OXAZOLIDONES ET DIOXOLONNES DU GERMANIUM (IV) ET (II) DU PHOSPHORE (III), DE L'ARSENIC (III) ET DU SOUFRE

Abstract

Diffèrents modes de synthèse d'oxazolidones 1.2.4-7 et de dioxolonnes 8-11 germaniées sont décrites.

La stabilité thermique de germadioxolonnes a été étudiée. La décomposition procède d'un méchanisme du type (2 + 2 + 1), avec ouverture du cycle et formation de germylène.

La réactivité chimique des oxazolidones et dioxolonnes germaniées a été étudité. Des réactions d'échange avec des dérives organominéraux dichlorés conduit facilement et avec de bons rendements aux derives isologues, phosphorés(III). arseniés(III), soufrés. ou germaniés(IV). La réaction d'échange entre une dioxolonne germaniée et le dichlorogermylène nous a permis d'obtenir un nouveau germylène fonctionnel cyclique stable 20 qui a été caractérisé par spectrographie (RMN ¹H. masse).

Different synthetic ways for germaoxazolidones 1.2.4-7 or dioxolonnes 8-11 have been described.

The thermal stability of germadioxolonnes has been studied. Decomposition occurs by a [2 + 2 + 1] ring opening with formation of germylene.

The chemical reactivity of germaoxazolidones or dioxolonnes has been studied. Exchange reactions with dihalogenated covalent compounds occur readily lcading to phosphorus(III). arsenic(III). sulphur or germanium(IV) analogs.

From dichlorogermylene, new stable fonctionnal cyclic germylene 20 is obtained and characterized.     

Te(CN)4] versus [Te(CN)3(micro-CN)](n)

Solvent molecules have a great influence on the structure and stability of tellurium tetracyanide; whereas Te(CN)4 x (diglyme)(2) contains monomeric Te(CN)4 units, [Te(CN)3(micro-CN) x diglyme](n) is a coordination polymer.     

Darstellung und Eigenschaften von AgB(CN)4 und CuB(CN)4

Preparation and Properties of AgB(CN)₄ and CuB(CN)₄ The crystalline compounds AgB(CN)₄ and CuB(CN)₄ were obtained by reaction of BCl₃ with AgCN or CuCN. Structure and properties of the compounds are discussed.     

Ba2(CN2)(CN)2 und Sr2(CN2)(CN)2 – die ersten gemischten Cyanamid-cyanide

Ba₂(CN₂)(CN)₂ and Sr₂(CN₂)(CN)₂ – the First mixed Cyanamide Cyanides The mixed cyanamide-cyanides M₂(CN₂)(CN)₂ (M = Ba, Sr) were synthesized by the reaction of Ba₂N and SrCO₃, respectively, with HCN at 630°C. The crystal structure of Ba₂(CN₂)(CN)₂ was determined from single-crystal X-ray investigations at room temperature and ?100°C; the isostructural Sr₂(CN₂)(CN)₂ was refined using powder methods (P6₃/mmc; Ba₂(CN₂)(CN)₂: a = 1 066.52(5) pm, c=696.82(3) pm; Sr₂(CN₂)(CN)₂: a = 1 035.91(1) pm, c = 664.23(1) pm; Z = 4). The crystal structure is a partially filled defect variant of the anti-NiAs structure type with a distorted hexagonal close packed arrangement of M²⁺-ions. All CN₂^2? and one quarter of the CN^? ions occupy 3/4 of the octahedrally coordinated interstices, the remaining cyanide anions are located at 3/8 of the tetrahedral sites. In the crystal structure the CN^? are coordinated to the cations both end-on and side-on. All anions can be distinguished by vibrational spectroscopy.     

Zur Struktur von H3Co(CN)6 und Ag3Co(CN)6

The X-ray powder patterns of H₃Co(CN)₆ and Ag₃Co(CN)₆ have been indexed on the basis of a hexagonal unit cell: The length of the N? X? N-bond along the c-axis is 3.29 Å for X ? H and 4.24 Å for X ? Ag. These distances are in agreement with data obtained from infrared spectra and with structural properties of similar compounds.     

Kinetics and mechanism of platinum-thallium bond formation: the binuclear [(CN)5Pt-Tl(CN)](-) and the trinuclear [(CN)5Pt-Tl-Pt(CN)5](3-) complex

Formation kinetics of the metal-metal bonded binuclear [(CN)(5)Pt-Tl(CN)](-) (1) and the trinuclear [(CN)(5)Pt-Tl-Pt(CN)(5)](3-) (2) complexes is studied, using the standard mix-and-measure spectrophotometric method. The overall reactions are Pt(CN)(4)(2-) + Tl(CN)(2)(+) <==> 1 and Pt(CN)(4)(2-) + [(CN)(5)Pt-Tl(CN)](-) <==> 2. The corresponding expressions for the pseudo-first-order rate constants are k(obs) = (k(1)[Tl(CN)(2)(+)] + k(-1))[Tl(CN)(2)(+)] (at Tl(CN)(2)(+) excess) and k(obs) = (k(2b)[Pt(CN)(4)(2-)] + k(-2b))[HCN] (at Pt(CN)(4)(2-) excess), and the computed parameters are k(1) = 1.04 +/- 0.02 M(-2) s(-1), k(-1) = k(1)/K(1) = 7 x 10(-5) M(-1) s(-1) and k(2b) = 0.45 +/- 0.04 M(-2) s(-1), K(2b) = 26 +/- 6 M(-1), k(-2b) = k(2b)/K(2b) = 0.017 M(-1) s(-1), respectively. Detailed kinetic models are proposed to rationalize the rate laws. Two important steps need to occur during the complex formation in both cases: (i) metal-metal bond formation and (ii) the coordination of the fifth cyanide to the platinum site in a nucleophilic addition. The main difference in the formation kinetics of the complexes is the nature of the cyanide donor in step ii. In the formation of [(CN)(5)Pt-Tl(CN)](-), Tl(CN)(2)(+) is the source of the cyanide ligand, while HCN is the cyanide donating agent in the formation of the trinuclear species. The combination of the results with previous data predict the following reactivity order for the nucleophilic agents: CN(-) > Tl(CN)(2)(+) > HCN.     

Zinc cyanamide,Zn(CN2)

Single crystals of the title compound have been grown by annealing microcrystalline zinc cyan­amide at 843 K in silver crucibles. Zn(CN₂) crystallizes as colourless prisms. The crystal structure is composed of corner‐linked ZnN_4/2 tetrahedra. Carbon and nitro­gen form (CN₂)^2? dumb‐bells with the C atom on a twofold axis. Nitro­gen is approximately trigonally planar, coordinated by two Zn atoms and one C atom.     

AgC(CN)3-based coordination polymers

Reaction of Ag(tcm), tcm = tricyanomethanide, C(CN)(3)(-), with a range of terminal and bridging ligands results in formation of a series of new coordination polymers. Recrystallization of Ag(tcm) from acetonitrile generates Ag(tcm)(MeCN), which is composed of corrugated (6,3) sheets displaying two-fold 2D --> 2D parallel interpenetration and is topologically identical to the parent Ag(tcm) structure. Ag(tcm)(L) species, L = 1,4-diazobicyclo-[2.2.2]-octane (dabco) or 4,4'-bipyridine (bipy), contain two interpenetrating 3D networks composed of 3-connecting (tcm) and 5-connecting (Ag) centers. The structure of Ag(tcm)(bpe), bpe = 1,2-bis(4-pyridyl)ethene, contains 1D ladderlike polymers connected by weak Ag-tcm interactions into two interpenetrating 3D nets. Ag(tcm)(Mepyz)(3/2), Mepyz = methylpyrazine, also contains 1D ladders, while Ag(tcm)(Me(4)pyz)(1/2), Me(4)pyz = tetramethylpyrazine, contains 2D sheets composed of Ag(tcm) 1D "tubes" linked by bridging Me(4)pyz ligands. Ag(tcm)(hmt), hmt = hexamethylenetetramine, has a 3D network structure in which the hmt ligands are 3-connecting, the tcm anions are 2-connecting, and the silver atoms are 5-connecting. The topology is the same as displayed by Ag(tcm)(L), L = dabco or bipy.     

A chiral molecular conductor: synthesis, structure, and physical properties of [ET]3[Sb2(L-tart)2].CH3CN (ET = bis(ethylendithio)tetrathiafulvalene; L-tart = (2R,3R)-(+)-tartrate)

The salt [ET](3)[Sb(2)(L-tart)(2)].CH(3)CN (1) has been obtained by electrocrystallization of the organic donor bis(ethylendithio)tetrathiafulvalene (ET or BEDT-TTF) in the presence of the chiral anionic complex [Sb(2)(L-tart)(2)](2-) (L-tart = (2R,3R)-(+)-tartrate). This salt crystallizes in the chiral space group P2(1)2(1)2(1) (a = 11.145(2) angstroms, b = 12.848(2) angstroms, c = 40.159(14) angstroms, V = 5750.4(14) angstroms(3), Z = 4) and is formed by alternating layers of the anions and of the organic radicals in a noncentrosymmetric alpha-type packing. This compound shows a room temperature electrical conductivity of approximately 1 S.cm(-1) and semiconducting behavior with an activation energy of approximately 85 meV. Analysis of the magnetic susceptibility and band structure, however, suggests that this compound should be a narrow band gap semiconductor.     

Kinetics of CN(v=0) and CN(v=1) with H2 HCl and HBr

CN radicals have been generated in their X ²Σ⁺ (v=0) and (v= 1 ) levels by pulsed laser photolysis of NCNO at 532 nm, and time-resolved laser-induced fluorescence has been used to measure the rates of their removal by H₂, HC1 and HBr. The rate constants for removal of CN(v= 1 ) by these three species are 1.2 ± 0.3, 1.1 ± 0.2 and 1.3 ± 0.1 times the rate constants for reaction of CN(v=0). The results can be interpreted in terms of vibrationally adiabatic theory and a CN vibrational frequency which is almost the same in the transition state as in the isolated radical.     

SPIROPHOSPHORANYLATION D'HYDROXYACIDES NATURELS (ACIDES MALIQUE,CITRIQUE ET TARTRIQUE)—EMETIQUES PHOSPHORES ET OLIGOMERES A PHOSPHORE PENTA ET HEXACOORDINE

Abstract

Condensing tartaric acid (R, R) and PCl₃, we obtained oligomers 3 and cyclic dimer 4. Oxidizing these compounds by DMSO, we prepared hydroxyphosphoranes 6–9, while reaction of orthoquinones gave six-coordinated compound 10. Compound 4 reacts with triethylamine leading to an equilibrium between phosphoranide 5 and phosphite 5'. The more likely structure of oligomers is a sequence of TBP arranged on a helix, whereas dimers should have an emetic structure with pentacoordinated phosphorus atoms. These results are supported by nmr analysis, molecular weight and elemental analysis. All these compounds have strong optical activity. On the other hand, condensing PCl₃ and malic or citric acids, we synthetized new functionalized spirophosphorans 2.

En condensant l'acide tartrique (R, R) et PCl₃, nous avons obtenu des oligomères 3 et le dimére cyclique 4. En oxydant ces composés par le DMSO, nous avons préparé les hydroxyphosphoranes 6–9, tandis que la réaction des orthoquinones a donné le composé a phosphore hexacoordiné 10. Le composé 4 réagit sur la triéthylamine, conduisant à un équilibre entre le phosphoranure 5 et le phosphite 5'. La structure la plus probable des oligomères est une série de BPT placées sur une hélice, tandis que les dimères devraient avoir une structure émétique avec les atomes de phosphore pentacoordinés. Ces résultats s'appuient sur l'analyse des spectres de RMN, les masses moléculaires et l'analyse élémentaire. Tous ces composés présentent une forte activité optique. Par ailleurs, en condensant PCl₃ et les acides malique ou citrique, nous avons synthétisé des spirophosphoranes fonctionnalisés nouveaux 2.     

Responsive Four-Coordinate Iron(II) Nodes in FePd(CN)4

Metal node design is crucial for obtaining structurally diverse coordination polymers (CPs) and metal–organic frameworks with desirable properties; however, Fe^II ions are exclusively six-coordinated. Herein, we present a cyanide-bridged three-dimensional (3D) CP, FePd(CN)₄, bearing four-coordinate Fe^II ions, which is synthesized by thermal treatment of a two-dimensional (2D) six-coordinate Fe^II CP, Fe(H₂O)₂Pd(CN)₄⋅4 H₂O, to remove water molecules. Atomic-resolution transmission electron microscopy and powder X-ray and neutron diffraction measurements revealed that the FePd(CN)₄ structure is composed of a two-fold interpenetrated PtS topology network, where the Fe^II center demonstrates an intermediate geometry between tetrahedral and square-planar coordination. This four-coordinate Fe^II center with the distorted geometry can act as a thermo-responsive flexible node in the PtS network.     

Kristallstruktur von Tl4Fe(CN)6

Crystal Structure of Tl₄Fe(CN)₆ Single crystals of Tl₄Fe(CN)₆ have been prepared for the first time and its crystal structure was determined. The pale yellow compound crystallizes in the triclinic space group P1 (No. 2) with the lattice parameters a = 726.6(1) pm, b = 797.4(8) pm, c = 1 336.0(1) pm, α = 104.7(9)°, β = 90.0(8)°, γ = 97.6(7)°, Z = 2 in a new structure type.     

Direct oxidation of L-cysteine by [FeIII(bpy)2(CN)2]+ and [FeIII(bpy)(CN)4]-

The oxidation of L-cysteine by the outer-sphere oxidants [Fe(bpy)2(CN)2]+ and [Fe(bpy)(CN)4]- in anaerobic aqueous solution is highly susceptible to catalysis by trace amounts of copper ions. This copper catalysis is effectively inhibited with the addition of 1.0 mM dipicolinic acid for the reduction of [Fe(bpy)2(CN)2]+ and is completely suppressed with the addition of 5.0 mM EDTA (pH<9.00), 10.0 mM EDTA (9.010.0) for the reduction of [Fe(bpy)(CN)4]-. 1H NMR and UV-vis spectra show that the products of the direct (uncatalyzed) reactions are the corresponding Fe(II) complexes and, when no radical scavengers are present, L-cystine, both being formed quantitatively. The two reactions display mild kinetic inhibition by Fe(II), and the inhibition can be suppressed by the free radical scavenger PBN (N-tert-butyl-alpha-phenylnitrone). At 25 degrees C and micro=0.1 M and under conditions where inhibition by Fe(II) is insignificant, the general rate law is -d[Fe(III)]/dt=k[cysteine]tot[Fe(III)], with k={k2Ka1[H+]2+k3Ka1Ka2[H+]+k4Ka1Ka2Ka3{/}[H+]3+Ka1[H+]2+Ka1Ka2[H+]+Ka1Ka2Ka3}, where Ka1, Ka2, and Ka3 are the successive acid dissociation constants of HSCH2CH(NH3+)CO2H. For [Fe(bpy)2(CN)2]+, the kinetics over the pH range of 3-7.9 yields k2=3.4+/-0.6 M(-1) s(-1) and k3=(1.18+/-0.02)x10(6) M(-1) s(-1) (k4 is insignificant in the fitting). For [Fe(bpy)(CN)4]- over the pH range of 6.1-11.9, the rate constants are k3=(2.13+/-0.08)x10(3) M(-1) s(-1) and k4=(1.01+/-0.06)x10(4) M(-1) s(-1) (k2 is insignificant in the fitting). All three terms in the rate law are assigned to rate-limiting electron-transfer reactions in which various thiolate forms of cysteine are reactive. Applying Marcus theory, the self-exchange rate constant of the *SCH2CH(NH2)CO2-/-SCH2CH(NH2)CO2- redox couple was obtained from the oxidation of L-cysteine by [Fe(bpy)(CN)4]-, with k11=4x10(5) M(-1) s(-1). The self-exchange rate constant of the *SCH2CH(NH3+)CO2-/-SCH2CH(NH3+)CO2- redox couple was similarly obtained from the rates with both Fe(III) oxidants, a value of 6x10(6) M(-1) s(-1) for k11 being derived. Both self-exchange rate constants are quite large as is to be expected from the minimal rearrangement that follows conversion of a thiolate to a thiyl radical, and the somewhat lower self-exchange rate constant for the dianionic form of cysteine is ascribed to electrostatic repulsion.     

Darstellung und Kristallstrukturen von Ag[N(CN)2](PPh3)2, Cu[N(CN)2](PPh3)2 und Ag[N(CN)2](PPh3)3

Preparation and Crystal Structures of Ag[N(CN)₂](PPh₃)₂, Cu[N(CN)₂](PPh₃)₂, and Ag[N(CN)₂](PPh₃)₃ The coordination compounds Ag[N(CN)₂](PPh₃)₂ ( 1 ), Cu[N(CN)₂](PPh₃)₂ ( 2 ), and Ag[N(CN)₂](PPh₃)₃ ( 3 ) are obtained by the reaction of AgN(CN)₂ or CuN(CN)₂ with triphenylphosphane in CH₂Cl₂. X‐ray structure determinations were performed on single crystals of 1 , 2 , and 3 · C₆H₅Cl. The three compounds crystallize monoclinic in the space group P2₁/n with the following unit cell parameters. 1 : a = 1216.07(9), b = 1299.5(2), c = 2148.4(3) pm, β = 99.689(13)°, Z = 4; 2 : a = 1369.22(10), b = 1257.29(5), c = 1888.04(15) pm, β = 94.395(7)°, Z = 4; 3 · C₆H₅Cl: a = 1276.6(4), b = 1971.7(3), c = 2141.3(5) pm, β = 98.50(3)°, Z = 4. In all structures the metal atoms have a distorted tetrahedral coordination. The crystal structure of 3 · C₆H₅Cl shows monomeric molecular units with terminal coordinated dicyanamide. The crystal structure of 1 is built up by dinuclear units, which are bridged by dicyanamide ligands. However, the crystal structure of 2 corresponds to a onedimensional coordination polymer, bridged by dicyanamide anions.