Allylic phosphates and allylic phosphinates as electrophiles in efficient silylcupration reactions of acetylenes

Atom-efficient stoichiometric silylcupration reactions of acetylenes followed by electrophilic trapping of the intermediate vinylcopper species with allylic phosphates have been developed. The reaction sequence was also carried out with the use of a catalytic amount of CuCN employing of both allylic phosphates and allylic phosphinates as electrophiles. The methods developed provide an easy access to silylated 1,4-diene systems.     

Oxide layers with titanium and zirconium phosphates

Oxide-phosphate layers 20 to 150 μm thick were obtained on titanium by plasma electrolytic deposition in individual and mixed aqueous electrolytes with polyphosphate complexes of zirconium(IV), barium(II), and copper(II). Formation features, thickness, elemental and phase compositions, and surface morphology of the films are presented. Depending on the electrolyte composition, synthesis conditions, and temperature of annealing in air, some simple and double phosphates of titanium and zirconium are formed, including ZrP₂O₇, NaTi₂(PO₄)₃, BaTi₂(P₂O₇)₂, Zr_0.2Ti_0.8P₂O₇, and CuTi₂(PO₄)₃.     

Pyridine based zirconium(IV) and tin(IV) phosphates as new and novel intercalated ion exchangers

Pyridine based zirconium(IV) phosphate (PyZrP) and tin(IV) phosphate (PySnP) have been synthesized as new and novel intercalated ion exchangers. These materials have been characterized using X-ray, IR spectra, TG, DTG and DTA studies in addition to their ion exchange capacity, elution, pH titration, concentration and distribution behaviour. The distribution studies towards several metal ions in different media/concentrations have suggested that PyZrP and PySnP are selective for Hg(II) and Pb(II), respectively. As a consequence some binary separations of metal ions involving Hg(II) and Pb(II) ions have been performed on a column of these materials, demonstrating their analytical and environmental potential.     

Synthesis,structure, and thermal expansion of sodium zirconium arsenate phosphates

Sodium zirconium arsenate phosphates NaZr₂(AsO₄) _x (PO₄)_3?x were synthesized by precipitation technique and studied by X-ray diffraction and IR spectroscopy. In the series of NaZr₂(AsO₄) _x (PO₄)_3?x , continuous substitution solid solutions are formed (0 ≤ x ≤ 3) with the mineral kosnarite structure. The crystal structure of NaZr₂(AsO₄)_1.5(PO₄)_1.5 was refined by full-profile analysis: space group R \(\bar 3\) c, a = 8.9600(4)Å, c = 22.9770(9) Å, V = 1597.5(1) ų, R _wp = 4.55. The thermal expansion of the arsenate-phosphate NaZr₂(AsO₄)_1.5(PO₄)_1.5 and the arsenate NaZr₂(AsO₄)₃ was studied by thermal X-ray diffraction in the temperature range of 20–800°C. The average linear thermal expansion coefficients (α_av = 2.45 × 10^?6 and 3.91 × 10^?6 K^?1, respectively) indicate that these salts are medium expansion compounds.     

Catalytic properties of zirconium phosphate and double phosphates of zirconium and alkali metals with a NaZr2(PO4)3 structure

Zirconium orthophosphate Zr₃(PO₄)₄ and double phosphates of zirconium and alkali metals AZr₂(PO₄)₃ (A = Na, K, Rb, Cs) with a NaZr₂(PO₄)₃ structure were synthesized and characterized by X-ray diffraction and electron microprobe analyses and capillary condensation of nitrogen. The catalytic properties of the phosphates in the dehydration of methanol were studied.     

二烷基苯基磷(膦)酸酯重排和水解反应的结构效应

本文用分子力学(MM)和量子化学(MNDO)方法研究了各种不同磷(膦)酸酯的Csp^2-O-P重排反主尖和碱性水解反应的结构效反应.计算结果表明,随着底物分子中C-P键数目的增多,发生重排反主尖的活化能也增加,这与实验结果完全一致.但由于计算得到的各类磷(膦)酸酯碱性水解反应的活化能同实验结果相矛盾,这可能是由于底物同过渡态之间溶剂化能的差别所致.     

Simultaneous thermal/mass spectral investigations of ammonium exchanged zirconium phosphates and zirconium arsenates

The half- and fully-ammonium ion exchanged forms of α- and γ-zirconium phosphates and of α-zirconium arsenate have been prepared. Their modes of thermal decomposition were studied by thermal methods of analysis, including simultaneous DTA/mass spectrometry. The samples heated to various temperatures were also characterized by X-ray diffraction analysis together with IR spectroscopy. The loss of water and ammonia of the various exchanged samples is compared in terms of the changes taking place in the layer lattice upon heating. The use of DTA/MS for a system involving water and ammonia as volatiles is demonstrated     

ESCA investigations of amorphous and crystalline zirconium acid phosphates

Amorphous and micro-crystalline α- and γ-zirconium acid phosphates have been investigated by the ESCA technique. α-zirconium phosphate has been also studied as a single crystal. Both the B.E. of zirconium and phosphorous electrons in zirconium phosphates are slightly higher than those reported for zirconium derivatives and trivalent metal phosphates, indicating a stronger polarization of the ZrO and PO bonds. Furthermore, it seems that some ESCA features of the zirconium phosphates investigated are structure dependent. However, no definitive conclusions have been drawn because of the lack of knowledge of the “charging-up” phenomena in protonic conductors such as zirconium phosphates. Satellite structures have been observed in the P_2s, P_2p, Zr_3d and Zr_4p regions. The position and the intensity of these “shake-up” effects are again dependent on the nature of the examined phase and they seem to be due to the presence of electron defect structures induced by X-rays or already present in the original samples.     

Structural motifs of Au(I)-Cu(I) N-heterocyclic carbene halide complexes

A series of Au(I)–Cu(I) N-heterocyclic carbene (NHC) halide complexes [AuCu₂(im(CH₂py)₂)₂X]²⁺ where X?=?Cl (1), Br (2), I (3) was prepared by refluxing [AuCu₂(im(CH₂py)₂)₂(NCCH₃)₄]³⁺ with the appropriate halide in acetonitrile. The compounds were characterized by NMR, absorption, and fluorescence spectroscopy. They feature similar solution behavior and solid-state photoemissions. The solid-state structures feature a rhomboidal [AuCu₂X]²⁺ core which is influenced by the type of halide. Compared to other Au(I)–Cu(I) NHC complexes, 1–3 comprise a new structural motif containing a bridging halide. The benzimidazolium analog of 1 was also characterized crystallographically. The structure of [AuCu₂(benzim(CH₂py)₂)₂Cl]²⁺(4) features different coordination modes of the NHC ligands with the carbenic carbon bonded to both gold and copper and the pyridyl groups bonded to the same copper(I) ion.     

Synthesis and structure of alkali metal zirconium vanadate phosphates

Mixed vanadate phosphates in the systems MZr₂(VO₄) _x (PO₄)_{3 ? x} , where M is an alkali metal, were synthesized and studied by X-ray diffraction, electron probe microanalysis, and IR spectroscopy. Substitutional solid solutions with the structure of the mineral kosnarite (NZP) are formed at the compositions 0 ≤ x ≤ 0.2 for M = Li; 0 ≤ x ≤ 0.4 for M = Na; 0 ≤ x ≤ 0.5 for M = K; 0 ≤ x ≤ 0.3 for M = Rb; and 0 ≤ x ≤ 0.2 for M = Cs. Apart from the high-temperature NZP modification, lithium vanadate phosphates LiZr₂(VO₄) _x (PO₄)_{3 ? x} with 0 ≤ x ≤ 0.8 synthesized at temperatures not exceeding 840°C crystallize in the scandium tungstate type structure. The crystal structures of LiZr₂(VO₄)_0.8(PO₄)_2.2 (space group P2₁/n, a = 8.8447(6) Å, b = 8.9876(7) Å, c = 12.3976(7) Å, β = 90.821(4)○, V = 985.4(1) ų, Z = 4) and NaZr₂(VO₄)_0.4(PO₄)_2.6 (space group $R\bar 3c$ = 8.8182(3) Å, c = 22.7814(6) Å, V = 1534.14(1) ų, Z = 6) were refined by the Rietvield method. The framework of the vanadate phosphate structure is composed of tetrahedra (that are statistically occupied by vanadium and phosphorus atoms) and ZrO₆ octahedra. The alkali metal atoms occupy extra-framework sites.     

Synthesis and ion-exchange properties of crystalline titanium and zirconium phosphates

The preparation of novel types of inorganic ion-exchangers, titanium and zirconium phosphates and their ion-exchange properties towards strontium ions, are reported and discussed. Ti(HPO₄)₂·2H₂O is shown to be very stable to hydrolysis and to have high exchange capacity in strongly acid medium. In the case of zirconium phosphate, the titration curves with alkaline earth metal hydroxides are strongly affected by hydrolysis of the exchanger and precipitation of insoluble phosphate. The degree of conversion of the exchanger at which phosphate precipitation begins was found to be 80% for Sr²⁺. The comparison of Ti(HPO₄)₂·2H₂O with the corresponding zirconium phosphate dihydrated phase suggests that the former possesses a lattice structure different from that reported for the monohydrated exchanger.This revised version was published online in November 2005 with corrections to the Cover Date.     

Synthesis and transformations of acyloxy(chloromethyl)phosphonates and acyloxy(chloromethyl)phosphinates

The reactions ofO-phenyl chloromethylphosphonochloridate and bis(chloromethyl)phosphinous chloride with sodium acetate afford the corresponding acyloxyphosphonates and acyloxyphosphinates, which are readily transformed due to disproportionation into pyrophosphonates and pyrophosphinates. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp 2383–2385, November, 1998.     

Catalytic properties of sodium zirconium molybdate phosphates in methanol transformations

Molybdate phosphates Na_1?y Zr₂(MoO₄) _y (PO₄)_{3 ? y} (y = 0, 0.25, 0.5) having the NaZr₂(PO₄)₃ structure were prepared by the sol-gel method. The catalytic properties of the molybdate phosphates in dehydration and dehydrogenation of methanol in inert and oxidizing atmospheres were studied.     

Rapid and high yield oxidation of phosphine, phosphite and phosphinite compounds to phosphine oxides, phosphates and phosphinates using hypofluorous acid-acetonitrile complex

The hypofluorous acid acetonitrile complex was used as a mild, rapid, and effective agent to oxidize a wide variety of phosphines, phosphites and phosphinites to the corresponding phosphine oxide, phosphate and phosphinate compounds.