(Ph)3PBr][Br7], [(Bz)(Ph)3P]2[Br8], [(n-Bu)3MeN]2[Br20], [C4MPyr]2[Br20], and [(Ph)3PCl]2[Cl2I14]: extending the horizon of polyhalides via synthesis in ionic liquids

The five polyhalides [(Ph)(3)PBr][Br(7)], [(Bz)(Ph)(3)P](2)[Br(8)], [(n-Bu)(3)MeN](2)[Br(20)], [C(4)MPyr](2)[Br(20)] ([C(4)MPyr] = N-butyl-N-methylpyrrolidinium), and [(Ph)(3)PCl](2)[Cl(2)I(14)] were prepared by the reaction of dibromine and iodine monochloride in ionic liquids. The compounds [(Ph)(3)PBr][Br(7)] and [(Bz)(Ph)(3)P](2)[Br(8)] contain discrete pyramidal [Br(7)](-) and Z-shaped [Br(8)](2-) polybromide anions. [(n-Bu)(3)MeN](2)[Br(20)] and [C(4)MPyr](2)[Br(20)] exhibit new infinite two- and three-dimensional polybromide networks and contain the highest percentage of dibromine ever observed in a compound. [(Ph)(3)PCl](2)[Cl(2)I(14)] also consists of a three-dimensional network and is the first example of an infinite polyiodine chloride. All compounds were obtained from ionic liquids as the solvent that, on the one hand, guarantees for a high stability against strongly oxidizing Br(2) and ICl and that, on the other hand, reduces the high volatility of the molecular halogens.     

Synthese und Kristallstrukturen von [(Ph3As)2CCN–MnBr3], [(Ph3As)2CCN–CoBr3] und [(Ph3As)2CCN]+CuBr2–

Syntheses and Crystal Structures of [(Ph₃As)₂CCN–MnBr₃], [(Ph₃As)₂CCN–CoBr₃], and [(Ph₃As)₂CCN]⁺CuBr₂^– The di(arsa)acetonitrilium bromide [(Ph₃As)₂CCN]Br reacts with the anhydrous dibromides of manganese and cobalt in acetonitrile to form the molecular complexes [(Ph₃As)₂CCN–MBr₃] [M = ( 1 ), Co( 2 )] with zwitterionic structures. With copper(I)bromide, however, the ionic compound [(Ph₃As)₂CCN]⁺CuBr₂^– ( 3 ) is formed. All complexes are characterized by IR spectroscopy and by crystal structure analyses. 1 and 2 crystallize isotypically with each other in the space group P 1 with two formula units per unit cell. The MBr₃^– fragments in the molecular complexes are connected to the N atom of the [(Ph₃As)₂CCN]⁺ cation showing bond angles C–N–Mn of 156.9° and C–N–Co of 161°, and distances Mn–N of 215.6 pm and Co–N of 201 pm. In 3 , on the other hand, (space group C2/c, Z = 4) the ions [(Ph₃As)₂CCN]⁺ and the linear Br–Cu–Br^– ion are to be found concurrent but separate.     

[(Ph3PCH2)(Ph3P)PtCl][AlCl4], ein in CH2Cl2-lösung dreifach koordinierter kationischer platin(II)-komplex

The interaction of cis-[(Ph₃PCH₂)(Ph₃P)PtCl₂] with aluminium(III) chloride in CH₂Cl₂ affords the three coordinate cationic platinum(II) complex [(Ph₃PCH₂)(Ph₃P)PtCl][AlCl₄] which is a useful starting material for platinum complexes with four different ligands. With Ph₃As and Me₂S the cationic phosphorus ylide complexes [(Ph₃PCH₂)(Ph₃P)(Ph₃As)PtCl][AlCl₄] and [(Ph₃PCH₂)(Ph₃P)(Me₂S)PtCl][AlCl₄] are formed. 851 V 3     

Facile Ar-CF3 bond formation at Pd. Strikingly different outcomes of reductive elimination from [(Ph3P)2Pd(CF3)Ph] and [(Xantphos)Pd(CF3)Ph

Facile and highly selective perfluoroalkyl-aryl reductive elimination from a metal center (Pd) has been demonstrated for the first time. At temperatures as low as 50-80 degrees C, [(Xantphos)Pd(Ph)CF3] undergoes remarkably clean decomposition to produce CF3Ph in high yield and selectivity. In contrast, analogous trifluoromethylpalladium aryls stabilized by rigid cis-chelating ligands such as dppe are completely unreactive at temperatures up to 130-140 degrees C. Decomposition of [(Ph3P)2Pd(Ph)CF3] in the presence of PhI in benzene at 60 degrees C does not produce PhCF3 but rather leads to [(Ph3P)2Pd(Ph)I] and [Ph4P]+[(Ph3P)Pd(CF3)3]- in a 2:1 ratio with high selectivity.     

Competition of oxygen insertion and dehydrogenation in the o-phenylenediamine/Ph3P/COBALT(II) catalyst system

In addition to known catalytic dehydrogenations, the o-phenylene- diamine (OPD)/cobalt(II) system also effects the oxidation of PH₃P to Ph₃PO. A green intermediate of the formula [Ph₃P(OPD)₂Co-O₂-Co(OPD)₂- Ph₃P]⁴⁺ has been isolated and characterized. It is formed by the rapid co- ordination of Ph₃P to cobalt(III) in the μ-peroxo precursor [(OPD)₂Co—O₂—Co(OPD)₂]⁴⁺. The relative contribution of OPD dehydrogenation under catalytic conditions depends on the OPD to Ph₃P ratio. Dioxygen is ultimately converted to water and no H₂O₂ is formed. The proposed mechanistic path involves concerted or stepwise O-atom transfer by species mimicking biological ‘oxenoid’ reagents.     

Synthesis and structural characterisation of [(Ph3P)AuCo(CO)3(PPh3)]

Summary [(Ph₃P)AuCo(CO)₃(PPh₃)] has been synthesised from [(Ph₃P)AuCo(CO)₄], PPh₃v and Me₃NO in acetonitrile. Its molecular structure, determined by single-crystal x-ray crystallography, consists of an almost linear P-Au-Co-P arrangement in which the Co atom is in a slightly distorted trigonalbipyramidal geometry, with the Au and P atoms occupying the apical sites. The Au-Co bond length of 2.450(1) ? is shorter than that reported for [(Ph₃P)AuCo(CO)₄]. The carbonyl ligands are bent towards the Au atom and the mean Au-Co-C angle is 81(1)°.     

High-pressure vibrational study of the catalyst candidate cis-dimercaptobis(triphenylphosphine)platinum(II), cis-[(Ph3P)2Pt(SH)2

Infrared and FT-Raman spectra of cis-dimercaptobis(triphenylphosphine)platinum(II), cis-[(PPh3)2Pt(SH)2], have been measured at high external pressures up to 55 kbar with the aid of a diamond-anvil cell (DAC). The wavenumber (v) versus pressure (P) plots from the Raman data indicate the occurrence of a pressure-induced phase transition at around 15 kbar. The metal-ligand stretching mode, v(Pt-S), and the C-H stretching mode of the phenyl rings, v(C-H), are highly sensitive to the application of pressure (dv/dP approximately 1.0 cm(-1) kbar(-1)). The IR results are generally consistent with the Raman data. The pressure-induced phase transition is most probably attributable to the reorientation of the phenyl rings in the complex; similar results have been obtained for other phenyl derivatives.     

Replacement of Trimethylamine in Trimethylamine‐trispentafluoroethyl‐borane. Structures of [(C2F5)3BNMe3], [NMe4][(C2F5)3BOH], and K[(C2F5)3BCH2(CO)C6H5]

Trimethylamine‐tris(pentafluoroethyl)borane [(C₂F₅)₃BNMe₃] ( 1 ) reacts at 190 °C with water under displacement of the trimethylamine ligand to yield the hydroxy‐tris(pentafluoroethyl)borate [(C₂F₅)₃BOH]^? ( 2 ). In tributylamine 1 reacts with alkynes HC≡CR to form novel ethynyl‐tris(pentafluoroethyl)borate anions [(C₂F₅)₃BC≡CR]^? – R = C₆H₅ ( 3 ), C₆H₄CH₃ ( 4 ), Si(CH(CH₃)₂)₃ ( 5 ) – in moderate yields. Compound 3 adds water across the triple bond to form the novel anion [(C₂F₅)₃BCH₂(CO)C₆H₅]^? ( 6 ). The structures of [(C₂F₅)₃BNMe₃], [NMe₄][(C₂F₅)₃BOH] and K[(C₂F₅)₃BCH₂(CO)C₆H₅] have been determined by x‐ray crystallography.     

三苯基膦亚铜配合物光解反应的ESR研究

用自旋捕捉技术-柱色谱-电子自旋共振相结合的方法研究了(Ph3)3CunXn(n=1,2; x=Cl,Br,I,CN)和(Ph3P)(biL)CuX(X=Cl,Br,I;biL-2,2'-二吡啶基-1,10-菲绕啉光解中的活性自由基.通过在苯基自由基,二苯基膦自由基与苯基丁基氧化氮之间生成的自旋加合物的电子顺磁共振谱的超精细结构,证实了苯基自由基和二苯基膦自由基的生成.标题化合物对某些反应具有催化活性.     

苯酞类化合物重排反应的研究——————3－位烷基取代苯 酞的重排反应

发现了3-正丁基苯酞在三氯化铝作用下进行重排反应生成1-甲基-5-羧基四氢萘,并提出了氢迁移的重排反应机制。研究了3-位不同烷基取代的苯酞类化合物在三氯化铝作用下的重排反应。在重排过程中,既有氢迁移,也会有烷基迁移,这取决于形成的碳正离子的稳定性。     

Ring-Expanded N-Heterocyclic Copper(I) Boryl Complexes: The Structures of [(6-Dipp)CuBcat], [(6-Dipp)CuBneop], and [(6-Dipp)CuBhex]

σ-Bond metathesis reactions between [(6-Dipp)CuOtBu] (6-Dipp=:C({Dipp}NCH₂)₂CH₂, Dipp=2,6-iPr₂−C₆H₃) and three diboranes gave access to three new copper(I) boryl complexes [(6-Dipp)CuBcat], [(6-Dipp)CuBneop], and [(6-Dipp)CuBhex] (cat=1,2-O₂C₆H₄; neop=(OCH₂)₂C(CH₃)₂; hex=OC(CH₃)HCH₂C(CH₃)₂O). Whilst [(6-Dipp)CuBcat] and [(6-Dipp)CuBneop] formed rapidly in toluene, access to [(6-Dipp)CuBhex] required heating to 60 °C for days. The complexes were characterised by single-crystal X-ray crystallography which showed in all three cases that the systems were monomers and distorted-linear at the copper atom. The stability of [(6-Dipp)CuBneop] was found to be comparable to that of [(IPr*)Cu-Bneop] (IPr*=1,3-bis(2,6-(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene); it persisted in solution for days with no sign of decomposition. [(6-Dipp)CuBhex] is a rare crystallographically characterised example of a complex containing a boryl anion supported by the hexylene glycolato ligand.     

Shape and size control of Ag2Se nanocrystals from a single precursor [(Ph3P)3Ag2(SeC{O}Ph)2

Monodispersed Ag2Se nanocubes and faceted nanocrystals have been synthesized by hexadecylamine (HDA) induced thermolysis of [(PPh3)3Ag2(SeC{O}Ph)2] in a mixture of TOP (tri-n-octyl phosphine) and HDA in the temperature range 95-180 degrees C.     

Study of the reactions and reaction mechanisms of phosphine (Ph3P) and of phosphite ((PhO)3P) with sulphur (S8)

The reactions of sulphur with phosphine and phosphite were investigated by low-energy electron impact mass spectrometry and fast atom bombardment mass spectrometry. A previously reported mechanism of the Ph₃P–S₈ reaction was supported and a possible mechanism for the (PhO)₃P–S₈ reaction is proposed.     

Mechanisms of catalyst poisoning in palladium-catalyzed cyanation of haloarenes. remarkably facile C-N bond activation in the [(Ph3P)4Pd]/[Bu4N]+ CN- system

Reaction paths leading to palladium catalyst deactivation during cyanation of haloarenes (eq 1) have been identified and studied. Each key step of the catalytic loop (Scheme 1) can be disrupted by excess cyanide, including ArX oxidative addition, X/CN exchange, and ArCN reductive elimination. The catalytic reaction is terminated via the facile formation of inactive [(CN)4Pd]2-, [(CN)3PdH]2-, and [(CN)3PdAr]2-. Moisture is particularly harmful to the catalysis because of facile CN- hydrolysis to HCN that is highly reactive toward Pd(0). Depending on conditions, the reaction of [(Ph3P)4Pd] with HCN in the presence of extra CN- can give rise to [(CN)4Pd]2- and/or the remarkably stable new hydride [(CN)3PdH]2- (NMR, X-ray). The X/CN exchange and reductive elimination steps are vulnerable to excess CN- because of facile phosphine displacement leading to stable [(CN)3PdAr]2- that can undergo ArCN reductive elimination only in the absence of extra CN-. When a quaternary ammonium cation such as [Bu4N]+ is used as a phase-transfer agent for the cyanation reaction, C-N bond cleavage in the cation can occur via two different processes. In the presence of trace water, CN- hydrolysis yields HCN that reacts with Pd(0) to give [(CN)3PdH]2-. This also releases highly active OH- that causes Hofmann elimination of [Bu4N]+ to give Bu3N, 1-butene, and water. This decomposition mode is therefore catalytic in H2O. Under anhydrous conditions, the formation of a new species, [(CN)3PdBu]2-, is observed, and experimental studies suggest that electron-rich mixed cyano phosphine Pd(0) species are responsible for this unusual reaction. A combination of experimental (kinetics, labeling) and computational studies demonstrate that in this case C-N activation occurs via an S(N)2-type displacement of amine and rule out alternative 3-center C-N oxidative addition or Hofmann elimination processes.     

Selective hydrogenation of alkene in (3-trifluoromethyl) phenyldiazirine photophor with Wilkinson's catalyst for photoaffinity labeling

Selective hydrogenation of carbon-carbon double bond in the presence of nitrogen-nitrogen double bond in (3-trifluoromethyl) phenyldiazirine achieved with Wilkinson's catalyst.