Alcoolyse et glycolyse de derives organozinciques et organocadmiens par des composes chiraux

The reaction between organozinc or organocadmium derivatives and different chiral hydroxy compounds leads to the corresponding alcoholates and glycolates which can be used as initiators in polymerizations.The composition of such initiators is defined by the ratio i_S = R-M-O/O-M-O of the number of alkylalkoxy groups to the number of dialkoxy groups. This ratio depends on the nature of the organometallic and hydroxy compound and on the conditions of reaction used to prepare them.Toward a given hydroxy compound, the reactivity of the organometallic derivatives follows the order: ZnEt₂ > CdEt₂ > CdMe₂.Primary alcohols and 1,2-diols are more reactive than secondary alcohols in the case of organozinc compounds, while in the case of organocadmium compounds the secondary alcohols are more reactive than primary alcohols, but less reactive than 1,2-diols. The kinetics of the reaction can be followed by monitoring the variation of optical activity of the solution.Several compounds having definite stoichiometry have been isolated and identified by their NMR spectra.     

Reduction des halogenures de titane(IV) par les metaux: une nouvelle methode de synthese de Cp2 Ti(CO)2 et de CpTi(C7H7

A ready intermolecular ligand exchange process occurs when solutions of Co₂Rh₂(CO)₁₂ and Co₂Rh₂(CO)₈(PF₃)₄ are mixed at room temperature.     

Alkali metal complexes: Complexes of alkali metals with quinaldinic acid

Complexes having the general formula ML.HL, where M = Na, K, Rb or Cs and HL = quinaldinic acid, have been obtained. The isolation of adducts in the solid state appeared to be favoured by increase in atomic radius, and hence decrease in ionisation potential of the metal. Attempts to synthesise similar adducts of picolinic acid N-oxide and quinaldinic acid N-oxide did not succeed. Complexes have been characterised by elemental analyses, thermal, IR spectral and solution studies. Our findings suggest that pK value of the ligands cannot be regarded a dominant factor in the synthesis and isolation of alkali metal complexes.     

Metathese des olefines: intervention d'hydrures de tungstene et nouveau mode de coupure des alkyl-tungstenes

New data indicate that tungsten-hydrogen bonds must be present in catalysts active in olefin metathesis. Evidence for a C-C α-cleavage in alkyl-tungsten derivatives is also adduced, thus allowing a reasonable mechanism to be proposed for olefin metathesis     

Preparation and study of silver maleonitriledithiolate complexes

This paper reports the reaction of Ag₂(mnt) and [(NEt₄)Ag(mnt)] (mnt^2? = maleonitriledithiolate) with PPh₃ and 1,2-bis(diphenylphosph     

Mixed-ligand lanthanide complexes—II : Complexes of β-diketone and heterocyclic amine. Synthesis and spectroscopic studies

The imidazole adducts of tris(heptafluorooctanedionato)lanthanide(III), [Ln(fod)₃ · im] have been synthesized and characterized. The electronic spectra in the visible region have been analysed and spectral parameters ($\text{β}$, b^1/2, δ and T_λ) and oscillator strengths calculated and discussed. These complexes are more covalent than the analogous [Ln(fod)₃ · pz] complexes, pz = pyrazole. The covalency is more in solution than in the solid state. The experimental and the calculated oscillator strengths are in good agreement. The band shape for the hypersensitive transition in the solid and solution spectra is compared with the other known systems and discussed. The difference in the band shape of the hypersensitive transition in the solid and in solution is indicative of solvent molecule coordination. The Mössbauer spectrum of [Eu(fod)₃ · im] is reported. The dipolar shift produced in the NMR spectrum of [Eu(fod)₃ · im] is upfield in comparison to the signal of the organic moiety itself as well as in its diamagnetic analogues. The coordinated base does not dissociate even in DMSO solution. Due to their poor solubility these compounds are not suitable for use as induced NMR shift reagents.     

Interactions electroniques en serie organostannique aromatique. etude par rmn de 19F. : III. Subtituants asymetriques SnABC.

Linear relations observed between ¹⁹F chemical shifts δ$\text{M}\text{F}$ and δ$\text{P}\text{F}$ in the series 3 or 4-FC₆H₄SnA₃ confirm the validity of the relations established between δ$\text{P}\text{F}$ and o° constants of SnA₃ groups.This study has been extended to asymetric groups SnA₂B and SnABC.     

Spectres de vibration de composes organiques des elements de la colonne IVB : V. Derives cycliques oxygenes du silicium et de l'etain: Oxa-1 sila-2 cyclopentanes,oxa-1 stanna-2 cyclopentanes et cyclopentenes

Infrared and Raman spectra of two 1-oxa-2-stannacyclopentanes, three 1-oxa-2-stannacyclopentenes and three 1-oxa-2-silacyclopentanes have been examined in the 3600—100 cm^?1 region. Assignments of the main bands observed are discussed.     

Preparation and characterization of tetrahalodimolybdenum(II) complexes with alkyl-substituted pyridines

The preparation and characterization of new tetrahalodimolybdenum(II) complexes with alkyl-substituted pyridines is described. IR and visible data are used to infer structural information with respect to previously prepared complexes of this type.     

Preparation and characterization of heterobimetallic tetraxanthates and their complexes with Lewis bases

Some new heterobimetallic tetraxanthates of the type M[Ag(Etxant)₂]₂ [M = Co(II) or Ni(II), Etxant = ethylxanthate] and their complexes of general formula M[Ag(Etxant)₂]₂.xL [x = 2 when L= dimethylsulphoxide (DMSO), triphenylphosphine (Pph₃), pyridine(py) or 2-aminopyridine (2-ampy); x = 3 when L = 2,2′-bipyridine (bipy)] have been prepared and characterized by elemental analysis, molar conductance, magnetic susceptibility, infrared and electronic spectral studies. Magnetic and electronic spectral studies indicate square planar geometry around Ni(II) and Co(II) in heterobimetallic tetraxanthates and Ni[Ag(Etxant)₂]₂.2PPh₃ and octahedral geometry around the above metal ions in the remaining complexes.     

Arylation catalytique d'organophosphorés. Produits de l'arylation,catalysée par les sels de nickel (II), de composés du phosphore tricoordiné.

Analysis of the products from the nickel (II) bromide catalysed arylation of tricoordinated phosphorus compounds R₂P-Z (Z  H, Cl, SR, NR₂ pointed out that this arylation always takes place on phosphorus resulting at first in formation of pseudophosphonium salts. Only the aminophosphonium salts are stable under reaction conditions; the other salts undergo several transformations which can be brought together in a general reactivity scheme to account for all the side products. On regard to other heteroatoms these results point out a particular ability of phosphorus to be arylated under nickel (II) catalysis.The reaction with secondary phosphines can be applied to synthetise diarylphosphonium salts.     

Preparation,characterization and cyclic voltammetric behaviour of dimeric sulphidomolybdenum(V) dithiocarbamate complexes

Mo₂S₄(R₂dtc)₂ (R = methyl, ethyl or benzyl; R₂ = pyrrolidinyl, piperidinyl or 4-morpholinyl) have been prepared starting from ammon     

Cyanoalkyl complexes of transition metals . : II. Preparation and properties of some platinum complexes containing phosphorus as a donor atom

cis-PtCl(CH₂CN)(PPh₃)₂ was obtained by the reaction of Pt(PPh₃)₄ with ClCH₂CN in acetone. A solution of Pt(PPh₃)₄ and ClCH₂CN in benzene was heated under reflux to give trans-PtCl(CH₂CN)(PPh₃)₂. The reaction of the trans-isomer with Br^?, I^?, Ph₂PCH₂CH₂ PPh₂, Ph₂PCH₂CH₂AsPh₂ and cisPh₂PCHCHPPh₂ has been examined. The trans-influence of a ligand trans to the CH₂CN group seems to be indicated by the ²J(PtH) of the CH₂CN protons. The τ values of trans-PtX(CH₂CN)(PPh₃)₂ and PtX(CH₂ CN)(PP) (X = Cl, Br, I) are related by a linear function.     

Mixed metal PtxMyLz complexes of L = 1-methyluracil and 1-methylthymine: Preparation and spectroscopic studies

The reactions of cis-(NH₃)₂PtL₂ (L = 1-MeT or 1-MeU, the anions of 1-methylthymine or 1-methyluracil respectively) in water with various salts of Fe(II), Fe(III), Co(II), Ni(II), Cu(II) or Ag(I) have produced 14 new heteronuclear complexes of the general types: cis-[(NH₃)₂PtL₂ML₂Pt(NH₃)₂]X_n·mH₂O or cis-(NH₃)₂PtL₂MX_n·mH₂O, and also with silver(I) perchlorate a complex of stoichiometry cis-{(NH₃)₂Pt(1-MeU)₂}₂· 3AgClO₄·6H₂O. Comparisons are made with previously reported heteronuclear species derived from cis-(NH₃)₂PtL₂ and factors influencing the type of heteronuclear complex formed are discussed, particularly the versatility of binding patterns with Ag(I). A tetranuclear structure is suggested for the compound of stoichiometry cis-(NH₃)₂Pt(1-MeU)₂·FeSO₄·3H₂O involving iron(II) ions linked by sulphate bridges. The electronic spectra of the trinuclear complexes cis-[(NH₃)₂Pt(1-MeU)₂M(1-MeU)₂Pt(NH₃)₂] (NO₃)₂·mH₂O (M = Fe, Co or Ni) are reported. They show that the trans-MO₄Pt₂ geometry results in a very severely trans-elongated ligand field about the central metal ion, M. This conclusion is supported by the Mössbauer spectrum in the case of the iron(II) complex. The X- and Q-band EPR spectra of the Fe(III) analogue are also reported.     

Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic schiff bases

Novel tetraaza-macrocycles with N-substituted carbamoyl groups were prepared by the reaction of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,12-tetraene with isocyanates (RNCO, R = Ch₃ and C₆H₅). Their copper(II) and nickel(II) complexes were characterized by magnetic susceptibilities, electronic absorption spectra, and electrochemical properties. The complexing abilities and extractabilities of the ligands for the metal ions were investigated.     

Preparation and characterisation of copper,cobalt and nickel complexes of tetradentate N6 macrocyclic ligand

Macrocyclic complexes of copper, nickel and cobalt were synthesised via template reactions. These 14-membered N₆ tetradentate macrocyclic complexes were characterised by magnetic, conductance, electronic and IR spectral studies. The macrocyclic ligand coordinates through the four azomethine nitrogen atoms which are bridged by 2,3-butanedione, moieties, but far IR spectra suggest that the pyridine nitrogens are not coordinated. These macrocyclic complexes are considered to have distorted octahedral configurations.     

The Preparation and Reactions of Cationic Ruthenium(II) Complexes Containing 1,5-Cyclooctadiene and Acetonitrile

The polymer [(C₈H₁₂)RuCl₂]x, (C₈H₁₂  1,5-cyclooctadiene, x > 2), dissolves in refluxing acetonitrile to form [(C₈H₁₂)RuCl(CH₃CN)₃]⁺ and, on treatment with AgPF₆, [(C₈H₁₂)Ru(CH₃CN)₄]²⁺; some reactions of these cations are described.     

Transition metal complexes with 1,3-bis-(2-hydroxyphenyl)-1,3-propanedione—I : Mononuclear complexes

Reaction of 1,3-(2-hydroxyphenyl)-1,3-propanedione (BhPPH₃), a ligand with three possible sites of coordination acting as a chelating agent, with metal acetates results in the formation of mononuclear species M(BhPPH₂)₂S,S′ (M=Mn, Fe, Co, Ni, Zn; S,S′=CH₃OH, C₂H₅OH or H₂O); M′(BhPPH₂)₂ (M′=Cu, Pd), and M″(BhPPH₂)₃S,S′ (M″= Fe, Al). The complexes have been studied by ¹H-NMR when possible, and IR spectra. The position of the methine proton (=CH-) at 6.88 ppm in Zn(BhPPH₂)₂S,S′ indicates that BhPPH₃ behaves in mononuclear complexes as a common β-diketone. Most of the complexes lose S,S′ molecules on heating but a crystal structure of Zn(BhPPH₂)₂ · 2C₂H₅)OH indicates that the C₂H₅OH molecules are oxygen bonded to the metal centre.     

Organotellurium cations: Organotellurium perchlorates and their complexes with Lewis bases

Solutions of diorganotellurium(IV) diperchlorates R₂Te(ClO₄)₂ (where R = Ph, p-CH₃OC₆H₄, R₂Te = $\text{C}{}_4\text{H}{}_8\text{Te}$) may be prepared by the reaction of R₂TeCl₂ and AgClO₄ or by the reaction of diorganyltelluroxide with excess of 70% HClO₄.IR and conductivity data indicate that Ph₂Te(ClO₄)₂ possesses covalently bonded perchlorate groups in solution. Interaction of the freshly prepared solutions with Lewis bases affords cationic complexes of the types [R₂Te(ClO₄)(L)][ClO₄] and [R₂Te(L)₂][ClO₄]₂ which have been characterised by IR elemental analyses and conductivity measurements.     

Reactions of polynuclear complexes novel benzotriazole-allylamine cobalt complexes and their oxidizing properties

The absorption of oxygen by solutions of bis(triphenylphosphine)cobalt(II) chloride in allylamine in the presence of heterocyclic ligands has been studied. Novel complexes are formed in the presence of benzotriazole. A new class of trinuclear complexes has been discovered and studied by X-ray diffraction. Oxidation of triphenylphosphine takes place catalytically in the presence of oxygen under mild conditions.