Showing papers in "Journal of Coordination Chemistry in 1995"
TL;DR: Zinc has a relatively low abundance in nature (10−6 of the earth's crust) but the chemistry of zinc compounds has been extensively investigated, and the relation-ships between structure and biomedical activity are of major importance as mentioned in this paper.
Abstract: Zinc has a relatively low abundance in nature (10−6 of the earth's crust) but the chemistry of zinc compounds has been extensively investigated, and the relation-ships between structure and biomedical activity are of major importance. Zinc appears to bc one of the more biologically important metals,1 second only to iron among the heavy metals (i.e. excluding sodium, potassium, magnesium and calcium).
47 citations
TL;DR: The crystal structures of diaquobis (2-pyrazinecarboxylato) manganese(II), cobalt(II, nickel( II), copper (II) and zinc(II) have been determined using single crystal X-ray intensity data as discussed by the authors.
Abstract: The crystal structures of diaquobis (2-pyrazinecarboxylato) manganese(II) and isostructural diaquobis(2-pyrazinecarboxylato) cobalt(II), nickel(II), copper(II) and zinc(II) have been determined using single crystal X-ray intensity data. The former complex is orthorhombic (space group Fdd2), with unit cell dimensions a = 15.418(1), b 23.537(3)A, c = 6.940(4)A, the latter compounds are monoclinic (space group P21/c) with unit cell dimensions a = 5.241(1)A, b = 11.108(1)A, c = 10.286(2)A, β = 99.54(1)deg for the cobalt complex. All structures show monomeric molecules consisting of a metal ion chelated by two oxygen atoms belonging to two monodentate carboxylic groups and two heteronitrogen atoms of two pyrazinic acid molecules and two water molecules. In the case of manganese dipyrazinate dihydrate the coordination polyhedron around the manganese ion is a distorted octahedron with the water molecules cis, while in the remaining compounds the octahedra are fairly regular with two water molecules abov...
39 citations
TL;DR: The ligand 4-Cl-2,6-bis(benzimidazol-2′-yl)-pyridine(Cl-bzimpy;H2L) acts as a bidentate when coordinated with transition metal ions and was isolated as a solid as discussed by the authors.
Abstract: The ligand 4-Cl-2,6-bis(benzimidazol-2′-yl)-pyridine(Cl-bzimpy;H2L) acts as a bidentate when coordinated with transition metal ions and the complex [Fe(Cl-bzimpy)2](ClO4)2 was isolated as a solid. The protonation constants (logK). The free ligand and the complex were evaluated in 30:70 (v/v) H2O:EtOH at room temperature and ionic strength of 0.13M (KCl). Coordination of the ligand to the metal ion leads to an increase of the acidity of the imino-hydrogen of the benzimidazole group. Deprotonation leads to a change in the spin-state (to the low-spin state; HS → LS transition) of the complex associated with a decrease in the spin-crossover equilibrium constant (Ksc). An opposite shift of spin-state is observed when HClO4 is added to the complex solution, thus showing the reversibility of the process.
38 citations
TL;DR: In this article, the 1:1 and 2:1 (murexide to metal ion) complexes were determined from the absorbance-mole ratio data and found to vary in the order Cu 2+ > Cd2+ > Ni 2+ Ni 2 + Co 2+ Co2+> Zn2+
Abstract: Complexation reactions between murexide and Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ ions have been studied in different acetonitrile-dimethylsulfoxide mixtures at various temperatures by a spectrophotometric technique. Formation constants of 1:1 and 2:1 (murexide to metal ion) complexes were determined from the absorbance-mole ratio data and found to vary in the order Cu2+ > Cd2+ > Ni2+ Co2+ > Zn2+ > Pb2+. A linear relationship is observed between log β2 for different complexes and the mole fraction of acetonitrile in the solvent mixture. Enthalpy and entropy data for complexation were determined from the temperature dependence of stability constants. From the thermodynamic data obtained, the TΔS∗ - ΔH∗ plot shows a fairly good linear correlation and indicates enthalpy-entropy compensation in the reactions.
36 citations
TL;DR: In this article, a review summarizes the data for almost six hundred silver coordination and organometallic compounds, with the silver atom occurring in oxidation states of +1, +2, and two examples of +3 in a square-planar environment.
Abstract: This review summarizes the data for almost six hundred silver coordination and organometallic compounds, with the silver atom occurring in oxidation states of +1, +2, and two examples of +3 in a square-planar environment. The +2 oxidation state is found in digonal, square-planar, tetrahedral and hexa-coordinated environments. The +1 oxidation state is by far the most common in various geometries from two to seven. The nuclearity range from mono- to polynuclear utilizing a variety of ligand types. There are several examples of distortion isomerism, and a few examples of polymerization isomerism. Correlations between bond lengths, bond angles, ligating atom radius and silver oxidation state are discussed.
26 citations
TL;DR: A neutral complex of Cu(II) with the chiral bidentate nitrogen-chelating alkaloid (−)-sparteine, with nitrate groups occupying the remaining coordination sites, has been prepared and characterized as mentioned in this paper.
Abstract: A neutral complex of Cu(II) with the chiral bidentate nitrogen-chelating alkaloid (−)-sparteine, with nitrate groups occupying the remaining coordination sites, has been prepared and characterized. Solution conductivity measurements indicate that both nitrate groups are coordinated to copper to give a neutral molecule. Optical and electron-spin-resonance spectra in toluene/CHCl3, did not show a clear picture of the coordination geometry. A frozen-glass ESR spectrum showed the same evidence for mixed species, with the predominant species characterized by a very low A11 value of 118 G. Crystals 1 and 2 of Cu(C15H26N2)(NO3)2 were grown by two methods: 1 at 25°C from saturated acetonitrile, and 2 at 5°C from ethanol/dichloromethane under CCl4 vapor. Their structures were determined by X-ray crystallography. Crystals 1 were monoclinic, space group P21, with a = 7.851(6), b = 14.408(10), c = 16.079(10) A, β = 97.93(6)°, V = 1801(2) A and Z = 4. Crystals 2 were orthorhombic, space group P212121, with a ...
23 citations
TL;DR: The crystal structures of two mixed-ligand copper(II) complexes having iminodiacetate(2-) (IDA) or N-carboxymethyl-D,L-threoninato (2-) ion (CMT) as terdentate ligands and imidazole (ImH) as an N-heterocyclic ligand are reported in this paper.
Abstract: The crystal structures of two mixed-ligand copper(II) complexes having iminodiacetate(2-) (IDA) or N-carboxymethyl-D,L-threoninato(2-) ion (CMT) as terdentate ligands and imidazole (ImH) as an N-heterocyclic ligand are reported. Both compounds crystallize in the orthorhombic system, space group Pbca with Z = 8. Aqua(imidazole)(iminodiacetato)copper(II) monohydrate (I,R = 0.065, R w = 0.075) consists of H2O molecules and [Cu(IDA)(ImH)(H2O)] complex units in a hydrogen bonding network. The structure of imidazole(N-carboxymethyl)-D,L-threoninatocopper(II) (IV, R = 0.066, Rω 0.078) is built up of hydrogen bonded polynuclear chains. In both compounds the Cu(II) ion exhibits a flattened and distorted square-based pyramidal coordination, with a terdentate aminoacidate ion, IDA or CMT, and one ImH ligand at the base and H2O (in I) or the oxygen atom of the OH side chain from one adjacent CMT ion (in IV) as the fifth apical ligand. The nearly coplanar conformation of the two five-membered chelate rings in...
22 citations
TL;DR: The CoL3 as mentioned in this paper complex has three-fold symmetry and the three ligands each coordinate via the ketonic oxygen (Co-O 1.931) and oximic nitrogen atoms (CoN 1.892(4) A) such that the overall configuration about the cobalt atom is fac.
Abstract: The preparation and characterisation of the title complex, CoL3, is reported. The crystal structure determination shows that the complex has three-fold symmetry and that the three ligands each coordinate via the ketonic oxygen (Co-O 1.931(4) A) and oximic nitrogen atoms (Co-N 1.892(4) A) such that the overall configuration about the cobalt atom is fac. Crystals of CoL3 are trigonal, space group R3c, a = 18.645(5), c = 14.08(1) A, V = 4237(2) A3 and Z = 6. The structure was refined by a full-matrix least-squares procedure to Rw = 0.031 for 741 observed reflections.
21 citations
TL;DR: In this article, the photochemistry of Mo(CO)6 in heptane has been investigated using actinometry and photoacoustic calorimetry, and two heat decays were observed following flash photolysis in the presence of piperidine.
Abstract: The photochemistry of Mo(CO)6 in heptane has been investigated using actinometry and photoacoustic calorimetry. The quantum yield for CO substitution on Mo(CO)6 by piperidine in heptane was found to be 0.93 for 337 nm irradiation at 25°C This was clearly different than the quantum yield found for CO substitution on Cr(CO)6 by piperidine (0.75). Two heat decays were observed following flash photolysis of Mo(CO)6 in the presence of piperidine. The first heat decay is independent of piperidine concentration (8–80 mM), while the lifetime (τ 2 ) of the second heat decay decreases with increasing piperidine concentration. A plot of 1/τ2 shows a first-order dependence on piperidine concentration. The first heat decay has been assigned to the displacement of CO on Mo(CO)6 by heptane and the second, to the displacement of heptane on Mo(CO)5(heptane) by piperidine. The second-order rate constant for heptane displacement is 4.8 × 107 M−1S−1. The enthalpies of CO displacement by heptane (ΔH 1) and heptane di...
21 citations
TL;DR: In this article, the synthesis of diamagnetic complexes [Ni(H2L)] and the crystal structure of the NCS complex is described, which consists of well separated diamagnetic cations and NCS− anions and is refined using 2491 independent reflections to R = 0.051.
Abstract: The syntheses of dark-green diamagnetic complexes [Ni(H2L)]X (H2L = the monoanion of pentane-2,4-dionebis(thiosemicarbazone) and X is either NO3 or NCS) and the crystal structure of the NCS complex is described. Crystals of the NCS complex are monoclinic, space group C2/c, with a = 11.867(1), b = 10.715(1), c = 22.319(1)A, β = 90.11(1)°, V = 2838.0(4) A3, Z = 8. The crystal structure was refined using 2491 independent reflections to R = 0.051. The structure consists of well separated [Ni(H2L)]+ cations and NCS− anions. NiII has a slightly distorted square-planar geometry formed with two nitrogen (Ni-N = 1.863(4) and 1.856(4) A) and two sulphur atoms (Ni-S = 2.153(2) and 2.163(1) A) of the monodeprotonated tetradentate ligand.
19 citations
TL;DR: In this article, a triclinic, space group P1, with a = 5.007(1), b = 6.576(3) and c = 10.721(3), α = 75.63 (3), β = 86.79 (2) and γ = 78.65(2)
Abstract: From the system Ni(II)-ONC(CN)2 −-L, where L = pyrazole (pz), 3(5)-methylpyrazole, 3,5-dimethyl-pyrazole, 3,4,5-trimethylpyrazole (tmpz) and indazole in aqueous and aqueous-methanolic media, compounds of two types were isolated. Nitrosodicyanomethanide compounds of the type [Ni{ONC(CN)2}2L4], according to spectroscopic results, have octahedral structures with nitroso nitrogen bonded ONC(CN)2 − anions. Compounds of the second type, [Ni{ONC(CN)2 · CH3OH}2L2], where L = pz, H2O, tmpz, contain anionic chelate ligands NO(CN)CC(OCH3)NH− which arise by nucleophilic addition of methanol oxygen to the cyano carbon of ONC(CN2 − in the Ni(II) coordination sphere. This was established by X-ray crystallography of compounds with L = pz and H2O. The compound [Ni{ONC(CN)2 · CH3OH}2(H2O)2] is triclinic, space group P1, with a = 5.007(1), b = 6.576(3) and c = 10.721(3) A, α = 75.63(3), β = 86.79(2) and γ = 78.65(2)˚, and Z = 1. Full-matrix least-squares refinement gave R = 0.0372 and Rw = 0.0973 for 1304 reflectio...
TL;DR: In this article, a linear free energy relationship exists between the dissociation constant of the ligand, pKx, and the formation constant, log βx of the unidentate complex involving boric acid and the ligands.
Abstract: Unidentate complexes of borate in aqueous solution may be anionic, cationic or neutral species. Stability constants published for each type of complex are reviewed. In addition, stability constants, log KM,B, for monoboratolithium and monoboratopotassium complexes, 25°C, are calculated to be 0.64 and −0.18, respectively. Estimated values of stability constants log KM,B) for the monoborato-complexes for lead(II) (2.5), zinc(II) (2.3), cadmium(II) (1.6), aluminium(III) (4.5), cobalt(II) (1.2), nickel(II) (1.6), copper(II) (4.1) and iron(III) (5.5) are calculated from solubility data. It is shown that a linear free energy relationship exists between the dissociation constant of the ligand, pKx, and the formation constant, log βx of the unidentate complex involving boric acid and the ligand, i.e., log βx = (0.55 ± 0.04) pKx−(2.71 ± 0.47) at 25°C. This relationship is independent of the charge on the ligand and is applicable to all unidentate borate complexes, including monoborato-complexes of metal ions.
TL;DR: In this article, the reaction of Cu(ClO4)2·6H2O with 1,3,5-triazine in 95% ethanol resulted in partial hydrolysis of the triazine ring and isolation of bis(1, 3, 5-triaza-1, 4-pentadieno) copper(II) perchlorate, (1).
Abstract: Reaction of Cu(ClO4)2·6H2O with 1,3,5-triazine in 95% ethanol resulted in partial hydrolysis of the triazine ring and isolation of bis(1,3,5-triaza-1,4-pentadieno) copper(II) perchlorate, (1). Compound 1 crystallizes as violet needles. Crystal data for Cu(HN = CHNHCH = NH)2(ClO4)2 are: monoclinic, space group: C2/c, a = 13.342(3), b = 11.186(2), c = 18.045(4) A, β = 99.09(3)°, V = 2659.3(10) A3, Z = 8, Dcalc = 2.021 Mg/m3, μ = 2.096 mm−1, F(000) = 1624, MoKα (γ = 0.71069A), R = 0.063 for 1597 unique observed [≥Fα3σ(F)] reflections and 196 parameters. The bis-chelated copper(II) ion contains a planar coordination geometry with Cu-N(ave) = 1.97A and the perchlorate ions weakly coordinated (Cu - 0 = 2.84A) in the axial positions.
TL;DR: In this article, Li+ and Na+ with dibenzo-24-crown-8 were investigated in dimethylformamide-acetonitrile mixtures by means of a competitive spectrophotometric technique using murexide as metal ion indicator.
Abstract: Complexation of Li+ and Na+ with dibenzo-24-crown-8 has been studied in dimethylformamide-acetonitrile mixtures by means of a competitive spectrophotometric technique using murexide as metal ion indicator. Stabilities of the resulting 1:1 complexes were investigated at various temperatures and enthalpies and entropies of complexation were determined from the temperature dependence of the formation constants. Sodium forms a more stable complex with the crown ether than lithium. There is an inverse linear relationship between log Kf and the mole fraction of DMF in the solvent mixtures. The ΔH°-TΔS° plot of all thermodynamic data, obtained for both crown complexes in different solvent mixtures, shows a fairly good linear correlation, indicating the existence of an enthalpy-entropy compensation effect in complexation.
TL;DR: The ligand scrambling reaction of R3PAuC15N to form (R3P)2Au+ and Au(C 15N)2 − has been studied by 15N and 31P NMR spectroscopy for R = Me, Et, i-Pr, and Ph.
Abstract: The ligand scrambling reaction of R3PAuC15N to form (R3P)2Au+ and Au(C15N)2 − has been studied (by 15N and 31P NMR spectroscopy) for R = Me, Et, i-Pr, and Ph 31P NMR showed two resonances due to R3PAuCN and (R3P)2Au+ species, while 15N NMR showed only an averaged resonance due to R3PAuC15N and Au(C15N)2 − species, except for Et3PAuC15N, for which two separate resonances were detected R3PAu13C15N (where R = Me, Et and Ph) complexes were also prepared and 2J(31P-13C) as well as 3J(31P-15N) constants were measured The free activation energy for ligand scrambling in Ph3PAuCN was determined by 31P NMR band shape analysis to be 397 kJ/mol−1
TL;DR: In this paper, a mixture of excess Cu(I)I and 2-benzoylpyridine (2-Bzpy) stands in an ethanolic medium for two weeks, an intramolecular oxidative cyclization of 2-bzpy occurs with formation of the ionic complex [(9-oxo-indolo[1,2-a]pyridinium]- · CuI2 −(1).
Abstract: When a mixture of excess Cu(I)I and 2-benzoylpyridine (2-Bzpy) stands in an ethanolic medium for two weeks, an intramolecular oxidative cyclization of 2-Bzpy occurs with formation of the ionic complex [(9-oxo-indolo[1,2-a]pyridinium]+ · CuI2 −(1). In contrast the interaction of Cu(I)Br and 2-Bzpy in ethanol leads to formation of the dimer [CuBr(2-Bzpy)]2 (2). The structures of both compounds were established by spectroscopic methods and X-ray diffraction analysis: (1) Space group P21/a,a = 6.613(2), b = 16.792(5), c = 12.062(5) A, B = 94.35(3)° and Z = 4, (2) Space group P21/n, a = 6.896(2), b = 7.551(2), c = 22.454(4) A, B = 93.34(2)° and Z = 4. The structure of (1) consists of a packing of [9-oxo-indolo[1,2-a]pyridinium]+ cations and CuI2 − species with the four Cu[sbnd]I distances varying from 2.669(2) to 2.705(2) A. The centrosymmetric [CuBr(2-Bzpy)]2 (2) molecule has a short Cu[sbnd]Cu distance of 2.696(2) A.
TL;DR: In this paper, the reaction of anhydrous copper nitrate with 3,5-dimethyl pyrazole in methanol gave a deep green colored solution, which upon addition of excess sodium perchlorate afforded dark green crystals of bis[3,5dimethylpyrazole(1-methoxy,3, 5-dimethylamine) Cu(II) perchlorates] (1) upon slow evaporation of the solvent.
Abstract: The reaction of anhydrous copper nitrate with 1-hydroxy-methyl-3,5-dimethyl pyrazole in the presence of 3,5-dimethyl pyrazole in methanol gave a deep green colored solution, which upon addition of excess sodium perchlorate afforded dark green crystals of bis[3,5-dimethylpyrazole(1-methoxy,3,5-dimethyl pyrazole) Cu(II) perchlorate] (1) upon slow evaporation of the solvent. The structural assignment of (1) was made in part by elemental analysis and electronic spectroscopy and was confirmed by single crystal X-ray diffraction studies. The crystal structure reveals that compound (1) crystallizes in the monoclinic space group P21 In with four molecules in the unit cell of dimensions a = 8.927(3), b = 19.019(9), and c = 9.794(3)A, and β = 112.65(3)∗. The structure has been refined to an R(F) factor of 0.029 based on 2110 observed reflections. The geometry around each Cu(II) center is best described as a square pyramid, with the basal plane occupied by two ligating nitrogen atoms with an average Cu-N di...
TL;DR: In this article, the formation constants for binary systems involving L-α-alanine hydroxamic acid or ethylenediamine were determined under identical experimental conditions and pH-titration data were analyzed using the SUPERQUAD computer program.
Abstract: Mixed-ligand complex formation of M(II) (M = Ni, Cu, Zn and Cd) with l-α-alaninehydroxamic acid (α-Alaha) as primary ligand (A) and ethylenediamine (en) as secondary ligand (B) have been determined potentiometrically [298K, μ = 0.2 (KCl)]. Formation constants for binary systems involving L-α-alaninehydroxamic acid or ethylenediamine were determined under identical experimental conditions and pH-titration data were analysed using the SUPERQUAD computer program. The relative stability of each ternary complex was compared with that of the corresponding binary complexes in terms of Δlog K and log X values.
TL;DR: In this article, the crystal and molecular structure of the bromo complex is reported and discussed with respect to analogous copper(I) complexes, and reactivity of the title compound as well as of its iodo counterpart towards Lewis bases was also investigated; the two compounds react readily, in stoicheiometric amounts, with tertiary phosphine and arsine ligands forming monomeric four-coordinate Cu (I) species, the structures of which were deduced by spectroscopic measurements.
Abstract: Reaction of monovalent copper halides with excess tetrahydropyrimidine-2-thione (thpmtH(2)) in acetonitrile results in the formation of three-coordinate monomer products of formula Cu(thpmtH(2))(2)X. The crystal and molecular structure of the bromo complex is reported and discussed with respect to analogous copper(I) complexes. The compound crystallizes in the tetragonal system, space group, P4(1)2(1)2 with a = 8.005(1), c = 21.3 1(1) Angstrom, and Z = 4. The two Cu-S bonds are 2.215(4) A and the Cu-Br bond distance is 2.405(2) Angstrom, the interbond angles around copper being exactly 360 degrees. Reactivity of the title compound as well as of its iodo counterpart towards Lewis bases was also investigated; the two compounds react readily, in stoicheiometric amounts, with tertiary phosphine and arsine ligands forming monomeric four-coordinate Cu(I) species, the structures of which were deduced by spectroscopic measurements.
TL;DR: In this article, the interaction of oxovanadium(IV) ion with diphosphoric and triphosphoric acids in aqueous solution was investigated over the measurable pH range by means of potentiometry, electronic absorption and EPR measurements.
Abstract: The interaction of oxovanadium(IV) ion with diphosphoric and triphosphoric acids in aqueous solution was investigated over the measurable pH range by means of potentiometry, electronic absorption and EPR measurements. The results show that both diphosphate and triphosphate, partially or fully deprotonated depending on pH, are able to chelate the metal ion to yield several mononuclear species. With triphosphate, there is no evidence for the formation of a species analogous to the already reported and well-characterized trinuclear complex formed by diphosphate acting as a chelating and bridging ligand through the four unshared oxygen atoms.
TL;DR: In this article, the synthesis and characterization of tris(alkylisocyanide)bis(triarylphosphine)cobalt(I) complexes, [Co(CNR)3(PR3)2]ClO4, has been extended to include CNR = CNCMe3, PR3 = P(C6H4CF3-p)3,P(C 6H4F-p),P(c6H 4Me-p)-3,PR3 =PPh3,CNC6H11, CN
Abstract: Synthesis and characterization of tris(alkylisocyanide)bis(triarylphosphine)cobalt(I) complexes, [Co(CNR)3(PR3)2]ClO4, has been extended to include CNR = CNCMe3, PR3 = P(C6H4CF3-p)3, P(C6H4F-p)3, P(C6H4Me-p)3; PR3 = PPh3, CNR = CNC6H11, CNCH2Ph, CNC4H9-n. Reduction of [Co(CNCMe3)4H2O](ClO4)2 did not occur with PR3 = P(C6H4NMe2-p)3 and P(C6F5)3. Solution and solid state structures of the new [Co(CNR)3(PR3)2]ClO4 complexes appear to be distorted disubstituted trigonal bipyramidal examples with the phosphine ligands in axial positions, but the extent of distortion from rigorous D 3h symmetry in solution appears to vary for different complexes. Oxidation potentials, E1/2, measured in CH3CN, for the oxidation of Co(I) to Co(II), are essentially independent of the RNC ligands, remaining within the narrow range of +0.20 to +0.25V for [Co(CNR)3(PPh3)2]ClO4, R = CMe3, CHMe2, C6H11, CH2Ph, C4H9-n. Variation of the tertiary phosphine ligands has a pronounced effect on the E1/2 values, which range from +0.03...
TL;DR: In this paper, a series of compounds with composition RE(pic)32rac-besm were synthesized and characterized by CHNS elemental analysis and rare earths complexometric titration with EDTA, conductance measurements, X-ray powder patterns, infrared spectra, visible absorption of the neodymium and emission spectra of the europium materials.
Abstract: The compound β-dissulfoxide bis(ethylsufinyl)methane (besm) was prepared by oxidation of bis(ethylthio)methane with hydrogen peroxide in acetic acid, and obtained as a mixture of its meso and d,1 diastereomers. An analytical sample was obtained by recrystallization from chloroform-diethyl ether. The racemic-bis(ethylsulfinyl)methane was characterized and studied by CHS elemental analysis, high resolution mass spectrometry, infrared spectra, 1H and 13C NMR. A series of compounds with composition RE(pic)32rac-besm [RE = La, Ce, Nd, Eu, Gd, Er, Tm, Yb, Lu and Y; pic = picrate and rac-besm = racemic-bis(ethylsulfinyl)methane] were synthesized and characterized by CHNS elemental analysis and rare earths complexometric titration with EDTA, conductance measurements, X-ray powder patterns, infrared spectra, visible absorption of the neodymium and emission spectra of the europium materials. The coordination polyhedron around the Eu3+ center is probably a dodecahedron with coordination number eight.
TL;DR: In this paper, the synthesis and characterization of a new meso-(5-(4-pyridil) 10,15,20 triphenyl porphyrinate) chloro manganese (III)-porphyrin (ClMnP(Ph{sub 3}py) modified with one [(H{sub 2}O)Ru(bpy){sup 2}]{sup 2+} group coordinated with the pyridine on the meso-position of the porphrin ring.
Abstract: In this communication, the authors present results on the synthesis and characterization of a new meso-(5-(4-pyridil) 10,15,20 triphenyl porphyrinate) chloro manganese (III) porphyrin (ClMnP(Ph){sub 3}py) modified with one [(H{sub 2}O)Ru(bpy){sup 2}]{sup 2+} group coordinated with the pyridine on the meso-position of the porphyrin ring. The resulting bimetallic complex was characterized by resonance Raman, IR, far-IR and electronic spectroscopy. Cyclic voltammograms of this monoruthenated porphyrin compound in acetonitrile exhibit three reversible waves at 1.53, 0.96 and 0.03V vs NHE. Spectroelectrochemical experiments were performed in acetonitrile and dimethyl sulfoxide and the results are in agreement with the cyclic voltammetric results. The anodic peak current of the cyclic voltammogram waves of the manganese porphyrin moiety in the monoruthenated compound was suppressed in the presence of atmospheric oxygen. These results provide evidence for an associative process of O{sub 2} with the Mn(III) center of the porphyrin.
TL;DR: A review of recent achievements in the application of the theory of vibronic coupling to stereochemical problems of transition metal compounds is given in this article, where it is shown that in the crystal state long-range forces alone cannot produce distortions of high-symmetry lattice configurations.
Abstract: A review of recent achievements in the application of the theory of vibronic coupling to stereochemical problems of transition metal compounds is given. After the formulation of the concept of vibronic interactions relevant to stereochemistry, its general validity is discussed, and it is shown that in the crystal state long-range forces alone cannot produce distortions of high-symmetry lattice configurations. The latter may become unstable due to the vibronic coupling which is of local origin. For ferroelectric distortions in perovskite-type crystals this result is confirmed by quite a number of different experimental data; it casts heavy doubts on the very existence of displacive phase transitions. Among other stereochemical problems solved by means of the vibronic approach, the following are briefly considered: local distortions produced by d electrons using the CuCl5 3- vs ZnCl5 3- polyhedra in similar crystals; crystal implications in the effects of plasticity, distortion isomers, and tempera...
TL;DR: In this article, the bromide analog of 2, [YBr2(N-MeIm)5]+[Br]−, 3, has been obtained from YBr3(THF)3 and N-Meim.
Abstract: YCl3 crystallizes in the presence of N-methylimidazole (N-MeIm) to form [YCl2(N-MeIm)5]+ [YCl4(N-MeIm)2]−, 1 or [YCl2(N-MeIm)5]+[C1]-, 2, depending upon crystallization conditions. The bromide analog of 2, [YBr2(N-MeIm)5]+[Br]−, 3, has been obtained from YBr3(THF)3 and N-MeIm. Both 1 and 2 contain seven coordinate pentagonal bipyramidal [YCl2(N-MeIm)5]+ cations which have chloride atoms in the axial ligand positions. The anion in 1 has a trans octahedral geometry. Ceric ammonium nitrate crystallizes from N-MeIm to form Ce(NO3)3(N-MeIm)4, 4, which contains a formally ten-coordinate cerium center. 4 is best described as a seven coordinate distorted pentagonal bipyramid with the NO3 ligands occupying one axial and two equatorial sites. 1 crystallized from N-MeIm in the space group P1 with a = 8.1435 (10) A, b = 9.0448(8) A, c = 15.103(2) A, α = 93.872 (10)°, β = 94.117(11)°, γ = 107.288(9)°, V = 1054.8(2) A3 and Dcalcd = 1.520 Mg/m−3 for Z = 1. Least squares refinement of the model based on 3375 ref...
TL;DR: In this article, the crystal and molecular structures of the macrocyclic complexes [Tl(18crown-6){L], where {L} = {ONC(CN)C(S)N(CH)3)2}− (P21/n, monoclinic, a = 14.471(3), b = 8.447(2), c = 18.920(4) A, β = 92.84(3).
Abstract: Crystal and molecular structures of the macrocyclic complexes [Tl(18-crown-6){L}, where {L} = {ONC(CN)C(S)N(CH)3)2}− (P21/n, monoclinic, a = 14.471(3), b = 8.447(2), c = 18.920(4) A, β = 92.69°, Z = 4; R = 0.027) and {ONC(CN)-(4-methylthiazolyl-2)}− (P1, triclinic, a = 8.836(4), b = 11.908(5), c = 14.131(4) A, α = 62.84(3), β = 74.03(3), γ = 66.72°, Z = 2; R = 0.047) have been determined from X-ray diffraction data. The structures are made up of isolated T1(18-crown-6){L} molecules with irregular eight-coordination about T1. In both structures the thallium atom forms close contacts (2.73–3.14 A) with both the nitrogen and oxygen atoms of the nitroso group.
TL;DR: In this article, the synthesis and characterization of a copper-II phthalocyanate substituted with four 20-membered tetraaza-dioxa macrocycles from 21,22-dibromo-2,8,11,17-tetra(toluene-p-sulphonyl)-1,2,3,4,5,6,7, 8,9,10, 11,12,13,14,15,16,17,18-octadecahydrobenzox[l]
Abstract: The synthesis and characterization of a copper(II) phthalocyanate substituted with four 20-membered tetraaza-dioxa macrocycles from 21,22-dibromo-2,8,11,17-tetra(toluene-p-sulphonyl)-1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18-octadecahydrobenzox[l] [2,8,11,17]tetraaza[4,13]dioxacyclodi-contine is described. The detosylation of the macrocyclic aza groups provides four tetraaza-dioxa mixed donor sites for binding metal ions. The structures of the compounds were determined by elemental analysis, 1H, 13C NMR, IR and MS spectral data.
TL;DR: In this paper, the lithium arsenides (LiAs)4 ladder-like framework with four antiparallel adjacent As-Li rungs were determined and their solid-state structures determined by X-ray methods.
Abstract: The lithium arsenides {Li2[μ2-As(SiMe3)2] [μ3-As(SiMe3)2](THF)}2 (I) (THF = tetrahydrofuran) and [(Me3Si)2AsLi(THF)2]2 (II) were isolated and their solid-state structures determined by X-ray methods. Compound I crystallizes in the monoclinic system, space group P21/c, with a = 10.147(1)A, b = 19.665(2)A, c = 16.768(2)A, β = 107.78(1)° and Z = 2. The core structure consists of an [LiAs]4 ladder-like framework with four antiparallel adjacent As-Li rungs. The two lithium atoms of the central ring each bridge three arsenic centers while the two lithium atoms belonging solely to the outer rings each span two arsenic atoms and are coordinated to one THF molecule. Monoclinic crystals of compound II belong to space group C2/c, with a = 17.877(4) A, b = 14.077(3) A, c = 19.006(4) A, β = 109.16(2)° and Z = 4. The structure consists of a centrosymmetric dimer containing a four-membered As-Li-As-Li ring wherein each lithium atom is coordinated to two molecules of THF.
TL;DR: The N-C4H9)4NVO3 with the Schiff base N-benzoylacetone-mchlorobenzoylhydrazone (H2L) in absolute ethanol solution affords the title complex, which has been characterized by elemental analysis, EPR, IR, 1H NMR, electronic absorption spectra and TGA studies as discussed by the authors.
Abstract: The reaction of (n-C4H9)4NVO3 with the Schiff base N-benzoylacetone-m-chlorobenzoylhydrazone (H2L) in absolute ethanol solution affords the title complex, which has been characterized by elemental analysis, EPR, IR, 1H NMR, electronic absorption spectra and TGA studies. EPR and electronic absorption spectra confirm that the oxidation state of vanadium is + 5. Black crystals of the complex are triclinic, space group P 1 with a = 7.392(3), b = 11.229(4), c = 11.719(4)A, α = 83.20(3), β = 76.54(3), γ = 87.84(4)°, V = 939.2(8)A3, F(000) = 438 and Dc = 1.505 g cm−3 for Z = 2. The X-ray structure analysis reveals that the vanadium(V) coordination number is five and the coordination polyhedron is a square pyramid.
TL;DR: In this paper, the reaction of cobalt dichloride hexahydrate with two equivalents of 3,5dimethyl pyrazole under reflux in THF gave a deep blue solution of Co(3,5-dimethylpyrazole) dichlorides.
Abstract: The reaction of cobalt dichloride hexahydrate with two equivalents of 3,5-dimethyl pyrazole under reflux in THF gave a deep blue solution of Co(3,5-dimethylpyrazole) dichloride. Suitable crystals for X-ray structural determination were grown in THF. The structural assignment of (1) was made by elemental analysis and electronic spectroscopy and confirmed by single crystal X-ray diffraction studies. The crystal structure reveals that compound (1) crystallizes in the monoclinic space group C2/c with eight molecules in the unit cell of dimensions a = 15.012(2), b = 8.275(1), and c = 24.047(2)A, and β = 96.05 (1)°. The structure has been refined to an R(F) factor of 0.045 based on 1670 observed reflections. The geometry around the Co(II) center is best described as tetrahedral. The four ligating atoms consist of two chlorine atoms and two nitrogen atoms from the 3,5-dimethyl pyrazole. The solution electronic spectra of (1) in acetone and THF are consistent with the solid state crystal structure. Howev...