Hexamincyclotriphosphazenhemiammoniakat,P3N3(NH2)6 · 0,5 NH3, ein Produkt der Hochdruckammonolyse von weißem Phosphor

Hexaminecyclotriphosphazenehemiammoniate, P₃N₃(NH₂)₆ · 0.5 NH₃, a Product of High Pressure Ammonolysis of White Phosphorus White phosphorus gives at NH₃-pressures ≥5 kbar and temperatures above 250°C in a disproportionation reaction P₃N₃(NH₂)₆ · 0.5 NH₃; besides these products red phosphorus is formed. The yield on P₃N₃(NH₂)₆ · 0.5 NH₃ increases with T and is about 70–80% at 400°C as to the disproportionation reaction of the amount of white phosphorus. X-ray structure determination was successful on single crystals of P₃N₃(NH₂)₆ · 0.5 NH₃. Pbca, N = 8 a = 11.395(3) Å, b = 12.935(4) Å, c = 12.834(4) Å R = 0.035, R_w = 0.041 with w = 1, N (F_o²) ≥ 3σ(F_o²) = 1371, N(Var.) = 166. The molecules are connected by N? H? N-bridgebonds with 3.04 Å ≤ d(N …? N) ≤ 3,19 Å and d (N? H) = 0.87 Å. The compound is furthermore characterized by IR-data and its thermical behaviour.     

A three-dimensional network structure built from selenodiphosphate(IV) and copper selenide tetrahedral building blocks: K3Cu3P3Se9

The reaction of red phosphorus, potassium polyselenide, and copper metal at moderate temperatures yields K₃Cu₃P₃Se₉. The structure was determined by single crystal X-ray diffraction (P2₁/c, a = 8.741(2) Å, b = 10.774(2) Å, c = 20.033(3) Å, β = 92.96(2)°). The structure consists of [P₂Se₆]^4?-anions that link [CuSe₄] tetrahedra in an open, three-dimensional, framework structure. A Valence Electron Concentration treatment of this structure reveals six different primary tetrahedral building blocks.     

Evidence of Long-Range 13C-31P Couplings: A 13C NMR Investigation of Some Aryl Esters of Phosphor-Amidochloridic Acid and the Related Compounds

Abstract

In ¹³ NMR study organophosphorus compounds, sign and magnitude of ¹³ C-³¹ P spin-spin couplings has been of great interest to elucidate stereochemistry and electronic state of phosphorus central atom. However, a discussion about the mechanisms of carbon-phosphorus couplings is still complicated specially in the case of long-range couplings that also are not frequently observed. In this study, ¹³ C NMR chemical shifts and coupling constants have been determined for a series of aryl esters of phosphoramidochloridic acid with the general formula: R₂NP(O)(OAr)Cl, in which R = methyl and/or benzyl, Ar = p-tolyl. p-nitrophenyl, and phenyl. Besides usual W-couplings that could be found in these systems, we detected long-range couplings through five and six bonds. It has been shown that, these couplings are highly dependent on substituents on phosphorus nuclei. The data for some related compounds have been also obtained for a comparison.     

Investigations of reactions involved in electro-thermal atomic absorption procedures : Part 8. A theoretical and experimental study of factors influencing the determination of phosphorus

Ideal conditions for the determination of phosphorus by graphite-furnace atomic absorption spectrometry are investigated by the use of high-temperature equilibrium calculations. All reasonable reaction products resulting from the reaction between P, C, O, H, N, Ca and Ar are considered. The calculations show that phosphorus forms the volatile monoxide and dioxide molecules below 1800 K (P_o2? 10^-13 atm.). At higher temperatures the relative amount of atomic phosphorus is mainly controlled by the equilibrium between monatomic and diatomic phosphorus. The significance of the theoretical ' study was investigated experimentally. The relative amounts of P₂ and PO were monitored by molecular absorption using vaporization under isothermal conditions; the interfering effects of Ca, N₂, H₂, and O₂ on the atomic absorption signal for phosphorus were also studied. The sensitivity was greatly dependent on graphite tube conditions as well as the heating rate of the furnace. For CaHPO₄ the sensitivity for phosphorus was 4.5 × lO^-8 g. If samples were introduced into a preheated tube, this value was improved to 2 × 10^-9 g.     

Reactions of magnesium formate on supports

Thermal decomposition of supported magnesium formate has been studied by gas chro-matography.The reaction paths of decomposition of supported magnesium formate depend on thenature of the supports.For Mg(HCO_2)_2/HZSM-5,the zeolite behaves as a dehydration catalyst togive CO and H_2O at lower temperatures;when the zeolite is modified by phosphorus,the methanationreaction will be partly restrained.In the case of Mg(HCO_2)_2/AC,strong adsorption of CO_2 leadsto the formation of the shoulder peak of CO_2 at higher temperatures,however,CH_4 disappears aftermodified by phosphorus.For Mg(HCO_2)_2/Al_2O_3,the dehydrogenation of HCO_2~- takes place on thesurface of Al_2O_3.The decomposition of Mg(HCO_2)_2 on SiO_2 in hydrogen yields two peaks of COand only one appears after modified by phosphorus.When Mg(HCO_2)_2 decomposes on MgO,the firstpeak of CO_2 arises from the reaction of surface Mg~(2+) with HCO_2~- from dissociated Mg(HCO_2)_2.     

Synthesis and reactivity of [(RRN)2PH]Fe(CO)4 complexes. X-ray crystal structure of [(Ph2N)2PH]Fe(CO)4

KHFe(CO)₄ reacts with tris(amino)phosphines by substitution at phosphorus leading to [bis(amino)phosphine]tetracarbonyliron complexes [(R¹R²N)₂PH]Fe(CO)₄. The X-ray structure has been determined for R¹=R²=Ph. Deprotonation of these complexes with KH affords stable potassium phosphidotetracarbonylferrates which can be alkylated or acylated at phosphorus.     

Unusual Bonding and Properties in Main Group Element Chemistry: Rational Synthesis,Characterization, and Experimental Electron Density Determination of Mixed‐Valent Tetraphosphetes

Five dispirocyclic λ³,λ⁵‐tetraphosphetes [{R₂Si(NR¹)(NR²)P₂}₂] (R¹ = R² and R¹ ≠ R²) are easily prepared in almost quantitative yields via photolysis of the respective bis(trimethylsilyl)phosphanyldiazaphosphasiletidines with intense visible light. These deep‐yellow low‐coordinate phosphorus compounds can be considered as the first higher congeners of the well‐known cyclodiphosphazenes. The tetraphosphetes are remarkably stable in air and show unexpected molecular properties related to the unique bonding situation of the central four‐π‐electron four‐membered phosphorus ring. The extent of rhombic distortion of the central P₄ ring is remarkable due to an unusually acute angle at the σ²‐phosphorus atoms. All of the P?P bonds are approximately equal in length. The distances are in the middle of the range given by phosphorus single and double bonds. The anisotropic absorption of visible light that can easily be observed in the case of the yellow/colorless dichroic crystals of [{Me₂Si(NtBu)(NtBu)P₂}₂] and the exceptional ³¹P NMR chemical shift of the σ²‐phosphorus atoms are the most remarkable features of the λ³,λ⁵‐tetraphosphetes. In the case of [{Me₂Si(NtBu)(NtBu)P₂}₂], the Hansen–Coppens multipole model is applied to extract the electron density from high‐resolution X‐ray diffraction data obtained at 100 K. Static deformation density and topological analysis reveal a unique bonding situation in the central unsaturated P₄ fragment characterized by polar σ‐bonding, pronounced out‐of‐ring non‐bonding lone pair density on the σ²‐phosphorus atoms, and an additional non‐classical three‐center back‐bonding contribution.     

A Further Extension of Pnictide Oxide Chemistry – Synthesis and Structure of La2AuP2O

The phosphide oxide La₂AuP₂O was synthesized from lanthanum filings, dried La₂O₃, gold pieces, and ground red phosphorus in the ideal 1.33:0.33:1:2 ratio in an evacuated silica tube at 1473 K. Small single crystals were obtained by recrystallization in a NaCl/KCl flux. The structure was determined on the basis of single‐crystal X‐ray diffractometer data: new type, C2/m, a = 1537.3(3), b = 427.39(8), c = 1009.2(2) pm, β = 131.02(1) °, wR₂ = 0.046, 1102 F² values, 38 variables. La₂AuP₂O contains two striking structural motifs: The oxygen atoms are located in La₄ tetrahedra. The latter are cis‐edge‐shared forming polymeric cationic [La₂O]⁴⁺ chains. These cationic units are separated and charge‐balanced by [AuP₂]^4– polyanions which have monovalent gold in distorted trigonal planar phosphorus coordination. Two crystallographically independent phosphorus sites occur in the polyanion, i.e. isolated P^3– besides dumb‐bells P₂^4– (P2–P2 223 pm). La₂AuP₂O, which crystallizes in the form of ruby red transparent crystals, is an electron precise phosphide oxide (4La³⁺)(2Au⁺)(2P^3–)(P₂^4–)(2O^2–).     

Study of the electric dipole moments of the (C2H5)n PX3−n and P{EIVB (CH3)3}3 compounds (X = Cl,Br, I; EIVB = C,Si, Sn; n = 0, 1, 2, 3)

The dipole moments of the (C₂H₅)_nPX_3?n (X = Cl, Br, I; n = 0, 1, 2, 3) and P{E^IVB(CH₃)₃}₃ compounds (E^IVB = C, Si, Sn) have been determined by dielectric measurements in benzene at 25°C by Higasi's method. The results are interpreted in terms of an additive vector model from bond moment calculations and a maximum phosphorus lone pair contribution of 1.75 D as calculated for P(C₂H₅)₃. The high dipole moment of the mixed PA₂B-type compounds in comparison with PA₃ moments is mainly ascribed to a loss of C_3v symmetry, characterized by a quite asymmetric orientation of the phosphorus lone pair with respect to the phosphorus bonding orbitals.     

Structure Determination of a Low Temperature Phase of Calcium and Strontium Amide by means of Neutron Powder Diffraction on Ca(ND2)2 and Sr(ND2)2

Calcium and Strontium amide are ionic compounds crystallising in a tetragonally distorted anatase structure-type at ambient temperatures. The amide ions (NH₂^–/ND₂^–) resemble water molecules in structure and in charge distribution. By means of temperature dependent neutron diffraction investigations weak super-structure reflections were observed at temperatures below 90 K (Ca(ND₂)₂) and 60 K (Sr(ND₂)₂), respectively, indicating the existence of a so far unknown low-temperature (LT) phase. Using high resolution neutron powder diffraction at temperatures below 10 K the structure was determined for both compounds. The LT-phases are isotypic and crystallise monoclinic in the space group P2₁/c with four formula units within the unit cell: Ca(ND₂)₂ at 10 K a = 7.257(2) Å, b = 7.2434(2) Å, c = 6.300(1) Å, β = 124.73(1)° Sr(ND₂)₂ at 5 K a = 7.6950(1) Å, b = 7.68374(9) Å, c = 6.6324(3) Å, β = 124.917(2)°. Their structure is closely related to the tetragonal HT-phase, but an ordering of the amide ions occurs due to freezing of a lattice mode which is dominated by the librational motion of the amide ions in the {1 0 0} planes of the HT-phase.     

Preparation and crystal structure of the Copper Silicon Polyphosphide Cu4SiP8

The new compound Cu₄SiP₈ was prepared by solid state reaction of the elemental components. It crystallizes with a new structure type, which was determined from single-crystal X-ray diffractometer data: I4₁/a, a = 1 218.6(2) pm, c = 573.2(2) pm, Z = 8, R = 0.023 for 970 structure factors and 31 variable parameters. Tetrahedral SiP₄ groups are linked via additional phosphorus atoms to a three-dimensionally infinite silicon phosphorus network, accommodating Cu₂ pairs with octahedral phosphorus coordination as is known for the closely related structure of CuP₂. Using oxidation numbers the compound may be rationalized by the formula (Cu⁺¹)₄Si⁺⁴(P⁰)₄(P^?2)₄ in agreement with the Zintl-Klemm concept.     

Theoretical study of the dipole moment of oxygen monofluoride (OF)

Theoretical X²II potentials and dipole moment functions for OF are presented at the CASSCF, externally contracted Cl, and MRCI(SD) levels using DZP and extended gaussian basis sets. The best theoretical results (with experiment in parentheses) are μ_ν =0 = ?0.0089 (?0.0043) and μ_ν=1 = ?0.0318 (?0.0267) D, where the minus sign implies O⁺F^?.     

EPR of new phosphorus-containing centers in synthetic diamonds

The effect is studied of electron and X-ray irradiation on phosphorous centers in synthetic diamonds grown in the P-C medium by the Bars technology. After exposure to X-ray irradiation, a new paramagnetic phosphorus-containing center NP6, in addition to the phosphorous centers NP4 and NP5, is observed in diamonds annealed at a temperature of 2300°C and pressure of 7.5 GPa. The spectrum of NP6 is simulated to give the following parameters: A ₁ = 29.42 G, A ₂ = 23.28 G, A ₃ = 75.85 G, g ₁ = 2.00085, g ₂ = 2.00083, and g ₃ = 2.00083. The NP4-NP6 centers are assumed to be genetically related to the three nitrogenphosphorous centers NP1-NP3 and be formed as a result of the transformation of the tetrahedral environment around the phosphorous atom into an octahedral environment at an annealing temperature of 2300°C. The synthetic diamonds annealed at 2300°C were successively exposed to irradiation with electrons with energies of 3.5 MeV (5×10¹⁷ e/cm²) and annealing at temperatures of 500°C and 700°C. The EPR method is used to find that annealing of the electron-irradiated crystals at 700°C leads to the formation of a new paramagnetic center with spin S = 1 and hyperfine structure (HFS) from one phosphorus atom with the parameters: g = 2.0012, D = 19.7 G, and A(P) = 3.6 G. The center is likely to have an eightvacancy chain structure with a phosphorus atom located at the center.     

Calorimetric determination of thermodynamic quantities for chemical reactions in the system CO2−NaOH−H2O from 225 to 325°C

The phase equilibrium CO₂(g)=CO₂(aq) and the aqueous reactions CO ₃ ^2– +H⁺=HCO ₃ ^– , HCO ₃ ^– +H⁺=CO₂(aq)+H₂O, and Na⁺+CO ₃ ^2– =NaCO ₃ ^– were studied from 225 to 325°C using a flow calorimetric technique. Heats of mixing of gaseous CO₂ with liquid H₂O and with aqueous NaOH solutions were measured at these temperatures. Log K, H, S, and C_p values were determined for these reactions from the heat of mixing data. Equations for these thermodynamic quantities valid at infinite dilution (I=0) and 12.4 MPa are given as a function of temperature from 225 to 325°C. The log K and H values agree well with literature values at these temperatures for the first and third reactions, but not for the second reaction. No previous results have been reported for the fourth reaction at high temperatures. The isocoulombic reaction principle is tested using the log K values determined in this study. This principle is found to be valid for the reactions where each charge on one side of the equation is balanced on the other side by a charge of the same sign and magnitude, but not for the reaction where two single negative charges (HCO ₃ ^– and OH^–) are balanced by one double negative charge (CO ₃ ^2– ).Presented at the Second International Symposium on Chemistry in High Temperature Water, Provo, UT, August 1991.Taken in part from the Ph.D. Dissertation of X. Chen, Brigham Young University, 1991.     

Structural and Thermodynamic Characteristics of Compounds X2MYH2 (M = Al,Ga, In; X = F,Cl, Br,I; Y = N,P, As) Formed by Hydrogen Halide Elimination from Donor-Acceptor Complexes X3MYH3

Geometry and thermodynamic characteristics of complexes X₂MYH₂ (M = Al, Ga, In; X = F, Cl, Br, I; Y = N, P, As) and their components were found by the B3LYP density functional method with the LANL2DZ(d,p) basic set. The nitrogen complexes X2MNH2 have a planar structure, whereas the phosphorus and arsenic complexes are pyramidal. Upon HX elimination, the dissociation energy of the M-Y bonds considerably increases (by 150-270 kJ mol^{- 1}), which makes the dissociation of X2MYH2 into components thermodynamically unfeasible even at temperatures about 1000°C. A linear correlation between the dissociation enthalpies of M-Y bonds in the X₃MYH₃ and X₂MYH₂ complexes was found for each central atom M, which makes it possible to estimate the dissociation enthalpies of coordination-unsaturated compounds of the Group IIIa elements from the dissociation enthalpies of their coordination-saturated analogs. The enthalpies of dimerization of X₂MYH₂ fall in the range from 40 (Y = P, As) to 260 kJ mol^{- 1} (Y = N), which makes the process X₃MNH₃ = [X₂MNH₂]₂ + HX with the retention of the metal-nitrogen bond more favorable than the dissociation of the initial complex into the components. Thus, dimers [X₂MNH₂]₂ can be intermediates in chemical deposition of nitrides from the gas phase of donor-acceptor complexes.     

Salze von Halogenophosphorsäuren. XV. Sulfan-α,ω-diyl-bis(fluorodithiophosphate), Reaktionsprodukte des Fluoridabbaus schwefelreicher Phosphorsulfide

Salts of Halogenophosphoric Acids. XV. Sulfane-α,ω-diyl-bis(fluorodithiophosphates). Products of the Fluoride Degradation of Sulfur-rich Phosphorus Sulfides By the reaction of sulfur-rich phosphorus sulfides ?P₄S_10+m”? (m = 0,5 to 6) with fluorides MF (M = Na, K, NH₄) in acetonitrile or 1,2-dimethoxy-ethane mixtures of sulfane-α,ω-diyl-bis(fluorodithiophosphates) [(PFS₂)₂S_n]^2? (n = 1 to 8) are formed. The average chain length n of the sulfane derivatives depends on the S:P ratio of the starting phosphorus sulfides. The compounds are identified by ¹⁹F and ³¹P n.m.r. spectroscopy.     

The Charge Transfer Approach to Heavier Main‐Group Element Radicals in Transition‐Metal Complexes

The Co^II and Fe^II complexes 1Co and 1Fe with a coordinated phosphorus radical were easily obtained through a charge‐transfer approach from the M^I precursors LM^I(tol) (M=Co, Fe; L=CH(MeC=NDipp)₂, Dipp=2,6‐i Pr₂C₆H₃) to the diazafluorenylidene‐substituted phosphaalkene 1 . Structural, magnetic, and computational studies on 1Co and 1Fe indicate a weak antiferromagnetic interaction between the high‐spin M^II ion and the phosphorus radical, resulting in a triplet and quartet ground state, respectively. Complexes 1Co and 1Fe are the first examples of phosphorus‐radical‐coordinated transition‐metal complexes synthesized by charge transfer, providing a new approach to access radicals of heavier main‐group elements.     

Ein neues Oxophosphat (IV/III)-Anion – Darstellung und Kristallstruktur von Na6P4O10 · 2 H2O

A New Oxophosphate (IV/III) Anion – Preparation and Crystal Structure of Na₆P₄O₁₀ · 2 H₂O A new oxophosphate anion, P₄O₁₀^6?, was obtained by cleavage and simultaneous oxidation of the cyclo-hexaphosphate(III) anion in a solution of aqueous ammonia and ethanol. With sodium it forms a salt with the composition Na₆P₄O₁₀ · 2 H₂O. The crystal structure has been determined by single crystal X-ray diffraction (3 745 diffractometer data), the cell constants were obtained from X-ray powder data, space group P1 ; a = 6.004(1), b = 6.173(2), c = 11.496(2) Å, α = 99.26(2)°, β = 95.92(2)°, γ = 117.63(2)°, Z = 1, R = 0.044. The backbone of the anion is formed by phosphorus atoms directly bonded to each other. The coordination of each phosphorus atom is completed to four by oxygene. The resulting oxidation numbers are +III for the inner phosphorus atoms and +IV for the terminal phosphorus atoms. The site symmetry of the anion is approximately C_2h. Based on a ³¹P-NMR spectra of a solution the coupling constants of the AA ‘BB’ system were determined.     

Thermodynamics Analysis and Removal of P in a P-(M)-H2O System

In order to efficiently remove phosphorus, thermodynamic equilibrium diagrams of the P-H₂O system and P-M-H₂O system (M stands for Fe, Al, Ca, Mg) were analyzed by software from Visual MINTEQ to identify the existence of phosphorus ions and metal ions as pH ranged from 1 to 14. The results showed that the phosphorus ions existed in the form of H₃PO₄, H₂PO₄⁻, HPO₄²⁻, and PO₄³⁻. Among them, H₂PO₄⁻ and HPO₄²⁻ were the main species in the acidic medium (99% at pH = 5) and alkaline medium (97.9% at pH = 10). In the P-Fe-H₂O system ((P) = 0.01 mol/L, (Fe³⁺) = 0.01 mol/L), H₂PO₄⁻ was transformed to FeHPO₄⁺ at pH = 0–7 due to the existence of Fe³⁺ and then transformed to HPO₄²⁻ at pH > 6 as the Fe³⁺ was mostly precipitated. In the P-Ca-H₂O system ((P) = 0.01 mol/L, (Ca²⁺) = 0.015 mol/L), the main species in the acidic medium was CaH₂PO₄⁺ and HPO₄²⁻, and then transformed to CaPO₄⁻ at pH > 7. In the P-Mg-H₂O system ((P) = 0.01 mol/L, (Mg²⁺) = 0.015 mol/L), the main species in the acidic medium was H₂PO₄⁻ and then transformed to MgHPO₄ at pH = 5–10, and finally transformed to MgPO₄⁻ as pH increased. The verification experiments (precipitation experiments) with single metal ions confirmed that the theoretical analysis could be used to guide the actual experiments.     

Synthesis,molecular structure and reactions of the novel organometallic phosphine ligand, [WI2(CO) (η2-triphos) (η2-MeC2Me)]/0.75CH2Cl2{triphos=PhP(CH2CH2PPh2)2}

Reaction of [WI₂(CO)(NCMe)(η²-MeC₂Me)₂] with an equimolar quantity of triphos {triphos=PhP(CH₂CH₂PPh₂)₂} in CH₂Cl₂ at room temperature gave the triphos complex [WI₂(CO)(η²-MeC₂Me)] (1). The crystal structure of (1) shows that the triphos is attached to the tungsten via two adjacent phosphorus atoms, with the third phosphorus atom uncoordinated. Two crystallographically independent molecules are present, which are diastereoisomers. Preliminary studies of the reactions of (1) are described.