Showing papers in "Transition Metal Chemistry in 1989"

Peroxide derivatives of molybdenum(VI) in neutral and alkaline media

Abstract: The peroxidation of molybdenum(VI) was investigated in neutral and alkaline media. The stability constants of the peroxo complexes were determined by spectrophotometric measurement as (9.12±0.67)×10−7, (2.68±0.17) ×105, (1.26±0.06)×106 and (1.58±0.02) for the 1∶1, 2∶1 (yellow), 3∶1 and 4∶1 (red) species. The diperoxomolybdate disproportionates into the tetraperoxo derivative when treated with alkali. Formation of the tetraperoxo complex was found to be pH dependent according to a curve, with maximum at pH 10. Acidification of tetraperoxomolybdate solution results in the regeneration of hydrogen peroxide and the diperoxo complex is reformed.

Palladium (II)-kojic acid interaction

Abstract: The interaction of palladium(II) with the bidentate kojic acid compound, HL, was studied. The pkL and pkc (1∶1) values 7.65±0.15 and 5.22±0.10 were determined in aqueous media in the presence of different solvents (dioxane, MeOH, EtOH, Me2CO and DMF) at variable concentrations (20–50% v/v solvent/H2O). A reddish brown square planar 1∶1 solid palladium kojic acid complex, PdLCl·H2O, was prepared and characterized.

Kinetic study of the reaction betweentrans-tetracyanodioxorhenate(V) and thiocyanate ions

Abstract: The kinetics of the reaction between NCS− and the diprotonated forms of [ReO2(CN)4]3− have been studied in theca. 1 to 3 pH range. This study showed that the diprotonated form [ReO(OH2)(CN)4]−1 is the only reactive species and that only the aqua ligand is substituted by the thiocyanate ions according to the following reaction: $$[ReO(OH_2 )(CN)_4 ]^{1 - } + NCS - [\operatorname{Re} O(NCS)(CN)_4 ]^{2 - } + H_2 O$$ The k1 and k−1 values are 3.48(4)×10−3 M−1 s−1 and −3(2)×10−5 s−1 respectively at 25°C. A dissociative activated substitution process is proposed.

Synthesis and properties of binuclear nitride-bridged iron octaphenyltetraazaporphyrin. E.p.r. studies of dioxygen adduct formation

Abstract: The synthesis and characterization are reported for (μ-nitrido)bis[(octaphenyltetraazaporphyrinato)iron] ([OPTAP)Fe]2N). The [(OPTAP)Fe]2N dimer is paramagnetic with one unpaired electron per dimer unit and shows a typical axially symmetric e.p.r. spectrum in non-polar solvents at liquid N2 temperature (g⊥=2.126, g‖=2.001), with well-resolved superhyper-fine splitting resulting from the μ-nitrido bridge (A⊥N=2.48mT, A‖N=2.60mT).

The crystal structure of tetraphenylphosphonium tetracyanohydroxooxorhenium(V)

Abstract: The crystal structure of (PPh4)2[ReO(OH)(CN)4]·5H2O has been determined from three-dimensional x-ray diffraction data. The light brown crystals are monoclinic, space group P21/n, with cell dimensionsa=16.753(2),b=19.928(2),c=15.338(2) A and β=101,894(1)°,z=4, Dm=1.45(1) g cm−3. The anisotropic refinement of the 6088 observed reflections converged to R=0.077. The [ReO(OH)(CN)4]2− ion has a distorted octahedral geometry. Bond distances: Re =1.70(1), Re−OH=1.90(1) and ReℑCav=2.12(2) A. The Re atom is displaced by 0.08 A out of the plane formed by the four carbon atoms towards the terminal oxo ligand.

Structural chemistry of amino acid complexes

Abstract: Complex formation between CoII, NiII and CuII and the amino acids (cysteine, cystine and methionine) in the solid state were investigated by elemental analyses, i.r. and electronic spectra, and magnetic susceptibilities

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridine N -oxide. II. The 4 N -dimethyl derivative

Abstract: Metal ion complexes of 2-acetylpyridineN-oxide4 N-dimethylthiosemicarbazone (HLO4DM), have been prepared and spectroscopically characterised. The presence of two alkyl groups at4 N facilitates loss of the hydrogen from2 N since HLO4DM is found as the anionic ligand in the majority of its complexes. The anionic LO4DM bonds to the metal ions via theN-oxide oxygen, the azomethine nitrogen, and the thiol sulphur atoms. The infrared, electronic, and electron spin resonance spectra of these complexes are compared to 2-acetylpyridineN-oxide4 N-methylthiosemicarbazone as well as 2-acetylpyridine4 N-dimethylthiosemicarbazone.

Peroxide derivatives of molybdenum(VI) in acidic solution

Abstract: The peroxidation of molybdenum(VI) in dilute acidic solution was investigated by spectrophotometric, potentiometric and conductometric methods. At lower concentrations of hydrogen peroxide, diperoxo-and then hexaperoxoheptamolybdate are formed, whereas at higher concentrations, the peroxidized polyions progressively desaggregate and diperoxomonomolybdate is formed.

Tetraphenylphosphonium perosmate(VII) as an oxidant: comparison of [OsO4]- with [RuO4]-

Abstract: The osmium(VII) salt (Ph4P)[OsO4] functions as a stoichiometric oxidant for benzylic and allylic alcohols, oxidising primary alcohols to aldehydes and secondary alcohols to ketones. Its vibrational spectra and cyclic voltammetric behaviour are compared with those of the perruthenate ion, [RuO4]−.

Synthesis, spectroscopic and thermal studies on ruthenium(III), rhodium(III) and iridium(III) complexes with hydrazones derived from 2,6-diacetylpyridine and different aromatic hydrazides

Abstract: The reactions of MCl3·3H2O (M=Ru, Rh or Ir) with hydrazones have been studied by three different methods and complexes of the types [M(LH2)(H2O)2]Cl3, [M(L)Cl(H2O)] and [M(LH2)Cl2]Cl·H2O have been isolated. Tentative structural conclusions are drawn for these products based upon elemental analysis, electrical conductance, magnetic moment, and i.r. and1H n.m.r. data. The thermal stability and mode of decomposition for the complexes have been studied by t.g.a., d.t.g. and d.s.c. techniques.

The synthesis and crystal structure of a cubane-like tungsten copper sulphur cluster, [W4CuS42P(OEt)23(I)(μ2-PhCO2)(MeCN)]

Abstract: The title compound [W3C3S4{S2P(OEt)2}3(I)(μ2−PhCO2)(MeCN)] crystallized in triclinic system with space group P1 and cell dimensiona=11.645(6),b=18.565(2),c=11.292(7)A, α=96.15(3)°, β=113.65(3)°, γ=93.77(3)°, V=2207.6A3, Z=2, Mr=1588.09, Dc=2.39 g cm−3. MoKα radiation, λ=0.71073 A, μ=97.3 cm−1, F(000)=1488, R=0.042 for 5588 observed unique reflections I≥3ϖ(I). There are some distortions in the cubane-like W3CuS4 core, with three W-W bonds and three weak W-Cu bonds. Two W atoms are coordinated by PhCO2 bridge ligand, the other W atom is coordinated to the N atom of MeCN.

Equilibrium and hydrolysis ofα-amino acid esters in ternary complexes of copper(II) involving glycyl-L-tyrosine

Abstract: Binary and ternary complexes of copper(II) with glycyl-L-tyrosine and an amino acid ester were investigated by potentiometric and spectrophotometric techniques. The kinetics of base hydrolysis of the above esters in the presence of copper(II)-glycyl-L-tyrosine complex was studied at 30°C.

The crystal structure of 4,4′-dipyridinium tetracyanooxothiocyanatorhenate(V)

Abstract: The light purple crystals of (4,4′-dipyridinium) [ReO(NCS)(CN)4] crystallize in the monoclinic space group P21/m witha=6.615(1),b=16.043(1),c=8.405(1) A,β=93.20(1)°,z=2. The anisotropic refinement of the 1770 observed reflections converged to R=0.041. The [ReO(NCS)(CN)4]2− ion has a distorted octahedral geometry. The rhenium atom is displaced by 0.30 A out of the plane formed by the four carbon atoms towards the terminal oxo ligand. Bond distances: Re=0 =1.67(1), Re−N=2.12(1) and Re−Cav=2.11(1)A. The thiocyanate ion is nitrogen bonded to the rhenium atom.

Synthesis and solid-state structural characterization of di-μ-azido-bis[{azido(N, N-diethylethylenediamine)}copper(II)]

Abstract: The 1∶1 mixed-ligand [{Cu(N3)2(diEten)}2] (diEten=N,N-diethylethylenediamine) complex has been synthesized and characterized by i.r. spectroscopy and X-ray diffraction. The compound crystallizes in the triclinic space group P1. Its structure consists of a centrosymmetric Cu2N2 unit whose N atoms belong to “end-on” azido bridges. Each copper atom is also surrounded by three nitrogen atoms; two from oneN, N-diethylethylenediamine, and one from the remaining azide. The five nitrogen atoms altogether occupy the vertices of a slightly distorted trigonal bipyramid, and the azidobridges produced a rather short Cu...Cu distance of 3.37 A.

Transition metal ion complexes of theS-methyldithiocarbazate prepared from 2-acetylpyridineN-oxide

Abstract: Metal ion complexes of theS-methyldithiocarbazate of 2-acetylpyridineN-oxide, HONS, have been prepared and characterised by spectral and physical methods. Preparative ethanolic solutions on reflux yield complexes in which the deprotonated form of the ligand, ONS, is complexedvia itsN-oxide oxygen, azomethine nitrogen, and thione sulphur. Representative stoichiometries are as follows: [M(ONS)2]X (M=Fe3+, and X=ClO4−, FeCl4− or M=Co3+ and X=BF4−) and [M(ONS)X] (M=Co2+, Ni2+ and Cu2+ and X=Cl−, Br−). The i.r., electronic, and electron spin resonance spectra of the complexes are compared to analogous complexes of theX-methyldithiocarbazate of 2-acetylpyridine as well as the thiosemicarbazones of 2-acetylpyridineN-oxide.

Copper (I) complexes of pentatomic heterocyclic selone donors

Abstract: New complexes of copper(I) with some heterocyclic pentatomic rings, X·CH2·CH2·NR·CSe, where X=CH2, NH, NMe, NEt, S and R=H, Me, Et, were prepared by reacting copper(II) chloride and bromide in MeOH The stoichiometry of the complexes and the binding mode of the ligands have been discussed comparatively, together with those of the thione parents It is noteworthy that the selone ligands with R=H (L) yield complexes of the type CuLnY, (n=1,2 or 3; Y=Cl or Br) like the corresponding thione ones On the contrary, when R=Me or Et, the selonic ligands (L′) give complexes whose stoichiometries, Cu2L′Y2 and Cu3L′2Y3, differ from the thione homologues The ir spectra of the complexes compared with those of the ligands support the coordinative bondvia selenium atom

Formation of oxoperoxo complexes of vanadium(V) with aminopolycarboxylates in acidic aqueous solutions

Abstract: The electronic spectra of KVO3−H2O2−L−HClO4(KOH) aqueous solutions, where L is ethylenediaminetetraacetate (edta), 1,2-cyclohexanediaminetetraacetate (cdta),N-(carbamoylethyl)-iminodiacetate (keida) or iminodiacetate (ida) ion were measured and, based on their pH dependence changes (ca. 0.5–7.0) and time, the formation of carboxylato-oxoperoxo complexes of vanadium(V) and their stabilities at room temperature were studied. The monoperoxo complexes with edta, keida and ida are formed immediately after mixing stock solutions, whereas the monoperoxo complex with cdta is formed only by slow decomposition of the stable diperoxo complex. The stabilities of the monoperoxo complexes decrease in following order: cdta>edta>keida>ida.

Ligational, thermal, corrosion inhibition and antimicrobial properties of salicylidinebenzenesulphonylhydrazone

Abstract: Complexes of CuII, CoII, NiII, CdII, ZnII and HgII with salicylidinebenzenesulphonylhydrazone (HSBS) have been prepared and characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r., n.m.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. The magnetic and spectral studies confirm that the NiII complex is square, whereas the CoII complex is tetrahedral. The molar conductivities for the complexes lie in the non-electrolyte range. The corrosion inhibition of aluminium using HSBS was studied by chemical and electrochemical methods. Also, the antimicrobial activities of HSBS and its complexes have been investigated.

Kinetics of the oxidation of diaqua(nitrilotriacetato)-chromium(III) by periodate in aqueous solutions

Abstract: The kinetics of oxidation of [CrIII(nta)(H2O)2] (nta is nitrilotriacetate) by periodate obey the rate law d[CrVI]/dt=(k2[IO 4 − ]+k3[IO 4 − ]2)[CrIII(nta)(H2O)2] under fixed conditions. The activation parameters are reported and we propose that electron-transfer proceeds via an inner-sphere mechanism.

Organotitanium chemistry 12. Synthesis of some new chiral cyclopentadienyl titanium and zirconium complexes. The crystal structure of (S-cyclo-C4H2OCH2Cp)2TiCl2

Abstract: New chiral cyclopentadienyl-titanium and-zirconium complexes Cp′2TiCl2, Cp′CpTiCl2 and Cp′2ZrCl2 (Cp=η5 -cyclopentadienyl and Cp′=substituted cyclopentadienyl), have been synthesized. The (S,S)-3 complex, which forms red plate crystals, has been studied by x-ray analysis. It belongs to the monoclinic space groupC2, witha 23.963(3),b 6.6470(6),c 12.6618(9) A, β103.089(7)°, V=1964.4(3) A3 and Z=4. The structure was relined to an R factor of 0.048 for 868 observed reflections.

Synthesis and crystal structure of a cubane-like molybdenum copper sulphur bromide cluster [MoCu3S3Br(SCH2CH2S)(PPh3)3]·MeCN

Abstract: [MoCu3S3Br(SCH2CH2S)(PPh3)3]·MeCN, MW=1382.78, space group Pl, has the triclinic cell parametersa=12.272(11),b=13.172(7),c=20.363(3)A, α=106.26(3)o, β=95.64(5)o, γ=65.79(6)o; Z=2, V=2881.4A3. Dc=1.55 g cm−3. MoKα radiation. λ=0.71073A, μ=22.8 cm−1. F(000)=1348. R=0.69 for 4964 observed unique reflections [I>3σ(I)]. There are some distortions in the cubane-like MoCu3S3Br core, with three form Mo−Cu bonds. The Mo atom is bound by chelating SCH2CH2S and three μ3-S atoms.

Coordinated lanthanide metal complexes of N -benzoylglycine hydrazide

Abstract: N-benzoylglycine hydrazide (BzGH) reacts with trivalent lanthanide metal ions forming complexes of the type [Ln(BzGH)2Cl(H2O)2]Cl2·nH2O, where Ln=LaIII, PrIII, NdIII, SmIII, EuIII, GdIII, TbIII, DyIII, or YIII;n=1 or 2. The structures of the complexes have been studied by conductance, magnetic, electronic, i.r.,1H n.m.r. and13C n.m.r. spectral techniques. The nephelauxetic ratio, the bonding parameter, Sinha's parameter and the covalency angular overlap parameter have been calculated from the electronic spectra of PrIII, NdIII and SmIII complexes. Seven-coordination is proposed in the NdIII complex. The i.r. and1H n.m.r. spectral data suggest bidentate BzGH in all the complexes.

Ion exchangers as catalysts. II. Catalytic decomposition of hydrogen peroxide with resin-ethylenediamine-copper(II) complex ions

Abstract: The slow decomposition of H2O2 in the presence of Dowex-50 W resin in the form of an ethylenediaminecopper(II) complex ion in water is accompanied by an induction period. The reaction is first order with respect to [H2O2] and the rate constant (perg of dry resin) was deduced. Autocatalytic behaviour was found for the H2O2 decomposition with 2% crosslinked divinylbenzene. The induction period disappeared and the reaction rate increased when the decomposition was carried out with a resin in the form of a peroxo-copper complex, which proves that the formation of an intermediate (active species) retards the reaction rate. The precursor of the active species, formed during the induction period, was not the amine-copper(II) complex ion but a product of the latter with H2O2. It proved impossible to carry out the decomposition in acid or buffer solutions, in which the resin is regenerated.

Structural studies of 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone complexes

Abstract: Complexes of CuII, NiII, CoII, ZnII, CdII and HgII with 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone (H2BATS) are reported and have been characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. I.r. spectra show that H2BATS behaves as a dianionic, monoanionic or neutral tetradentate ligand or as a monoanionic tridentate ligand. [Cu2(H2BATS)Cl2]·2H2O and [Cu2(H2BATS)Ac2]·2H2O complexes are diamagnetic while [Co(HBATS)OH]·2H2O and [Ni(HBATS)OH]·2H2O are octahedral. All the complexes are non-electrolytes. Generally, the solid metal acetate complexes have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.

Transition metal ion complexes of the S-methyldithiocarbazate prepared from 2-acetylpyridine N-oxide

Abstract: Metal ion complexes of 2-acetylpyridineS-methyldithiocarbazate, HNNS, have been prepared and spectrally characterised. Preparations in EtOH yield complexes in which the deprotonated ligand, NNS, is complexedvia its pyridyl nitrogen, azomethine nitrogen, and thione sulphur. The stoichiometries are: [M(NNS)2]X (M=Fe3+, Co3+ and X=ClO4−, [FeCl4]−, BF4−, 1/2 [CoCl4]2− and 1/2 [CoBr4]2−), [M(NNS)X] (M=Ni2+, Cu2+ and X=Cl−, Br−), [Cu(NNS)H2O]BF4 and ‘Ni(HNNS)(NNS)F(EtOH)]BF4. The spectral (i.e., i.r., u.v.-vis.-n.i.r. and e.s.r.) and physical properties of these complexes are compared to those of theS-methyldithiocarbazates of 2-formylpyridine and 2-acetylpyridineN-oxide, as well as the related thiosemicarbazones prepared from 2-acetylpyridine. Thermal studies of the nickel(II) complexes indicate that the nature of thermal decomposition of coordinated NNS is different from that of HNNS.

Coordination compounds and microorganisms, Part 12. Rhodium compounds of S-nicotine and their bacterial activity

Abstract: The activities of the nicotine complexes of rhodium(III)-[RhCl3(nicH+)3](PF6)3 andtrans-[RhCl2(nic)4](PF6) (nicH+=monoprotonated S-nicotine, nic=unprotonated S-nicotine)—were studied onEscherichia coli B growing in a minimal glucose medium in both lag- and log-phases.

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

Abstract: Complexes of bidentate 3-amino-5-(α)-pyridyl-1,2,4-triazole (L1) and 3-amino-5-(β)-pyridyl-1, 2, 4-triazole (L2) of composition [ML1Cl2·H2O], [ML2Cl2·H2O], [M′L 3 2/1 Cl2] and [M′L 3 2/2 Cl2] [M=CoII, NiII, CuII, M′=ZnII] have been prepared and characterized by elemental analyses, i.r., u.v./visible, e.s.r. spectra, magnetic moments and molar conductances.

Cobalt(0) catalysed synthesis of N -substituted dihydropyrrolopyridines

Abstract: Preparation de pyrrolo [3,4-c] pyridines a partir d'(alkyl dipropargyl) amines et d'acetonitrile

Study of binuclear copper(II) complexes involving bridging Schiff bases—I

Abstract: The synthesis of binuclear complexes obtained by the reaction of aromatic diamines with the ternary complexes of copper(II) with bis(2-pyridyl)amine (dpa) as primary ligand and salicylaldehyde or 2-hydroxynaphthaldehyde as secondary ligand have been reported. The complexes have been characterized by elemental analyses, conductance, electronic and i.r. spectral studies. Magnetic measurements indicate antiferromagnetic exchange between two copper(II) centres. E.s.r. spectra exhibit a ΔMs=2 transition, supporting the antiferromagnetic coupling.

2-Aminoacetophenone-2-thenoylhydrazone complexes of bivalent 3d metal ions

Abstract: 2-Aminoacetophenone-2-thenoylhydrazone, Haath, C4H3SC(O)NHN=C(Me)C6H4NH2-o, forms complexes with metal(II) salts of empirical compositions [VO(Haath)2SO4], [M(Haath)2Cl2] [M=CoII, NiII, CuII or ZnII] and [M(aath)2] [M=VIVO, CoII, NiII, CuII or ZnII] which have been characterized by elemental analyses, molar conductance, magnetic susceptibility, electronic, e.s.r., i.r. and n.m.r. (1H and13C) spectral studies. X-ray and electron diffraction patterns have been obtained in order to elucidate the structure of the CuII complexes. Photoacoustic spectra of powder NiII complexes have been recorded and interpreted in the light of u.v./vis. spectra.