Crystal Structure of Ordered White Phosphorus(β-P)

Abstract

The low-temperature form of white phosphorus (β-P, T_trans= -76.4°C) is triclinic, P1. The asymmetric unit contains 3 independent tetrahedral P₄ molecules. Intramolecular angles are 60 ± 0.5° and the P-P distances are d=220.9(5) pm. The structure of β-P is related to that of γ-Pu, the Pu atoms being substituted by P₄.     

Amidoalkylation of Tervalent Phosphorus Chlorides with N-α-Hydroxypolyhalogenoalkyl Amides

Abstract

A new preparative method for synthetically and biologically important N-acyl-, N-phosphoryl-, and N-sulfonylaminopolyhalogenoalkylphosphonyl derivatives 2 is presented.     

Preparation and characterization of octacyanomolybdates(IV and V) and octacyanotungstates(IV and V) with 2,2′-bipyridylium cation

Reaction of protonated 2,2′-bipyridine (bpy) with octacyanometalates(IV and V), [M(CN)₈]ⁿ⁻ (M = Mo or W, n = 3 or 4), gave the following complexes: {(bpyH)₃[M(CN)₈]·4H₂O}, {(bpyH)₃(H₃O)[M(CN)₈]·H₂O}, {(bpyH₂)₂[W(CN)₈]·3H₂O} and {(bpyH₂)K₂[W(CN)₈]·2H₂SO₄·7H₂O}. These salts were characterized by electron absorption and reflectance spectrometry, IR, Raman and ESR spectrometry, thermo gravimetry and differential thermal analysis, cyclic voltammetry and potentiometry. The solubility of the salts in water and some polar organic solvents has been measured. The intensively coloured salts of molybdenum(IV) and tungsten(IV) have been discussed in terms of the bpyH⁺-[M(CN)₈]⁴⁻ ion pairs, which exhibit an outer-sphere electron transfer between adjacent redox sites.     

α,ω-Bis(Dialkylthiophosphoryl)Sulfanes-Products of the Alcoholysis of Sulfur-Rich Phosphorus Sulfides

Abstract

The high solubility of sulfur-rich phosphorus sulfides in CS₂-especially in the range S:P=2.7 to 4-is the motive for new investigations on this system. DEMARCQ¹ suppsed the existence of “molecular products”, but he coulds not prove it by spectroscopic and chemical methods. As we have found the formation of α, ω-bis (fluorodithicphosphoryl) oliqosulfanes at the nucleophilic degradation of phosphorus sulfides with fluorides gives no proof for the existence of oligosulfane bridges in the sulfur-rich phosphorus sulfides. On the reaction of P₄S₁₀, elementary sulfur and alka-lifluorides the same products are formed. Sulfur-rich phosphorus sulfides and alcohols also react to mixtures of α,ω-bis (dialkylthiophosphoryl)sulfanes. But these compounds are not obtained by the reaction of P₄S₁₀ and sulfur with alcohols.     

Cycloaddition Reactions of N-Sulphdvylanilines and N-(αCyano-α-aryl)-Methylanilines

Through the cycloaddition of N-(α-cyano-α-aryl)-methylanilines (II) on to N-sulphinylanilines (III) are synthesized 2,3,5-triaryl-4-imino-2H, 3H, 5H-[1.2.5]thiadiazoIidin-l-oxides (TV) in aood vields.     

One-Pot Synthesis Op N-Alkyl (Aryl) N-(α-Alkoxybenzyl) and N-(α-Alkoxymethylene) Carboxamides

A convenient synthesis of N-alkyl (aryl) N-(α-alkoxybenzyl) and N-(α-alkoxymethylene) carboxamides has been developed, starting from the corresponding amines, aldehydes, carboxylic acids, ortho esters and thionyl chloride.     

Selective Sorption–Spectrometric Determination of Nanogram Amounts of Vanadium(IV) and Vanadium(V)

Conditions of the selective sorption–spectrometric determination of vanadium(IV) and vanadium(V) using sulfonitrophenol M were found. The determination of vanadium (visual test (RSD = 30%) using a reference color scale or quantitative determination (RSD < 10%) by diffuse reflectance spectra is performed immediately after the dynamic-mode sorption of its colored complexes with sulfonitrophenol M at pH 3.5 (vanadium(IV)) or with sulfonitrophenol M and hydroxylamine at pH 1.5 (vanadium(V), 650 nm) at the surface of polyamide membrane disks (d= 1 cm, l= 0.1 mm, m= 2.7 mg). The flow rate is 10–20 mL/min. The detection limit is 5–7 ng of vanadium in the support zone or 0.2–0.5 ng/mL. The determination of 0.5–5 ng/mL vanadium(V) at pH 1.5 does not interfere with 20-fold amounts of V(IV) and 1000-fold amounts of Ni, Zn, Cd, Mg, Co, Cr(III), Mn, PO^3- ₄, and F^–.     

全钒液流电池高浓度下V(IV)/V(V)的电极过程研究

采用循环伏安、低速线性扫描和阻抗技术, 以石墨为电极, 研究了V(IV)/V(V)在较高浓度下的电极过程. 结果表明, 采用2.0 mol•L-1 的V(IV)溶液时, H2SO4浓度低于2 mol•L-1, V(IV)/V(V)反应极化大, 可逆性差, 表现为电化学和扩散混合控制; H2SO4浓度增至2 mol•L-1以上, V(IV)/V(V)反应的可逆性提高, 转为扩散控制, 且增加H2SO4浓度有利于阻抗的降低; 但H2SO4浓度超过3 mol•L-1, 溶液的粘度和传质阻力大, 阻抗反而增大. 在3 mol•L-1的H2SO4中, 随着V(IV)浓度的增加, 体系的可逆性和动力学改善, 阻抗减小; 但V(IV)浓度超过2.0 mol•L-1, 较高的溶液粘度导致溶液的传质阻力迅速增加, V(IV)/ V(V)的电化学性能衰减, 阻抗增大. 因此, 综合考虑电极反应动力学和电池的能量密度两因素, V(IV)溶液的最佳浓度为1.5～2.0 mol•L-1, H2SO4浓度为3 mol•L-1.     

Thermal properties of hafnium(IV) and zirconium(IV) β-diketonates

Five volatile hafnium(IV) and zirconium(IV) β-diketonates: hafnium(IV) acetylacetonate, hafnium(IV) trifluoroacetylacetonate, hafnium(IV) pivaloyltrifluoroacetonate, hafnium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate and zirconium(IV) 2,2,6,6-tetramethylheptane-3,5-dionate were obtained, purified and identified. Thermal behavior of solid compounds was investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC) in helium atmosphere and in vacuum. DSC method was also used for definition of thermodynamic characteristics of melting processes. Using the static method with quartz membrane zero-manometer and the flow method the temperature dependencies of saturated vapor pressure for hafnium(IV) complexes was obtained. The standard thermodynamic characteristics ΔH _T⁰ and ΔS _T⁰ of sublimation and evaporation processes were calculated from the temperature dependences of saturated vapor pressure.     

Electrochemical Behavior of Novel Bis(β-diketonate)phthalocyanine Complexes of Zr(IV) and Hf(IV)

We have used cyclic voltammetry to study the electrochemical properties of novel bis(-diketonate)phthalocyanine complexes of Zr(IV) and Hf(IV) in dichloromethane. We found three waves for the studied complexes that can be attributed to one-electron processes MPc(L)^0/1– ₂, MPc(L)^1+/0 ₂ and MPc(L)^2+/1+ ₂. We have shown that the electrochemical behavior of the complexes depends on the nature of the substituents in axial ligands and does not depend on the nature of the metals. We have analyzed the stability of the one-electron oxidation products of the complexes relative to disproportionation.     

Monomeric and dimeric products of protonation of dioxotetracyanometalates(IV)—I: Complexes of tungsten(IV)

A series of tungsten(IV) complexes of formula Me₃[WO(OH)(CN)₄]xH₂O and Me₆[W₂O₃(CN)₈]xH₂O (where Me = Na, K) have been synthesized. The solids obtained were characterized by chemical analysis, thermogravimetric and differential thermal analysis, IR, Raman and visible spectrophotometry and magnetic susceptibility measurements. The analysis of the IR and Raman spectra has led to an assignment of the fundamental vibrations which was supported by studies of IR spectra of the deuterated and anhydrous salts.     

Crystal structures of hafnium(IV) and zirconium(IV) complexes with β-diketones

Preparation methods are developed for a number of 7- and 8-coordinated derivatives of Hf(IV) and Zr(IV) with β-diketonate ligands (R¹-CO-CH-CO-R²). The complexes obtained are examined by IR spectroscopy, mass spectrometry, and X-ray crystallography. All structures are molecular. The M-O distances fall within 2.09–2.28 Å. In the crystals, the molecules are joined only by van der Waals interactions. It is demonstrated that the series of hafnium(IV) and zirconium(IV) chelates with identical ligands are isostructural, and the introduction of CF₃- or tert-butyl groups in the terminal positions of the ligand as well as chlorine substitution for one of the ligands do not essentially affect the basic geometric characteristics of the ligand in the complexes.     

Selective Preparation of Phosphorus Mononitride (P≡N) from Phosphinoazide and Reversible Oxidation to Phosphinonitrene

The interstellar candidate phosphorus mononitride PN, a metastable species, was generated through high-vacuum flash pyrolysis of (o-phenyldioxyl)phosphinoazide in cryogenic matrices. Although the PN stretching band was not directly detected because of its low infrared intensity and possible overlaps with other strong bands, o-benzoquinone, carbon monoxide, and cyclopentadienone as additional fragmentation products were clearly identified. Moreover, an elusive o-benzoquinone-PN complex formed when (o-phenyldioxyl)phosphinoazide was exposed to UV irradiation at λ=254 nm. Its recombination to (o-phenyldioxyl)-λ⁵-phosphinonitrile was observed upon irradiation with the light at λ=523 nm, which demonstrates for the first time the reactivity of PN towards an organic molecule. Energy profile computations at the B3LYP/def2-TZVP density functional theory level reveal a concerted mechanism. To provide further evidence, UV/Vis spectra of the precursor and the irradiation products were recorded and agree well with time-dependent DFT computations.     

The influence of comonomer on ethylene/α-olefin copolymers prepared using [bis(N-(3-tert butylsalicylidene)anilinato)] titanium (IV) dichloride complex

We describe the synthesis of [bis(N-(3-tert-butylsalicylidene)anilinato)] titanium (IV) dichloride (Ti-FI complex) and examine the effects of comonomer (feed concentration and type) on its catalytic performance and properties of the resulting polymers. Ethylene/1-hexene and ethylene/1-octene copolymers were prepared through copolymerization using Ti-FI catalyst, activated by MAO cocatalyst at 323 K and 50 psi ethylene pressure at various initial comonomer concentrations. The obtained copolymers were characterized by DSC, GPC and 13C-NMR. The results indicate that Ti-FI complex performs as a high potential catalyst, as evidenced by high activity and high molecular weight and uniform molecular weight distribution of its products. Nevertheless, the bulky structure of FI catalyst seems to hinder the insertion of α-olefin comonomer, contributing to the pretty low comonomer incorporation into the polymer chain. The catalytic activity was enhanced with the comonomer feed concentration, but the molecular weight and melting temperature decreased. By comparison both sets of catalytic systems, namely ethylene/1-hexene and ethylene/1-octene copolymerization, the first one afforded better activity by reason of easier insertion of short chain comonomer. Although 1-hexene copolymers also exhibited higher molecular weight than 1-octene, no significant difference in both melting temperature and crystallinity can be noticed between these comonomers.     

Photochemistry of tetramethyl(2,2′-bipyridine)platinum(IV)

It is shown that photolysis of [PtMe₄(bipy)] using incident radiation with λ 436 or 473 nm occurs with high quantum efficiency of 0.8–1.0 to give homolysis of a methylplatinum bond; this has allowed a study of the chemical reactions of the [PtMe₃(bipy)] radical.