Showing papers in "Transition Metal Chemistry in 1985"

Iron(III) complexes of some thiosemicarbazones derived from 2-acetylpyridine, its 6-methyl derivative and itsN-oxide

Abstract: A series of iron(III) complexes of thiosemicarbazones derived from 2-acetylpyridine, 6-methyl-2-acetylpyridine and 2-acetylpyridineN-oxide have been prepared from Fe(ClO4)3 and FeCl3. All of the isolated solids have cations involving two monobasic tridentate ligands, and either perchlorate or tetrachloroferrate(III) anions and are 1∶1 electrolytes. Coordinationvia the pyridine nitrogen (or theN-oxide oxygen), the imine nitrogen and the sulphur atom are confirmed by infrared spectra and x-ray diffraction. The presence of two different iron(III) species is indicated by the electron spin resonance spectra of the tetrachloroferrate(III) solids. E.s.r. along with electronic spectra prove the spin-paired configuration of these cationic iron(III) complexes.

Synthesis and characterization of copper(II) and nickel(II) complexes of the Schiff base derived from 2-(2-aminophenyl)benzimidazole and salicylaldehyde

Abstract: Copper(II) and nickel(II) complexes with the Schiff base derived from 2-(2-aminophenyl)benzimidazole and salicylaldehyde, L, have been prepared. They are of the general types ML2X2 (M = Ni or Cu and X = Cl, Br, NO3 or ClO4) and NiL(NCS)2.

Monooxorhenium(V) Complexes with the Tridentate Schiff Base N- (2-hydroxyphenyl)salicylideneimine

Abstract: The reactions of the tridentate Schiff base ligandN-(2-hydroxyphenyl) salicylideneimine (HOPhsalH) with oxotetrachlororhenate (IV) have been investigated. The complexes (Bu4N)[ReOCl3(HOPhsal)], (Bu4N)[ReOCl2(OPhsal)],cis- [ReOCl(MeOH)(OPhsal)],trans-[ReOCl(MeOH)(OPhsal)] (1), trans-[ReOCl(OH2)(OPhsal)] · Et2O (2), trans-[ReOCl(OH2)(OPhsal)] · Me2CO,cis-[ReOCl(PPh3)(OPhsal)],cis-[ReOCl(PMe2Ph)(OPhsal)](3) have been synthesized and characterized. The crystal structures of(1), (2) and(3) have been solved from three-dimensional x-ray data by Patterson and Fourier methods and refined by least-squares methods to R 0.10 for(1), 0.042 for(2) and 0.059 for(3). In all the three complexes, the ligands surrounding the rhenium atom are at the apices of a distorted octahedron, with the equatorial ONO donor atoms of the tridentate Schiff base bent away from the Ooxo and toward the loosely bound MeOH in(1), H2O in(2) and Cl in(t3). The fourth equatorial substituent is Cl (1 and2) and PMe2Ph(3) and the rhenium atoms lie 0.30–0.37 A above the best plane through the four equatorial atoms, in the direction of the Ooxo. All interatomic distances and angles are normal.

Oxopentacyano-complexes of molybdenum (IV) and tungsten (IV) in photolysis of octacyanometalates (IV)

Abstract: Ligand-field (LF) photolysis of aqueous alkaline solutions of K4[M(CN)8] (M = Mo or W) containing KCN produces [MO(CN)5]3− species. NaCs2]MO(CN)5] was isolated and characterised by u.v.-vis., i.r. and Raman spectroscopy. In addition, the reactions of [MO(OH)(CN)4]3− with free CN− are described and the relations between octa-, penta- and tetra-cyanocomplexes are summarised.

Rhodium(I) complexes with bidentate nitrogen heterocycles and their reactions with tin(II) chloride and carbon monoxide

Abstract: Cleavage of [{Rh(diolefin)Cl}2] by bidentate heterocyclic chelating ligands (LL) has been studied, and diolefin neutral, ionic or ion-pair type compounds are formed depending on the ligands and/or the Rh: (LL) ratio employed. When the reactions are performed in media saturated with CO and with Rh: (LL)=2∶1, only carbonylated ion-pair complexes are formed. The diolefin compounds react with tin(II) chloride yielding species containing trichlorostannato-groups. Subsequent reaction with CO leads to displacement of the diolefin and formation of the corresponding dicarbonyl species.

Electrochemical behaviour of a series ofN,N′-1,2-Phenylenebis(salicylideneimin)ato transition metal complexes

Abstract: The electrochemistry of a series of nickel(II), copper(II), cobalt(II), manganese(II) and oxovanadium(IV) complexes with theN,N′-1,2-phenylenebis(salicylideneimin)ate ligand has been studied in dimethyl sulfoxide solution. Kinetic and thermodynamic aspects of the electron-transfer processes are discussed, also with respect to those of the correspondingN,N′-ethylenebis(salicylideneimin)ate and bis(salicylideneiminate-3-propyl)amine derivatives

Kinetic and spectroscopic studies of the substitution reactions of [Rh(acac)(CO) 2 ] with triphenylphosphite

Abstract: The substitution reactions of [Rh(acac)(CO)2] with triphenylphosphite (P) to produce [Rh(acac)(CO)P], [Rh(acac)P2] and [PhP3P′], were studied in detail using spectroscopic (n.m.r., i.r. and u.v.-vis.) and kinetic techniques. The kinetic data demonstrate that the first substitution process is very fast and followed by the rate-determining second step. The subsequent loss of acac is relatively slow. The activation enthalpy for the formation of [Rh(acac)P2] is extremely low and possibly accounts for the catalytic nature of this system in hydrogenation and hydroformylation reactions.

Transition metal complexes with 2-methyl-, 3-methyl-, and 4-methyl-piperidine dithiocarbamate as ligands

Abstract: A new series of manganese(III), cobalt(II), nickel(II), zinc(II), cadmium(II) and mercury(II) complexes with monomethylsubstituted dithiocarbamates as ligands has been synthesized and studied Their structures are discussed in relation to their spectroscopic, magnetic and thermal properties The dithio-ligands exhibit bidentate behaviour acting as S,S′donors in all the complexes In the far ir region particular attention is paid to a comparison of the spectra of the octahedral complexes with those of the other metal derivatives (1∶2 metal to ligand molar ratio) The esr spectra are indicative of aD2h symmetry in the cobalt(II) complexes

Transition metal ion complexes of a thiosemicarbazone derived from 6-methyl-2-acetylpyridine

Abstract: A series of metal ion complexes of the thiosemicarbazone, 3-azabicyclo[3.2.2]nonane-3-thiocarboxylic acid 2-[1-(6-methyl-2-pyridinyl)ethylidene]hydrazide (6 MLH) have been prepared and spectrally characterized. The ligand undergoes deprotonation to coordinatevia the thione sulphur, the imine nitrogen and the pyridyl nitrogen. A single anionic ligand such as Cl−, Br− and NO3 − completes the bonding to the CuII and NiII centre. The compound derived from CoCl2 contains two 6 MLH ligands bound to a CoII centre and a CoCl 4 2− counter ion. Complexes derived from perchlorate salts may feature 6 MLH, 6 ML, or both with the CoII being oxidized to CoIII. The solids were characterized by i.r., electronic and e.s.r. spectroscopy. In addition, electronic and e.s.r. spectra of their chloroform solutions were recorded.

Ligational behaviour of biacetylmonoxime-o-aminobenzoylhydrazone (H2BMAB) towards some dipositive metal ions

Abstract: Several new dipositive metal complexes with the hydrazoneoxime, derived from biacetylmonoxime ando-aminobenzoylhydrazine, have been synthesized and their structures elucidated by elemental analyses, conductivities, spectra (visible, i.r. and n.m.r.), magnetic and molecular weight measurements. The i.r. spectra show that the ligand, (H2BMAB), behaves in a bidentate and tridentate manner. The stereochemistry of the cobalt(II), nickel(II) and copper(II) complexes is discussed. The cobalt(III) complex, [Co(BMAB)OH]n, has also been isolated and characterized by conventional physical and chemical measurements and on the basis of molecular weight determination is probably a polymer, whereas the remaining complexes are monomers. I.r. and n.m.r. data suggest that the cobalt(III) complex contains hydroxo-bridge linking.

Transition metal chemistry of oxime ? Containing ligands, Part XXVIII; manganese(II) complexes of 2,6-diacetylpyridine dioxime

Abstract: Complexes of manganese(II) with the tridentate oxime ligand 2,6-diacetylpyridine dioxime (H2dapd) have been synthesized and characterized. The complexes [Mn(H2dapd)X2] are pentacoordinate for X = Cl, Br or I but apparently octahedralvia bridging anions for X = NCS or NCSe. The complex [Mn(H2dapd)(NO3)2] adopts an octahedral structure involving monodentate and bidentate coordination of nitro groups. The complexes [Mn(H2dapd)2]X2 (X = Cl, Br, I, NO3, NCS or NCSe) involve an octahedral cation.

Bis( N -propyl-1,3-imidazolidine-2-thione)gold(I) chloride: Crystal and molecular structure

Abstract: The crystal and molecular structures of bis(N-propyl-1,3-imidazolidine-2-thione)gold(I) chloride, [(PrImt)2Au]Cl, has been determined from three-dimensional x-ray intensity data collected on a CAD4 diffractometer. The compound crystallizes in the monoclinic space group P21/n witha=7.195(7),b=15.283(3),c=15.899(6) A, β=91.7(1) and Z = 4. Atomic parameters were refined by full-matrix least-squares methods to the R value of 6.2% for 2272 observed reflections. Gold(I) exhibits the usual linear coordination with S(1)-Au-S(10) angle of 177.7(1)°. The two [Prlmt] molecules are arranged intrans configuration which is attributed to the effects of intermolecular H-bonding between N-H and the halogen. The Au-S bond length is compared with the corresponding bond length in several known structures in order to evaluate thetrans influence of phosphorus, sulfur and chloride ligands on the Au-S bond.

Computer analysis of equilibrium data in solution. A method for computing the formation constants of two mass balance systems, from potentiometric measurements, applied to the hydrolysis of copper(II)

Abstract: A computer program for two mass balance systems (in solution) has been written in FORTRAN IV. This program (ES3TM) refines the formation constants and some titration parameters (E0, analytical concentrations) from potentiometric data, using the Marquardt algorithm for the Gauss nonlinear least squares method. The program has been compared with some other programs reported in the literature. In order to test the ES3TM program and to obtain reliable values of formation constants for the species, [Cup(OH)q](2p−q)+, we studied the hydrolysis of copper(II) by pH-metric measurements at 37°C and I=0.15 mol dm−3 (NaNO3). The results of the refinement have been discussed in the light of the characteristics of the ES3TM program and of the reliability of the speciation models on copper(II) hydrolysis reported up to now.

Kinetics of oxidation of manganese(II) by peroxomonosulfuric acid in aqueous acidic solution

Abstract: Oxidation of Mn aq 2+ by HSO 5 − in acetate buffer to manganese(IV) is autocatalytic, and obeys a rate expression of the general form -d[MnII]/dt = k0[MnII] + k1[MnII][MnOx]. The first-order (k0) and heterogenetic (k1) rate constants show first-order dependences on [HSO 5 − ] and on 1/[H+]. The reaction is catalyzed by the addition of the chelating ligand glycine; k1 shows a first-order dependence on [glycine] at a fixed pH. This catalysis is ascribed to complexation, whereby the redox potential for Mn(gly) n (2−n)+ is lower than that for Mn aq 2+ , facilitating oxidation. The stoichiometry of the reaction is Mn2+: HSO 5 − = 1∶1, and the manganese(IV) oxide formed is of battery-active grade. Purity of the recovered product is not affected by the presence of high concentrations of natural sugars in the initial solution.

The crystal and molecular structure of acetonitrilechlorodicyclopentadienyltitanium tetrachloroferrate(III). Some Mössbauer and X-ray photoelectron spectroscopic data

Abstract: The title compound crystallizes in the orthorhombic space group P212121 with Z=4 and lattice parametersa=1744.2(4),b=1360.7(4),c=751.3(5) pm. An x-ray analysis shows the compound to consist of discrete (h5-C5H5)2-Ti(Cl)NCMe+ cations and FeCl 4 − anions. The cation has a distorted tetrahedral structure (Ti-C: 231.9-237.6 pm; Ti-Z: 203 and 204pm; Ti-Cl: 230.4 pm; Ti-N: 213.5 pm; Z-Ti-Z: 133.2°; Cl-Ti-N: 91.7° (Z: centre of cyclopentadienyl ring). The relatively short Ti-Cl bond length indicates a modest Ti-Cl π-bonding contribution. The tetrachloroferrate(III) anion possesses a nearly undistorted tetrahedral geometry (Fe-Cl: 216.0–218.5 pm; Cl-Fe-Cl: 109.0–111.1°). Mossbauer and x-ray photoelectron spectroscopic data confirm the crystallographically derived structural features.

Synthesis and electronic, magnetic and E.s.r. studies of some bimetallic alkoxides of copper(II) with niobium(V) and Tantalum(V)

Abstract: Novel bimetallic alkoxides of copper(II) of the type Cu[M(OPr-i)6]2 (M = Nb or Ta) have been synthesised by the interaction of CuCl2 (1 mol) with K[M(OPr-i)6] (2 mol). These bimetallic isopropoxides undergo facile alcohol interchange with primary alcohols such as MeOH, EtOH,n-PrOH andn-BuOH. However, witht-BuOH, the reaction cannot be driven to completion even under prolonged continuous azeotropic fractionation of the liberatedi-PrOH and the final product corresponded in analysis to Cu[Ta(OPr-i)2(OBu-t)4]2.I.r., electronic and electron spin resonance spectral and magnetic susceptibility measurements indicate a distorted octahedralD4h geometry for copper(II) in these bimetallic alkoxides.

Facile preparation of diethylether complexes of molybdenum and tungsten tetrachloride

Abstract: Preparation des complexes [MCl 4 (Et 2 O) 2 ] (M=Mo, W), a partir de solutions dans Et 2 O de MoCl 5 et WCl 6 en presence d'olefines ou diolefines

Synthesis of [SCo3(CO)7(S2COMe)] and the structure of its PPh3 derivative

Abstract: The title compound has been prepared in reasonable yield by reaction of a methanolic solution of CoCl2 and MeOCS2K with CO. I.r. spectra have been analyzed both in the C-O stretching region and in the region of the main vibrations of the xanthate ligand: an explanation of the appearance of only 4 out of 7 i.r.-active ν(CO) modes is proposed. The structure of the triphenylphosphine derivative has been solved by x-ray diffraction analysis: [SCo3(CO)6(PPh3)(S2COMe)] crystallizes in the triclinic space group P¯1, witha = 10.710(3),b = 10.199(3) andc = 16.208(4) A, α = 113.57(2)°, β = 98.14(2)°, γ = 104.32(2)°, Z = 2, λ(MoKα) = 0.7107 A. The final R value is 0.045 [4461 reflections with F > 6 σ(F)]. The molecule is formed by an SCo3 cluster, in which each Co atom coordinates two CO groups. The chelating xanthate ligand is equatorially bonded to two cobalt atoms forming a nonplanar pentaatomic ring; the phosphine is equatorially bonded to the other cobalt atom.

Coordination chemistry of poly(1-pyrazolyl)alkanes, part IV. Copper(II) complexes of bis- and tris-(1-pyrazolyl)methane

Abstract: The reactions of some copper(II) salts with bis(1-pyrazolyl)methane, H2Cbpz, bis(3,5-dimethylpyrazolyl)methane, H2Cbdmpz, and tris(1-pyrazolyl)methane, HCtpz give the following solid complexes: CuLX2 · nH2O (L=H2Cbpz, H2Cbdmpz or HCtpz; X=Cl−, Br−, NO 3 − , OAc−, or 1/2 SO 4 2− and n=0, 1, 3 or 5) and CuL2X2 · nH2O (L=HCtpz, X= C−, Br−, NO 3 − or ClO 4 − and n=0 or 2) The complexes have been characterised by elemental analysis, visible and ir spectral measurements The reactions of Cu(HCtpz)X2 · nH2O (X=Cl− or Br−) with acetylacetonate (acac−), dialkyldithiocarbamate (S2CNMe 2 − , S2CNEt 2 − ) or poly(1-pyrazolyl)borate (H2Bbpz−, HBtpz−) in aqueous solutions lead to the displacement of HCtpz and the subsequent formation of neutral [Cu(acac)2], [Cu(S2CNR2)2], [Cu(H2Bbpz)2] and Cu(HBtpz)2 while the reaction with oxalate ion, C2O 4 2− yields a stable neutral solid compound, [Cu(HCtpz)(C2O4)]

Tetrabutylammonium perruthenate: A new mild oxidant for alcohols

Abstract: Ce nouveau sel relativement facile a preparer, soluble dans les solvants organiques, permet une oxydation selective des alcools primaires en aldehydes et des alcools secondaires en cetones

Substitution of [M(bpyMe)Cl3] and [M(bpyMe-H)Cl2] (M = Pd or Pt; bpyMe =N-methyl-2,2′-bipyridylium ion) withN-heterocycles

Abstract: The complex Pt(bpyMe)Cl3 (bpyMe = N-methyl-2,2′-bipyridylium cation) reacts with pyridine(py) to give cis-[Pt(bpy-Me) (py)Cl2]+, which on heating cyclometallates with loss of py to give Pt(bpyMe-H)Cl2; some Pt(py)2Cl2 is also formed. Pt(bpyMe)Cl3 reacts with 2,2′-bipyridyl (bpy) to yield a mixture of [Pt(bpyMe-H)(bpy)]2+ and [Pt(bpy)2]2+. The analogous reactions with Pd(bpyMe)Cl3 proceed under very mild conditions to afford PdL2Cl2 (L2 = 2py, bpy).

Mixed metal complexes in solution. Part 4. Formation and stability of heterobinuclear complexes of cadmium(II)-citrate with some bivalent metal ions in aqueous solution.

Abstract: The systems, Cd-Ni-citrate, Cd-Mn-citrate and Cd-Zn citrate have been investigated pH-metrically at 25°C and I = 0.1 mol dm−3 (KNO3).

Plasma desorption mass spectrometry of transition metal complexes of thio- and selenosemicarbazones of 2-acetylpyridines.

Abstract: Californium-252 plasma desorption mass spectra were recorded for complexes of the anions of various thio-and seleno-semicarbazones of 3-acetylpyridines(1–4) with the transition metal ions iron(III) and cobalt(II). Positive ion spectra gave clear evidence of the cation present and fragmentation with loss of ligands or parts of ligands was straightforward. Negative ion spectra likewise provided evidence of the intact anion except with tetracoordinate metal halide systems [MX4]− which lost one or more halide atoms. Evidence of fragmentation of the ligand and recombination of the fragments with the metal ion was also observed in the negative ion mode. Spectra were used to revise the structure of a complex previously reported as [FeLCl2](1) to [FeL2]+[FeCl4]−.

The ligating behaviour of 3-hydroxyimino-2-butanone-1-benzoylhydrazone towards NiII and CuII ions

Abstract: The ligating behaviour of the normally tridentate but potentially tetradentate ligand 3-hydroxyimino-2-butanone-1-benzoylhydrazone (LH2) towards CuII and NiII ions has been investigated The ligand reacts in either its keto or enol form, depending on the pH of the reaction medium Metal complexes of the type [Cu(LH2)]X2 · H2O (X = Cl, NO3 or ClO4), [Ni(LH2)2]X2 · 2H2O (X = Cl, Br, NO3 and ClO4), Cu(L) and Ni(L) have been isolated and characterised by spectral (uv-vis, ir and epr) and magnetic susceptibility measurements Location of the bonding sites and the probable structures of the complexes has also been discussed The reactions of Cu(L) and Ni(L) with pyridine have also been examined

Preparative and spectroscopic features of ferricenium tetrachloroferrate(III). Interconversion to diferricenium μ-oxo-bis[trichloroferrate(III)]

Abstract: Ferricenium tetrachloroferrate(III)(1), one of the more frequently cited ferricenium salts, has recently attracted biomedical interest because of its pronounced antineoplastic activity against Ehrlich ascites murine tumor. In this paper, synthetic methods are reinvestigated in an effort to prepare pure(1) free from a common contaminant, diferriceniumμ-oxo-bis(trichloroferrate)(3). The oxodiferrate, or mixtures of this salt with(1), can readily be converted into pure(1) under acidic conditions. Conversely, dimerization of(1) with participation of water to give the oxodiferrate(3) is brought about by recrystallization of the former from moist acetonitrile/methanol in the presence of base; this reaction thus represents a simple procedure for the preparation of pure(3) from crude(1) readily obtainable by the long known interaction of ferrocene and iron(III) chloride in indifferent media. The i.r. and electronic absorption spectra of(1) are presented, as are the Mossbauer and x-ray photoelectron spectra. The room-temperature effective magnetic moment, 6.40μB, of the salt is lower than would be expected on the basis of typical ferricenium cation (2.4μB) and tetrachloroferrate(III) anion (5.9μB) moments determined for related salts. This suggests the possibility of weak inter- or intra-molecular antiferromagnetic interaction in the crystal.

Crystal structure and electronic properties of bis(mepirizole) copper(II) perchlorate. Correlation between the electronic spectrum and CuN4 chromophore distortion from tetrahedral symmetry

Abstract: The crystal structure of the title compound has been determined from single-crystal x-ray diffraction data. The crystals are tetragonal, space group P42212, withz=2 in a unit cell of dimensionsa=b=9.575(2),c=16.135(5) A. The structure was solved by the usual Patterson and Fourier techniques, and was refined by least-squares analysis to an R value of 0.057 for 545 observed reflexions. Two mepirizole molecules are arranged in a flattened tetrahedral manner (average Cu-N, 1.974 A) around Cu, and coordinated through N atoms. The dihedral angle between N-Cu-N planes of the two ligands is 53.6+°. This geometry seems to result from steric interaction between the ligands. The e.s.r. spectrum is axial (g∥ ≫ g⊥ > 2.0). A study of the maximum d-d transition as a function of CuN4 chromophore distortion from Td symmetry is reported.

The twotrans-[NiL2(NCS)2] (L =N, N-dimethyl-1,3-propanediamine) isomers in the solid state and in solution

Abstract: Two complextrans-NiL2 (NCS)2] (L =N, N-dimethyl-1,3-propanediamine) synthesised from solution in two isomeric forms (1) and (2), exhibit similar colours, magnetic moments and electronic spectra, but differ in their i.r. spectra and x-ray powder diffraction patterns. We suggest they possesstrans- chair-chair andcis-chair-chair chelate conformations, respectively. Complexes (1) → (2) isomerise (temperature range 382–397.5 K; ΔH = 5.12 kJ mol−1) in the solid state. Isomer (2) is converted into isomer (1) upon recrystallisation from chloroform. Thetrans-[NiL2NCSe)2] complex does not isomerise upon heating. The compound [NiL(NCS)2], prepared by thermal decomposition of [NiL2(NCS)2], possesses octahedral polymeric structure in which the diamine is chelated and all the thiocyanato groups are bridging.

Stoichiometry and kinetics of the oxidation of hydroxylammonium ion by 12-tungstocobaltate(III) anion in aqueous solution

Abstract: The stoichiometry and kinetics of the oxidation of hydroxylammonium ion by the 12-tungstocobaltate(III) anion has been studied in hydrochloric acid medium. The ratio of mols of oxidant consumed per mol of hydroxylammonium ion is 1∶1 and the evolution of nitrogen is confirmed. In the 0.1–1.0 mol dm−3 [H+] region, the oxidation is acid-independent and obeys the empirical rate law: −d[oxidant]/dt=k[oxidant] [reductant] where k=(3.51±0.18)×10−4 mol−1dm3s−1 at 22.4±0.1‡C and I=2.0 mol dm−3 (NaCl). Possible reaction steps and mechanism are suggested.

Complexes of TiCl4, VCl4 and SnX4 (X = Cl or Br) with Schiff bases derived from 2-aminobenzimidazole

Abstract: The reactions of anhydrous titanium(IV), tin(IV) and vanadium(IV) halides with Schiff bases derived from 2-aminobenzimidazole and 4-methylbenzaldehyde (abimbz) and salicylaldehyde (abisal), yield hexacoordinated complexes M(abimbz)Cl4 and M(abisal)2X4 (M = Ti, Sn or V; X = Cl or Br). The compounds have been characterized by elemental analyses, magnetic measurements, e.p.r., electronic and i.r. spectral studies. I.r. spectra suggest that the Schiff base (abimbz) is coordinated as a bidentate ligand with the metal ion and the (abisal) base acts as a monodentate ligand.