds between the oxygen atoms of water and the nitrogens and oxygens of the ligand, resulting in a two-dimensional supramolecular network with a regular triatomic water cluster. The thermal gravimetric analyses of the two complexes are also given.     

Synthesis,crystal structure and magnetic properties of Co(NIT4Py)(H2PDA)(H2O)3

A Co(II)-pyridyl substituted nitronyl nitroxide complex Co(NIT4Py)(H₂PDA)(H₂O)₃ has been synthesized and structurally characterized (NIT4Py: 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide and H₂PDA: 2,5-pyridine dicarboxylic acid). The compound is in the monoclinic space group P2(1)/c, a = 16.892(5) Å, b = 7.371(2) Å, c = 18.856(5) Å, β = 108.770(5)°, V = 2223.0(11) ų, Z = 4 and F(000) = 1064. The cobalt is in a distorted octahedral environment with one nitrogen from NIT4Py, one oxygen atom from H₂PDA, two oxygens from two water molecules in the basal plane and one nitrogen from H₂PDA and one water in the axial positions. The molecules are connected as a layered structure by intermolecular hydrogen bond interactions. Variable temperature magnetic susceptibility measurements reveal the occurrence of weak antiferromagnetic interactions in the compound.     

Synthesis,spectral studies,and antimicrobial activity of binary and ternary Cu(II), Ni(II), and Fe(III) complexes of new hexadentate Schiff bases derived from 4,6-diacetylresorcinol and amino acids

Two new hexadentate N₂O₄ donor Schiff bases, H₄L¹ and H₄L², were synthesized by condensation of 4,6-diacetylresorcinol with glycine and alanine, respectively. The structures of the ligands were elucidated by elemental analyses, IR, ¹H NMR, electronic, and mass spectra. Reactions of the Schiff bases with copper(II), nickel(II), and iron(III) nitrates in 1 : 2 molar ratio gave binuclear metal complexes and, in the presence of 8-hydroxyquinoline (8-HQ) or 1,10-phenanthroline (Phen) as secondary ligands (L′), mixed-ligand complexes in two molar ratios 1 : 2 : 2 and 1 : 2 : 1 (L¹/L² : M : L′). The complexes were characterized by elemental and thermal analyses, IR, electronic, mass, and ESR spectral studies, as well as conductivity and magnetic susceptibility measurements. The spectroscopic data reveal that the Schiff-base ligands were dibasic or tetrabasic hexadentate ligands. The coordination sites with the metal ions are two azomethine nitrogens, two oxygens of phenolic groups, and two oxygens of carboxylic groups. Copper(II) complexes were octahedral and square planar while nickel(II) and iron(III) complexes were octahedral. The Schiff bases, H₄L¹ and H₄L², and some of their metal complexes showed antibacterial activity towards Gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and Gram-negative (Pseudomonas fluorescens and Pseudomonas phaseolicola) bacteria and antifungal activity towards the fungi Fusarium oxysporium and Aspergillus fumigatus.     

Complexes of organometallic compounds : XXXVII. Mössbauer and other studies on adducts of organotin(IV) chlorides with N,N′-ethylenebis(salicylideneiminato)-nickel(II)

Novel 1/1 adducts have been obtained from the complex N,N′-ethylenebis(salicylideneiminato)nickel(II) (NiSalen) with di- and mono-organotin(IV) chlorides, and their solid state configuration investigated by Mössbauer , IR and electronic spectroscopy and magnetic measurements. In coordinated NiSalen the square planar structure is maintained around Ni^II, and the coordination to tin involves three-coordinate phenolic oxygens. The environment of Sn^IV is judged to be octahedral in both types of compounds. A trans-R₂, cis-Cl₂ configuration is advanced for R₂SnCl₂NiSalen.     

Synthesis,characterization, and antibacterial activity of a manganese(II) complex of triaryltriazole

A manganese(II) complex of 4-(4-methylphenyl)-3,5-bis(2-pyridyl)-4H-1,2,4-triazole (MBPT) was synthesized and characterized by X-ray crystallography. [Mn(MBPT)₂(H₂O)₂](ClO₄)₂?·?4H₂O is a divalent mononuclear manganese(II) complex with manganese coordinated to four nitrogens from two triazole ligands and two oxygens from two water molecules in a slightly distorted octahedral geometry. The complex and ligand were tested in vitro for their antibacterial activities. The title complex showed a wide range of bactericidal activities.     

Crystal structure of barium (cyclohexane-1,2-diaminetetraacetato)cobaltate(III) nonahydrate Ba[Co(Cdta)]2 · 9H2O

The crystal structure of Ba[Co(Cdta)]₂ · 9H₂O has been determined by X-ray diffraction. The crystals are monoclinic, a = 15.9415(10) Å, b = 7.8449(6) Å, c = 32.230(2) Å, β = 100.387(8)°, Z = 4, space group C2/c)). The cyclohexane-1,2-diaminetetraacetate ion forms the octahedral [Co(Cdta)]^? complex through two donor nitrogen atoms and four oxygen atoms and is also connected to two barium atoms through oxygens. The Ba atoms are on a twofold axis. Its nearest environment comprises five O atoms of water molecules, one also being located on a twofold axis, and four O atoms of the four neighboring complex ions. This gives infinite layers parallel to the ab plane. All water molecules form hydrogen bonds within one layer.     

Hydrogen-bonded Networks in Crown Ether Complexes of Hydrated Metal Ions

Abstract

The hydrated metal nitrates (M(NO₃)₃.6H₂O, M[dbnd]Co, Ni, Cu, Zn and Cd) have been crystallised from water in the presence of 18-crown-6 and their structures determined by X-ray crystallography. In the case of copper, a pseudo four-coordinate square planar complex resides in an extended six-coordinate octahedral array which is further bound in a single-stranded one-dimensional hydrogen bonded polymeric mode. For M[dbnd]Co,Ni,Zn and Cd isomorphous complexes are isolated where the octahedral [M(H₂O)₅(NO₃)⁺ cation resides in a two-dimensional polymeric network through hydrogen bonds between the water ligands and either the crown ether oxygens or unbound nitrate ions or water molecules.     

Field-induced Co(II) single-ion magnet with nearly perfect octahedral ligand field

In this paper, a mononuclear Co(II) compound [Co(H₂O)₆]Cl₂·2C₆H₁₂N₄·4H₂O ( 1 ) was synthesized and characterized. X-ray single crystal diffraction analyses shows that the Co(II) ion adopts almost perfect octahedral coordination geometry with O6 donors provided by six water molecules. Magnetic properties studies show it has strong in-plane anisotropy with D = +66.7 cm⁻¹. AC susceptibility measurements indicate it is a field-induced SMM with U_eff = 56.11 K via Raman relaxation process and/or direct process. It is rare for Co(II) ion in cobalt-based compound showing almost perfect octahedral coordination geometry.     

Transition metal polymeric chelates: Spectral, magnetic, thermal behaviour of polymeric chelates of poly(resacetophenone diyl ethylene)s with Ni(II), Cu(II), Mn(II), Zn(II) and Co(II)

Polymeric chelates of the type [ML₂]_n where M = Ni(II), Cu(II), Zn(II) or Co(II), L = poly(resacetophenone diyl ethylene)s, andn= degree of polymerization, have been synthesized. Their structures have been elucidated on the basis of analytical, magnetic, electronic and IR spectral studies. Electronic spectra in conjunction with magnetic moments are in accord with an octahedral environment around the central metal ion in all polymeric chelates except Cu(II) and Zn(II) polymeric chelates which have been shown to possess square planar and tetrahedral geometries, respectively. IR spectral studies further suggest that the metal ions are coordinated through the oxygens of the carbonyl and the phenolic hydroxyl groups. All the chelates are paramagnetic except Zn(II), which is found to be diamagnetic.     

Novel ternary cobalt(II) and nickel(II) complexes of N-phthaloylglycinate. Synthesis, characterization and X-ray crystal structure

A new series of N-phthaloylglycineate (N-phthgly) ternary complexes of cobalt(II) and nickel(II) with imidazole (imi), N-methylimidazole (mimi) and 2,2′-bipyridyl (bipy) have been synthesized and characterized by elementary analyses, IR spectroscopy, thermogravimetric analysis. X-ray crystal structure analyses of the three complexes of [Co(mimi)₂(N-phthgly)₂] (1), [Co(bipy)(OH₂)₄](N-phthgly)₂ (2) and [Ni(imi)₂(N-phthgly)₂(OHCH₃)₂] (3) were also carried out. In complex (1), the Co(II) exists in a distorted tetrahedral enviroment, where two nitrogen atoms of two methylimidazole molecules and two oxygen atoms of the carboxylate group of two N-phthaloylglycinate molecules are coordinated. On the other hand, in complex (2) the cobalt atom coordinates a 2,2′-bipyridine molecule and four water oxygen atoms forming a distorted octahedral conformation. A molecule of N-phthaloylglycinate is connected by van der waals contact and H-bonds. For complex (3), the nickel atom is surrounded by four oxygens (two oxygens of two different N-phthaloylglycinate molecules and two of methanol ligand) in the basal plane of octahedron along with two imidazole nitrogen atoms at the apical positions. Strong intramolecular H-bond exists between the uncoordinated carboxylic oxygen of the N-phthaloylglycinate ligand and the O–H of the methanol group.     

Synthesis,structures and Hirshfeld surface analysis of Ni(II) and Co(III) complexes with N2O donor Schiff base ligand

Two octahedral complexes [NiL(HL)]ClO₄.0.5CH₃OH and [CoL₂]ClO₄ have been synthesized with N₂O donor Schiff base ligand {((2-(phenylamino)ethyl)imino)methyl}phenol (HL) and characterized by spectroscopic techniques and single crystal X-ray diffraction studies. The molar conductivities data of the two complexes show that the complexes are 1:1 electrolyte. Single crystal X-ray diffraction data shows both Ni(II) and Co(III) complexes have distorted octahedral geometry and two ligands are coordinated to the metal centers and one ClO₄⁻ ion outside the coordination sphere. The intermolecular interactions in the complexes are evaluated by Hirshfeld surface analysis and revealed a significant contribution of non- or weakly polar interactions to the packing forces for both molecules, with crystal structure of Co(III) complex featuring short H/H contacts.     

Synthesis and Characterization of New M‐Triazole Complexes (M = Co,Cu, Zn)

Three new complexes with the ligand 3,5‐diamino‐1,2,4‐triazole (Hdatrz), [Co₃(μ₂‐Hdatrz)₆(H₂O)₆]·(NO₃)₈·4H₂O ( 1 ), [Cu₃(μ₂‐Hdatrz)₄(μ₂‐Cl)₂(H₂O)₂Cl₂]·Cl₂·4H₂O·2C₂H₅OH ( 2 ) and {[Zn₂(μ₂‐SO₄) (μ₃‐datrz)₂]·2H₂O}_n ( 3 ) have been synthesized and structurally characterized. Complex 1 has a linear trinuclear mixed‐valence cobalt structure with six neutral triazole ligands in the N(1), N(2)‐bridging mode. The central cobalt atom, Co(1), is coordinated to six nitrogen atoms (octahedral) whereas the terminal cobalt atom, Co(2), is coordinated to an N₃O₃ moiety (octahedral). In complex 1 , the uudd cyclic water clusters, nitrate anions and the trimeric cations are linked to a supramolecular structure. Complex 2 features a linear trinuclear copper(II) core, with four N(1), N(2)‐bridging triazole ligands and two chlorido bridges. The central copper atom is coordinated to an N₄Cl₂ moiety (octahedral) whereas the terminal copper is coordinated to an N₂Cl₂O moiety (square‐pyramidal). In complex 2 , tetrahedral hydrogen bonding interactions play an important role to form a supramolecular network. Complex 3 exhibits a polymeric structure, with N(1), N(2), N(4)‐bridging triazolate ligands and sulfate bridges, in which zinc is coordinated to an N₃O moiety (tetrahedral). In complex 3 , water molecules and sulfate anions construct the sulfate‐water supramolecular chain with hydrogen bonding interactions. In addition, the complexes were investigated by elemental analyses, IR spectroscopic, and thermogravimetric measurements.     

Crystal structure of the new compound Co6(TeO3)2(TeO6)Cl2

The new compound Co₆(TeO₃)₂(TeO₆)Cl₂ has been isolated during an investigation of the system CoO:CoCl₂:TeO₂. The new compound is deep purple in color and crystallizes in the tetragonal system, space group P4₂/mbc, a=8.3871(7) Å, c=18.5634(19) Å, Z=4. The Co(II) ions have octahedral [Co1O₆] and tetrahedral [Co2O₃Cl] coordinations. Tellurium is present both as Te(IV) with a tetrahedral [Te1O₃E] coordination, where E is the 5s² lone-pair and as Te(VI) with an octahedral [Te2O₆] coordination. The structure is made up of intersecting layers of tetrahedra forming channels comprising octahedra chains that run along the c-axis. The new compound is the first cobalt tellurium oxochloride described.     

Synthesis,crystal structures and spectroscopic studies on trans and cis isomers of Co(II) complexes with 1-benzyl-2-hydroxymethylimidazole

By carrying out the synthesis in a special way, two novel cobalt(II) isomers of trans(O)-[Co(1-Bz-2-CH₂OHIm)₄](NO₃)₂ (1) and cis(O)-[Co(1-Bz-2-CH₂OIm)₄](NO₃)₂·1.5H₂O (2) have been separated. The crystal structures of the Co(II) isomers show the triclinic space group P1̄ (1) and the monoclinic space group C2/c (2). The coordination geometry around the Co atom is approximately octahedral (1) or very distorted octahedral (2) and the Co(II) ions are surrounded by four nitrogen atoms of the four imidazole rings and two oxygen atoms of the hydroxymethyl group. Two of the ligands act as a monodentate and two as a bidentate, forming the five–membered chelate ring with the central ion. The structural data obtained for the Co(II) isomers were confirmed by IR and UV–Vis spectroscopic methods.     

X-ray structure and magnetochemical study on a Co(II) complex of 2-acetyl-1,3-indandione

An X-ray structure of a Co(II) complex of bidentate chelating 2-acetyl-1,3-indandione (2AID) is reported–Co(2AID)₂(H₂O)₂ · 2H₂O. The compound crystallizes in the monoclinic space group P2₁/n with four molecules per unit cell. The molecular structure shows distorted octahedral geometry of the metal center. The complex is characterized by EPR and magnetic measurements, which show high-spin electronic structure for the metal ion.     

Catalytic activity of Co/SiO2 and Co/TiO2 nanosized systems in the oxidation of carbon monoxide

The effects of the preparation procedure, active component concentration, and conditions of formation of nanosized cobalt-containing systems based on TiO₂ and SiO₂ mesoporous powders on their catalytic activity in the oxidation of carbon monoxide were studied. The active phase in the systems was cobalt spinel CoCo₂O₄ found in all samples. High catalytic activity was found in the samples characterized by relatively high contents of surface active centers (cobalt cations with octahedral surroundings).     

Tyrrellite,Cu(Co0.68Ni0.32)2Se4, isostructural with spinel

Tyrrellite, a naturally occurring Co–Ni–Cu selenide, has been studied by single‐crystal X‐ray diffraction. It possesses the normal spinel‐type structure, with Cu occupying the tetrahedral site and (Co+Ni) the octahedral site. The average Cu—Se distance of 2.3688 (2) Å is close to that of 2.3703 (8) Å in CuCr₂Se₄, whereas the average (Co+Ni)—Se distance of 2.3840 (1) Å appears to be slightly shorter than most octahedral Co—Se or Ni—Se distances (∼2.40–2.50 Å) in other selenides. The refined structure provides a basis for a redefinition of the ideal chemical formula of tyrrellite, which should be Cu(Co,Ni)₂Se₄, rather than the previously suggested (Cu,Co,Ni)₃Se₄.