Catalase activity of cobalt(II) complexes with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides

On the base of the kinetic and activation parameters of the hydrogen peroxide decomposition in the presence of chelates of CoX₂ salts (X = Cl, Br, I, NCS) with N,N,N′,N′-tetrasubstituted thiocarbamoylsulfenamides containing exocyclic (out-of-chelate) fragments of dimethylamine (I), piperidine (II), and piperazine (III) the nature of acido-ligands influence on catalase activity of complexes I–III was revealed, depending on the structure and composition of the chelating ligand. Mononuclear complexes I(Br) and II(Br) can transform into 10-membered binuclear macrochelate intermediates.     

N,N′-(1,2-phenylene)bis­(pyridine-2-carboxamide) and N,N′-(1,2-cyclohexanediyl)bis(pyridine-2-carbox­amide) toluene hemisolvate

The crystal structures of N,N′-(1,2-phenyl­ene)­bis­(pyridine-2-carbox­amide), C₁₈H₁₄N₄O₂, (I), and N,N′-(1,2-cyclo­hexane­diyl)­bis­(pyridine-2-carbox­amide) have been determined, the latter compound as the toluene hemisolvate, C₁₈H₂₀N₄O₂·0.5C₇H₈, (II). In (I), the benzene ring is nearly coplanar with one of the pyridine rings and forms a dihedral angle of 59.4 (1)° with the other. However, in (II), the dihedral angle of the two pyridine rings is 70.0 (1)°.     

Kinetics of the oxidation of [N-(2-hydroxyethyl)-ethylene-diamine-N,N′,N′-triacetato]cobalt(II) by N-bromosuccinimide

The kinetics of the oxidation of [N-(2-hydroxyethyl)-ethylene-diamine-N,N,N-triacetato] cobalt(II), [Co^II-(HEDTA)]^–, by N-bromosuccinimide, NBS, have been studied in aqueous solutions and water-methanol solvent mixtures under various conditions. The reaction stoichiometry indicates that one mole of NBS reacts with one mole of [Co^II(HEDTA)]^–. In aqueous solutions the reaction obeys the following rate law:

Synthesis and X-ray crystal structures of N,N,N′,N′-tetraalkylpyridine-2,6-dithiocarboxamides (S-dapt) complexes of cobalt(II) and nickel(II)

Reactions of anhydrous CoX₂ (X?=?Br^?, SCN^?) and Ni(ClO₄)₂ with N,N,N′,N′-tetraisobutylpyridine-2,6-dithiocarboxamides (S-dbpt), N,N,N′,N′-tetraisopropyl pyridine-2,6-dithiocarboxamides (S-dppt), and N,N,N′,N′-tetraethylpyridine-2,6-dithiocarboxamides (S-dept) lead to the formation of [Co(S-dbpt)Br₂] (1), [Co(S-dppt)(SCN)₂] (2), and [Ni(S-dept)₂]·(ClO₄)₂·H₂O (3), respectively. The X-ray crystal structures of the three S-dapt ligands and three complexes along with spectroscopic analyzes are presented. The molecular structure investigations of the S-dapt ligands show that the thiamide planes are twisted with respect to the pyridine ring, which is more in the case of phenyl groups. The structures of the Co(II) complexes reveal that an increase in steric crowding on the amide side arms of the ligands has no substantial effect on the geometry adopted by the corresponding complexes. The Co(II) gives only 1?:?1 five-coordinate, ion-paired complexes with a distorted square pyramidal geometry. Ni(II), on the other hand, prefers an octahedral geometry with 1?:?2 metal–ligand ratio. The coordination behavior of S-dapt has been compared to the analogous oxo(O-daap) ligands. Lesser propensity of S atom to get involved in H-bonding interactions ensures an S-N-S type of tridentate coordination by S-dapt.     

Pyridinium tetrakis(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerate(III) pyridine solvate and bis(methanol-κO)tris(nitrato-κ2O,O′)(2,2′:6′,2′′-terpyridine-κ3N)cerium(III)

The title complexes, (C₅H₆N)[Ce(NO₃)₄(C₁₅H₁₁N₃)]·C₅H₅N or (Hpy)­[Ce(NO₃)₄(terpy)]·py, (I) (py is pyridine, C₅H₅N, and terpy is ter­pyridine, C₁₅H₁₁N₃), and [Ce(NO₃)₃­(C₁₅H₁₁N₃)(CH₄O)₂] or [Ce(NO₃)₃(terpy)(OHCH₃)₂], (II), are 11-coordinate. The coordination polyhedron of the Ce atom in (I) is irregular, while that in (II) can be described as an icosahedron with two vertices replaced by one.     

Synthesis and characterization of nitrogen-containing Lewis base adducts of bis(O,O′-dialkylmonoselenophosphato)cobalt(II) complexes

The adducts of bis(O,O′-dialkylmonoselenophosphato)cobalt(II) complexes, Co{O(Se)P(OR)₂}₂(L)₄ (where R?=?n-Pr, i-Pr; L?=?C₅H₅N, NC₅H₄Me-2, NC₅H₄Me-3), were synthesized by in situ reactions of CoCl₂?·?6H₂O, Lewis base, and NaO(Se)P(OR)₂. The single crystal structure of Co{O(Se)P(OⁱPr)₂}₂(C₅H₅N)₄ shows distorted octahedral geometry around cobalt(II) and monoselenophosphates are trans. The CoN₄ forms a square plane. These bis(O,O′-dialkylmonoselenophosphato)cobalt(II) adducts were characterized by elemental analyses, spectroscopic techniques (UV-Vis, infrared, ¹H and ³¹P), and magnetic moment measurements.     

Nitrogen-donor base adducts of bis(O,O′-di-isoamyldithiophosphato)nickel(II)

A series of Ni^II complexes with the O,O-di-isoamylester of dithiophosphoric acid and nitrogen-donor ligands of composition [Ni(i-Am₂dtp)₂(L)]; [dtp = O₂PS₂ ^–; L = 2,2-bipyridine (bpy); 1,10-phenanthroline (phen); 5-nitro-1,10-phenanthroline (nphen); 4,7-diphenyl-1,10-phenanthroline (baphen); 2,9-dimethyl-1,10-phenanthroline (neo), 2-aminomethylpyridine (amp), 2-(2-aminoethyl)pyridine (aep), 2,2-dipiridylamine (dpa), 1,2-diaminopropane (1,2-dap) or trans 1,2-diaminocyclohexane (dch)] have been prepared. The compounds have been characterized by elemental analyses (C,H,N,S), electronic and i.r. spectroscopy, magnetic and conductivity measurements and by cyclic voltammetry. The results show that all complexes behave as non-electrolytes in acetone. Electronic spectra and magnetic moments suggest a distorted cis-octahedral geometry around the Ni^II atom [_eff/_B <3.10, 3.40 >], except for [Ni(i-Am₂dtp)₂(aep)], where the measured temperature dependence of the magnetic susceptibility proved the tetrahedrally coordinated nickel [4.06 _eff/_B (298 K) – 3.20 _eff/_B (80 K)]. In the [Ni(i-Am₂dtp)₂(neo)] complex, the nickel atom is penta-coordinated. The X-ray crystal and molecular structure of [Ni(i-Am₂dtp)₂(1,2-dap)] has been determined.     

Synthesis and crystal structure of bis[(μ-κO:κO′-acetato)(μ-κO:κ2O′-acetato)][(η5-Cp)tris(dimethylphosphito-P)cobalt-O,O′,O″]yttrium(III)

The [η⁵-CpCo{P(O)(OMe)₂}₃Y(O₂CCH₃)₂]₂, yttrium(III) complex has been synthesized by the stoichiometric mixture of YCl₃, NaL_OMe and NaAc in a 1:1:2 molecular ratio in dry THF solvent and we have determined the structure by X-ray diffraction. The molecule is a dimeric compound, which consists of one tripodal ligand (L_OMe=CpCo[P(O)(OMe)₂]₃) and two bridging acetato (Ac) ligands on each yttrium atom. The acetate ligands of this complex have two different coordination modes, which are μ-κO:κO′-acetato and μ-κO:κ²O′-acetato bound to each yttrium atom.     

Manganese(II), nickel(II) and copper(II) complexes of (1,3-bis-aminomethyl) cyclohexane-N,N,N′,N′-tetrakisbenzimidazole

Summary Mn^II, Ni^II and Cu^II complexes of (1,3-bis-aminomethyl)-cyclohexane-N,N,N,N-tetrakisbenzimidazole (CDTB) have been prepared and characterized by spectral techniques. The complexes are monomeric and pseudo-octa-hedral, as evidenced by their e.p.r. spectra and analytical data. Parameters ², ², ² and for Cu^II complexes, and the crystal field splitting parameter (10 Dq) together with the Nephelauxetic ratio (), for Ni^II complexes, are reported.     

Synthesis,structure and methyl methacrylate polymerization of cobalt(II), zinc(II) and cadmium(II) complexes with N,N′,N-bidentate versus N,N′,N-tridentate N,N′,N-bis((1H-pyrazol-1-yl)methyl)amines

Mononuclear Co(II), Zn(II) and Cd(II) complexes derived from bidentate or tridentate N,N′,N-bis((1H-pyrazol-1-yl)methyl)amines (L_n = L_A, L_B), where L_A is N,N-bis((1H-pyrazol-1-yl)methyl)-3-methoxypropan-1-amine and L_B is 3-methoxy-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)propan-1-amine, have been synthesized and characterized. The geometry at Co(II) and Cd(II) for [L_ACoCl₂], [L_BCoCl₂] and [L_BCdBr₂] with N,N′,N-tridentate ligands (L_n = L_A, L_B) can be described as a distorted trigonal bipyramid achieved by coordinative interaction of N_pyrazole, two halides and the nitrogen of amine moiety. However, the molecular structure of four-coordinate [L_AZnCl₂] can be best described as tetrahedral, resulting in an eight-membered chelate ring. [L_ACoCl₂] polymerized methyl methacrylate in the presence of modified methylaluminoxane at 60 °C and resulted in poly(methylmethacrylate) (PMMA) with higher molecular weight and narrower polydispersity index compared to the other synthesized complexes. However, all the synthesized complexes yielded syndiospecific PMMA, characterized using ¹H NMR spectroscopy, with ca. 0.70.     

Five coordinate complexes of N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide with copper Crystal and molecular structures of dichloro(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II) and chloro(perchlorato)(N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamido)copper(II)

The title compound N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamide (DEAP) forms a 1:1 complex with anhydrous CuCl₂, [Cu(DEAP)Cl₂], (1) which was crystallized from EtOH solution in the monoclinic space group P2_{1/ n} with cell constant, a = 10.024(1); b = 13.122(1); c = 14.404(1) Å β = 101.31(1)° V = 1857.8(3) ų and Z = 4. The chloro-perchlorato complex, [Cu(DEAP)Cl(ClO₄)], (2) obtained in near quantitative yield by reacting (1) with an excess of NaClO₄ in EtOH, crystallized in the monoclinic space group P2_{1/ n} with cell constants, a = 7.965(1); b = 25.827(2); c = 10.046(1) Å β = 98.81(1)° V = 2042.2(4) ų and Z = 4. Both (1) and (2) contain 5-coordinated copper linked to DEAP through O～N～O donor set of atoms with covalently bonded chlorine atoms in (1) and chlorine and perchlorate groups in (2). The coordination geometry is intermediate between square pyramidal and trigonal bipyramidal, and is probably best described as a trigonally distorted rectangular pyramid.     

Synthesis,characterization and nucleolytic property of bis(N,N′-dimethylglycinato)copper(II)

Aquabis(N,N-dimethylglycinato)copper(II) dihydrate, [Cu(dmg)₂(H₂O)]·2H₂O, has been synthesized and characterized by elemental analysis, FT-IR, magnetic data, thermal analysis, solution UV-visible spectroscopy, X-ray crystal structure analysis and electrospray ionization mass spectroscopy. The square pyramidal copper(II) complex crystallizes in the orthorhombic space group P2₁2₁2₁. The complex cleaves circular plasmid DNA (pBR322) in the presence of H₂O₂. The extent of cleavage varies with the concentration range of the complex, the type of buffer used, pH of buffer and the concentration of H₂O₂. Hydroxyl radical scavenger can inhibit the nucleolytic ability of this complex.     

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.     

Syntheses and structures of cobalt(II), nickel(II), and copper(II) complexes with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides (O-daap) containing nitrate as the counter ion

Reactions of M(NO₃)₂?·?xH₂O [M?=?Co(II), Ni(II), and Cu(II)] with N,N,N′,N′-tetraalkylpyridine-2,6-dicarboxamides(O-daap) in CH₃CN yield [Co(O-dmap)(NO₃)₂] (1), [Co(O-deap)(NO₃)₂] (2), [Co(O-dpap)(NO₃)₂] (3), [Ni(O-dmap)(H₂O)₃](NO₃)₂] (4), [Ni(O-deap)(H₂O)₂(NO₃)](NO₃)] (5), [Cu(O-deap)(NO₃)₂] (6), and [Cu(O-dpap)(NO₃)₂] (7). X-ray crystal structures of 1, 2, 4, 5, and 7 reveal that O-daap ligands coordinate tridentate to each metal, O–N–O, with nitrate playing a vital role in molecular and crystal structures of all the complexes. The coordination geometry in the two Co(II) complexes, 1 and 2, is approximately pentagonal bipyramidal with nitrate bonded in a slightly unsymmetrical bidentate chelating mode. [Ni(dmap)(H₂O)₃](NO₃)₂ (4) and [Ni(deap)(H₂O)₂(NO₃)](NO₃) (5) exhibit octahedral geometry, the former containing uncoordinated nitrate while the latter has one nitrate coordinated unidentate and the other nitrate outside the coordination sphere. The Cu(II) in [Cu(dpap)(NO₃)₂] (7) occupies a distorted square pyramidal geometry and is linked to two unidentate nitrates, although one nitrate is also involved in a weak interaction with the metal through its other oxygen. IR spectra and other physical studies are consistent with their crystal structural data. O-dmap?=?N,N,N′,N′-tetramethylpyridine-2,6-dicarboxamides; O-deap?=?N,N,N′,N′-tetraethylpyridine-2,6-dicarboxamides; and O-dpap?=?N,N,N′,N′-tetraisopropylpyridine-2,6-dicarboxamides.     

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.     

Structural characterization of dicyanidobis-(N,N′-dimethylthiourea-κS)cadmium(II)

A cadmium(II) complex dicyanidobis(N,N′-dimethylthiourea-S) cadmium(II) [Cd(Dmtu)₂(CN)₂] (1) is prepared and its structure in the solid state is determined by single crystal X-ray structural analysis. The cadmium(II) ion is four-coordinate having a distorted tetrahedral geometry composed of two cyanide C atoms and two thione S atoms of N,N′-dimethylthiourea (dmtu). The molecular structure is stabilized by intermolecular N-H…N(CN) hydrogen bonding interactions that lead to a 3D network structure. The complex was also characterized by IR and NMR spectroscopy.     

A NOVEL BINUCLEAR COPPER(II) COMPLEX: BIS[1,10-PHENANTHROLINE-N,N′-MALEATO- O,O′-COPPER(II)] DIMETHANOL TETRAHYDRATE

Abstract

A novel binuclear Cu(II) complex, [Cu₂(mal)₂(phen)₂]. 4H₂O. 2MeOH (phen= 1,10-phenanthroline, mal = maleato dianion), has been synthesized and characterized by elemental analysis, IR spectroscopy, solid-state ESR analysis and X-ray single crystal study. The complex consists of [Cu(mal)(phen)] subunits with two water and one methanol solvate molecules. The subunits show a distorted planar arrangement, existing in centrosymmetrically related pairs in the crystal packing. They have a distorted four-coordinate square-planar arrangement of N and O atoms about the central Cu atom; pairs of these [Cu(mal)(phen)] subunits form dimers by interaction of the fifth position on each Cu center with an O atom of a maleato ligand of the associated subunit with a Cu-Cu distance of 3.3425(9) å. The coordination around each Cu atom is best described as distorted square-pyramidal. The lattice water and methanol molecules are also confirmed by the TG study and IR spectra. The X-band solid-state ESR spectrum at room temperature exhibits an anisotropic feature with g′ = 2.24, g′ = 2.06.     

THE POLYMERIC COPPER COMPLEX 2,2′-BIPYRIDINE-N,N′-(μ-MALEATO-O,O′:O″)COPPER(II) DIHYDRATE

Abstract

Preparation and isolation of the polynuclear copper(II) complex, {[Cu(bipy)(maleato)] · 2H₂O} _n , was accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Cu(NO₃)₂·4H₂O and bipy. The crystal structure of the title complex was determined by single-crystal X-ray methods. The structure consists of one-dimensional infinite chains. The copper atom is five-coordinate and presents a square-pyramidal coordination sphere, which consists of the two imine N atoms of bipy and two terminal carboxylate O atoms of a maleate^2- ligand in the basal plane with Cu-N bond distances of 2.016(3) and 1.987(3) A and Cu-O distances of 1.909(2) and 1.947(2) Å, respectively. In the apical site an O atom of the maleate^2- ligand from an adjacent complex coordinates to copper (2.264(2) Å). The coordination fashion of the maleato ligand is also confirmed by the IR spectrum.