Preparation of CuAsF6 and Ni[AsF6]2.2SO2

Arsenic pentafluoride reacts with excess copper in sulphur dioxide to give CuAsF₆. A similar reaction with elemental nickel yields Ni(AsF₆)₂.2SO₂, the structure of which is discussed. The X-ray powder diffraction photograph of CuAsF₆ was indexed on a rhombohedral unit cells a = 5.49±.01Å, α = 55.7±.1°, V = 105.4ų, Z = 1, and is of the same structural type as LiSbF₆ showing that the cuprous ion is octahedrally surrounded by fluorines. Comparison of the unit cell volume of CuAsF₆ with other structurally similar hexafluoroarsenate salts shows that the effective volume of cuprous ion is small indicating substantial anion-cation interaction. Arsenic pentafluoride reacts with Monel in the presence of sulphur dioxide give a mixtures of CuAsF₆ and Ni[AsF₆]₂.2SO₂.     

The ethoxyethynyl carbinol—αβ-unsaturated ester conversion: Stereomutation accompanying a selenium dioxide oxidation

Benzsuberone reacts with ethoxyethynyl magnesium bromide to give 1-ethoxyethynyl-1-hydroxy-2,3-benzocycloheptene, which on rearrangement with mild acid (carbon dioxide) yields ethyl cis-1,2-benzo-3-cycloheptenylidene acetate (4, R′= CO₂Et, R¹ = H) and the corresponding trans -compound. With selenium dioxide, both esters yield the same γ-lactone,     

The insertion of the dioxides of carbon and sulphur into the palladium-carbon bond

Bis ( η¹, η²-allyl) palladium phosphine complexes react with carbon dioxide and sulphur dioxide by insertion into the palladium-carbon σ-bond to give η³-allylpalladium-carboxylate and -S-sulphinate complexes.     

Umsetzungen von schwefeldiimiden mit dreikernigen osmiumclustern: Synthese,kristallstruktur und stereochemie von (μ-H)Os3(CO)8(μ3-AstBu)[μ(N,As)-NSNAstBu2]

The arsino-substituted sulphur diimide, S(NAs^tBu₂)₂, reacts with Os₃(CO)₁₂ in boiling octane to give the trinuclear cluster (μ-H)Os₃(CO)₈(μ₃-As^tBu)[μ(N, As)-NSNAs^tBu₂]. An X-ray crystal structure analysis revealed the molecule to contain an open isosceles Os₃ framework capped by a μ₃-As^tBu ligand. The outer two osmium atoms are fixed by an NSNAs^tBu₂ unit maintaining the sulphur diimide substructure as a μ₂(N, As) bridge. According to temperature-dependent ¹³C NMR measurements, the molecule remains rigid in solution up to 70° C.     

3,3′-Dicarbomethoxy-2,2′-bipyridyl complexes of palladium(II), platinum(II) and rhodium(III)

3,3′-Dicarbomethoxy-2,2′-bipyridyl(DCMB)reacts with K₂MCl₄(M = Pd,Pt) to give M(DCMB)Cl₂ and with RhCl₃ to give the cis-[Rh(DCMB)₂Cl₂]⁺ ion. Attempts to prepare the tris (DCMB) complex with Rh(III) and analogous Co(III) complexes were unsuccessful.     

The synthesis,structure and reactions of the novel cationic bisbut-2-yne complex [W(CO)(NCMe)(S2CNC4H8)(η2-MeC2Me)2][BPh4]

The complex [WI(CO)(S₂CNC₄H₈)(η²-MeC₂Me)₂] reacts with an equimolar amount of Na[BPh₄] in acetonitrile at room temperature to give the cationic bisbut-2-yne complex [W(CO)(NCMe)(S₂CNC₄H₈)(η²-MeC₂Me)₂][BPh₄] (1) by replacement of an iodide ligand by acetonitrile. The crystal structure of 1 has been determined and reveals a pseudo-octahedral geometry with the mid points of the two cis-but-2-yne ligands approximately coplanar with the sulphur atoms of the dithiocarbamate ligand. Carbon monoxide and acetonitrile occupy the axial sites. ¹³C NMR spectroscopy shows the two but-2-yne ligands in 1 donate a total of 6 electrons to the tungsten. Preliminary studies of the chemistry of 1 are also described.     

The isolation of intermediates in hydrogen halide additions to some iridium complexes

The complexes [Ir(cod)L_n]PF₆(I, L = PPh₃, PMePh₂; n = 2. L = PMe₂Ph; n = 3) react with HX to give [IrHX(cod)L₂]PF₆ (II, L = PMePh₂ or PMe₂Ph) or [IrHX₂(cod)(PPh₃)] (III). The intermediates [IrX(cod)L₂] have, in two cases (L = PMePh₂, X = I, Br), been directly isolated from the reaction mixtures at 0°C, and are also formed from I with KX (L = PPh₃, X = Cl; L = PMePh₂, X = Cl, Br, I); these intermediates protonate to give II (L = PMePh₂), or an equimolar mixture of III and I (L = PPh₃, X = Cl). Surprisingly, I₂ reacts with I in MeOH to give III (L = PPh₃). The stereochemistries of II and III were determined by < ¹H NMR and especially by new methods using ¹³C NMR spectroscopy. The complexes I exhibit a Lewis acid reactivity pattern.     

Synthese und reaktionen von zinn-substituierten pentadienderivaten

(1E, 4E)-1,5-Bis(trimethylstannyl)pentadiene-1,4 (III), 1E-1-trimethylstannyl-pent-1-ene-4-yne (IV) and the 1,1-dialkyl-1-stannacyclohexadienes-2,5 VII and VIII have been synthesized by hydrostannation of pentadiyne-1,4. (1E, 4E)1,5-Dibromapentadiene-1,3 (IX) is formed from III and 1,1,2,4,5,5-hexabromopentane (X) from IX by reaction with bromine. Butyllithium reacts with III to give (1E, 4E)-1,5-dilithium pentadiene-1,4 (XI). The reactions of butyl- and methyllithium with VII and VIII give only the monolithium compounds XIII, XV and XVII. All lithium compounds are characterised in the form of their trimethylsilyl derivatives XII, XIV, XVI and XVIII. ¹H NMR, IR, UV and mass spectral data are described.     

Organophosphorus chemistry—II: P1P2-disubstituted pyrophosphoric acids formation from organothiophosphoryl dichlorides or organophosphorus(III) dichlorides and dimethyl sulphoxide

Organothiophosphoryl dichlorides and organophosphorus(III) dichlorides undergo a strongly exothermic reaction with DMSO to give P¹P²-disubstituted pyrophosphoric acids. Reaction involving PO bond formation by oxidation of P(S) or P(III) compounds has been found to occur.MeSCH₂Cl, (MeS)₂CH₂ Me₂S and Me₂S₂ were the sulphur compounds detected as by-product of the reaction. Elemental sulphur also separated in the cases that thiophosphoryl compounds were used in the reaction.     

Metallacycloalkanes : II. Reactions of α,α′-bipyridyl-5-nickela-3,3,7,7-tetramethyl-trans-tricyclo[4.1.0.02,4]heptane

The title compound (II) underwent reductive elimination on treatment with maleic anhydride, tetracyanoethylene or triphenylphosphite to give 3,3,6,6,-tetramethyl-trans-tricyclo[3.1.0.0^2,4]hexane (III). With triphenylphosphite bi(2,2-dimethylcyclopropyl) (V) and 1-(2,2-dimethylcyclopropyl)-3-methyl-1,3-butadiene (VI) were also formed. Acidolysis of II with either HCl, malonic acid or methanol gave V. An intermediate complex α,α′-bipyridyl(phenoxy)-3-nickel-1,1′-bi-(2,2′-dimethylcyclopropyl) (VIII) was isolated by reaction of II with phenol. Methylene dibromide reacts with II to give III and 3,3,7,7-tetramethyl-trans-tricyclo[4.1.0.0^2,4]heptane (IV). With triethylaluminum and II complete exchange of the alkyl groups occurred and V was released on hydrolysis. Trifluoroborane diethyl ether and II gave 3,3,6,6-tetramethylcyclohexa-1,4-diene in a rearrangement-displacement reaction. The cyclodimerisation of 3,3-dimethylcyclopropene (I) to III catalysed by II and the fact that II can be recovered from the reaction mixture provides strong evidence for the intermediacy of metallacyclopentanes in these transition-metal-catalysed [2π + 2π] cyclo-additions.     

Photoreaktion von dekacarbonyl-dimangan mit allen

Decacarbonyldimanganese(0) (I) reacts, when irradiated with UV light, with allene (II) at 233 K to give a mixture of three dinuclear complexes with allene and two isomeric dimers of allene as ligands. The products, μ-η^2:2-allene-octacarbonyl-dimanganese(0) (III), octacarbonyl-μ-η^3:3-tetramethyleneethane-dimanganese (IV) and enneacarbonyl-μ-η^3:1-2-methylene-4-penten-1,4-diyldimanganese(V) were separated by HPLC. The complexes III—V were characterized by C and H elemental analyses and by spectroscopic means (IR, NMR). In addition, the molecular structures of III and IV were determined by X-ray structure analyses.     

A sulphur dioxide adduct of triphenylindium

The product from the reaction of triphenylindium with sulphur dioxide, previously considered to be O-benzenesulphinatodiphenylindium(III), is now formulated as the $\text{1}\text{1}$ adduct, Ph₃In(O₂S).     

Reactions of Ketones XVI. 5,5-I)imethoxy-Δ2-1,2,3-triazoline/2,2-Dimethoxy-2-aminodiazoethane Mutual Conversion

Phenylketene dimethylacetal reacts with ethyl azidoformate to give 1-ethoxyearbonyl-4-phenyl-5,5-dimethoxy-Δ²-1,2,3-triazoline (III). The behaviour of the latter and of its isomerization product, 1-phenyl-2,2-dimethoxy-2 (N-ethoxyearbonylamino)diazoethane (IV), have been investigated in detail. The results point out a triazoline III/diazoethane IV mutual conversion.     

Behavior of N,S-divinyl-2-mercaptobenzimidazole in the thiylation reaction

N,S-Divinyl-2-mercaptobenzimidazole reacts with thiols under free-radical initiation conditions at both vinyl groups to giveβ-addition products, whereas it reacts with sulfur dioxide to give a stable complex. N-Vinylbenzimidazole-2-thione was obtained by heating the divinyl derivative of benzimidazole-2-thione in the presence of a mercaptan without a catalyst. The former on reaction with thiols under the influence of azobisisobutyronitrile readily forms N-(β-alkylthio)ethylbenzimidazole-2-thiones; in the presence of ionic catalysts, N-(α-alkylthio)ethylbenzimidazole-2-thiones are formed.     

Photochemisch induzierte oxidative addition von aldehyden an dekacarbonyldirhenium(0)

Decacarbonyldirhenium(O) (I) reacts photochemically with acetaldehyde or propionaldehyde (II, III) to give predominantly tetradecacarbonyl-μ-hydridotrirhenium (VI). In addition, μ-acyloctacarbonyl-μ-hydridodirhenium complexes (IV, V) are obtained in oxidative addition reactions with simultaneous loss of two CO ligands. Complexes IV and V were characterized by their elemental analyses, IR, ¹H NMR, and ¹³C NMR spectra. Furthermore, the molecular structure of IV was determined by X-ray structure analysis. IV shows approximate (C_s-symmetry. Two Re(CO₄) groups are connected via the C and O atoms of the carbonyl function of an acetyl bridge, and from the steric arrangement of the Re(CO)₄ moieties and NMR spectroscopic evidence, a hydrido bridge has to be assumed between the Re atoms, which rules out a ReRe bond. The two coordination octahedrons are joined by the hydrido bridge. The connection of two further edges by the acetyl bridge causes an eclipsed arrangement of the CO ligands in IV.     

Simultaneous determination of carbon dioxide and sulphur dioxide in wine by gas-diffusion/flow-injection analysis

A method is proposed for the simultaneous determiantion of carbon dioxide and sulphur dioxide in complex matrices. The method involves preseparation of the analysis with a flow-through gas-diffusion unit. The analytes are sensed by two detectors in series, a potentiometric detector responsive to both analytes and a photometric detector for SO₂ (p-rosaniline—formadehyde method). The usefulness of the method was tested by applying it to samples of fruity wines and the results were compared with those obtained with the standard EEC recommended method. The reproducibility was generally 7% or better, with a sampling frequency of about 25 h^-1.     

Synthesis, spectroscopy and cyclic voltammetry of new iron(III) complexes with 5-methyl-3-formyl pyrazole 3-hexamethyleneiminyl thiosemicarbazone (HMPz3Hex): X-ray crystallographic identification of [Fe(MPz3Hex)2]ClO4 · 2H2O with an indication for unusual rotation about the azomethine double bond on complexation with iron(III)

New iron(III) complexes of 5-methyl-3-formylpyrazole 3-hexamethyleneiminylthiosemicarbazone (HMPz3Hex), [Fe(MPz3Hex)₂]X · nH₂O (where X = Cl, NO₃or ClO₄ and n = 1–2) have been synthesized and physico-chemically characterized by magnetic data (polycrystalline state), electronic, i.r. and e.p.r. spectral studies. The reported complexes are all cationic electrolytes (1:1) containing two moles of monodeprotonated title ligand and an anionic counterpart. I.r. spectra (4000–200 cm^?1) indicate coordination to the central iron(III) ion via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulphur atoms of the primary ligand molecule. E.p.r. data (r.t. and l.n.t.) show the presence of a low-spin iron(III) cation with d _xz ² d _xz ² d _xz ¹ configuration. Cyclic voltammograms of iron(III) complexes indicate a reversible Fe⁺³/Fe⁺² couple. X-ray data of [Fe(MPz3Hex)₂]ClO₄ · 2H₂O (P₁, triclinic) authenticate a FeN₄S₂ distorted octahedral coordination with the two azomethine nitrogens trans to each other; the pyrazolyl nitrogens and thiolato sulphurs are in cis-positions, indicating an unusual rotation about the azomethine (C=N) double bond of the free HMPz3Hex during complexation with iron(III).     

Hochdruckversuche: Umsetzungen von kohlenstoffdisulfid mit aminen,amiden und olefinen—V

Suitable tertiary amines react with CS₂, 100°C, 10⁴ atm to give N,N-disubstituted thioformamides. Salts of dialkyldithiocarbamic acids decompose at the same conditions into dialkylthioformamide and sulphur. After addition of cyclohexene, mainly N,N-dialkyldithiocarbamic acid cyclohexyl ester has been obtained. Carbon disulfide and sulphur add to olefins yielding trithiocarbonates. Dimethyl formamide reacts with CS₂ giving dimethyl thioformamide. Mechanisms are discussed with help of¹⁴CS₂ and¹⁴C-dimethyl formamide.     

Synthesis of a novel chelating ligand from pentane-2,4-dione and 3-aminopropyl[tris(trimethylsilyloxy)]silane. europium(III) and erbium(III) imino enolates

Acetylacetone reacts with 3-aminopropyl[tris(trimethylsilyloxy)]silane to give a mixture of the isomers 4-[3′-tris(trimethylsilyloxy)silylpropyl]iminopent-2-en-2-ol (90%) and 4-[3′-tris(trimethylsilyloxy)silylpropyl]aminopent-3-en-2-one (10%). According to ¹H and ¹³C NMR data, both isomers exist in the cis-and trans-forms. Anhydrous europium(III) and erbium(III) tris{4-[3′-tris(trimethylsilyloxy)silylpropyl]iminopent-2-en-2-olates} were obtained from the mixture of the isomers and the corresponding propan-2-olates Eu(OPr _i )₃ and Er(OPr _i )₃. The resulting complexes are transparent air-stable liquids that are distillable in vacuo and well soluble in photopolymerizable polyorganosiloxane caoutchoucs and urethane acrylate oligomers. The volatility parameters of the europium(III) complex were studied.     

Colorimetric Determination of Sulphur Dioxide and Sulphites in Various Environmental Samples

Rhodamine‐B has been proposed as a simple and sensitive colorimetric reagent for the estimation of sulphur dioxide in air. The air sample containing sulphur dioxide is passed through the absorbing solution of aqueous potassium iodate and N‐chlorosuccinimide to liberate iodine. The liberated iodine bleaches the pinkish red coloured rhodamine‐B dye, which measured at 555 nm. Beer's law was obeyed in the range of 0.5–5.0 μg, of sulphite per 25 mL (0.02–0.2 ppm) equivalent to 0.4–4.0 μg of sulphur dioxide (0.016–0.16 ppm). The molar absorptivity and Sandell's sensitivity were found to be 4.56 × 10⁵ l mol^?1 cm^?1 and 0.00017 μg cm^?2, respectively. The method has been suitably modified and successfully applied to the determination of sulphites in water after liberation of sulphur dioxide in acidic medium.