Preparation de β-cetonitriles via l'acylation du cyanacetate de trimethylsilyle par les anhydrides mixtes.

β-ketonitriles R¹COCH₂CN and R¹COCH(R²)CN are respectively prepared from (CH₃)₃SiOCOCHLiCN or R²CHLiCN by acylation reaction with mixed anhydrides RCOOCO₂Et.     

Studies of layered uranium (VI) compounds. VI. Ionic conductivities and thermal stabilities of MUO2PO4 · nH2O,where M = H,Li,Na,K,NH4 or 12Ca, and where n is between 0 and 4

We have measured the ionic conductivities of pressed pellets of the layered compounds MUO₂PO₄ · nH₂O, and correlated the results with TGA data. The conductivities (in ohm^?1 m^?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li⁺4H₂O, 10^?4; Li⁺, Na⁺, K⁺, and NH₄⁺3H₂O, 10^?4, 10^?2, 10^?4, and 10^?4; H⁺, Li⁺, and Na⁺1.5H₂O, 10^?2, 10^?4, and 10^?4; Na⁺1H₂O, 10^?5; H⁺, K⁺, and NH₄⁺0.5H₂O, all 10^?5; and H⁺, Li⁺, Na⁺, K⁺, NH⁺₄, and $\text{1}\text{2}\text{Ca}{}^{\mathrm{2+}}\text{}\text{OH}{}_2\text{O}$, 10^?5, 10^?5, 10^?4, 10^?5, 10^?5, and 10^?6. A ring mechanism is proposed to account for the high conductivity found in NaUO₂PO₄ · 3.1H₂O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO₂PO₄(A ? x)H₂O, where x can be between 0 and 0.3.     

Zur koordination mehrfunktioneller thioether in cyclopentadienyleisen-komplexen

[C₅H₅Fe(CO)₂thf]⁺ reacts with the ligands LL and LLL to give the cations [C₅H₅Fe(CO)₂LL]⁺ (LL = RS(CH₂)_nSR, 1,4-dithiane) and [C₅H₅Fe(CO)₂LLL]⁺ (LLL = 1,3,5-trithiane, tris(methylmercapto)methane) containing monodentate coordinated sulfur ligands. In a similar way, sulfur ligand bridged dinuclear dications [(C₅H₅Fe(CO)₂)₂(μ-LL)]²⁺ and [(C₅H₅Fe(CO)₂(μ-LLL)]²⁺ and tri-nuclear trications [(C₅H₅Fe(CO)₂)₃(μ-LLL)]³⁺ are formed. Irradiation of the mononuclear cations gives the chelate complexes [C₅H₅Fe(CO)(η²-LL)]⁺.     

Gas-phase electron diffraction determination of the molecular structure of perfluoro(methyloxirane)

The molecular geometry of perfluoro(methyloxirane) has been studied using gas-phase electron diffraction data, effective least-squares refinement of the structure being achieved with the aid of constraints to limit the number of variable parameters. With the CCF₃ bond constrained to be 0.078 Å longer than the ring CC, the refined bond- length values CF (av.) = 1.323(2), CO (av.) = 1.410(8), and CC (ring) = 1.467(7) Å ($\text{r}$_g values, with e.s.d. in parentheses) were obtained; the angles between ring bonds and substituent CF bonds were CCF (av.) 121(1) and OCF (av.) 114(1)^o, the corresponding parameters involving the bulkier CCF₃ fragment being larger by 3^o in each case [∠CCCF₃ 124(1)^o∠OCCF₃ 117(2)^o]. The remaining refined parameters were ∠CCF(of CF₃) = 110.6(4)^o and τ , a torsion angle defining the orientation of the CF bonds of the CF₃ group with respect to ring bonds, = 29(2)^o. Dependent bond angles possessed the values 62.7 (COC), 58.7 [OCC (ring)], 108.3 [FCF (CF₃ group)], 114 [FCF (ring CF₂)], and 111^o (FCCF₃).     

Lineare oligophosphaalkane: XVIII. Addition Ph-funktioneller methylenbisphosphane an die MoMo-Dreifachbindun in (η5-C5H5)2Mo2(CO)4

By means of the addition of the PH-functional methylenebisphosphanes R¹R²-PCH₂PR³H (PCP) to the MoMo triple bond in (η⁵-C₅H₅)₂Mo₂(CO)₄(MoMo) the complexes (η⁵-C₅H₅)₂Mo₂(CO)₄(PCP) containing a five-membered ring system Mo₂P₂C are obtained. Starting with unsymmetrically substituted methylenebisphosphanes R′₂PCH₂PRH only one isomer is formed, while the disecondary derivatives RHPCH₂PHR (as the diastereomeric mixture) gave two isomers of (η⁵-C₅H₅)₂Mo₂(CO)₄(PCP) (A₂ and AB) as indicated by the ³¹P{¹H} and ¹³C{¹H} NMR spectra.X-ray structural analysis of the derivative of the racemate of t-BuHPCH₂PH(t-Bu) space group C2/c, monoclinic, a 18.034(2), b 14.909(1), c 11.106(1) Å, α 90, β 99.788(8), γ 90°) reveals a puckered Mo₂P₂C five-membered ring system (dihedral angle PMoMo′P′ 54.4(2)°) with square-pyramidal coordination geometry at the Mo atoms. Two of the CO ligands (C(6)O(1) and C(6′)O(1′)) are almost coplanar with the molybdenum atoms, while the terminal CO groups (C(7)O(2) and C(7′)O(2′)) are about orthogonal (dihedral angle C(7)MoMo′C(7′) 88.4(3), MoMo′ 3.2109(4), MoP 2.4567(8), PC(8) 1.834(3), PH(P) 1.37(3) Å).     

Electron-transfer transitions during the collision of O2, N2, NO and CO with their respective ions

An improved theory of electron transfer absorption is proposed. The possibility of such absorption during the collision of ion-molecule pairs is discussed and frequencies for the O₂O₂⁺, O₂O₂^?, NONO^?, COCO⁺ and N₂N₂⁺ pairs are estimated. Oscillator strengths are also estimated for the O₂O₂⁺ pair.     

Synthese d'ethers et de thioethers allyliques fluores par catalyse par transfert de phase

Several fluorinated allylic ethers, thioethers and diethers have been prepared in excellent yields by phase transfer catalysis (CTP). The used halogenated compounds are allyl chloride and bromide, p-chloromethylstyrene. The used fluorinated alcohols are aromatic pentafluorophenol and various aliphatics: CF₃CH₂OH, CF₂HCF₂CH₂OH ClCF₂CF₂CH₂OH,C₆F₁₃C₂H₄OH, HOCH₂CF₂CFClCF₂CH₂OH and HOC₆H₄C(CF₃)₂C₆H₄OH. All these new compounds have been characterized by ¹H and ¹³C NMR. We conclude that CTP is the best method to obtain allylic and diallylic compounds.     

Intramolecular metallation of o-carboranylphosphine-palladium(II) and -platinum(II) complexes

Preparation of trans-[P^cb₂MCl₂]-type complexes (P^cb= o-HCB₁₀H₁₀CCH₂PPh₂ M = Pd, Pt), which readily undergo intramolecular metallation through the BH bonds of the carborane cage to form exocyclic compounds involving a $\text{PCCBM}$ bond system, is described. Both monomeric compounds, trans-[MCl(B-P)P^cb], and bridged complexes, such as [Pd₂Cl₂(BP)₂], are formed, where (BP) is intramolecular-metallated carborane phosphine. The bridging bond is readily cleaved under the action of various ligands (pyridine, PEt₃, etc.) to form monomeric compounds.     

Compounds containing CSF4 and CS+F4

The preparations of CH₂SF₄ and CH₃CHSF₄ are presented and the structures are discussed. Addition reactions of polar species give a wide range of new compounds, like Hg(CH₂SF₅)₂, F₄AsCH₂SF₅, cisBrSF₄CH₃, cisF₅SeOSF₄CH₂Br, a.o. While CH₂SF₄ decomposes at room temperature slowly to CH₂CH₂ and SF₄, at high temperatures HF and CSF₂ are formed. CH₃CHSF₄ gives mainly CH₃CHF₂ at room temperature. The “saturated” compounds CH₃SF₅ and C₂H₅SF₅ have been prepared. They react with SbF₅ in SO₂ at low temperatures to form the cations CH₃SF₄⁺ and C₂H₅SF₄⁺. The CH₃SF₄⁺ ion has been investigated in detail by nmr methods at low temperatures. It decomposes to CH₃ and SF₄, which react further in the SO₂/SbF₅ system to CH₃OSO⁺ and SF₃⁺.     

Synthesis and structure of hexabenzyl-dimolybdenum (MoMo)

The homoleptic benzyl Mo₂(CH₂Ph)₆ has been obtained by reaction of either MoCl₄(thf)₂ or Mo₂(OPrⁱ)₆ with Mg(CH₂Ph)₂. The dark-red, sparingly soluble complex has been characterized by ¹H and ¹³C NMR as well as by a solid-state structure analysis. Pertinent bond distances (Å) and angles (°) for the unbridged, ethane-like molecule which contains crystallographic S₆-symmetry are: MoMo = 2.175(1), MoC = 2.162(2), MoMoC = 97.61(6), and MoCC(Ph) = 98.9(1).     

Reaction of PF5·CH3CN with sulfide

Nitriles react with PF₅ and also with AsF₅, SbF₅ forming 1:1-adducts. Using C₂Cl₃F₃ as a solvent is of advantage for this reaction. PF₅·CH₃CN and [N(C₂H₅)₄]SH give [N(C₂H₅)₄][P₂S₂F₈] with a sulfur double bridge and hexafluorophosphate in acetonitrile [1]. In case of AsF₅·CH₃CN a salt with the anion [AsF₅NHCSCH₃]^? has been isolated [2]. Following products have been confirmed in a reaction mixture of PF₅·CH₃CN and SH^? in acetonitrile by NMR (³¹P and ¹⁹F): [PF₆]^?, [F₅PSPF₅]^2?,

, F₄PSH, F₃PS, HPS₂F₂, [PS₂F₂]^?, [F₅PNC(SH)CH₃]^?, [F₅PNHCSCH₃]^?, [F₅PSH]^?. With a ratio PF₅·CH₃CN: SH^? = 2:1 the S-bridge-complexes are prefered whereas in case of a ratio 1:1 the non-bridged P-complexes are the main products.     

Über polystannane: II. I(t-Bu2Sn)4I,ein 1,4-difunktionelles tetrastannan

The compound I(t-Bu₂Sn)₄I has been synthesized by controlled cleavage of the related cyclotetrastannane (t-Bu₂Sn)₄ with iodine in toluene. Both compounds have been investigated by mass, NMR and vibrational spectra. I(t-Bu₂Sn)₄I: δ(¹¹⁹Sn_terminal) 67.7, δ(Sn_central) 17.4 ppm; ¹J(SnSn) 2199 (terminal-central) and 1575 (central-central), ²J(SnSn) 20 (terminal-central), ³J (SnSn) 307 Hz (terminal-terminal); ν(SnSn) 119, ν(SnI) 167 cm^?1. (t-Bu₂Sn)₄: δ(Sn) 87.4 ppm; ν(SnSn) 125 cm^?1. The crystal structure of I(t-Bu₂Sn)₄I has been determined (R = 0.071): bond lengths SnSn 289.5(1) (terminal-central) and 292.4(1) (central-central), SnI 275.3(1) pm. The conformation of the chain ISn₄I is all trans.     

Etude structurale de composes organosilicies par diffusion rayleigh depolarisee : V. Proprietes acceptrices d'electrons du silicium dans les systemes SiOC et SiOSi

Among the characteristic properties of the SiOC and SiOSi systems relative to those of the corresponding COC systems, the optical anisotropy is a new example which shows the electron-acceptor ability of silicon by (p → d)π interaction in compounds of the type R₃SiO∑ (R = Me, Et, Pr; ∑ = H, Me, SiMe₃, CH₂-t-Bu, CHMe₂, CMe₃). Effectively, the existence of a linear relationship between the optical anisotropy or the principal optical polarisabilities of the OSiR₃ groups and the Taft's parameter σ^★ of the ∑ groups in this series of compounds, shows that the electron-accepting character of silicon increases with increasing electron-donating ability of the group ∑; this relationship simultaneously translates an increase of the electronic density and mobility perpendicular to the OSi axis to the detriment of the parallel direction. In application, we calculated the σ^★ values for the groups ∑ = SiEt₃, SiPr₃ and the OSiMe₃ optical anisotropy value in PhOSiMe₃.     

Nature of the hydrogen bridge in transition metal complexes: I. Molecular orbital calculations of binuclear carbonyls of Cr,Mo Fe and Ni with single hydrogen bridges

Determination of the electronic structure was performed by the parameter-free Fenske-Hall method for the complexes [(CO)₅MHM(CO)₅]⁻ with D_4h, C_2v and C₂ symmetries (wehre M = Cr, Mo) as well as for the complex [(CO)₃NiHNi(CO)₃]⁻ with C_2v and D_3h symmetries and for the complex [(CO)₄FeHFe(CO)₄]⁺ with a D_3h symmetry.The character and stability of the metalhydrogenmetal bridge bond in each of these complexes was compared. The effect of lowering the symmetry on the electronic structure of these complexes is also discussed. The influence of the bridging hydrogen atom on terminal ligands, i.e. its cis effect, was characterized.     

Bis(fluorbenzoyloxy)methylphosphanoxide

Bis(fluorbenzoyloxy)methyl phosphane oxides CH₃P(O)[OC(O)R]₂ [R = C₆H₄2F (1), C₆H₄3F (2), C₆H₄4F (3), C₆H₃2,6F₂ (4), C₆H2,3,5,6F₄ (5)] were prepared by treating silver salts of carboxylic acids AgOC(O)R with CH₃P(O)C?₂ (IR-, ¹H-, ¹⁹?F-and ³¹P{¹H}-NMR-data). The mixed anhydrides 1–5 show unusual thermal stability at room temperature. Stability against hydrolysis decreases with increasing number of fluorine-atoms. The reaction of R′P(O)C?₂ [R′ = CH₃, C₆H₅, (CH₃)₃C] with M^IOC(O)R_F [R_F = CF₃, C₂F₅, C₆F₅; M^I = Ag^I, Na^I T?^I] was investigated.     

Studies pertaining to the mechanism of “Pt(PCy3)“ addition. The reaction of MPt(μ-H)(μ-PnPr2)Pt(CO)(PCy3) with Pt(C2H4)2(PCy3)

The reaction of Pt(C₂H₄)₂(PCy₃) with (OC)₄M(μ-H)(μ-PⁿPr₂)Pt(CO)(PCy₃, (1: M  Cr, Mo, W) occurs in a highly specific, kinetically controlled manner to give MPt₂(μ²_MPt-CO)(η²_PtPt-H)(μ²_MPt-PⁿPr₂)(CO)₄ (PCy₃)₂ (5), as the first formed trimer. The trimer 5 (M  Mo, W) isomerizes to give MPt₂(μ²_PtPt-CO) ((μ²_MPtH)(μ²_MPt-PⁿPr₂)(CO)₄)PCy₃)₂ (6) which in turn isomerizes to MPt₂μ²_MPtCO)(μ²_MPt (μ²_PtPt-PⁿPr₂)(CO)₄(PCy₃)₂ (7, as the final isolable product. These results provide a detailed insight into the mechanism of “Pt(PCy₃) addition”, a cluster assembly process.     

Fourier transform heteronuclear magnetic triple resonance in complex spin systems—III: Symmetrical ditertiary phosphine complexes of group VI metal carbonyls

Magnetic multiple resonance experiments of the types ¹³C-{³¹P, ¹H}, ¹³C{¹H} and ³¹P{¹⁸³W, ¹H} have been used to determine the magnitudes and signs of PC and PP coupling constants in the symmetrical complexes LM(CO)₄ (L = Ph₂P(CH₂)_nPPh₂, Ph₂PN(H)PPh₂, (Ph₂P)₂CCH₂, cis-Ph₂PCHCHPPh₂; M = Cr, Mo, W; n = 1–4). A knowledge of the signs of the couplings shows that they display a systematic pattern of behaviour according to metal atom and ring size and this may have diagnostic value. ¹³C, ³¹P and ¹⁸³W chemical shifts are also reported.     

Diorganotin(IV) bis(O,O-alkylenedithiophosphates)

O,O-Alkylenedithiophosphates of diorganotin(IV) of the type R₂Sn[SP(S)O₂G]₂ (R = Me, Et, n-Bu, Ph; G = CH₂CMe₂CH₂, CMe₂CMe₂, CMe₂CH₂CHMe) have been synthesized by the reactions of diorganotin(IV) dichlorides with ammonium O,O-alkylenedithiophosphates or that of diorganotin(IV) oxides with O,O-alkylenedithiophosphoric acids in 1:2 molar ratio in benzene. These new complexes are white solids which are soluble in common organic solvents and are monomeric in refluxing benzene; and they have been characterized by elemental analysis and by different spectroscopic (IR, ¹H, ¹³C, ³¹P and ¹¹⁹Sn NMR) studies, on the basis of which a six coordinated octahedral structure has been suggested in solution.     

Fluoration de telomeres polyhalogenes par le fluorure de potassium (2ème partie). Synthese d'olefines perfluorees de hauts poids moleculaires

Fluorination of chlorofluorinated telomers of general formula Cl(CFClCF₂)_nCCl₃ (n ? 7) was studied using potassium fluoride in dimethylsulfoxide as fluorinating agent. The reaction leads to a mixture of perfluorinated linear olefins having 15 to 30 carbon atoms : CF₃(CF₂)_pCFCF(CF₂)_mCF₃ (p + m = 2n?3).We perfected a method to determine molecular weights of the telomers by gel permeation chromatography (G.P.C.). The olefins obtained by fluorination are analyzed both by vapor phase chromatography (V.P.C.) and by ¹⁹F nuclear magnetic resonance (N.M.R.).     

C-Phosphinosubstituierte phosphaalkene und ein erstes carbodiphosphan

A series of novel phosphaalkenes, YoshPCHP(X)R (Yosh = 2,4,6-^tBu₃C₆H₂) has been prepared, as well as the first stable carbodiphosphane, YoshPCPYosh, which has been characterized by elemental analysis, NMR and mass spectroscopy.