Cyanphosphorverbindungen. IX. Cyanidabbau von weißem Phosphor zu Dicyanphosphiden und die Dicyanphosphid-Struktur

Cyanophosphorus Compounds. IX. Breakdown of White Phosphorus by Cyanide Yielding Dicyanophosphides and Dicyanophosphide Structure White phosphorus is degraded by strong enough anionic nucleophiles X^? with more or less disproportionation. With crown ether alkali, ammonium or phosphonium cyanides, X^? = CN^?, selectively the corresponding dicyanophosphide, P(CN)₂^?, is formed and a polyphosphide, preferentially P₁₅^?. [18] Crown-6-KP(CN)₂ is also obtained from the reaction of P(CN)₃, KF, and crown ether. In the crystal of this salt the dicyanophosphide anions (bent at phosphorus by an angle of 95°) coordinate with both nitrogen ends towards (different) cations. The PC distance (168 pm on the average) is as short as in phosphaalkenes. δ¹³C and J_PC of P(CN)₂^? fit well into a correlation with the charge density at phosphorus generally valid for cyanophosphorus compounds.     

2-甲基-2-丁醇的低温热容和热力学性质

本文用精密自动绝热量热仪测定了2-甲基-2-丁醇在80～305 K温区的热容,从热容曲线(Cp-T) 发现三个固－固相变和一个固－液相变, 其相变温度分别为T = 146.355, 149.929, 214.395, 262.706 K。从实验热容数据用最小二乘法得到以下四个温区的热容拟合方程。在80～140K温区, Cp,m = 39.208 + 8.0724X - 1.9583X2 + 10.06X3 + 1.799X4 - 7.2778X5 + 1.4919X6, 折合温度X = (T –110) / 30; 在 155 ～ 210 K温区, Cp,m = 70.701 + 10.631X + 12.767X2 + 0.3583X3 - 22.272X4 - 0.417X5 + 12.055X6, X = (T –182.5) /27.5; 在220 ～ 250 K温区, Cp,m = 99.176 + 7.7199X - 26.138X2 + 28.949X3 + 0.7599X4 - 25.823X5 + 21.131X6, X = (T – 235)/15; 在 270～305 K温区, Cp,m =121.73 + 16.53 X- 1.0732X2 - 34.937X3 - 19.865X4 + 24.324X5 + 18.544X6, X = (T –287.5)/17.5。从实验热容计算出相变焓分别为0.9392, 1.541, 0.6646, 2.239 kJ×mol-1; 相变熵分别为6.417, 10.28, 3.100, 8.527 J×K-1×mol-1。根据热力学函数关系式计算出80～305 K温区每隔5 K的热力学函数值 [HT –H298.15]和 [ST –S298.15]。     

Theoretical study on a chemosensor for fluoride anion‐based on a urea derivative

The sensing mechanism of the N‐Phenyl‐N′‐(3‐quinolinyl)urea (PQU) chemosensor for fluoride anion has been investigated by density functional theory/time‐dependent density function theory. The double intermolecular hydrogen bonds are formed between the three anions (X^??F^?, AcO^?, Cl^?) and the urea fragment of PQU. In the S₀ states, the H_b? X^? hydrogen bonds are slightly stronger than the H_a? X^? hydrogen bonds and the fluoride‐induced deprotonation occurs at the N? H_b position rather than at the N? H_a position. Consequently, the absorption peaks, including an intramolecular charge transfer transition and a ππ* transition, are significantly red‐shifted. Thermodynamic calculations confirm that the deprotonation in the ground state is favorable in energy only when excess fluoride anion exists. Along with the S₀ → S₁ transition, the H_a? X^? hydrogen bonds strengthen and the H_b? X^? hydrogen bonds weaken. However, the emission spectra of [PQU‐H_b]^?, instead of [PQU‐H_a]^?, are observed upon addition of fluoride anion. © 2013 Wiley Periodicals, Inc.     

对氨基苯甲酸热力学性质的量热和热分析研究

在80～400 K温区,用高精度全自动绝热量热仪测定了对氨基苯甲酸摩尔热容,得到摩尔热容随温度的变化的关系式为：     

b1Σ+ and a1Δ emissions from group VI-VI diatomic molecules: b0+ → X10+, x21 emissions of TeO and TeS

Near infrared emissions of the b0⁺→X₁0⁺, X₂1 band systems of TeO and TeS have been observed by chemiluminescence studies in a fast flow system. In both cases the b → X₁ and b → X₂ subtransitions were found to occur with similar intensities. Analysis of the spectra yielded values of the b0⁺ energies T_e of 9966 ^± 10 cm^?1 and 8457 ^± 10 cm^?1 for TeO and TeS, respectively, and vibrational separations ω_e in these states of 726 ^± 10 cm^?1 and 436 ^± 5 cm^?1. The energy splittings of the X₁0⁺ and X₂1 ground state levels were determined to be 789 ^± 10 cm^?1 and 829 ^± 5 cm^?1.     

New Host Molecules with Imidazoliums as Functional Arms:Syntheses and Anion Recognition

The bridged tri-imidazoliums 3.3X^--5.3X^-(X^-=PF6^-,Br^-,I^-)and bis-imidazoliums 6.2PF6^- were synthesized by N-quaternization of imidazole derivative 1 in acetonitrile under reflux.UV spectroscopic titration experiments showed that the halide salts and hexafluorophosphate salts of these imidazoliums exhibited good recognition toward anions in water and in acetonitrile,respectively.     

Thermal decompositions of N-methylpyridinium,quinolinium, isoquinolinium and phenanthridinium salts in a mass spectrometer. Evidence for a specific HI elimination and for an oxidation to amides

The mass spectra of some N-methylpyridinium, quinolinium, isoquinolinium and phenanthridinium salts (R⁺X^?)

1 The salt will be represented by R⁺X^? or RX, R⁺ being the organic moiety, with its associated mass and X- the inorganic anion.

are analyzed (X^? = I^? or ClO₄^?). For X^? = I^?, thermal decomposition gives rise mainly to the superimposed spectra of CH₃I and the free base. Hence, iodide salts cannot be determined specifically by their mass spectra. When an α-methyl group is present, e.g. 2-methylpyridinium methiodide, elimination of HI becomes an important thermal process. For X^? = ClO₄^?, the same pattern is observed, but in addition a generally important peak at [R + 15] is present. This peak is due to the oxidation, mainly α to the nitrogen of the organic moiety by the ClO₄^? ion, giving rise to the corresponding amide. In some cases, chlorination of the organic moiety has been observed as well as double oxidation. The thermal processes for the perchlorate salts are characteristic and are useful in the elucidation of the quaternary structure.     

Ion‐Pairing of Phosphonium Salts in Solution: C?H⋅⋅⋅Halogen and C?H⋅⋅⋅π Hydrogen Bonds

The ¹H NMR chemical shifts of the C(α)? H protons of arylmethyl triphenylphosphonium ions in CD₂Cl₂ solution strongly depend on the counteranions X^?. The values for the benzhydryl derivatives Ph₂CH? PPh₃⁺ X^?, for example, range from δ_H=8.25 (X^?=Cl^?) over 6.23 (X^?=BF₄^?) to 5.72 ppm (X^?=BPh₄^?). Similar, albeit weaker, counterion‐induced shifts are observed for the ortho‐protons of all aryl groups. Concentration‐dependent NMR studies show that the large shifts result from the deshielding of the protons by the anions, which decreases in the order Cl^? > Br^? ? BF₄^? > SbF₆^?. For the less bulky derivatives PhCH₂? PPh₃⁺ X^?, we also find C? H???Ph interactions between C(α)? H and a phenyl group of the BPh₄^? anion, which result in upfield NMR chemical shifts of the C(α)? H protons. These interactions could also be observed in crystals of (p‐CF₃‐C₆H₄)CH₂? PPh₃⁺ BPh₄^?. However, the dominant effects causing the counterion‐induced shifts in the NMR spectra are the C? H???X^? hydrogen bonds between the phosphonium ion and anions, in particular Cl^? or Br^?. This observation contradicts earlier interpretations which assigned these shifts predominantly to the ring current of the BPh₄^? anions. The concentration dependence of the ¹H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD₂Cl₂ solution. The cation–anion interactions increase with the acidity of the C(α)? H protons and the basicity of the anion. The existence of C? H???X^? hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well as by X‐ray analyses of the crystals. The IR spectra of the Cl^? and Br^? salts in CD₂Cl₂ solution show strong red‐shifts of the C? H stretch bands. The C? H stretch bands of the tetrafluoroborate salt PhCH₂? PPh₃⁺ BF₄^? in CD₂Cl₂, however, show a blue‐shift compared to the corresponding BPh₄^? salt.     

Coordination d'anions organophosphores: 2eme partie. Perturbations provoquées par les coordinats “halogéno” et “pseudohalogeno” dans des complexes du zinc(II). Étude par spectro

Infrared and nuclear magnetic resonance spectroscopy data are presented for a series of complexes [ZnXL], where L^? denotes the {(C₂H₅O)₂POCHCOCH₂NR₂}^? anion with R = CH₃ (La^?) or C₂H₅ (Lb^?) and X a halogen or pseudohalogen. The infrared data reveal that the splitting of the absorption v(P → O) depends on the nature of X^? and is interpreted in terms of a crystal effect. The following order Cl^? < NCO^? ~ Br^? < I^? < NCS^? < NCSe^? is consistent with the ligand size. Nonequivalent protons on a given methylene group and nonequivalent methyl or ethyl groups bonded to nitrogen are detected by NMR spectroscopy of deuterochloroform solutions of these complexes. With La^?, the rate of exchange increases in the order NCO^?, Cl^?, Br^?, X^? (X^? = I^?, NCS^?, NCSe^?). The kinetic parameters for exchange of nonequivalent N(CH₃)₂ groups were determined.     

Low-temperature thermodynamics of Ln(Me2dtc)3(C12H8N2) (Me2dtc = dimethyldithiocarbamate, Ln = La, Pr, Nd, Sm)

The heat capacities of Ln(Me₂dtc)₃(C₁₂H₈N₂) (Ln = La, Pr, Nd, Sm, Me₂dtc = dimethyldithiocarbamate) have been measured by the adiabatic method within the temperature range 78–404 K. The temperature dependencies of the heat capacities, C _p,m [La(Me₂dtc)₃(C₁₂H₈N₂)] = 542.097 + 229.576 X ? 27.169 X ² + 14.596 X ³ ? 7.135 X ⁴ (J K^?1 mol^?1), C _p,m [Pr(Me₂dtc)₃(C₁₂H₈N₂)] = 500.252 + 314.114 X ? 17.596 X ² ? 0.131 X ³ + 16.627 X ⁴ (J K^?1 mol^?1), C _p,m [Nd(Me₂dtc)₃(C₁₂H₈N₂)] = 543.586 + 213.876 X ? 68.040 X ² + 1.173 X ³ + 2.563 X ⁴ (J K^?1 mol^?1) and C _p,m [Sm(Me₂dtc)₃(C₁₂H₈N₂)] = 528.650 + 216.408 X ? 16.492 X ² + 12.076 X ³ + 4.912 X ⁴ (J K^?1 mol^?1), were derived by the least-squares method from the experimental data. The heat capacities of Ce(Me₂dtc)₃(C₁₂H₈N₂) and Pm(Me₂dtc)₃(C₁₂H₈N₂) at 298.15 K were evaluated to be 617.99 and 610.09 J K^?1 mol^?1, respectively. Furthermore, the thermodynamic functions (entropy, enthalpy and Gibbs free energy) have been calculated using the obtained experimental heat capacity data.     

EPR Study of some Copper(II) Coordination Compounds with substituted Biguanides. III

Copper(II) coordination compounds with p-chlorphenylbiguanide of the type: [Cu(Cl-PhBig)₂]X₂ and [Cu(Cl–PhBig)X₂] with X =Cl^?, Br^? NO₃, OH^?, NCS^?, NCO^?, N₃, have been studied by EPR spectroscopy using polycrytalline powders and solutions in DMF. The parameters of the EPR spectra have been used to estimate molecular orbital coefficient, in these compounds and to discuss details of the chemical bonding.     

Densities of Melts of the System KF?K2MoO4?B2O3

The density of melts of the system KF? K₂MoO₄? B₂O₃ was measured. The molar volume in the binary system KF? K₂MoO₄ deviates only little from the ideal course, which indicates the extended thermal dissociation of the congruently melting additive compound K₃FMoO₄. In the KF? B₂O₃ binary system the formation of KBF₄ and K₂B₄O₇ leads to the volume expansion, like in the K₂MoO₄? B₂O₃ system, where the volume expansion may be described by the formation of the heteropolyanions [BMo₆O₂₄]^9?. The significant deviation from the ideal behaviour in the ternary system KF? K₂MoO₄? B₂O₃ refers to the pronounced interaction, most probably due to the substitution of oxygen atoms in the coordination sphere of the heteropolyanion with the fluorine ones.     

Structures and stabilization energies of methyl anions with main group substituents from the first five periods

The effects of substituents (X) on the structures and stabilities of CH₂X^? anions for groups comprised of fourth- and fifth-period main group elements (X = K, CaH, GaH₂, GeH₃, AsH₂, SeH, Br, Rb, SrH, InH₂, SnH₃, SbH₂, TeH, and I) have been investigated by ab initio pseudopotential calculations. Full geometry optimizations have been carried out on the CH₂X^? anions and the corresponding neutral parent molecules, CH₃X, at HF/DZP + and MP2/DZP + levels. Results for substituents from the second (X = Li? F) and third (X = Na? Cl) periods provide comparisons of substituent effects of the main group elements of the first four rows of the periodic table on methyl anions. Frequency calculations characterize the nature of stationary points and show pyramidal CH₂X^? anion structures to be the most stable unless π acceptor interactions (e.g., with BH₂, AlH₂, GaH₂, and InH₂ favor planar geometries. The CH₂X^? stabilization energies [at QCISD(T)/DZP + /MP2/DZP + + ZPE level for X = K? I and QCISD(T)/6?31 + G*/MP2/6?31 + G* + ZPE level] for X = Li? Cl) also show strong π-stabilizing effects for the same substituents. With the exception of CH₃ and NH₂, all substituents stabilize methyl anions, although the σ stabilization by OH and F is small. The SiH₃? PH₂? SH? Cl, GeH₃? AsH₂? SeH? Br, and SnH₃? SbH₂? TeH? I sets of substituents give stabilization energies between 19 and 30 kcal/mol. The stability of methyl anions substituted by the halogens and the chalcogens (X = OH, SH, SeH, and TeH) increases down a group in accord with the increasing substituent polarizability, while for π acceptors (BH₂, AlH₂, GaH₂, and InH₂) the stability decreases down a group in line with their π-accepting ability. © 1994 by John Wiley & Sons, Inc.     

Nucleophilic Substitution at Phosphorus Centers (SN2@P)

We have studied the characteristics of archetypal model systems for bimolecular nucleophilic substitution at phosphorus (S_N2@P) and, for comparison, at carbon (S_N2@C) and silicon (S_N2@Si) centers. In our studies, we applied the generalized gradient approximation (GGA) of density functional theory (DFT) at the OLYP/TZ2P level. Our model systems cover nucleophilic substitution at carbon in X^?+CH₃Y (S_N2@C), at silicon in X^?+SiH₃Y (S_N2@Si), at tricoordinate phosphorus in X^?+PH₂Y (S_N2@P3), and at tetracoordinate phosphorus in X^?+POH₂Y (S_N2@P4). The main feature of going from S_N2@C to S_N2@P is the loss of the characteristic double‐well potential energy surface (PES) involving a transition state [X? CH₃? Y]^? and the occurrence of a single‐well PES with a stable transition complex, namely, [X? PH₂? Y]^? or [X? POH₂? Y]^?. The differences between S_N2@P3 and S_N2@P4 are relatively small. We explored both the symmetric and asymmetric (i.e. X, Y=Cl, OH) S_N2 reactions in our model systems, the competition between backside and frontside pathways, and the dependence of the reactions on the conformation of the reactants. Furthermore, we studied the effect, on the symmetric and asymmetric S_N2@P3 and S_N2@P4 reactions, of replacing hydrogen substituents at the phosphorus centers by chlorine and fluorine in the model systems X^?+PR₂Y and X^?+POR₂Y, with R=Cl, F. An interesting phenomenon is the occurrence of a triple‐well PES not only in the symmetric, but also in the asymmetric S_N2@P4 reactions of X^?+POCl₂? Y.     

Anion production from Cs + CF3X: evidence for stripping

Crossed beams of energetic cesium atoms (25–350 eV) and thermal Cf₃X (X = Cl, Br and I) produce X^? and F^? as the major anions. The intensity ratio (F^?/X^?) is measured as a function of energy. A hard-sphere stripping model is in reasonable accord with the data.     

Stability of gold(I) glycinate complexes in aqueous solution

The stepwise substitution equilibrium AuCl ₂ ^? +iX^?=AuCl_2?i X _i ^? +iCl^?, β_i, where X^? is the glycinate ion (H₂N-CH₂-COO^?), i = 1 or 2, at 25°C in an aqueous solution with I = 1.0 mol/L (NaCl) has been studied pH-metrically. The corresponding constants are logβ₁ = 3.60 ± 0.10, and logβ₂ = 6.2 ± 0.2.     

The solid state reaction between hexaamminechromium(III) complexes and L-α-alanine

The solid reaction between [Cr(NH₃)₆]X₃(X^? = Cl, I, SCN and NO₃) and L-α-alanine was studied under continuous rise in temperature and isothermal heating. Under continuous rise in temperature, the main products were [Cr(NCS)₃-(NH₃)₃] (X^? = NCS) and [Cr(L-ala)₃] (X^? = NO₃), when [Cr(NH₃)₆]Cl₃ and [Cr(NH₃)₆]I₃ as starting complexes were used; in both cases only the decomposition proceeds. Under isothermal heating at 150°C the main products were [CrCl(NH₃)₅]-Cl₂ (X^? = Cl), [Cr(NH₃)₆]I₂ (X^? = I), [Cr(NCS)₃(NH₃)₃] (X^? = SCN) and [Cr(L-ala)₃] (X^? = NO₃). In those matrix reactions, the ease of anion coordination was: SCN^? > Cl^? > I^? > alanine. For the synthesis of tris(alaninato)chromium(III) complex the most desirable starting complex was [Cr(NH₃)₆](NO₃)₃.The solid state reaction between [Cr(en)₃]X₃ type complexes and NH₄X (X^? = F, Cl, Br, I and SCN), KX (X^? = Cl, Br and I), and NaSCN have been reported by Wendlandt and Stembridge¹. They reported that the reaction product in most cases, was cis-[Cr(en)₂Y₂]X, where Y and X are the same or different anions, depending upon the matrix material employed and the thermal matrix method appears to be a useful new route for the synthesis of bis(ethylendiamine(chromium(III) complexes.In the previous paper², the solid state reaction between [Cr(NH₃)₆](NO₃)₃ and L-amino acids has been utilized in the preparation of tris(amino acidato)chromium(III) complexes. The preparation of [Cr(L-ala)₃] by the solid state reaction between [Cr(NH₃)₆](NO₃)₃ and L-alanine have been reported. No studies on the effect of the counter-ion have been reported.In this paper, various hexaamminechromium(III) complexes, [Cr(NH₃)₆]X₃ (X^? = Cl, I, SCN and NO₃), were heated with L-α-alanine under continuous rise in temperature and under isothermal heating at 150°C for studies on the ease of anion coordination. It will seen that the anion which replaces the ammonia in the hexaamminechromium(III) complex comes from either the alanine or counter-ion.     

b 1Σ+ emissions from group V-VII diatomic molecules: bo+ → X10+, X21 emissions of SbBr

Chemiluminescence studies of the reactions of microwave-discharged oxygen with SbBr₃ have led to the observation of some band sequences in the near infrared region which are attributed to b0⁺ → X₁0⁺ and b0⁺ → X₂1 transitions of SbBr. Analysis of the spectra yielded T_e values for the X₂1 and b0⁺ states of 874 ± 10 and 12756 ± 10 cm^?1, respectively, and vibrational frequencies in the X₁0⁺, X₂1 and b0⁺ states of ω′'_e(X₁, X₂) = 257 ± 10 and ω′_e(b) = 270 ± 10cm^?1.     

Cinetique complexe de l'halogenation de cetones en milieu acide—II : Controle par la diffusion des vitesses d'halogenation des enols-consequences

The kinetics of the bromination and chlorination of acetone, diethylketone and di-isopropylketone (bromination only) have been studied at [X₂]_a^o ≈ 10^?7 to 10^?5 M; the apparent rate constants k_II^X₂ = K_Ek₂^X₂ (where K_E is the keto-enol equilibrium constant) for iodination, bromination and chlorination are approximately equal. This result is attributed to diffusion-controlled kinetics. The order of magnitude of such a limiting rate constant, 10⁹ M^?1s^?1 calculated from Smoluchowski's equation, leads to new values for K_E in solution (1·5 x 10^?8 for acetone) much smaller than those in the literature. The rate constants derived for enol ketonisation are then in good agreement with those from proton addition to the corresponding enol ethers.     

The anomeric effect: Ab-initio studies on molecules of the type X?CH2?O?CH3

The anomeric effect of the functional groups X = C?N, C?CH, COOH, COO^?, O? CH₃, NH₂, and NH⁺₃ has been studied with ab initio techniques. Geometry effects upon rotation around the central C? O bond in X? CH₂? O? CH₃ have been compared in the various compounds. The energy differences between the conformers with a gauche and trans (X? C? O? C) arrangement were calculated at the 6-31G* level in the fully optimized 4-21G geometries. Energy differences calculated at the 4-21G level appeared not to be reliable, especially for the groups X that contain non-sp³ hybridized atoms. The 6-31G* energy differences indicate a normal anomeric effect for X = COO^?, O? CH₃, and NH₂(g⁺) (ca. 13 kJ/mol) and a small anomeric effect for X = COOH, C?N, and C?CH (ca. 6 kJ/mol). For X = NH₂(t) and NH⁺₃ a reverse anomeric effect occurs. These observations are in line with experimental results and evidence is given for a competition among various stereoelectronic interactions that occur at the same anomeric center. Geometry variations can be understood in terms of simple rules associated with anomeric orbital interactions. Trends followed when the group X is varied cannot be related in a straightforward way to the energy differences between the trans and the gauche forms in these compounds. Only the variation in the gauche torsion angle X? C? O? C follows roughly the same trend.