Pseudohalogenometallverbindungen: LXVII. Reaktionen von komplexen Metallcyaniden trans-(R3P)2M(CN)2 (M = Pd,Pt; R = Et,Ph) mit 1,3-Dioxolenium-tetrafiuoroborat

The cyano complexes (R₃P)₂Pt(CN)₂ (R = Et, Ph) und (Ph₃P)₂Pd(CN)₂ react with the dioxolenium salt [$\text{O-CH}{}_2\text{CH}{}_2\text{O-C}$H]⁺ BF₄^? with ring opening to give the isocyanide complexe [(R₃P)₂M(CNCH₂CH₂OCHO)₂]²⁺ (BF₄^?)₂ and [(R₃P)₂M-(CN)(CNCH₂CH₂OCHO)]⁺BF₄^?, which contain the new ligand (2-isocyanoethanol)-formiate. The complexes have been characterized by analysis and from their IR and NMR spectra.     

The hydrolysis of dibromofluoromethyltriphenylphosphonium bromide

Hydrolysis of [Ph₃$\text{P}\text{+}$PCFBr₂]Br^? afforded a high yield of dibromofluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine gave evidence that the mechanism of this reaction proceeds $\text{via}$ the dibromofluoromethide ion and not $\text{via}$ a bromofluorocarbene intermediate.     

Reactions of triphenylarsine oxide with aqueous hydrogen fluoride: Crystal structure of bis(triphenylarsine oxide)hydrogen(I) tetrafluoroborate

Fluorination of triphenylarsine oxide by aqueous hydrogen fluoride (1–40%) in the absence of glass readily gives triphenylarsine difluoride. When the reaction with dilute (1%) aqueous hydrogen fluoride is carried out in borosilicate glass apparatus, the glass participates in the reaction resulting in the formation of the crystalline 2:1 adduct 2Ph₃AsO·HBF₄. Crystals of this compound are monoclinic, $\text{P}$2₁/$\text{c}$, $\text{a}$ = 12.926(4), $\text{b}$ = 17.819(6), $\text{c}$ = 14.994(4) Å, β = 98.97(3)°, Z = 4. The structure contains cations [(Ph₃AsO)₂H]⁺ in which $\text{O}\text{?}$O is 2.44(2)Å, and anions BF₄^?.     

The hydrolysis of bromodifluoromethyltriphenylphosphonium bromide [1]

Hydrolysis of [Ph₃$\text{P}\text{+}$CF₂Br]Br^? afforded a high yield of bromodifluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine or sodium iodide gave unequivocal evidence that the mechanism for this reaction proceeds through a difluorocarbene intermediate.     

Equilibrium and kinetics of reversible capture of solvated electron-sodium+ pairs by 1,1-diphenylethylene in tetrahydrofuran

Solvated electron-Na⁺ pairs, e^?,Na⁺, and 1,1-diphenylethylene reversibly recombine in THF, the capture constant = 3 × 10⁷ M^?1 s^?1 and the detachment constant = 46 s^?1; the e^?,Na⁺, formed by flash-photolysis of Na⁺,$\text{C}\text{?}$(Ph)₂CH₂CH₂$\text{C}\text{?}$(Ph₂, Na⁺ survive for 0.1 s in this solvent at ambient temperature without any detectable decay.     

Synthesis of cationic dialkylgold(III) complexes: nature of the facile reductive elimination of alkane

A series of gold(III) cations of the type cis-[CH₃)₂AuL₂]⁺ X^? where L  Ph₃, PMePh₂, PMe₂Ph, PMe₃, AsPh₃, AsPh₃, SbPh₃, $\text{1}\text{2}$H₂NCH₂CH₂NH₂, $\text{1}\text{2}$ Ph₂PCH₂CH₂-PPh₂, $\text{1}\text{2}$ Ph₂AsCH₂CH₂AsPh₂, and $\text{1}\text{2}$o-C₆H₄(AsMe₂)₂ and X  BF₄^?, PF₆^?, ClO₄^?, and F₃CSO₃^? has been prepared. In addition, the cis complexes [(CH₃)(CD₃)-Au(PPh₃)₂]F₃CSO₃, [(C₂H₅)₂Au(PPh₃)₂]F₃CSO and [(n-C₄H₉)₂Au(PPh₃)₂]F₃-CSO₃ have been synthesized. All have been characterized by PMR, Raman and infrared spectroscopy. These [R₂AuL₂]X compounds yield only ethane, butane, or octane via reductive elimination, and no disproportionation is observed. The alkane eliminations have been studied in CHCl₃, CH₃Cl₂, and CH₃COCH₃ solution as a function of temperature, concentration of the complex, and concentration of added ligand L. Elimination is fastest when L is bulky (PPh₃ > PMePh₂ > PMe₂Ph > PMe₃), decreases in the sequence SbPh₃ > AsPh₃ > PPh₃, is slow with chelating ligands, is inhibited by excess ligand, and there is small anion effect as X is varied. As R is varied, the rate of elimination decreases Bu ? Et > Me. An intramolecular dissociative mechanism is proposed which involves rapid elimination of alkane from an electron deficient dialkylgold(III) complex with nonequivalent gold—carbon bonds and produces the corresponding [AuL₂]X complex.     

Preparation and synthetic utility of fluorinated phosphonium salts,bisphosphonium salts and phosphoranium salts

The synthesis and mechanism of formation of phosphonium salts of the type [R₃$\text{P}\text{+}$CFXY]Z^? (where X = F, Cl, Br; Y = Br, Cl; Z = Br, Cl), $\text{bis}$-phosphonium salts of the type [R₃$\text{P}\text{+}$CF₂$\text{P}\text{+}$R₃]2Br^?, and phosphoranium salts of the type [R₃$\text{P}\text{+}$$\text{C}\text{?}$F$\text{P}\text{+}$R₃]X^? (X = Br, Cl) will be presented. The applicability of these substrates in the generation of useful nucleophilic or electrophilic synthetic intermediates will be discussed.     

Polymerizations of ethylenic monomers initiated by superacids—II: Complexation of some trifluoromethanesulphonates by their conjugate acid

Ionic trifluoromethanesulphonates (triflates) are strongly solvated with their conjugate acid in dichloromethane (Ph₃C⁺, n-Bu₄N⁺, Ag⁺) and acetonitrile (Na⁺, Ag⁺). A ¹H and ¹⁹F NMR study of the chemical shifts of various acid-salt mixtures show that in CH₂Cl₂ three homoconjugates A^? · HA, A^?. (HA)₂ and A^?(HA)₃ were formed with large formation constants whereas in acctonitrile only the 1:1 homoconjugate was formed with an equilibrium constant K₁ ～ 4 1 · M^?1. This result explains why the protonation by CF₃SO₃H of non-polymerizable olefins such as 1,1-diphenylethylene and 3-phenylindene is always incomplete ($\text{1}\text{3}$ and $\text{1}\text{2}$ respectively) in CH₂Cl₂. Conditions in which covalent triflates could be obtained have been investigated. As a consequence of homoconjugation, reaction of Ph₃COH with triflic anhydride led to Ph₃C⁺ CF₃SO^?₃ HOSO₂CF₃. Other tertiary alcohols were dehydrated by triflic anhydride and led to ethylenic compounds (1,1-diphenylethanol) or ethers (2-phenyl 2-propanol). Esters were only observed in the case of benzyltriflate (at ?20°) and in the case of 1-phenylethyltriflate which is a model of polystyryltriflate (stable at room temperature).     

Synthesis,Reactions and Catalytic Activities of a Cationic Acrylonitrile-Rhodium(I) Complex

Reaction of RhCl (CO)(Ph₃P)₂(Ph₃P = triphenylphosphine) with AgClO₄ in acrylonitrile at 30°C produces a new cationic rhodium(I) complex, [Rh(CH₂CHCN)(CO) (Ph₃P)₂]ClO₄ ($\text{1}$) and AgCl. The ¹H-NMR and IR spectra of $\text{1}$ suggest that acrylonitrile is coordinated to rhodium through the π-system of the vinyl group. The complex $\text{1}$ reacts with molecular hydrogen to give a propionitrile-rhodium(I) complex, [Rh(CH₃ CH₂CN) (CO)(Ph₃P)₂ClO₄($\text{2}$) where the coordination of propionitrile through nitrogen is suggested by the ¹H-NMR and IR spectral data. The coordinated acrylonitrile in $\text{1}$ is readily replaced with triphenylphosphine and propionitrile to give [Rh(CO)(Ph₃P)₃] ClO₄ and $\text{2}$, respectively. The complex $\text{1}$ is catalytically active for the hydrogenation and polymerization of acrylonitrile at 25°C under the atmospheric pressure of hydrogen.     

The chemical oxidation and electronic spectra of the complexes trans-[M(CNR)2(Ph2PCH2CH2PPh2)2] (M = Mo or W)

Oxidation of the complexes $\text{trans}$-[M(CNR)₂(dppe)₂] (A) (M = Mo or W; R = Me, Bu^t or CH₃C₆H₄-$\text{4}$; dppe = Ph₂PCH₂CH₂PPh₂) with diiodine or silver (I) salts gives the paramagnetic cations $\text{trans}$-[M(CNR)₂(dppe)₂]⁺, (M = Mo, R = CH₃C₆H₄-$\text{4}$; M = W, R = Bu^t) and $\text{trans}$-[M(CNR)₂(dppe)₂]²⁺ (M = Mo, R = Me or CH₃C₆H₄-$\text{4}$; M = W, R = Me or Bu^t). Mixtures of products are generally produced when dichlorine or dibromine are the oxidising agents, however pure salts, the seven-coordinate complex cations [MX(CNC₆H₄CH₃-$\text{4}$)₂(dppe)₂]⁺ (B, X = Cl or Br) have been isolated. A simple molecular orbital scheme is proposed for complexes (A) and used to discuss their electronic spectra and their oxidation.     

The first nitrosyl derivatives of high nuclearity carbonyl clusters: Synthesis and X-ray analysis of the [(Ph3P)2N]+ salts of the anions [Os10C(CO)24(μ2-NO)]− and [Os10C(CO)23(NO)]−

The carbido dianion [Os₁₀C(CO)₂₄]^2? reacts with NOBF₄ in MeCN to give [OS₁₀C(CO)₂₄(μ₂-NO)]^? (1) in which the nitrosyl ligand adopts a novel bonding mode bridging the wingtips of a “butterfly” indentation of metal atoms. The anion 1 undergoes rearrangement and CO loss in solution to give [OS₁₀C(CO)₂₃(NO)]^? (2); the overall molecular geometry of 2 is close to that previously found for the dianion [Os₁₀C(CO)₂₄]^2? with the nitrosyl ligand bonded in a terminal fashion to the tetrahedral Os₁₀ metal skeleton. Crystals of the [(Ph₃P)₂N]⁺ salt of 1 are triclinic, space group P$\text{1}$, with a 20.389(4), b 14.670(3), c 12.333(3) Å, α 99.55(3), β 94.43(3), γ 103.03(3)°, Z = 2, refinement of atomic parameters using 2699 absorption corrected data converged at R = 0.0952. The [(Ph₃P)₂N]⁺ salt of 2 crystallises with one molecule of CH₂Cl₂ in the triclinic space group P$\text{1}$, with a 19.374(3), b 16.813(3), c 11.791(2) Å, α 85.00(3), β 101.81(3), γ 99.43(3)°, Z = 2, refinement of atomic parameters using 8736 absorption corrected data converged at R = 0.0943.     

Characteristic structural features of cyclopentadienyl derivatives of post-transition metals : II. Synthesis and structure of tris(triphenylphosphinegold)tetraphenylcyclopentadiene tetrafluoroborate

The trinuclear cationic complex [Ph₄C₅(AuPPh₃)₃⁺[BF₄]^- (I) obtained by interaction of C₅HPh₄AuPPh₃ or Ph₄C₅(AuPPh₃)₂ with [AuPPh₃⁺[BF₄]^- in THF was studied by X-ray diffraction. In the presence of benzene, triclinic crystals of the solvate [Ph₄C₅(AuPPh₃)₃]⁺[BF₄]^-· 2 C₆H₆ are formed, a = 12.845(6), b = 16.042(8), c = 22.642(11) Å, α = 86.62(4), β = 77.51(4), γ = 76.05(4)°, space group P$\text{1}$, Z = 2, 9494 reflections with I > 2σ (λ(Mo-K_α), θ/2θ scan, 2θ < 46°), with absorption correction R = 0.054. The complex represents a diaurated cation of tetraphenylcyclopentadienyl(triphenylphosphine)gold, containing a triangular Au₂C fragment (AuAu 2.820(1) Å) which is bonded to the third Au atom (AuAu 3.021(1) Å), coordinated to the cyclopentadienyl ligand by a bond intermediate between η¹(σ) and η³ (AuC 2.21(2), 2.60(2) and 2.71(2) Å).     

Boron trifluoride catalysed reactions of 2,2,2-trichloroethyl 6-diazopenicillanate with aromatic aldehydes: rearrangements via penam c(5)-c(6) bond cleavage.

The BF₃·Et₂O catalysed reactions of diazopenicillanate 1 with aromatic aldehydes provide 2,3-dihydrothiazolo[2,3-b][1,3]oxazin-5-ones 4 $\text{via}$ C(5)-C(6) cleavage of 6-formyl-penicillanates 8.     

Micellar alkylation: a methylating surfactant

Micellar $\text{n}$-C₁₆H₃₃$\text{N}\text{+}$(CH₃)₂CH₂$\text{S}\text{+}$(CH₃)₂, 2CF₃SO₃^? rapidly methylates bound thiophenoxide ions.     

Syntheses and Crystal Structures of Copper and Silver Complexes with the Ylide Ph3PCHP(O)PPh2 as Ligand

The reactivity of the hydrolysis product of hexaphenylcarbodiphosphorane, PPh₃CHP(O)Ph₂, towards different soft Lewis acids, such as CuI and Ag[BF₄] are reported. While CuI exclusively binds at the ylidic carbon atom, reaction of the silver cation in CH₂Cl₂ leads to proton abstraction from the solvent to give the cation [PPh₃CH₂P(O)Ph₂]⁺. Surprisingly, Ag⁺ replaces the methyl group of [PPh₃CHMeP(O)Ph₂]⁺ to produce a dimeric complex, in which Ag⁺ is coordinated to C and O forming an eight membered ring. The compounds were characterized by spectroscopic methods and X‐ray diffraction.     

Theoretical study on interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate

It is critically important to understand the interactions between thiophene/dibenzothiophene/cyclohexane/toluene and 1-methyl-3-octylimidazolium tetrafluoroborate ([C8MIM]⁺[BF₄]^?) due to desulfurization by ionic liquids. In this work, the structures of thiophene, dibenzothiophene, cyclohexane, toluene, [C8MIM]⁺[BF₄]^?, [C8MIM]⁺[BF₄]^?-thiophene, [C8MIM]⁺[BF₄]^?-dibenzothiophene, [C8MIM]⁺[BF₄]^?-cyclohexane, and [C8MIM]⁺[BF₄]^?-toluene were optimized systematically at the GGA/PW91/DNP level, and the most stable geometries were performed by NBO and AIM analyses. It was found that [BF₄]^? anion tends to locate near C2–H2 and four hydrogen bonds between [C8MIM]⁺ and [BF₄]^? form in [C8MIM]⁺[BF₄]^?. There exist hydrogen bonds and C–H···π interactions between [C8MIM]⁺[BF₄]^? and thiophene/cyclohexane/toluene, while the hydrogen bonding interactions, π···π and C–H···π interactions occur between [C8MIM]⁺[BF₄]^? and dibenzothiophene confirmed by NBO and AIM analyses. The interaction energies between [C8MIM]⁺[BF₄]^? and thiophene, dibenzothiophene, cyclohexane, toluene are 18.83, 20.93, 6.83, 12.99 kcal/mol, showing the preferential adsorption of dibenzothiophene and thiophene by ionic liquid, in agreement with the experimental results of dibenzothiophene and thiophene extraction by [C8MIM]⁺[BF₄]^?.     

Theoretical study of interactions between 1-alkyl-3-methyimidazolium tetrafluoroborate and dibenzothiophene: DFT,NBO, and AIM analysis

Density functional theory is employed to study the interaction energies between dibenzothiophene (DBT) and 1-alkyl-3-methylimidazolium tetrafluoroborate ([C _n mim]⁺[BF₄]^?). The structures of DBT, 1-ethyl-3-methylimidazolium tetrafluoroborate ([C₂mim]⁺[BF₄]^?), 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim]+[BF₄]?), 1-hexyl-3-methylimidazolium tetrafluoroborate ([C₆mim]⁺[BF₄]^?), 1-octyl-3-methylimidazolium tetrafluoroborate ([C₈mim]⁺[BF₄]^?), [C₂mim]⁺[BF₄]^?–DBT, [C₄mim]⁺[BF₄]^?–DBT, [C₆mim]⁺[BF₄]^?–DBT and [C₈mim]⁺[BF₄]^?–DBT systems are optimized systematically at the B3LYP/6-31G(d,p) level, and the most stable geometries are obtained by NBO and AIM analyses. The results indicate that DBT and imidazolium rings of ionic liquids are parallel to each other. It is found that the [BF₄]^? anion prefers to be located close to a C1–H9 proton ring in the vicinity of the imidazolium ring and the most stable gas-phase structure of [C _n mim]⁺[BF₄]^? has four hydrogen bonds between [C _n mim]+ and [BF₄]?. There are hydrogen bonding interactions, π–π and C–H–π interactions between [C₈mim]⁺[BF₄]^? and DBT, which is confirmed by NBO and AIM analyses. The calculated interaction energies for the studied ionic liquids can be used to interpret a better extracting ability of [C₈mim]⁺[BF₄]^? to remove DBT, due to stronger interactions between [C₈mim]⁺[BF₄]^? and DBT, in agreement with the experimental results of dibenzothiophene extraction by [C _n mim]⁺[BF₄]^?.     

Oxygenation of 2,6-di-t-butylphenols with superoxo Co(III) complexes

Superoxo Co(III) complexes, [Co(CN)₅O₂][X]₃ where X = Et₃N⁺ and (Ph₃P)₂N⁺, mediate the dioxygen incorporation into 2,6-di-$\text{t}$-butylphenols ($\text{1}$) with the same regioselectivity as that in the base-catalyzed oxygenation of $\text{1}$. The superoxo species acts as a base but is not incorporated into the substrate.     

Crystallographic report: Tetraphenylphosphonium nitratobis (chlorodiphenylstannate)methane, [Ph4P]+[(Ph2ClSn)2CH2 ·NO3]−

The nitrate anion coordinates to the Sn? CH₂? Sn unit of the title phosphonium stannate, [Ph₄P]⁺ [(Ph₂ClSn)₂CH₂ ·NO₃]^?, to give a six‐membered ring having the penta‐coordinated tin atoms in a trigonal bipyramidal geometry. Copyright © 2003 John Wiley & Sons, Ltd.     

[Ph2P(O)CH2Im][F3B(μ‐OH)BF3]. Erste strukturanalytische Charakterisierung des Hexafluoro(μ‐hydroxo)diborat‐Ions [1]

[Ph₂P(O)CH₂Im][F₃B(μ‐OH)BF₃]. First Structural Characterization of the Hexafluoro(μ‐hydroxo)diborate Ion [1] The hexafluoro(μ‐hydroxo)diborate ion has been isolated as it's Ph₂P(O)CH₂Im salt [Im = 2‐(1, 3, 4, 5‐tetramethylimidazolio)] ( 2 ) through basic hydrolysis of [Ph₂P(OBF₃)CH₂Im]BF₄ ( 1 ). The crystal structure of 2 · CH₂Cl₂ reveals the presence of ion pairs linked by unsymmetrical O‐H‐O hydrogen bonds.