Tris(triphenylphosphine)rhodium cyano and triphenylcyanoborate complexes: Structures and a DFT study

The structures of [Rh(CN)(PPh₃)₃](EtOH) (1), [Rh(NCBPh₃)(PPh₃)₃] (2), and [Rh(CNBPh₃)(PPh₃)₃] (3) are reported together with a density functional theory (DFT) study of the model compounds [Rh(NCBH₃)(PH₃)₃] and [Rh(CNBH₃)(PH₃)₃]. Compound 1 crystallizes in space group Pc with a = 10.4798(15) Å, b = 12.5410(18) Å, c = 19.974(3) Å and = 112.215(6)°; compound 2 crystallizes in space group with a = 12.929(2) Å, b = 14.362(2) Å, c = 17.575(3) Å and = 92.544(3)°, = 90.214(3)°, = 113.831(3)°; compound 3 crystallizes in space group with a = 12.915(2), b = 14.296(2), c = 17.664(3) Å and = 92.469(3)°, = 90.088(3)°, = 113.768(3)°. All three complexes show slight tetrahedral distortion from ideal square planar geometry (largest for 1). Differences in the reactivity and stability of 2 and 3 are interpreted according to the results of a density functional theory study.     

Ph_3P/Mo~Ⅵ体系对吡啶-N-氧化物的脱氧反应

近年来,吡啶-N-氧化物在吡啶衍生物的合成中,日见重要。由于吡啶环上氮原子的电子效应,使吡啶环上的亲电取代反应较难发生,但将吡啶转变成其N-氧化物后,就改变了吡啶环上的电荷密度,使亲电反应能顺利地在2、     

Synthesis of Alkyl (5-Oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates by the Reaction of N-Aminorhodanine,Dialkyl Acetylenedicarboxylates,and Triphenylphosphine

Protonation of the reactive zwitterionic intermediate produced from the reaction between triphenylphosphine and dialkyl acetylenedicarboxylates by N-aminorhodanine followed by the addition of the conjugate anion of N-aminorhodanine on the produced vinylphosphonium cation leads to alkyl (5-oxo-2-thioxo-[1,3,4]thiadiazinan-6-ylidene)acetates in good yields.     

Crystal structure of tetrakis(triphenylphosphine)palladium(0)

Crystal structure of widely employed precatalyst [Pd(Ph₃P)₄] is reported. It crystallizes in P-3 space group [a = 19.0828(8) and c = 26.4423(18) Å] with six molecules per unit cell. It is demonstrated that the phase purity of this important compound can now be routinely controlled via powder X-ray diffraction analysis.     

Triphenylphosphine oxide-based bismaleimide and poly(bismaleimide): Synthesis,characterization, and properties

A novel phosphorus-containing bismaleimide, 3,3′-bis(maleimidophenyl)phenylphosphine oxide (BMPPPO), was synthesized from triphenylphosphine oxide. This bismaleimide exhibited good solubility in common organic solvents, such as methylethylketone, methylisobutylketone, dichloromethane, chloroform, tetrahydrofuran, acetone, methanol, ethanol, and hot toluene. A low melting point (T_m = 148 °C), a relatively low polymerization temperature (T_p = 214 °C), and a wide processing window (T_p − T_m = 66 °C) were also obtained for BMPPPO. This implies better processing capability. In contrast to most known phosphorus-containing polymers, the incorporation of BMPPPO into poly(bismaleimide) enhanced the polymer glass-transition temperature. Thermal stability at temperatures over 550 °C and char yields in the high-temperature region over 700 °C were also improved. As a result, the flame-retardant properties of the poly(bismaleimide)s were improved. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1716–1725, 2001     

Oxidation of Triphenylphosphine by Vanadium Oxytrichloride

A kinetic study on triphenylphosphine oxidation with VOCl₃ was carried out in CCl₄ and THF. The different mechanisms were elucidated; oxygen was activated dissociatively on solid vanadium complex in CCl₄, while oxygen was coordinated molecularly on soluble vanadium complex in THF.     

Synthesis and reactivity of N-hydroxy-2-aminoindoles

Catalytic hydrogenation of (2-nitrophenyl)acetonitriles bearing an electron-withdrawing substituent α to the nitrile, using Pd/C and (Ph₃P)₄Pd, affords N-hydroxy-2-aminoindoles in good to excellent yields. (Ph₃P)₄Pd decreases the reduction rate of the intermediate hydroxylamine and acts as a catalyst during the cyclization onto the nitrile.     

Hydrogenation of carbon dioxide in the presence of rhodium catalysts

The results of CO₂ hydrogenation in the presence of the Wilkinson complexes, viz., RhCl₃ and acacRh(CO)₂, at room temperature and excess PPh₃ are presented. The influence of different ions on the catalytic properties of the Rh complexes was studied. Methanol and methyl formate are formed along with formic acid in the presence of an inorganic salt. Ions that are the most active in the formation of formic acid are the least active in methanol formation.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2436–2439, November, 2004.     

Enthalpy of formation of triphenylphosphine sulfide

The first measurements of the enthalpies of combustion, sublimation, and fusion of an organo-phosphorus sulfide, triphenylphosphine sulfide, are reported: _c H _m ^o (C₁₈H₁₅PS, cr)=–(10752.58 ±2.90), _sub H _m ^o (C₁₈H₁₅PS, 403 K)=(136.80±6.09), and _fus H _m ^o (C₁₈H₁₅PS, T_m=435.92 K) =(30.53±0.21) kJ·mol^–1. Correction of the phase change enthalpies toT=298.15K and p^o =0.1 MPa results in the standard phase change enthalpy values of _sub H _m ^o (298.15 K)=(142.8 ±6.8) and _fus H _m ^o (298.15 K)=(19.28±0.21) kj·mol^–1. Accordingly, the enthalpies of formation of solid, liquid, and gaseous triphenylphosphine sulfide are derived: _f H _m ^o (C₁₈H₁₅PS, cr) =(63.20±2.56), _fH _m ^o (C₁₈H₁₅PS, l)=(82.48±2.57), and _fH _m ^o (C₁₈H₁₅PS, g)=(206.0±7.3) kJ·mol^–1. From these ancillary data, the P=S double-bond enthalpy is 394 kJ-mol^–1 and in good agreement with earlier reaction calorimetry results. These phosphorus sulfide values are compared with those for the arsenic sulfides. Plausibility arguments are given for our results.     

Iridium(iii)-(hydrido)cyclometallated-imine complexes and metal-promoted hydrolytic cleavage of imines

The room temperature reaction of the complex cis,trans,cis-[Ir(H)₂(PPh₃)₂(Solv)₂]PF₆ (Solv is a solvent) with the imine PhCH₂N=CHPh in acetone generates (with loss of H₂) the orthometallated complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(Me₂CO)]PF₆ (3) containing a five-membered cyclometallated imine moiety. In MeOH, the reaction at an imine : Ir ratio = 1 leads to the corresponding MeOH analog of 3, while with excess imine, the mixed orthometallated imine/bezylamine complex [Ir(H){PhCH₂N=CH(o-C₆H₄)}(PPh₃)₂(PhCH₂NH₂)]PF₂ (4) is formed; the source of the coordinated amine is an Ir-promoted hydrolysis of the imine, the water likely coming from imine. Complexes 3 and 4 are fully characterized by elemental analysis, ¹H and ³¹P{¹H} NMR spectroscopy, and X-ray crystal structure analysis.