Synthèse régiosélective par voie organométallique de pyridines, 4-picolines et 3,5-lutidines substituées en 2 par un groupe insaturé et/ou fonctionnel

A regioselective one-pot synthesis of 2-substituted pyridine derivatives from N-alkoxycarboxylpyridinium salts and α-unsaturated organozinc compounds is described. Similarly, functional alkynyl organomagnesium compounds lead to 2-alkynyl-ω-functional pyridines, from which (E)-2-alkenyl or 2-alkyl-ω-functio pyridines can be obtained by partial or complete reduction.     

Etude RMN1H et radiocristallographique de la stéreochimie de 3-aryl-9b-hydroxy-1,3,3a,9b-tétrahydro-4H-thiéno[3,4-c] benzo[e]pyrane-1-carboxylates d'éthyle. Configuration et conformation

The reaction of ethyl mercaptoacetate with some 3-aryliden-4-chromanones yields the corresponding ethyl 3-aryl-9b-hydroxy-1,3,3a,9b-tetrahydro-4H-thieno[3,4-c]benzo[e]pyrane-1-carboxylates. In spite of the presence of four chirality centers, the reaction is diastereospecific and gives a single diastereoisomer whose configuration and conformation were specified by its PMR data.The cis-fused tetrahydrothiophenic and dihydropyranic cycles lie in half-chair conformation. The 9b-hydroxyl and the 3-aryl groups are in a cis equatorial and pseudoequatorial disposition. The ester group, also cis with the hydroxyl group, presents a hydrogen bond with the hydroxyl. In the presence of an ortho-substituent at the phenyl group (particularly a chlorine atom), this phenyl group undergoes a notable rotation as is pointed out by a radiocristallographic study. A comparative study between the NMR and radiocristallographic data allows the confirmation of the maintenance of the same conformation in solid and dissolved states.     

Etude cristallographique et par résonance magnétique nucléaire du bismuthooctadécatungstate Na7[H2BiW18O60]·24H2O

The heteropolytungstate [H_nBiW₁₈O₆₀]^(9-n)- crystallized in a rhombohedral space group (R3, a = 19.575(4), c = 18.112(4) A) with seven sodium cations identified by X-ray diffraction. Electroneutrality implies the occurrence of two protons per molecule hence the formula Na₇[H₂BiW₁₈O₆₀]·24H₂O. Proton magnetic resonance with triiodomethane as standard also led to two protons per molecule of bismuthooctadecatungstate. They showed up at 6.18 ppm with respect to tetramethylsilane.     

Un nouveau polytungstate [As4W20O72(H2O)2]12− formé par la réunion de deux unités α-B-AsW9O33 par deux ponts originaux O2AsOWO4(H2O)

The heteropolytungstate [As₄W₂₀O₇₂(H₂O)₂]¹²⁻ is obtained by adding the corresponding amount of sodium tungstate to a solution of [As₂W₈O₃₀(OH)]⁷⁻ bringing the pH down to 4.2. Although [As₂W₈O₃₀(OH)]⁷⁻ is made of eight octahedrons assembled as in β-B-AsW₉, the reaction leads to a species containing two α-B-AsW₉O₃₃ units which are bound together by two novel bridges O₂As-O-W(H₂O)O₄ made of an AsO₃ pyramid and a WO₅(H₂O) octahedron sharing one vertex. Single crystals were grown from the mother liquor at 40 °C. The title compound crystallizes with a centric triclinic unit cell and with lattice constants a = 11.194(3), b = 13.516(3), c = 19.533(3) A, α = 77.99(1), β = 73.77(1), γ = 67.43(2) dg, V = 2603(1) ų. 9707 independent reflections collected at room temperature were used in refinement. Final reliability factors R and R_w are respectively equal to 4.02 and 4.66.     

Synthesis and structure of antimony iodide complexes: [Ph3MeP] + 2 [SbI5]2−, [Ph3MeP] + 3 [Sb3I12]3−·Me2C=O, [Ph3MeP] + 3 [Sb3I12]3−, and [Ph3MeP] + 3 [Sb2I9]3−

Complexes with antimony-containing anions, [Ph₃MeP] ₊ ² [SbI₅]^2? (I), [Ph₃MeP] ₊ ² [Sb₃I₁₂]^3? (II), [Ph₃MeP] ₊ ³ [Sb₃I₁₂]^3? · Me₂C=O (III), and [Ph₃MeP] ₊ ³ [Sb₂I₉]^3? (IV), were synthesized by reacting triphenylmethylphosphonium iodide with antimony iodide. The central atom in the cations of the complexes has a distorted tetrahedral coordination. In the trinuclear anions of complexes II and III, each of the terminal SbI₃ groups is bound to the central Sb atom through two μ₂- and one μ₃ iodine bridges (SbSbSb angles are 103.0° and 102.2°, respectively). In the binuclear anion of complex IV, antimony atoms are linked with each other via three bridging iodine atoms.     

Synthesis and structure of bismuth complexes [Ph3MeP] 2 + [BiI3.5Br1.5(C5H5N)]2− · C5H5N, [Ph4Bi] 4 + [Bi4I16]4− · 2Me2C=O, and [Ph3(iso-Am)P] 4 + [Bi8I28]4− · 2Me2C=O

Complexes [Ph₃MeP] ₂ ⁺ [BiI_3.5Br_1.5(C₅H₅N)]^2? · C₅H₅N(I), [Ph₄Bi] ₄ ⁺ [Bi₄I₁₆]^4? · 2Me₂C=O (II), and [Ph₃(iso-Am)P] ₄ ⁺ [Bi₈I₂₈]^4? · 2Me₂C=O (III) were synthesized by reactions of bismuth iodide with triphenylmethylphosphonium bromide, triphenylbismuthonium sulfosalicylate, and triphenylisoamylphosphonium iodide, respectively. The crystal structures of complexes I–III were determined by X-ray crystallography. The complexes contain, in addition to cations and solvent molecules, mono-, tetra-, and octanuclear anions, in which bismuth atoms are in octahedral coordination.     

Le problème de la réduction des intégrales électroniques dans la méthode L.C.A.O. améliorée

Résumé L'auteur reprend les principes de la méthode L.C.A.O. améliorée en vue d'une justification plus complète des procédés employés. La théorie des perturbations permet d'une façon simple de tenir compte de la corrélation entre les électrons grâce à l'introduction d'une fonction universelle de la distance entre deux électrons. Le problème est ainsi ramené de l'échelle moléculaire à l'échelle atomique. On montre que la corrélation entre les électrons entraîne la réduction des intégrales atomiques. Le problème de la réduction des intégrales coulombiennes est traité en détail. La possibilité de négliger les autres intégrales biélectroniques est ensuite examiné. Enfin est étudié le problème de la réduction des intégrales de coeur.

---

The principles of the improved LCAO theory are investigated to give a better justification for its methods. Perturbation theory allows a simple account for electronic correlation, when a universal function of interelectronic distance is introduced. The problem is hereby reduced from molecular to atomic scale. The reduction of electronic energy integrals by correlation is shown, especially for Coulomb integrals. The possibility of neglecting the other bielectronic integrals is examined. Finally the problem of core integral reduction is studied.

---

Zusammenfassung Die Grundlagen der verbesserten LCAO-Methode werden untersucht, um dieses Verfahren besser zu rechtfertigen. Mit einer allgemeinen Funktion des Abstandes je zweier Elektronen und der Störungstheorie läßt sich die Elektronenkorrelation auf einfache Weise berücksichtigen. Damit wird das Problem vom molekularen auf den atomaren Maßstab zurückgeführt. Die Elektronenkorrelation bringt eine Reduktion der Elektronenenergieintegrale mit sich; die Coulombintegrale werden im einzelnen behandelt. Anschließend wird die Möglichkeit untersucht, die übrigen Zweielektronenintegrale zu vernachlässigen. Schließlich wird die Reduktion der Rumpfintegrale behandelt.

---

---

Nous tenons à remercier très vivement le Docteur Chr. K. Jørgensen (Cyanamid European Research Institut, Genève) pour les intéressants échanges de vue que nous avons eu sur les divers problèmes évoqués dans cet article ainsi que le Docteur G. Berthier (Institut de Biochimie théorique, Paris) et Monsieur H. v. Hirschhausen.     

COMPLEX SALTS [Pd(NH3)4][Pd(NH3)3NO2] [CrOx3]·H2O AND [Pd(NH3)4][Pd(NH3)3NO2] [CoOx3]·H2O AND SOLID SOLUTIONS [Pd(NH3)4] [Pd(NH3)3NO2][CoOx3]x[RhOx3]1–x·H2O : PROMISING PRECURSORS FOR POROUS NANOALLOYS

Journal of Structural Chemistry - New complex salts [Pd(NH3)4][Pd(NH3)3NO2][CrOx3]·H2O I, [Pd(NH3)4][Pd(NH3)3NO2][CoOx3]·H2O II, and a series of solid solutions...     

过氧多酸盐[NBu4]3[M(O2)W5O18]的合成及表征

过渡金属过氧化合物是一类性能良好的催化剂,在有机合成中得到广泛的应用[1,2].过氧多酸催化过氧化氢氧化有机物的反应,近年来倍受重视[3～5].     

The Oxalato-Titanium-Containing Tungstophosphate(V) Dimers, [Ti8(C2O4)8P2W18O76(H2O)4]18− and [Ti6(C2O4)4P4W32O124]20−

The oxalato-titanium(IV)-containing, dimeric 18-tungsto-2-phosphate [Ti₈(C₂O₄)₈P₂W₁₈O₇₆(H₂O)₄]^18? (1) and the 32-tungsto-4-phosphate [Ti₆(C₂O₄)₄P₄W₃₂O₁₂₄]^20? (2) are formed upon reaction of the oxalato-titanium complex [TiO(C₂O₄)₂]^2? with the trilacunary Keggin precursor [A-α-PW₉O₃₄]^9? and the hexalacunary Wells–Dawson precursor [H₂P₂W₁₂O₄₈]^12?, respectively. Polyanion 1 consists of two {PW₉} units encapsulating eight titanium centers and connected to each other via two Ti–O–Ti bridges, and crystallizes as a mixed potassium-sodium-lithium salt in the triclinic space group $P{\bar{1}}$ . Polyanion 2 comprises two {P₂W₁₆} units containing each two titanium atoms, and the two half-units are connected via two titanium atoms decorated by two oxalate groups each, and crystallizes as a mixed potassium-lithium salt in the rhombohedral space group $R{\bar{3}}c$ . Polyanions 1 and 2 were characterized in the solid state by single-crystal XRD, FT-IR, and TGA, whereas polyanion 2 was also investigated by ³¹P and ¹⁸³W NMR.     

Reaktionen von [CpRuOMe]2: XI. Austausch mit Thiolen und Molekülstruktur von [C5Me4EtRuSEt]2

Complexes [CpRuSR]₂ and [Cp RuSR]₂, where Cp = η⁵-C₅Me₅, Cp = η⁵-C₅Me₄Et, R Et, ^tBu, (^tBuO)₃Si, are synthesized by exchange of the metboxo groups in [CpRuOMe]₂ with the respective thiols. An X-ray molecular structure determination of [Cp RuSEt]₂ confirms the dimeric structure with co-ordinatively unsaturated 16 VE Ru. The molecular geometry of the thiol-bridged dimer is compared to that of the oxo analogue.     

Mécanismes de corrosion sous contrainte par l'iode dans le zirconium et le zircaloy-4. Transposition aux conditions dtnteraction pastille-gaine dans les réacteurs à eau pressurisée

The aim of tnis work was to explain the very rapid cladding rupture occuring by iodine-induced Stress Corrosion Cracking, by means of a study of parameters specific to Pellet-Cladding Interaction loadings in Pressurized-Water Reactors (neutron irradiation and recoil implantation).     

Synthese und Kristallstruktur von Cu9Ti2[B2O5]2[BO3]2O6 — ein Kupfertitanboratpyroboratoxid?

Synthesis and Crystal Structure of Cu₉Ti₂[B₂O₅]₂[BO₃]₂O₆ — a Copper Titanium Borate Pyroborate Oxide? The new compound Cu₉Ti₂[B₂O₅]₂[BO₃]₂O₆ was prepared by a B₂O₃ flux-technique and crystallizes in a triclinic and completely novel structure type. X-ray investigations on single crystals led to the space group C–P1 (Nr. 2); a = 7.246(4) Å; b = 10.637(5) Å; c = 11.436(6) Å; α = 104.53(5)°; β = 96.25(4)°; γ = 90.36(3)°; Z = 2. The metal distribution is ordered. Ti^IV-sites are distorted octahedraly coordinated by oxygen-ions. The copper oxygen polyhedra are distorted square planar or pyramidal respectively. The structure contains isolated planar BO₃-units, nearly planar pyroborate groups and oxygen which is not coordinated to boron.     

Dawson结构多金属氧酸电荷转移化合物[CH3NH2CH3]2[CH3NHCH3]4H4[P2W18O62]·H2O的合成、表征及晶体结构

钨磷酸;二甲胺;Dawson结构多金属氧酸电荷转移化合物[CH3NH2CH3]2[CH3NHCH3]4H4[P2W18O62]·H2O的合成、表征及晶体结构     

Synthesis,structure and the e.s.r. spectrum of the mixed-valence molybdovandate Na2(NH4)4[(VIVVV8Mo)O28] · 10H2O

The mixed-valence molybdovanadate compound Na₂(NH₄)₄[V^IVV^V ₈Mo)O₂₈] · 10H₂O [Vanadata(6-)tetradeca--oxotetra-₃-oxodi-₆-oxoheptaoxo(oxomolybdate) nonatetrammonium disodium, decahydrate] has been synthesized from sodium molybdate(VI) dihydrate and sodium metavanadate dihydrate in aqueous solution by adding NH₂OH · HCl. The molecular structure has been determined by X-ray diffraction and is based on the isopolydecavanadate structure. The molybdate atom is crystallographically disordered over 6MO₆ octahedral sites. The e.s.r. spectrum clearly indicates that one vanadium atom has the oxidation number +4.