Synthesis and Structure of Bis[2,6-bis(2-pyridylamino)pyridinium] Tetrachlorocadmiumate(II)

1 INTRODUTION The d10 configuration of Cd(II) permits a wide variety of coordination numbers and geometries[1~3]. In recent years, one-, two- and three-dimensional infinite supramolecular coordination assemblies of Cd(II) have been the subject of great interest owing to their potential applications in catalysis, optical properties, clathration, etc[4~8]. In fabricating the coordination assemblies, organic ligands as well as inorganic anions have been observed to control the structural di…     

Chiral N,N′-dioxide-iron(II) complexes catalyzed enantioselective oxa-Michael addition of α,β-unsaturated aldehydes

The enantioselective oxa-Michael addition reaction of 1-(4-methoxyphenyl) ethanone oxime to various α,β-unsaturated aldehydes was accomplished by using chiral N,N′-dioxide-FeSO₄·7H₂O (1:1) complex. Aromatic acid was employed as additive to increase the yield of the reaction. The corresponding adducts were obtained in moderate yields with up to 76% ee under mild conditions.     

Trialkyl borate assisted amination of fluorinated 1,3-diketones for synthesis of N,N′-1,2-phenylen-bis(β-aminoenones) and their Ni(II), Cu(II) and Pd(II) complexes

An effecient synthetic method for fluorinated tridentate β-aminoenones and tetradentate bis(β-aminoenones) via amination of fluorinated 1,3-diketones with o-phenylenediamine in the presence of trialkyl borates was developed. Ni(II), Cu(II) and Pd(II) complexes with tetradentate bis(β-aminoenones) were obtained. Their gaschromatographic behaviour and main fragmentation paths in the electron ionization mass spectra were described.     

Reactions of titanocene dihalides with N,N′,N″-chelates: Preparation,X-ray structure and characterization of bis(chloro){2,6-bis[(3,5-dimethyl)pyrazol-1-yl]pyridine}(η-peroxo)titanium(IV)

The reaction of [Ti^IV(Cp)₂Cl₂] (Cp⁻ = η⁵-C₅H₅⁻) and 2,6-bis(3,5-dimethylpyrazolyl-1-yl)pyridine (bdmpp) in Me₂CO has afforded complex [Ti^IVCl₂(O₂)(bdmpp)] (1). The complex can also be prepared from the 1:1:1 [Ti(Cp)₂Cl₂]/bdmpp/H₂O₂ reaction mixture in various solvents. Single-crystal, X-ray crystallography has revealed that the Ti^IV center is in a distorted pentagonal bipyramidal environment in both of the two, crystallographically independent molecules that are present in the asymmetric unit; the equatorial positions are occupied by the two O atoms of the side-on (η²) O₂²⁻ group and the three N-atoms of the tridentate chelate, while the two chloro ligands are on the axial positions. IR, Raman, electronic and ¹H NMR data are discussed in terms of the known structure and the coordination modes of the peroxo and bdmpp ligands.     

Synthesis,structure and magnetic studies of copper(II)-nickel(II) complexes withN,N′-bis(2-aminopropyl)oxamidocopper(II)

Three novel heterobinuclear complexes have been prepared and identified as [Cu(oxap)Ni(L)₂](ClO₄)₂·ξH₂O, where oxap denotes theN,N′-bis(2-aminopropyl)oxamido dianion and L denotes 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) or 5-nitro-1,10-phenanthroline (NO₂-phen). The crystal structure of [Cu(oxap)Ni(phen)₂]-(ClO₄)₂·2H₂O has been determined. Crystal data: triclinic, space group , a=12.079 (6), b=12.409 (4), c=17.261 (8) ?, α=70.91 (2), β=86.72 (4), γ=89.19 (3)^o. At room temperature, Z=2. The Cu^II is in a square planar environment and the Ni^II is in an octahedral environment. The Cu−Ni distance is 5.292 ?. The temperature dependences of the magnetic susceptibilities of [Cu(oxap)Ni(phen)₂]-(ClO₄)₂·2H₂O and [Cu(oxap)Ni(bipy)₂](ClO₄)₂ have been studied in the 4.2–300 K range, giving the exchange integral J=−92.4 cm⁻¹ for bipy and J=−94.3 cm⁻¹ for phen. These results are commensurate with antiferromagnetic interactions between the adjacent metal ions.     

Synthesis and crystal structure of new cobalt(II) and copper(II) complexes with deprotonated N -[2′-(4-methyl) pyrimidinyl]-2-nitrobenzenesulfonylurea

Cobalt(II) and copper(II) complexes with deprotonated N-[2′-(4-methyl)pyrimidinyl]-2-nitrobenzenesulfonylurea were synthesized and their structures were characterized by IR spectrum, elemental analysis and X-ray diffraction. The deprotonated sulfonylurea is a bidentate ligand to Co(II) or Cu(II) in octahedral geometry. In the packing diagrams of the complexes, C–H ··· O hydrogen bonds are observed. The UV and fluorescence spectra of the complexes are described, and the thermogravimetric analyses of the complexes were performed.     

Dinuclear Nickel(II) and Zinc(II) Complexes of 2,6-[N,N′-bis(2-hydroxyphenylmethyl)-N,N′-bis(2-pyridylmethyl)aminomethyl]-4-methylphenol

Abstract

The symmetric 'end-off' compartmental proligand 2,6-[N,N′-bis(2-hydroxy-phenylmethyl)-N,N′-bis(2-pyridylmethyl)aminomethyl]-4-methylphenol (H₃L) has been used to generate homodinuclear nickel(II) and zinc(II) complexes. The crystal structures of the complexes reveal that the di-nickel(II) complex is donor asymmetric and the di-zinc(II) complex is coordination number asymmetric. In both complexes non-coordinated acetic acid molecules are tightly hydrogen-bonded to the pendant phenols of the ligand generating a double acid salt of the type[CH₃COO…H…L…H…OOCCH₃]^3? in the dinickel complex and a single acid salt of the type [CH₃COO…H…L]^3? in the dizinc complex. In both cases the ligand periphery has been extended to provide a supraligand in which the donor potential of the original ligand has been enhanced.     

Synthesis and magnetic properties of copper(II)-MII-copper(II) trinuclear complexes with N,N′-bis(2-aminoethyl)oxamidocopper(II) [M = Co and Ni]

Summary Two novel trinuclear complexes were prepared, namely [Cu₂(oxae)₂(H₂O)₂M] (ClO₄)₂, [oxae = N,N-bis(2-aminoethyl) oxamido dianion; M = Co and Ni]. Based on elemental analyses, conductivity measurements and i.r. spectra, the complexes are proposed to have extended oxamidobridged structures. The magnetic susceptibility of [Cu₂-(oxae) ₂(H₂O)₂Co](ClO₄)₂ were measured over the 4–300 K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian, =–2J(₁·₂·₂·₃). The exchange integral, J, was found to be equal to –29.2 cm^–1, indicating an antiferromagnetic spin-exchange interaction between the adjacent metal ions.     

Binuclear titanium(III) complex derived from diphenylphosphanylmalononitrile, [μ(N,N′)-Ph2PC(CN)2TiCp2]2: Synthesis, structure and properties

Diphenylphosphanyl malononitrile, Ph₂P-CH(CN)₂ (1) reacts with Cp₂TiCl in the presence of triethylamine in THF to give air sensitive Ti(III) complex [μ²(N,N′)-Ph₂PC(CN)₂TiCp₂]₂ (2), which is centrosymmetric dimer in the solid state, containing nearly planar 12-member metallocycle. Solution of 2 (200 K) exhibits anisotropic EPR spectrum; every spectral component contains splitting on a single phosphorus nucleus.     

Synthesis and Structure of Di(μ-Ophenoxy)-bis{nitrato-2-[2-(hydroxyethylimino)-methyl]-phenoloimidazolecopper}

The crystal structure of di(-O_phenoxy)-bis{nitrato-2-[2-(hydroxyethylimino)-methyl]-phenoloimid-azolecopper} was determined. The crystals are monoclinic: a = 10.222(2) Å, b = 13.810(3) Å, c = 10.620(2) Å, =103.67(3)°, space group P2₁/n, Z = 2, R = 0.050. The copper atom coordinates the singly deprotonated 2-[2-(hydroxyethylimino)-methyl]-phenol molecule, imidazole, and nitrate ion. The coordination polyhedron of the central atom is an extended tetragonal bipyramid with imine and imidazole nitrogen atoms and phenol and alcohol oxygen atoms lying in its base. One axial vertex of the bipyramid is occupied by the oxygen atom of the nitrato group and the other vertex, by phenol oxygen atom of the neighboring complex joined with the initial complex by the symmetry center. Two bridging phenol oxygen atoms unite the complexes into a centrosymmetrical dimer.     

Enantio- and diastereoselective cyclopropanation with tert-butyl α-diazopropionate catalyzed by dirhodium(II) tetrakis[N-tetrabromophthaloyl-(S)-tert-leucinate]

The first successful example of a catalytic asymmetric cyclopropanation with α-diazopropionates is described. The cyclopropanation reaction of 1-aryl-substituted and related conjugated alkenes with tert-butyl α-diazopropionate has been achieved by catalysis with dirhodium(II) tetrakis[N-tetrabromophthaloyl-(S)-tert-leucinate], Rh₂(S-TBPTTL)₄, providing the corresponding cyclopropane products containing a quarternary stereogenic center in good to high yields and with high diastereo- and enantioselectivities (trans:cis = 90:10 to >99:1, 81-93% ee).     

N- vs O-Coordination in cyclomanganation of 1,5-diaryl-3-(2-pyridyl)pentane-1,5-diones and 3-(2-pyridyl)chalcones; cyclomanganation at saturated carbon and the crystal structure of [1,5-diphenyl-κC-3-(2-pyridyl- κN)pentan-2-yl-κC-1,5-dione-κOκO]tetracarbonylmanganesetricarbonylmanganese

Reaction of 1,5-diphenyl-3-(2-pyridyl)pentane-1,5-dione (5a) with 2.5 moles of benzylpentacarbonylmanganese in petroleum spirit under reflux gives a small amount of the symmetric di-aryl-manganated product [1,5-diphenyl-κC²-3-(2-pyridyl)pentane-1,5-dione-κO¹κO⁵]bis-(tetracarbonylmanganese) (7a), but mostly [1,5-diphenyl-κC²-3-(2-pyridyl-κN)pentan-2-yl- κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6a) which is manganated at only one aryl carbon [by Mn(CO)₄] but also [by Mn(CO)₃ with N and O coordination] at the methylene carbon adjacent to the Mn(CO)₄-coordinated ketone carbonyl. The latter is a rare example of direct cyclomanganation at a saturated carbon and the only known case adjacent to a carbonyl group; the X-ray crystal structure of 6a is reported. With 3 moles of benzylpentacarbonylmanganese the yield of 6a remains unchanged but some trimanganation product [1,5-diphenyl-κC^2′κC^2?-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tris-(tetracarbonylmanganese) (8a) is formed, presumably from 7a. Routes to products are proposed and activating factors considered. 1,5-Di-(2-thienyl)-3-(2-pyridyl)pentane-1,5-dione (5b) and its 3-thienyl isomer (5c) similarly give 6a analogues [1,5-di-(2-thienyl-κC³)-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6b) and [1,5-di-(3-thienyl-κC²)-3-(2-pyridyl-κN)pentan-2-yl-κC²-1,5-dione-κO¹κO⁵]tetracarbonylmanganesetricarbonylmanganese (6c).Also reported are the mono-cyclomanganation product [1-(2,6-dimethoxyphenyl)-3-(2-pyridyl-κN)prop-2-en-2-yl-κC²-1-one]tetracarbonylmanganese (16) and dicyclomanganation product [1-(2,5-dimethyl-3-thienyl-κC⁴)-3-(2-pyridyl-κN)prop-2-en-2-yl- κC²-1-one-κO ]bis-(tetracarbonylmanganese) (17) from reaction of the respective (E)-1-aryl-3-(2-pyridyl)prop-2-en-1-ones (3-(2-pyridyl)chalcones), the first reported examples of enone metallation at the α-carbon via N-coordination by a β-2-pyridyl group.     

Copper(II)–1,2-bis(thiocarbamoyl)hydrazine and copper(II)–(1-carbamoyl-2-thiocarbamoyl)hydrazine complexing in copper(II)hexacyanoferrate(II) gelatin-immobilized matrix systems

The complex formation that occurs in gelatin-immobilized copper(II)hexacyanoferrate(II) matrices upon contact with aqueous alkaline (pH 12.0) solutions of 1,2-bis(thiocarbamoyl)hydrazine, H₂NC(S)NHNHC(S)NH₂ and 1-carbamoyl-2-(thiocarbamoyl)hydrazine, H₂NC(O)NHNHC(S)NH₂ has been studied. The reaction of each of these ligands with copper(II) is preceded by the destruction of copper(II)hexacyanoferrate(II) in an alkaline medium to form a polymeric copper(II) hydroxide, which is involved in the subsequent copper(II)–ligand complex formation. In both Cu^II–N ligand systems, two complex compounds are formed; the water-insoluble Cu₂B₂(H₂O)₂ dimer and a water-soluble product of tentative composition [CuB(HB)]^– (H₂B=ligand).     

Crystal structure of tetra(μ-acetato)-bis{[1-ethyl-3-(pyridine-2-yl)carbamide]copper}

The crystal structure of tetra(μ-acetato)-bis{[1-ethyl-3-(pyridine-2-yl)carbamide]copper} Cu₂(L)₂(CH₃COO)₄ (I), where L is 1-ethyl-3-(pyridine-2-yl)carbamide, is determined. The asymmetric unit cell of the crystal structure of I contains a copper complex with two acetate ions and a monodentate molecule of 1-ethyl-3-(pyridine-2-yl)carbamide, which is coordinated via the pyridine nitrogen atom. Due to the symmetry center, binuclear complexes form in the crystal, in which the acetate ions act as bridges between the metal atoms. In them, the coordination polyhedron of the central copper atoms represents an almost ideal tetragonal pyramid. Its base is formed from the oxygen atoms of acetate ions. In the crystal of the binuclear complex, hydrogen bonds form between the acetate ions and the L ligand along with an intramolecular hydrogen bond, which stabilize the conformation of the organic L molecule. Between the neighboring complexes in the crystal, the van der Waals interaction occurs.     

Structure and Photosynthetic Mimicking of Bis(2,6-bis(benzimidazol-2-yl)pyridine)manganese(II)

Introduction　　Manganeseionsplayanimportantroleinthelight in ducedoxidationofwatertomolecularoxygeninphotosys temII (PSII)ofgreenplants.1 3Inrecentyears ,man ganesecomplexesofpolypyridineligands ,suchasbipyri dine ,1,10 phenanthrolineand 2 ,2′:6′,2″ terpyridine ,havehadconsiderableattentionasthecomplexesformedareusefulmodelsformanganese containingbimolecu lars .4 6 Therefore ,synthesisandcharacterizationofman ganeseinitsvariousoxidationstates ,withvariousligandtypesandnuclearities ,hav…     

Metal-ligand complexes involved in rheumatoid arthritis—V: Formation constants for calcium(II)-, magnesium(II)- and copper(II)-salicylate and acetylsalicylate interactions

Values of log β are reported for HSal⁻, H₂Sal, MgSal, CaSal, CuSal, CuSal₂²⁻, HAcSal, MgAcSal⁺, CaAcSal⁺, CuAcSal⁺ and CuAcSal₂ at 37°, I = 150 mmol dm⁻³ in spite of limits imposed by precipitation. These constants are used to compute the concentrations of metal complexes as the drugs pass through the body and are in accord with biological data that orally administered salicylates and copper salicylates have equivalent activities against arthritis but copper salicylate, because of its large log β (10.045) for a neutral complex, causes less gastric damage than Aspirin and its copper complex. Parenteral administration of copper salicylates produce anti-inflammatory responses through the ions acting separately, the complexes per se not existing under plasma conditions.     

Spectroscopic and electrochemical studies on (2-hydroxypicolinate)-bis(2,2′-bipyridine)ruthenium(II) and related complexes

Summary The synthesis, spectra and electrochemistry of [Ru(bipy)₂-(picOH)]⁺ and -picO-[Ru(bipy)₂]₂ ²⁺ (bipy = 2,2-bipyridine and picOH = 3-hydroxypicolinate ion) are described. The spectroscopic properties in the visible region are dominated by the intense Ru bipy chargetransfer transitions. In the binuclear complex, the two [Ru(bipy)₂L]²⁺ moieties are nonequivalent, exhibiting E _1/2 = 0.69 and 1.20 V versus s.h.e. The partially oxidized species exhibits a weak intervalence transfer band at 1085 nm, and is consistent with a Robin-Day class II mixed valence complex.     

Ruthenium(II) complexes of 2-(2′-pyridyl)naphthoimidazole: synthesis,characterization and DNA-binding studies

The perchlorate salts of two new ruthenium(II) complexes incorporating 2-(2′-pyridyl)naphthoimidazole are synthesized in good yield. Complexes [Ru(phen)₂(PYNI)]²⁺ (phen = 1,10-phenanthroline) 1 and [Ru(dmp)₂(PYNI)]²⁺ (dmp = 2,9-dimethyl-1,10-phenanthroline, PYNI = 2-(2′-pyridyl)naphthoimidazole) 2 are fully characterized by elemental analysis, FAB-MS, ES-MS, ¹H NMR and cyclic voltammetric methods. The DNA-binding behavior of the complexes have been studied by spectroscopic titration, viscosity measurements and thermal denaturation. Absorption titration and thermal denaturation studies reveal that these complexes are moderately strong binders of calf-thymus DNA (CT-DNA), with their binding constants spanning the range (2.73–5.35) × 10⁴ M^?1. The experimental results show that 1 interacts with calf thymus DNA (CT-DNA) by intercalative mode, while 2 binds to CT-DNA by partial intercalation.