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.     

L'addition des organomagnesiens aliphatiques satures sur les triples liaisons disubstituees non conjuguees: IV. Influence d'un groupement fonctionnel thioether en α de la triple liaison. Action catalytique du cuivre

The addition reaction of ethylmagnesium bromide to the triple bond of the compounds of general formula EtSCH₂CCCH₂Y (where Y is the basic group OH, OR, NR₂, or SEt) is very weakly activated by the thioether group. Catalysis by magnesium impurities may be involved.With 1-ethylthio-4-dialkylamino-2-butynes (Y NR₂), (E) trisubstituted ethylenic compounds are selectively obtained. The reaction more readily occurs after the addition of cuprous chloride to the Grignard solution, and then its stereoselecitvity may be reversed.     

Complexes dinucleaires pontes des metaux d8: VII. Reactions d'addition oxydante d'halogenures d'alkyle et d'acycle aux complexes μ-halogenes du rhodium(i) [RhX(CO)(PR3)]2. Structure cristalline de [RhCl(CO)(PMe2Ph)(Me)(Br)]2

The halogen bridged binuclear complexes of rhodium(I) [RhCl(CO)(PR₃)]₂ undergo oxidative addition with methyl halides to yield the complexes [RhCl(CO)(PR₃)(Me)(X)]₂ (X = Cl, Br). The crystal and molecular structures of [RhCl(CO)(PMe₂Ph)(Me)(Br)]₂ have been determined from a single crystal by use of X-ray crystallographic methods. The space group is Pca2₁ or Pacm with a 19.501(5), b 10.381(4), c 13.641(5) e? Z = 4. Parameters of 30 nonhydrogen atoms in the space group Pca2₁ were refined by the full-matrix least squares technique to a conventional R factor of 0.073. In a binuclear unit, each rhodium atom is in an octahedral environment being bonded to a carbonyl group, a methyl group and a tertiary phosphine ligand and three halogen atoms for which, due to a disorder phenomenon, the diffusion factors have been determined as the average between those of chlorine and bromine atoms. In solution the cis-migration of the methyl groups occurs, leading to the acetyl complexes. In the case of CH₃I, it is shown that an equilibrium is present in solution: [RhCl(CO)(PR₃(Me)(I)]₂ ? [RhCl(COMe)(PR₃)(I)(solvant)]₂] Carbonylation reactions shift this equilibrium to give the complexes [RhCl(CO)(COMe)(PR₃(I)]₂. Such complexes are readily prepared by direct oxidative addition of acyl halides to the compounds [RhCl(CO)(PR₃)]₂.     

Etude des aldimines lithiees : I. Synthese d'aldehydes ω-halogenes et de dialdehydes

Aldimines are conveniently metallated, at a position α to the functional group, by using very powerful bases i.e. activated lithium dialkylamides generated in situ from lithium and a secondary amine in benzene/hexamethylphosphoric triamide. The anions obtained are alkylated with various ω,ω′-dihalogenoalkanes to give, after aqueous acid hydrolysis, good yields of ω-halogenated aldehydes and dialdehydes.     

Électrochimie dans le chlorure d'acétyle: I. Étude des complexes chlorure et acétylium

Complex formation with salicylic acid and calcium and bivalent copper ions has been investigated from potentiometric measurements at 25°C, μ=0.1 (NaNO₃), using glass (H⁺) and specific ion (Ca²⁺ and Cu²⁺ electrodes. From least squares treatment of the data, the following species were found to exist (log β values in parentheses; salicylic acid=H₂Sal): HSal (13.30), H₂Sal (16.36), CuHSal (15.24), CuH₂Sal₂ (31.23), CuSal (10.34), CuSal₂ (19.01), CaHSal (15.57), CaSal (5.77), CaSal₂ (11.88), HSal (11.22), H₂Sal (14.34). The previously reported species CuH₃Sal₃ and CuH₄Sal₄ were found not to exist.     

Insertion d'une phosphine acétylénique dans un complexe μ-alkylidénique du tungstène suivie de la rupture d'une liaison CP

The diphosphinoalkyne Ph₂PCCPPh₂ (2) reacts with the μ-alkylidene complex (CO)₉W₂[CHCHC(CH₃)₂] (1) to give, upon insertion of the alkyne into one of the CW bonds of the bridging carbene followed by rupture of a CP bond, a phosphido complex (CO)₈W₂[C(PPh₂)CCHCHC(CH₃)₂] PPh₂ (3). An unexpected long-range ¹H³¹P coupling, through five bonds, is observed in complex 3.     

Etudes stereochimiques dans la serie du silacyclopentane: synthese de dimethyl-1,2 alcoxy-1 silacyclopentanes a stereoisomere preferentiel

The stereoselective alcoholysis of 1,2-dimethyl-1-chlorosilacyclopentane and the catalytic alcoholysis of 1,2-dimethylsilacyclopentane are described.     

Contribution a l'etude des metaux asymetriques—II : Voie d'acces aux premiers complexes pseudo tetraedriques du chrome (0) enantiomeriquement stables

Modes of access to several pseudo tetrahedral complexes having an asymmetric chromium atom are presented. The chirality at the metal atom is demonstrated by NMR. The first enantiomers of chiral chromium (0) are obtained in optically pure forms.     

Utilisation des melanges H2O−H2SO4−SO3 en tant que solvants: II. Etude d'hydrocarbures aromatiques dans les oleums et l'acide sulfurique concentre ou pur

Solutions of toluene, naphthalene, perylene and coronene in concentrated sulphuric acid and in oleums were investigated by electrochemical and spectroscopic techniques. More particularly, the naphthalenedisulphonic acids which are formed from naphthalene in most of these media, can be oxidized in a one-electron step; the corresponding cations are not stable. Coronene dissolves in concentrated sulphuric acid solutions into Cor^·+; this radical gives an anodic wave corresponding to a reversible one-electron step, Cor²⁺ being unstable; these properties remain identical in dilute oleums, only if operations are carried out at 5°C.     

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.     

Polysilane derivatives of the transition metals III. Preparations and spectra of manganese and iron derivatives

The preparations of derivatives of Mn(CO)₅, Mn(CO)₄PPh₃ and π-Cp(CO)₂Fe containing the polysilyl ligands (Me₃Si)_nMe_3?nSi— (n = 1–3) are presented. The infrared and proton NMR spectra of the compounds are given and for the Mn(CO)₅ derivatives, force constants are derived and discussed in terms of the σ-donor/π-acceptor properties of the silyl ligands.     

Untersuchungen über benzylübergangsmetallverbindungen : III. Darstellung und eigenschaften des tetrabenzylthoriums

Tetrabenzylthorium can be obtained in crystalline form by interaction of benzyllithium with thorium tetrachloride. All properties of the compound indicate σ-bonds between the metal atom and the benzyl groups. The IR spectrum of tetrabenzylthorium is discussed together with that of tetrabenzylzirconium.     

Influence des impuretés sur la conductivité cationique dans l'oxyde de magnesium monocristallin

The measurement of the cationic transport numbers in MgO single crystals has been performed, using the dilatocoulometric method. In the oxygen partial pressure range 1 to 10^?10 atm at temperatures of 1100 to 1300°C the ionic conduction in MgO is extrinsic.     

Réduction électrochimique des sels d'ammonium quaternaire: Partie V. Orientation sélective en faveur de la réaction de dimérisation dans le cas du cation paranitrobenzyltriméthylammonium

Whereas the reduction of the benzyltrimethylammonium (BTA) cation can be oriented selectively by the choice of the cathode metal, reduction of para-nitrobenzyltrimethylammonium (pNO₂BTA) cation leads to the formation of the dimerization product only. The 4,4′-dinitrobibenzyl results from the dimerization of the pNO₂ΦCH₂ radical which in turn arises from the decomposition of the (pNO₂BTA)^? radical anion. The reduction of the pNO₂BTA cation is related to that of other nitro derivatives of the type XΦNO₂ (X=pCH₃, H, pCF₃ and mNO₂) as is shown by the linear correlation between the half-wave potentials E_1/2X and Hammett's substituent constants σ_X.     

Thermogenese: Application des filtrages electronique et numerique inverses en calorimetre a conduction

The results of the application of the numerical and electronic inverse filtering to the same calorimetric output are presented. These two techniques, used to reduce the inertia of conduction calorimeters, give very similar results.     

Organocuivreux vinyliques : II. Deuterolyse,iodolyse, couplage et alcoylation stereospecifiques des vinyl-cuivres

Vinylcopper derivatives, obtained by stereospecific addition of alkylcopper compounds to 1-alkynes, are transformed with retention to various ethylenic structures; 1-deutero-1-alkenes, symmetrical conjugated dienes, 1-iodo-1-alkenes, di- or tri-substituted alkenes and primary or secondary allylic alcohols.     

Cristallochimie de TlIII6TeVIO12 et TlI6TeVIO6E6: un exemple original de l'activite´ste´re´ochimique de la pairee´lectronique 6s2(E) du thallium(I)

Both crystal structures of Tl₆TeO₁₂ and Tl₆TeO₆E₆ compounds have been determined, the former by X-ray single crystal techniques, the latter by powder neutron diffraction techniques. They crystallize in the trigonal system, space groupR3¯ the corresponding hexagonal cell parameters area = 9.645(2) Å,c = 9.421(2) Å, anda = 9.5722(3) Å,c = 9.3494(4) Å, respectively, withZ = 3. In both compounds tellurium(VI) is octahedrally coordinated to oxygen atoms with TeO distances of 1.936Åfor the Tl(III)-containing compound, i.e., Tl₆TeO₁₂, and 1.946Åfor Tl₆TeO₆ (Tl(I)). Tl(III) is surrounded by seven oxygen atoms sitting at the summits of a distorted monocapped trigonal prism. Tl(I) is linked to three oxygen atoms, forming a distorted TlO₃ pyramid. The lone pairs brought by Tl(I) are in the positions precedingly occupied by oxygen atoms in the crystal structure of Tl₆TeO₁₂. This is an outstanding example of the crystallochemical role of the lone pairsE which act like oxygen atoms, making Tl^I₆Te^VIO₆E₆ isostructural with Tl^IIITe^VIO₁₂. Structural relationships with fluorite type network are discussed.     

Elementorganische amin/imin-verbindungen : XV. [Bis(trimethylsilyl)]amino-n-t-butylphospha(III)azen,ein reaktionsfähiges ylid des dreibindigen phosphors

[Bis(trimethylsilyl)]amino-N-t-butylphospha(III)azene is made in a two step synthesis. It can be oxidized by sulfur and selenium to a stable monomeric metathio- and metaselenophosphoric acid derivative and it forms with methanol the bis(amino)phosphine derivative which can be oxidized by CCl₄ to the aminophospha(V)azene derivative.     

Finite-field method calculations. III. Dipole moment gradients,polarisability gradients and field-induced shifts in bond lengths,vibrational levels,

In this paper, the finite-field method is applied in calculating polarisabilities and, by extension, polarisability gradients. The method is also used to examine the shifts in a number of properties induced by electric fields of given strength. Model calculations at the SCF and Cl levels are reported for LiH. Estimates of the Raman scattering intensity and depolarisation ratio, obtained from the calculated polarisability gradient components, are presented. The dipole moment gradient, which is related to the infrared absorption intensity, is also reported. The properties for which field-dependent shifts are given comprise bond length, vibrational levels, spectroscopic constants, harmonic force constant, first anharmonic constant and dipole moment gradient.     

Reaction des lithiens avec les organophosphores. Reaction d'addition du t-butyllithium sur le noyau benzenique des sels de phenylphosphoniums

A new reaction of organolithium compounds with phosphonium salts is described; reaction of t-butyllithium with dibenzylaminophosphonium or tetraphenylphosphonium bromides takes place through addition of the t-butyl group on a benzene ring at the position para to the phosphorus atom, the ylid formed reacts in a characteristic Wittig reaction with p-tolylaldehyde.