Homo- and heterodinuclear 2,2′-bipyrimidine-bridged complexes

[M(hfacac)₂(bpym)] complexes, where M = Co^II, Ni^II or Zn^II, hfacac = hexafluoroacetylacetonate and bpym = 2,2bipyrimidine; and [Cl₂M(bpym)M(hfacac)₂] complexes, where M = Co^II, Ni^II Mn^II or ZnII M = Ni^II; M = NiII or Zn^II and M = Zn^II; M = Ni^II and M = Co^II have been prepared and characterized by chemical analysis, conductance measurements, IR and electronic spectroscopies and magnetic susceptibility measurements (4.2–292K range). The dinuclear NiII–Ni^II, Co^II–Ni^II and Mn^II–Ni^II complexes are antiferromagnetic, with an intramolecular exchange parameter, J, of –2.3–8.9cm–1. Co^II and Mn^II are in a high spin state. The low temperature effect observed in monomers and in Ni^II–Zn^II dimers is considered a consequence of either an intermolecular antiferromagnetic interaction or the zero-field splitting in NiII.     

Complexation of cobalt(II) with histidinato(pentaammine)cobalt(III) in aqueous medium. A kinetic and mechanistic study

Summary The kinetics of formation and dissociation of the binuclear complex of Co^II with histidinato(pentaammine)Co^III have been studied at 10.0°Ct°C25°C and I = 0.3 mol dm^–3 (ClO _inf4 ^sup– ). The formation of the binuclear complex, [(NH₃)₅Co^IIILCo^II]⁴⁺ (L = histidinate), in the 5.7–6.8 pH range involves the reaction of Co(OH₂) _inf6 ^sup2+ with the deprotonated, (NH₃)₅CoL²⁺, and monoprotonated, (NH₃)₅CoLH₃₊, forms of the complex. The rate and activation parameters for the formation are consistent with an I _d mechanism. The binuclear species undergoes dissociation to yield the parent Co^III substrate and Co(OH₂) _inf6 ^sup2+ via spontaneous and acid-catalysed paths. Comparison of spontaneous dissociation rate of the binuclear complex with other related systems indicated the chelate nature of the binuclear species.     

Spektrophotometrische Bestimmung von Nickel und Kobalt nebeneinander mit N,N'-Bis-(o-aminobenzyliden)-?thylendiamin

Zusammenfassung N,N'-Bis-(o-ammobenzyliden)-äthylendiamin (ABAD) bildet mit Ni²⁺ und Co³⁺ stabile Chelate, wobei schon durch Luftsauerstoff eine Oxydation von Co^IIzu Co^III-ABAD erfolgt. Ni-ABAD kann quantitativ mit Benzol extrahiert und spektrophotometrisch bei 486 nm bestimmt werden. Co^III-ABAD wird in der wäßrigen Schicht bei 430 nm bestimmt. Die Grenzkonzentrationen betragen 0,5 g Ni/ml und 0,6 g Co/ml in Konzentrationsverhältnissen von 1001 bis 1100. Die Methode ist ebenfalls zur quantitativen Bestimmung von Co neben Cu geeignet.

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Summary N,N'-Bis-(o-aminobenzylidene)-ethylenediamine (ABAD) quantitatively reacts with Ni²⁺ and Co³⁺ to form stable chelates. Co^II-ABAD is easily oxidised by air to Co^III-ABAD. Ni-ABAD can be extracted with benzene and determined spectrophotometrically at 486 nm, Co^III-ABAD is determined in the water-layer at 430 nm. The limit of detection is 0.5 g Ni/ml and 0.6 g Co/ml by the ratio from 1001 to 1100. The method is also suitable for separation and determination of Co in the presence of Cu.

     

Axial-ligation and macrocyclization of novel (E,E)-dioximes of nickel(II) palladium(II), platinum(II) and cobalt(III)

Summary The synthesis and characterization of new Ni^II, Pd^II, Pt^II and Co^III complexes, with the BF _inf2 ^sup+ -bridged,bis(-di-oximato) ligands are described. The initially formed six-coordinate hydrogen-bonded macrocycles, were used as metal templates to prepare the corresponding BF _inf2 ^sup+ - capped macrocycles. The complexes were characterized by¹H-n.m.r. and i.r. spectroscopy, and by elemental analysis.     

Synthesis,spectroscopic studies and magnetic properties of binuclear complexes of the first transition series cations bridged by 2,2′-bipyrimidine

Binuclear complexes [M₂Cl₄(-bpym)], where M = VO²⁺, Fe^II, Co^II or Cu^II and bpym = 2,2-bipyrimidine, and [M₂(hfacac)₄(-bpym)] complexes, where hfacac = hexafluoroacetylacetonate and M = Fe^II, Ni^II or Co^II have been synthesized and characterized by chemical analysis, conductance measurements, i.r., electronic and e.p.r spectroscopies and by magnetic susceptibility measurements (in the 4.2–291K range). Co^II and Fe^II are in a high spin state. [(VO)₂Cl₄(-bpym)] is paramagnetic, without significant interactions. [Fe₂Cl₄(-bpym)] shows a singular behaviour explained by an antiferromagnetic intradimer exchange and a ferromagnetic interdimer interaction. All other complexes are antiferromagnetic, with an intramolecular exchange parameter, J, varying from –3.3 cm^–1 for Co^II/math> to –109 cm^–1 for Cu^II.     

Darstellung und spektroskopische Charakterisierung von Kupfer(II)- und Nickel(II)-tricyanmethanid-Komplexen mit Imidazol-Derivaten – Kristallstruktur von [Cu{C(CN)3}2(2-meiz)2]

Synthesis and Spectroscopic Characterization of Copper(II) and Nickel(II) Tricyanomethanide Complexes with Imidazoles – Crystal Structure of [Cu{C(CN)₃}₂(2-meiz)₂] The copper(II) and nickel(II) tricyanomethanide complexes with imidazoles of the type [Cu{C(CN)₃}₂L₄], [L = 2- or 4-methylimidazole (meiz)] and [M{C(CN)₃}₂L₂] [M = Cu, L = imidazole (iz), 2- or 4-meiz; M = Ni, L = iz, 2- or 4-meiz] were prepared and characterized by electronic, infrared, and – some of them – by ESR spectroscopy. The structure [Cu{C(CN)₃}₂(2-meiz)₂], solved by X-ray crystallographic analysis, shows a two-dimensional network with unsymmetric C(CN)₃-bridges between the Cu^II atoms. Polymeric structures with bridging C(CN)₃-groups were identified by means of spectroscopic methods also for the other [M{C(CN)₃}₂L₂] complexes. On the other hand, for the complexes [M{C(CN)₃}₂L₄] follow molecular structures, in which monodentate C(CN)₃ ligands are present. All compounds under investigation show a tetragonal-bipyramidal geometry with various degree of tetragonal distortion.     

Controlled-potential coulometric studies on fluoride and sulphate complexes of neptunium (VI)

Fluoride and sulphate complexing of Np(VI) has been studied by controlled-potential coulometry at a constant ionic strength. The values of ₁ ^* and ₂ ^* for fluoride complexes were found to be 9.4 and 8.9, respectively, at an ionic strength =0.5. At an ionic strength =1.0, ₁ ^* and ₂ ^* obtained were 6.6 and 10.5, respectively. Sulphate complexing of Np(VI) was studied only at an ionic strength =0.5. The value of ₁ ^* obtained was 5.6.     

Preparation and structure of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with 3-amino-5-(α/β)pyridyl-1, 2, 4-triazoles

Summary Complexes of bidentate 3-amino-5-()-pyridyl-1,2,4-triazole (L¹) and 3-amino-5-()-pyridyl-1, 2, 4-triazole (L²) of composition [ML¹Cl₂·H₂O], [ML²Cl₂·H₂O], [ML ₃ ^2/1 Cl₂] and [ML ₃ ^2/2 Cl₂] [M=Co^II, Ni^II, Cu^II, M=Zn^II] have been prepared and characterized by elemental analyses, i.r., u.v./visible, e.s.r. spectra, magnetic moments and molar conductances.     

New bis-macrocyclic complexes with transition metal ions

Template condensation of benzidine, formaldehyde, ethylenediamine or 1,3-diaminopropane, metal salt and 1-phenyl-1,3-butanedione or 2,3-butanedione in a 1:4:2:2 molar ratio results in the formation of two new series of binuclear pentaaza macrocyclic complexes: dichloro[1,1-phenylbis(7-methyl-9-phenyl-1,3,6,10,13-pentaazacyclotetradeca-6,9-diene) metal(II)], [M₂LCl₄] (M = Co^II, Cu^II, Fe^III and Zn^II) and dichloro[1,1-phenylbis(8,9-dimethyl-1,3,7,10,14-pentaazacyclopentadeca-7,9-diene) metal(II)], [M₂LCl₄] (M = Ni^II, Co^II, Cu^II and Cd^II). Both series were characterized by i.r., ¹H-n.m.r., u.v.–vis. spectral studies, conductivity and magnetic susceptibility measurements.     

Kinetics and mechanisms of the oxidation of the octacyanoniobate(III)ion by oxyanions in alkaline aqueous media

Summary The kinetics and mechanisms of the oxidation of Nb(CN) _inf8 ^sup5– by the oxyanions S₂O _inf8 ^sup2– , BrO _inf3 ^sup– , and IO _inf4 ^sup– have been investigated in alkaline aqueous media (pH 12). The second-order rate constant for the electron transfer reaction between Nb(CN) _inf8 ^sup5– and S₂O _inf8 ^sup2– at 25.0 °C, I = 0.36m (K⁺), is 11.1± 0.3 m ^–1 s ^–1 with H = 30 ± 2kJmol^–1 and S = - 125 + 7JK^–1 mol^–1. The rate constant for the oxidation of Nb(CN) _inf8 ^sup5– by BrO _inf3 ^sup– at 25.0 °C, I = 0.20m (Na⁺), is 2.39 ± 0.08m ^–1 s ^–1 with H = 28 ± 2kJmol^–1 and S = -139 ± 7JK^–1mol^–1. The oxidation of Nb(CN) _inf8 ^sup5– by IO _inf4 ^sup– proceeds by two parallel pathways involving the monomeric IO _inf4 ^sup– ion and the hydrated dimer H₂I₂O _inf10 ^sup4– . The second-order rate constant for the oxidation of Nb(CN) _inf8 ^sup5– by monomeric IO _inf4 ^sup– at 5.0 °C, I = 0.050m (Na⁺), is (3.3 ± 0.6) × 10³ m ^–1 s ^–1 with H = 75 ± 6 kJ mol^–1 and S = 94 ± 15 J K^–1 mol^–1, while the rate constant for the oxidation by H₂I₂O _inf10 ^sup4– is (1.8 ± 0.1) × 10³ m ^–1 s ^–1 with H = 97 ± 5 kJ mol^–1 and S = 166 ± 16 J K^–1 mol^–1 under the same reaction conditions. The rate constants for each of the oxidants employed display specific cation catalysis with the order of increasing rate constants: Li⁺ < Na+ < NH _inf4 ^sup+ < K⁺ < Rb⁺ < Cs⁺, in the same direction as the electronic polarizability of the cations. The results are discussed in terms of the outer-sphere electron-transfer processes and compared with the corresponding data and mechanisms reported for other metal-cyano reductants.     

Multinuclear macromolecule metal complexes 2. Preparation and characterization of Prussian blue and its analogs bonded to pofy(vinylamine hydrochloride)

Prussian blue and its analogs bonded to poly(vinylamine hydrochloride) (PVAm · HCl) containing Fe^II or Fe^III and M²⁺ (M=Fe, Co, Cu) in a 11 molar ratio were obtained by the reaction of [Fe(CN)₆] ^n– (n=3,4) with M²⁺ ion-PVAm · HCl mixture in aqueous solution. Under a limited polymer concentration (T_VAm/T_Fe over 10), these polymer complexes thus obtained were stable and soluble in water. By casting these solutions, colored films can be produced. The formation of Prussian blue and its analogs bonded to PVAm · HCl was also investigated by the Benesi-Hildebrand method. The molar extinction coefficients of intervalence charge transfer (Fe^IIFe^III, Co^IIFe^III, Fe^IICu^II) band for MFe(CN)₆]^(n–2)– bound to PVAm · HCl (M=Fe, Co, Cu) were found to be 10,100–9601 · mol^–1 · cm^–1 at 25 C. The formation constants were found to be in the range of 10⁷ to 10¹⁰ M^–1. The changes of enthalpy (H) and entropy (S) were found to be in the range of –10.4 to –22.5 kJ · mol^–1 and 5.7 to 52.9 J · K^–1 mol^–1 respectively, at 25C.     

Complexes of N-aroyl-N′-thiobenzohydrazide with cobalt(II), nickel(II) and zinc(II)

Summary New potential tetradentate ligands, N-benzoyl-N-thiobenzohydrazide (H₂BTBH) and N-salicyl-N-thiobenzohydrazide (H₂SBTH) have been prepared and characterized. Their complexes with Co^II, Ni^II and Zn^II have been prepared and characterized on the basis of elemental analyses, magnetic susceptibility measurements, and u.v.-vis., i.r. and ¹H-n.m.r. spectral studies. The bonding and stereochemistries of the complexes are discussed. H₂BTBH, H₂SBTH and the complexes have been screened towards a number of bacteria.     

Complexes of N-nicotinoyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(II), iron(II & III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new potential tetradentate ligand, N-nicotinoyl-N-2-furanthiocarbohydrazide (H₂Nfth), and its complexes with VO^IV, Mn^II, Fe^II,III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis, i.r., n.m.r., ES⁺ and FAB mass spectral data. The room temperature e.s.r spectra of the VO^IV and Fe^III complexes yield g values, characteristic of octahedral complexes. The Mössbauer spectra of [Fe(HNfth)₂] and [Fe₂(Nfth)₃] at room temperature and at 78 K suggest the presence of high-spin iron(II) and iron(III), respectively. The complexes are electrically insulating at room temperature, however, their conductivities increase as the temperature increases from 333–383 K, with a band gap of 0.46–0.77 eV, indicating their semiconducting behaviour. H₂Nfth and its soluble complexes have been screened against several bacteria and fungi.     

Dynamic viscosity of polymer solutions

The dynamic viscosity of different long chain polymers in Aroclor permits an easy extrapolation to zero concentration only in the limiting cases of Newtonian, i. e., constant viscosity at low and high frequency, respectively. The first intrinsic viscosity []₀ is independent of any concept of the internal viscosity. In the case of polystyrene it is proportional toM ^0,65 which shows that Aroclor is a good solvent for this polymer. The second intrinsic viscosity [] turns out to be independent ofM. It is best reproduced by the model where the internal viscosity resists only the deformation rate of the single link. The displacement rate of more distant beads is affected by the internal viscosity only in the case that it involves the deformation rate of the links. The angles between successive links may be changed at any rate.In the intermediate range of frequencies the extrapolation of the observed dynamic viscosity to the intrinsic value was never made. The experimental data are so much affected by the concentration, i. e., by the interaction of adjacent molecules, that no conclusion may be derived from them about the properties of the isolated macromolecule. A master curve independent ofM andc is obtained by plotting of (G- )K/c over ₁. This means that the deformation mode in the whole molecular weight and concentration range investigated is the same. But this mode is different from that of the independent macromolecule in infinite dilution. The master curve may be described by the excess intrinsic viscosity of the Rouse model with the internal viscosity acting either between the beads on the same link only or between any distinct beads. As a consequence of the concentration effects, however, no conclusions about the properties of the single molecule can be derived from such an agreement.Dedicated to Prof. Dr. F. H. Müller.     

Synthesis,structure and biological activity of the O,O′-diethylphosphorohydrazonothionate Schiff base and its complexes with transition metals

N-2-Hydroxy-3-methoxy-benzalmethylene-O,O-diethylphosphorohydrazonothionate (HL) and its six complexes (ML₂) with Cu^II, Zn^II, Ni^II, Fe^II, Co^II and Mn^II have been synthesized and characterized. The crystal structure of CuL₂ shows that the metal ion is tetracoordinated, bound to 2N from imine and 2O from hydroxybenzene to form a parallelogram. The effects on Stenostigma remota cells of complexes CuL₂, CoL₂ and MnL₂ have been determined by microcalorimetry, which indicates that the compounds inhibit the metabolism of the insect cells.     

Formation of cobalt(iii) cations with semiquinonediimine ligands

The reactions of polynuclear cobalt(ii) trimethylacetates [Co(OH) _n (OOCCMe₃)_2–n ] _x , Co₆(₃-OH)₂(OOCCMe₃)₁₀(HOOCCMe₃)₄, or Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with an excess of N-phenyl-o-phenylenediamine (1) in toluene followed by treatment with atmospheric oxygen afforded the diamagnetic complex [Co{²-(NPh)(NH)C₆H₄}₂{¹-(NH₂)C₆H₄(NPhH)}]⁺(Me₃CCOO...H...OOCCMe₃)^– (3), whose cation contains the Co^III atom. The reaction of Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with a deficient amount of diamine 1 in acetonitrile under an argon atmosphere gave rise to the antiferromagnetic ionic complex [Co{²-(NPh)(NH)C₆H₄}₂MeCN]⁺[Co₂(₂,²-OOCCMe₃)(₂-OOCCMe₃)₂(²-OOCCMe₃)₂]^–·2MeCN (4), whose cation is an isoelectronic analog of the cation in complex 3. The structures of the new compounds were established by X-ray diffraction analysis.     

Ternary complexes of N-(2-acetamido)iminodiacetic acid and some aromatic acids. Isolation and stability constants in solution

Summary Ternary 1:1:1 complexes of Y^III, Co^II, Ni^II, Cu^II, La^III, Ce^III and UO ₂ ²⁺ with N-(2-acetamido)iminodiacetic acid (H₂ADA) as primary ligand and salicylic, anthranilic or phthalic acid as secondary ligand are described. The complexes of Co^II and Cu^II were isolated and characterized by microanalysis, molar conductance measurements, thermal analysis, i.r. and u.v.-vis. spectra. The formation constants of the 111 ternary complexes were determined potentiometrically in 20% (w/w) EtOH-H₂O at 24 °C. The stabilities of the 111 M ⁿ⁺ :ADA^2–:aromatic acid ternary complexes are higher than those of the corresponding 11 M ⁿ⁺ :aromatic acid binary complexes.     

2-Acetylfuran-2-furoylhydrazone complexes of some 3d-metal ions

Summary 2-Acetylfuran-2-furoylhydrazone (1), [HL] reacts with metal ions to yield the complexes of two types, compounds [VO(HL)SO₄] and M(HL)₂Cl₂ [M = Co^II, Ni^II or Cu^II] and compounds M(L)₂(H₂O)₂ [M = Co^II, Ni^II or Cu^II], depending on the pH of the medium. These complexes have been characterized by elemental analyses, molar conductance, magnetic susceptibility, visible, e.s.r. and i.r. spectral studies. Square pyramidal geometry for [VO(HL)SO₄] and octahedral geometry for the remaining complexes are proposed. Part of this work was presented at the Second EUCHEM Conference on Electronic Structures of Transition Metal Complexes, St. Patrick's College, Maynooth, Ireland, 1985.     

On the Applicability of Duolite GT-73 to Column Preconcentration of Gold and Palladium Prior to Determination by Inductively Coupled Plasma Atomic Emission Spectrometry

The preconcentration of Au and Pd on Duolite GT-73 chelating resin with the thiol functional group was investigated prior to determination of these noble metals by means of inductively coupled plasma atomic emission spectrometry. It was found that Au^III and Pd^II were retained on the resin along with other concomitant metals (Al, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn) from different HCl-containing media. A two-step elution procedure was developed for the release of the noble metals. First 4.0molL^–1 HNO₃ solution was used to elute the base metals. The recovery of Au and Pd was performed afterwards using 0.50molL^–1 solution of (NH₂)₂CS. Retrieval of Au and Pd retained on Duolite GT-73 was also carried out by decomposition of the resin in the open vessel system using H₂SO₄ with H₂O₂. The detection limits of Au and Pd evaluated for the devised protocol, with a preconcentration factor of 50, were 0.085µgL^–1 and 0.28µgL^–1, respectively. The proposed method was applied to the determination of Au and Pd in spiked electrolytic bath samples.     

Synthesis and Structure of Acetonitrile Solvates of Copper(II) Monofluoroacetate and Silver(I) Trifluoroacetate, [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

Compounds [Cu₂(CH₂FCOO)₄· 2CH₃CN](CH₃CN) (I) and Ag₃(CF₃COO)₃(CH₃CN)₂(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, = 106.82(3)°, V= 4292(2) ų, Z= 8, R ₁= 0.0426; crystals IIare triclinic, space group , a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, = 95.27(3), = 109.59(3)°, = 104.60(3)°, V= 911.4(3) ų, Z= 2, R ₁= 0.0252. Structure Iis composed of the structural units (lanterns) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.