Composés d'addition des chlorures de terres rares avec le méthanol,l'éthanol et le propanol-2. Préparations,solubilités et réactions de transsolvatation

By reaction of hydrated rare earths chlorides (M = La, Nd, Sm, Gd, Dy, Er, Yb, Y) with orthoformates, the following adducts have been prepared: MCl₃· 4MeOH, MCl₃ ·3EtOH (M = La, Nd, Sm, Gd, Yb), MCl₄ · 4 EtOH (M = Dy, Er, Y); adducts MCl₃ · 3iso-PrOH have been prepared by successive action of methyl orthoformate and of 2-propanol. The solubilities of these adducts in the corresponding alcohols at 25° (for the lanthanum adducts equally at 0 and 50°) are given. Two examples of the transsolvatation of these compounds, yielding adducts with weakligands, are described.     

Reactions of Chalcogen Oxide Chlorides EOCl2 (E = S,Se) with Group 5 Metal Chlorides

The tantalum derivative TaCl₅(SOCl₂), thermally unstable above 290 K, was prepared from Ta₂Cl₁₀ and SOCl₂ and studied by X‐ray crystallography at 180 K. Tantalum atom is octahedrally coordinated by five chlorides at Ta–Cl distances comprised between 2.32 and 2.36 Å and by the oxygen atom of SOCl₂ at the Ta–O distance of 2.34 Å. No evidence for the existence of an analogous compound of niobium(V) has been obtained. The halides of Group 5, M₂Cl₁₀, M = Nb, Ta, react with SeOCl₂ to give the solid adducts MCl₅(SeOCl₂) stable at room temperature. The reaction of NbCl₅(SeOCl₂) with SOCl₂ affords [SeCl₃][NbCl₆] which contains trigonal‐pyramidal (SeCl₃)⁺ cations with Se–Cl distances of 2.13–2.16 Å and octahedral [NbCl₆]^– anions (Nb–Cl: 2.27–2.45 Å). A distorted octahedral coordination around the selenium atom is achieved by additional interactions [Se…Cl, 2.81–2.98 Å] between selenium and the [NbCl₆]^– anion.     

Composés d'addition des halogénures de niobium(V) et de tantale(V). VII. Composés du chlorure de niobium(V) avec l'oxytrichlorure et l'oxytribromure de phosphore

The adducts NbCl₅ · OPCl₃ and NbCl₅ · OPBr₃ are observed in chloroform solution by ³¹P-NMR spectroscopy. The enthalpy and entropy of activation for the exchange reaction between bulk and coordinated OPCl₃ are found equal to 17 ± 3 kcal/mole and 18 ± 10 cal/°mole. The stability of NbCl₅ · OPCl₃ is compared on a semi-quantitative basis to the stability of other adducts NbCl₅ · OPR₃ (R = Br, OMe, NMe₂).     

Composés d'addition des halogénures de niobium(V) et de tantale(V) IV. Stabilité relative des composés de chlorures avec quelques nitriles

The relative stability constants of the adducts of MCl₅ (M ? Nb, Ta) with acetonitrile, halogenoacetonitriles, pivalonitrile, acrylonitrile and benzonitriles are determined in dilute solutions by NMR. methods. The stability of the adducts is controlled by inductive factors. Chemical shifts and analysis of the new compounds are reported.     

Adducts of niobium(V) and tantalum(V) halides. XIV. Structure and relative stability of the adducts with some phosphoryl compounds

The adducts of niobium(V) and tantalum(V) halides with some phosphoryl compounds have been studied in chloroform solution by ¹H- and ¹⁹F-FT-NMR. spectroscopy. These octahedral adducts of general formula MX₅ · L (M = Nb, Ta; X = F, Cl, Br; L = phosphoryl ligand) are monomeric and neutral. Their relative stability constants have been determined at ?60°. The stabilities are controlled by electronic effects of substituents on the phosphoryl group.     

Composés d'addition des halogénures de niobium(V) et de tantale(V): VI. Réactions d'échange des composés du chlorure de niobium(V) avec quelques nitriles

The ligand exchange reactions NbCl₅·?N + RCN* ? NbCl₅ · RCN* + RCN are studied by NMR. spectroscopy for R = Me₃C, Me, FCH₂, CICH₂, BrCH₂, ICH₂. The reaction is of zero order in RCN and of first order in NbCl₅ · RCN and thus a dissociative mechanism is suggested for all the ligands studied. The enthalpies and entropies of activation are determined over 50° to 90° temperature ranges. There is a linear correlation between ΔG≠ and the free enthalpy of formation of NbCl₅ RCN. However this correlation is shown to hold only for series of adducts having the same donor group.     

Electrochemical Studies of Tantalum(V) Chlorides and Bromides in Acetonitrile. Electrochemical Generation of Tantalum(IV) Species

The electrochemical properties of tantalum halides, TaX₅ Et₄NTaCI₆ and Bu₄NTaBr₆ (X = Cl^? and Br^?) were investigated in rigorously dried acetonitrile using cyclic voltammetry and constant potential electrolysis. A special vacuum electrochemical cel1 equipped with a sample loading device and an AI₂O₃ column was used in order to prevent the hydrolysis of tantalum halides with the small amount of water present in “dry” acetonitrile. Two one-electron reduction waves were observed for al1 tantalum(V) species which correspond to consecutive Ta(V) → Ta(IV) and Ta(IV) → Ta(III) reduction. The E_1/2 values for the Ta(V) → Ta(IV) reduction process are criticalIy dependent on the number of CI^? ligands coordinated to the tantalum atom. As the number of Cl^? is increased from 4 to 5 and 6, it becomes more difficult, by 0.4 V, to reduce Ta(V) to Ta(IV). Constant potential electrolysis at –20°C generates Ta(IV) species; thus TaCl₆ ^2-. TaBr₆ ^2-, TaCl₅NCMe^?, TaBr₅NCMe^? and TaCI₄(NCMe)₂, are obtained in acetonitrile solution after electrolysis. It was found that the reduction product of TaCl₅NCMe depends upon the temperature. At a higher temperature (0°C) the initial electron transfer step is fol1owed by a chemical reaction in which some of the product, TaCI₅NCMe^?, reacts with the starting material, TaCI₅NCMe. to produce TaCl₆ ^? and TaCl₄(NCMe)₂. At lower temperatures (–20°C) the rate of the folIowing chemical reaction is much slower and the reduction product is almost exclusively TaCl₅NCMe^?.     

Etude de composés d'addition des acides de Lewis XXVIII. Constantes de Hammett et vibration carbonyle des composés formés par TiCl4 et SbCl5 avec des chlorures de benzoyle parasubstitués

The adducts of benzoyl chlorides p-substituted by CH₃O? , CH₃? , and H? with the electronic acceptors SbCl₅ and TiCl₄ have been prepared, and the IR. absorption spectra of the solid products studied.     

Composés d'addition des halogénures de niobium (V) et de tantale(V): III. Détermination de constantes de stabilité par résonance magnétique nucléaire

In view of a systematic study of the Lewis acidity of niobium (V) and tantalum (V) halides, NMR. methods for the determination of stability constants are discussed. In the case of rapid exchange chemical shifts are used to determine the relative amounts of adduct(s) and free base(s) in equilibrium. In the case of slow exchange the relative concentrations of the species are given by the peak areas.     

Mass spectral studies of some complexes of niobium(V) and tantalum(V) with chloro,alkoxy, acetylacetonato or salicylaldehydato ligands

Mass spectra of complex compounds of niobium (V) and tantalum (V) of the type MCl₂(OR)₂L have been measured, where M = Nb and Ta; HL = 2,4-pentanedione, R = CH₃, C₂H₅ and HL = Salicyladehyde, R = CH₃. The fragmentation upon electron-impact depends on the nature of the ligands and to a minor extent on the central metal atom. A fragmentation scheme has been constructed on the basis of measurements of metastable transitions and accurate masses of important fragment ions. Rearrangement reactions involving hydrogen migration among ligands have been observed.     

Etude des composés d'addition des acides de Lewis - XXXV. Note sur les composés d'addition entre amides et,respectivement, PdCl2 et PtCl2

The adducts of dimethylformamide, diethylformamide, dimethylacetamide and diethylacetamide with PdCl₂ and PtCl₂ have been prepared and the IR. spectra of the compounds in nujol mull or in CH₂Cl · CH₂Cl solution are studied. The lowering of the carbonyl frequency (amide I) shows that the metal is linked by a dative bond to the amide oxygen atom acting as a donor; the lowering is about 33 to 59 cm^?1. The decrease of the frequency of the carbonyl group vibration, observed in these cases as for other addition compounds of Lewis acids, is due to an intramolecular electronic displacement in the direction of the amid oxygen atom.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XVIII. Darstellung und Eigenschaften von Vanadintetrabenzyl und von Benzyltantalchloriden

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XVIII. On the Preparation and Properties of Tetrabenzyl Vanadium and Benzyl Tantalum Chlorides Pure tetrabenzyl vanadium was isolated and characterized by elementary analyses, EPR and ¹H-NMR spectra, by hydrolysis and thermal decomposition. — Experiments for the preparation of tetra or pentabenzyl compounds of niobium and tantalum failed, but we could prepare C₆H₅CH₂TaCl₄, (C₆H₅CH₂)₂TaCl₃, and (C₆H₅CH₂)₃TaCl₂, the last two in form of bipyridyl complexes.     

Oxo- und Thiotantal(V)-Verbindungen: Synthese von TaOX3 und TaSX3 (X = OR,SR)

Oxo- and Thiotantalum(V) Compounds: Synthesis of TaOX₃ and TaSX₃ (X = OR, SR) TaO(OR)₃ [R = ^tC₄H₉, Mes* ( 2 )], TaO(SR)₃ [R = ^tC₄H₉, p-Tolyl], TaS(OR)₃ [R = ^tC₄H₉, Mes* ( 6 )] and TaS(SR)₃ [R = ^tC₄H₉, p-Tolyl] have been prepared by reaction of TaOCl₃ and TaSCl₃ with LiOR or LiSR. The reaction of TaCl₅ with an excess of LiOMes* yields the chlorotantalum(V)compounds TaCl₃(OMes*)₂ and TaCl₂(OMes*)₃ ( 10 ). The synthesis of TaCl₂(ⁿC₄H₉)(OMes*)₂ ( 11 ), Ta(Sp-Tolyl)₅ and TaCl₂(OEt)₃ · C₅H₅N are also described. 2, 6, 10 and 11 decompose in benzolic solution or by heating under vacuum splitting off 2,4,6-tri-tert-butyl-phenol, n-butane respectively, and forming cyclometallated tantalum(V) complexes with the bidentate ligand OC₆H₂^tBu₂CMe₂CH₂. TaCl₂(OEt)₃ was investigated by X-ray diffraction analysis; the crystal structure has been found to be a binuclear tantalum complex with two bridging ethoxo ligands.     

Über 2-(Dimethylaminomethyl)ferrocenyl-Verbindungen des Vanadiums,Niobs und Tantals

On 2-(Dimethylaminomethyl)ferrocenyl Compounds of Vanadium, Niobium, and Tantalum Former results, indicating the ability of (dimethylaminomethyl)ferrocenyl groups forming stable σ-organo transition-metal derivatives, were proved by the synthesis of heterobimetallic 2-(dimethylaminomethyl)ferrocenyl compounds of the three-valued vanadium as well as five valued niobium and tantalum from VCl₃, NbCl₅, TaCl₅, and (FcN)Li ( I ). The synthesis and properties of the compounds (FcN)₂VCl ( II ), (FcN)_nNbCl_5–n(THF)_x [n = 1, x = 1,3 ( III ); n = 2, x = 0 ( IV ); n = 3, x = 0 ( V )] as well as (FcN)TaCl₄(THF)_1.5 ( VI ) are reported. An intensive characterization, especially in respect of possible chelate structures was tried by i.r., ¹H-n.m.r., uv-vis, mass spectroscopy, and elementary analysis.     

Untersuchungen an Wasseraddukten des Antimon(V)-chlorids

Studies on Water Adducts of Antimony(V) Chloride Antimony(V) chloride gives four solid adducts of sbCl₅ · nH₂O I-IV (n = 1, 2, 3, 4) at room temperature. In the solid state I is oligomer by hydrogen bridges. In II, III, and IV are besides the adducts ionic products of the constitution H⁺(H₂O)_n] SbCl₅OH^? (n = 1, 2, 3). I and II reacts with sodium chloride to yield sodium hexachloroantimonate(V) · 1 resp. 2 H₂O. The vibrational spectra were discussed.     

Allyl complexes of dicyclopentadienyl-niobium(III) and -tantalum(III)

The synthesis and the properties of the complexes Cp₂TaCl₂, Cp₂M(allyl), Cp₂M(1-methylallyl) and Cp₂M(2-methylallyl) with M  Nb, Ta are described. The complex Cp₂TaCl₂ has one unpaired electron per tantalum atom, while the allyl complexes are diamagnetic. The IR and PMR spectra indicate that the allyl group is π-bonded to the metal. The mass spectra of the complexes are discussed; the thermal stability of the Cp₂Nb- and Cp₂Ta-(allyl) complexes was investigated by differential thermal analysis. The properties of the niobium and tantalum complexes are compared with those of the corresponding titanium complexes.     

Thermolyse von Phosphor(V)-Schwefel(VI)-nitridhalogeniden

Thermolysis of Phosphorus(V) Sulfur(VI) Nitride Halides Thermolysis of compounds of the type R₂PCl = N–SO₂X (R = Cl, CH₃, C₆H₅; X = F, Cl) results in the formation of the compounds R₂P(O)Cl and [NS(O)X]_n. Pyrolysis of the title compounds with longer chains yields, among others, the cyclic compounds III and IX. IX is also one of the decomposition products of a sulfamide derivative (XXI). Finally the thermal behaviour of carbon containing phosphorus(V) sulfur(VI) nitride chlorides has been investigated.     

Etude des composés d'addition des acides de LEWIS XXVII. Composés d'addition de la cyclohexanedione-1, 4 avec HgCl2, ZnCl2, et TiCl4

The adducts of cyclohexane-1,4-dione with HgCl₂, ZnCl₂, and TiCl₄ have been prepared, and the IR. absorption spectra of the solid products studied. The lowering of the carbonyl frequency shows that the acceptor is linked by dative bonds to the carbonyl oxygen donors. This result confirms the cyclohexane-1,4-dione · HgCl₂ structure which has been determined by X rays diffraction.     

Ionisation et Fragmentation en Spectrométrie de Masse. VI—Energie d'Activation de la Fragmentation Principale des Monohalogénobenzènes

The activation energy of the fragmentation [C₆H₅X?]⁺ → [C₆H₅]⁺ + X? (X = Cl, Br, I) is calculated by various methods. These results are compared with determinations of kinetic energy release and with rate constant values available in the literature.     

Etude de composés d'addition d'acides de Lewis. XXXVI [1] Composés d'addition de l'anthraquinone-9, 10 et de l'anthrone avec divers acides de Lewis

Solid stoichiometric adducts of 9, 10-anthraquinone with SbCl₅, ZrCl₄, TiCl₄ SnCl₄, AlCl₃, have been prepared. The very important lowering Δω of the IR. carbonyl frequency, ranging from ?175 cm^?1 for SbCl₅ to ?117 cm^?1 for SnCl₄, shows that the acceptor is linked by a dative bond to the carbonyl oxygen atom acting as a donor; an assignment of most of the fundamental IR. frequencies is proposed for anthraquinone and the mentioned adducts. Similar assignments and interpretation have been made for anthrone and its solid adduct with SbCl₅, ZrCl₄, TiCl₄, SnCl₄, AlCl₃ and ZnCl₂, where the C?O lowerings range from ?164 cm^?1 for SbCl₅ to ?97 cm^?1 for ZnCl₂.