Untersuchungen an Metallkatalysatoren. XXXII. Zur Legierungsbildung und Dispersität von Nickel-Rhenium-Katalysatoren

Investigations on Metal Catalysts. XXXII. On Alloying and Dispersion of Nickel-Rhenium Catalysts Unsupported Ni? Re catalysts were prepared by reduction of mixtures from NiO and NH₄ReO₄ at 400°C with hydrogen (1^st series), followed by a heat treatment at 650°C in flowing hydrogen (2^nd series). The bimetallic powders were characterized by DTA investigations, X-ray measurements, N₂ adsorption, and CO chemisorption. The degree of alloying and the changes in dispersion as a result of adding a second metal to a basic one is discussed.     

Untersuchungen an Metallkatalysatoren. XVII. Phasenaufbau,Dispersität und Dehydrieraktivität Molybdän- und wolframmodifizierter Palladiumkatalysatoren

Investigations on Metal Catalysts. XVII. Phase Structure, Dispersity, and Dehydrogenation Activity of Palladium Catalysts Modifided by Molybdenum and Tungsten Molybdenum and tungsten containing palladium catalysts were prepared by reduction of mixtures from Pd(NO₃)₂ with MoO₃ and WO₃, respectively, with hydrogen at 600°C and 800°C. The powders were characterized by means of several methods: Determination of the oxidation state for molybdenum and tungsten, X-ray measurements, N₂ adsorption, CO chemisorption, H₂ sorption, dehydrogenation of cyclohexane. The properties of the samples (heated at 600°C) are determined to a high degree by the co-existence of the palladium phase as well as the molybdenum and tungsten oxide, respectively, in the mean oxidation state +4. The after-reduction at 800°C leads to a great portion of metallic molybdenum and tungsten in the concerned catalysts. There are references that the treatment at 800°C in the presence of hydrogen causes for the Pd? Mo catalysts an increase of the palladium content in the surface of the crystallites.     

Festkörperreaktionen in Katalysatoren und Katalysatorkomponenten. XV. Zum Reduktionsverhalten von Sulfat-lonen in γ-Al2O3

Solid State Reactions in Catalysts and Components of Catalysts. XV. On the Reduction Behaviour of Sulfate Ions in γ-Al₂O₃ Different sulphuric acid modified alumina samples were used as model systems for sulfided and regenerated Al₂O₃ carrier catalysts. From investigations of temperature programmed reduction can be concluded that sulphur is reduced by hydrogen to sulfide state at temperatures between 500 and 750°C. The greater part will desorbed as H₂S but a smaller one remains adsorbed on the alumina surface.     

Tungsten Sulfides obtained by Decomposition of Ammonium Tetrathiotungstate

The decomposition of ammonium tetrathiotungstate, (NH₄)₂WS₄, and the nature of the resulting tungsten sulfides have been studied, mainly by X-ray diffraction, differential thermal analysis, optical microscopy and electron spin resonance. Non-stoichiometric tungsten trisulfide may be obtained by decomposition of (NH₄)₂WS₄ at about 200°C. At 330°C crystallization of tungsten disulfide starts. Characteristic electron spin resonance spectra have been obtained for both sulfides.     

Struktur und katalytische Eigenschaften von Molybdänoxid-Trägerkatalysatoren bei einigen Oxydationsreaktionen

Structure and Catalytic Properties of Molybdenum Oxide Supported Catalysts in Some Oxidation Reactions Molybdenum supported catalysts were prepared by using different precursor compounds such as Mo(π-C₃H₅)₄, [Mo(OC₂H₅)₅]₂, MoCl₅, (NH₄)₆Mo₇O₂₄, and their catalytic behaviour in some oxidation reactions was studied. During the preparation process, as a result of interaction between the molybdenum compound used and the support, different surface compounds with strongly differing catalytic properties have been formed. MoO₃ and supported catalysts with MoO₃ crystallites on the surface, catalyse the H₂ oxidation at temperatures above 400°C and the CO oxidation at temperatures of about 500°C. The reaction proceeds according to a redox mechanism. On surface compounds of molybdenum which exist on the surface if organic complexes are used as precursors, the catalytic H₂ oxidation occurs even at 100°C with a high reaction rate. The catalytic CO oxidation on these catalysts occurs at temperatures of about 300°C. An associative mechanism on coordinative unsaturated Mo^VI sites is discussed.     

Rhodium amino complexes [Rh(COD)(Amine)2]PF6 immobilized on poly(4-vinylpyridine) as catalysts in the water gas shift reaction

Catalysts for the water gas shift reaction prepared from Rh(COD)(amine)₂ PF₆ (COD=1,5-cyclooctadiene, amine=4-picoline, 3-picoline, 2-picoline, pyridine, 3,5-lutidine or 2,6-lutidine) immobilized on poly(4-vinylpyridine) in contact with 80% aqueoux 2-ethoxyethanol for 1×10⁻⁴ mol Rh/0.5 g of polymer, P(CO)=0.9 atm at 100 °C, are described. The role of the coordinated amine effect on the catalytic activity was investigated.     

The effect of impregnation conditions on the surface structure of silica-supported CuO catalysts

CuO/SiO₂ catalysts with varying amounts of copper were prepard using meso- and microporous silica supports at pH > 10 and pH = 4.5. Structural and textural changes were followed using X-ray diffraction, TG and DTA techniques. Impregnation for periods > 10 days at high pH produces crystalline catalysts with two distinct peaks at d-spacings of 2.33 and 2.03 Å resulting from a surface silicate which is structurally stable up to 800°C. At copper concentrations > 5% CuO also forms. Catalysts prepared at pH = 4.5 are amorphous to X-rays in spite of the presence of CuO which may either be < 50 Å or from a surface solid solution. The copper ammine complex, if adsorbed on mesoporous silica, attains its maximum coordination number as [Cu(NH₃)₄(H₂O)₂]²⁺, whereas on microporous silica it loses the two water molecules as a result of pore restrictions. The surface complex releases its coordinated ammonia exothermally in the temperature range 200–400°C, whereas chemisorbed ammonia is evolved endothermally at ～280°C. Ligand water is evolved at <200°C. An exotherm at ～545°C is observed for all catalysts, resulting form the shrinkage of the solid/void matrix which disappears upon aging. Increase of copper content to 22.7% at high pH lowered the temperature of constant weight attainment from 1000°C for the pure silica to 750°C.     

Untersuchungen an oxidischen Katalysatoren. XXIII. Magnetische und Redoxeigenschaften von CrNaY-Zeolithen

Studies on Oxide Catalysts. XXIII. Magnetic and Redox Properties of Zeolites CrNaY After pretreatment in vacuo (110–460°C) and in air (45O°C) CrNaY zeolites with different exchange degrees are characterized by EPR and magnetic measurements. The chromium hyperfinc structure in the EPR spectra shows that stable octahedral [Cr(H₂0)]³⁺ complexes exist up to temperatures of 350–390°C. The decrease of EPR signal intensity with increasing temperature of vacuum pretreatment can be explained by migration of Cr³⁺ ions into the sodalite cage (S_I″, S_II″) and hexagonal prism (S_I), resp. The high values of μ_eff. correspond with the tetrahedra1 environment of Cr³⁺ ions. In the evacuated samples Cr²⁺ ions are present. The oxidizing pretreatment of samples with high Cr³⁺ exchange degrees leads to lattice break down. After pretreatment in air all CrNaY zeolites contain chromium with oxidation number +5 and +6.     

Methyl branching in polyethylene from homopolymerization of ethylene with N‐arylcyano‐β‐diketiminate methallyl nickel‐B(C6F5)3

N‐Arylcyano‐β‐diketiminate methallyl nickel complexes activated with B(C₆F₅)₃ were used in the polymerization of ethylene. The microstructure analysis of obtained polyethylene (PE) was done by differential scanning calorimetry and ¹³C nuclear magnetic resonance (NMR). The branched polymer structures produced by these catalysts were attributed to one step isomerization mechanism of the catalyst along the polymer chain. The ortho or para position of the cyano group with co‐ordinated B(C₆F₅)₃ in both methallyl nickel catalysts influenced the polymer molecular weight, branching, and consequently melting and crystallization temperatures. NMR spectroscopic studies showed predominantly the formation of methyl branches in the obtained PE. Catalysts under study gave linear low‐density PEs with good crystallinities at temperatures of reaction between 50 °C and 70 °C at moderate pressures (12.3 atm). A propylene–ethylene copolymer produced by the metallocene catalyst had the same concentration of branches as the PE synthesized from methallyl nickel/B(C₆F₅)₃. Comparing the two polyolefins with the same degree of branching, it was observed that the polymer obtained with the nickel catalyst proved to be twice more crystalline and had greater T_m. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 452–458     

Ab initio studies of structural features not easily amenable to experiment. 25. Conformational analysis of methyl propanoate and comparison with the methyl ester of glycine

The molecular geometries of three conformations of methyl propanoate (MEP) (C? C? C?O torsions of 0°, 120°, and 180°) and the potential-energy surfaces of MEP (C? C? C?O torsions) and of the methyl ester of glycine (MEG) (N? C? C?O torsions) have been determined by ab initio gradient calculations at the 4-21G level. MEP has conformational energy minima at 0° and 120° of the C? C? C?O torsion, while the 60–90° range and 180° are energy maxima. For MEG there are two minima (at 0° and 180°) and one barrier to N? C? C?O rotation in the 60–90° range. The N? C? C?O barrier height is about twice as high (4 kcal/mol) as the C? C? C?O barrier. The 180° N? C? C?O minimum is characteristically wide and flat allowing for considerable flexibility of the N? C? C?O torsion in the 150–210° range. This flexibility could be of potential importance for polypeptide systems, since the N? C? C?O angles of helical forms are usually found in this region. The molecular structures of the methyl ester group CH₃OC(?O)CHRR′ in several systems are compared and found to be rather constant when R ? H and R′ ? H, CH₃, CH₃CH₂; or when R ? NH₂ and R′ ? H, CH₃, or CH(CH₃)₂.     

Friedel-crafts copolymerization of thiophene and p-di(chloromethyl)benzene. I. Products,kinetics, and mechanism of the early stages of the reaction

The rate of polymerization of thiophene, at concentrations of catalyst (SnCl₄), and thiophene of the same order as was subsequently used in studying the reaction between thiophene and di(chloromethyl)benzene, is of the order of 10^-2%/hr at 30°C. There is no significant self-condensation of DCMB under the same conditions. Since the reaction between thiophene and DCMB is complete at 30°C in minutes rather than hours, it is assumed that self-condensation of thiophene or DCMB during the reaction between them will be negligible and should not influence the course of the reaction or the structure of the resulting polymer. Reaction at 30°C is much too fast for convenient study. A temperature of 0°C is more appropriate and was used in subsequent kinetic work. The first two products of the condensation of p-di(chloromethyl)benzene (DCMB) with thiophene have been identified by a combination of mass, infrared, and nuclear magnetic resonance spectroscopy as thenylchloromethylbenzene (TCMB) and dithenylbenzene (DTB). DCMB, TCMB, and DTB have been estimated quantitatively during the course of the reaction by gas-liquid chromatography (GLC), and it has been established that the rates of each of the two reaction steps is first-order with respect to the chloro compound (DCMB and TCMB respectively), thiophene, and SnCl₄. Rate constants for these two consecutive reactions were calculated to be k₁ = 2.79 × 10^-4l.²/mole²-sec, k₂ = 6.37 × 10^-3l.²/mole²-sec; the corresponding energies of activation are E₁ = 7.93 kcal/mole, E₂ = 7°67 kcal/mole. These rate constants are appreciably higher than values previously obtained for the corresponding DCMB–benzene reactions.     

Intramolecular charge transfer complexes. VIII. Poly[N-(2-hydroxyethyl) carbazolyl acrylate-co-2,4-dinitrophenyl methacrylate]

Radical copolymerization of N-(2-hydroxyethyl) carbazolyl acrylate (HECA, M₁) with 2,4-dinitrophenyl methacrylate (DNPM, M₂) can be described by a simple terminal mechanism having the relative reactivities r₁ = 0.14, r₂ = 1.10 (at 60°C); 0.28, 0.96 (80°C); and 0.41, 0.79 (100°C), respectively. The dependence of the reactivity ratio values on copolymerization temperature, analyzed by Arrhenius equation, takes place mainly through the frequency factor. The copolymers obtained are intramolecular charge transfer complexes. The intramolecular interaction is evidenced by the shift of the aromatic protons from the DNPM structural unit in the copolymers' ¹H-NMR (nuclear magnetic resonance) spectra. This shift depends on sequence distribution and chain conformation, but is not affected by the copolymerization temperature.     

Hybrid silica-organic material with immobilized amino groups: surface probing and use for electrochemical determination of nitrite ions

A sol–gel based hybrid process was developed by manipulating different techniques in sol–gel process to synthesize γ-alumina and (CuO, CuO + ZnO) doped γ-alumina spherical particles. Catalysts having spherical geometry have an important advantage over powders or pellets which are impervious to fluids, when packed in a reactor. Boehmite sol was used as alumina precursor for synthesizing porous γ-alumina and doped materials. γ-alumina particles having 5 wt% CuO, 4 wt% CuO + 1 wt% ZnO, 3 wt% CuO + 2 wt% ZnO and 2 wt% CuO + 3 wt% ZnO were prepared by adding required amounts of Cu(NO₃)₂ and Zn(NO₃)₂ solutions prior to gelation of the sol. Methanol dehydration studies were carried out by employing these synthesized catalysts. Hundred percent conversion of methanol to dimethyl ether was observed with (4 wt% CuO + 1 wt% ZnO)-γ-alumina and (5 wt% CuO)-γ-alumina microspheres at 325 and 350 °C, respectively.     

Über Chalkogenolate. 191. Ester der 2-Oxophenyldithioessigsäure 2. Kristall- und Molekülstruktur des Methylesters

On Chalcogenolates. 191. Esters of 2-Oxophenyldithioacetic Acid. 2. Crystal and Molecular Structure of the Methyl Ester The title compound C₆H₅? CO? CS? SCH₃ crystallizes with Z = 2 in the triclinic space group P1 with cell dimensions (?60°C) a = 6.236(4) Å, b = 7.972(2) Å, c = 9.589(4) Å, α = 88.42(3)°, β = 75.39(5)°, γ = 81.54(4)°. The structure has been determined from single crystal X-ray data measured at ?60°C and refined to R = 0.085 and R_w = 0.087 for 2307 independent reflections. With nearly 20° the C?O bond is turned out of the plane of the phenyl ring.     

(NH4)3[M2NCl10] (M = Nb,Ta): Synthese,Kristallstruktur und Phasenumwandlung

(NH₄)₃[M₂NCl₁₀] (M = Nb, Ta): Synthesis, Crystal Structure, and Phase Transition The nitrido complexes (NH₄)₃[Nb₂NCl₁₀], and (NH₄)₃[Ta₂NCl₁₀] are obtained in form of moisture-sensitive, tetragonal crystals by the reaction of the corresponding pentachlorides with NH₄Cl at 400 °C in sealed glass ampoules. Both compounds crystallize isotypically in two modifications, a low temperature form with the space group P4/mnc and a high temperature form with space group I4/mmm. In case of (NH₄)₃[Ta₂NCl₁₀] a continuous phase transition occurs between –70 °C and +60 °C. For the niobium compound this phase transition is not yet fully completed at 90 °C. The structure of (NH₄)₃[Nb₂NCl₁₀] was determined at several temperatures between –65 °C und +90 °C to carefully follow the continuous phase transition. For (NH₄)₃[Ta₂NCl₁₀] the structure of the low temperature form was determined at –70 °C, and of the high temperature form at +60 °C. The closely related crystal structures of the two modifications contain NH₄⁺ cations and [M₂NCl₁₀]^3– anions. The anions with the symmetry D_4h are characterized by a symmetrical nitrido bridge M=N=M with distances Nb–N = 184.5(1) pm at –65 °C or 183.8(2) pm at 90 °C, and Ta–N = 184.86(5) pm at –70 °C or 184.57(5) pm at 60 °C.     

Katalysatordesaktivierungen bei der Acetylen-Polymerisation mit Titanocen- bzw. Zirconocen-Komplexen des Bis(trimethylsilyl)acetylens

Desactivation of Catalysts in the Polymerization of Acetylene by Bis(trimethylsilyl)acetylene Complexes of Titanocene or Zirconocene Unexpected inactive byproducts were observed in the catalytic polymerization of acetylene using metallocene alkyne complexes Cp₂M(L)(η²-Me₃SiC₂SiMe₃), 1 : M = Ti, without L; 2 : M = Zr, L = thf. The reaction of 1 was investigated in detail by NMR to give quantitatively at –20 °C the titanacyclopentadiene Cp₂Ti–CH=CH–C(SiMe₃)=C(SiMe₃) ( 3 ). Around 0 °C 3 starts to rearrange to yield the dihydroindenyl complex 4 via coupling of one Cp-ligand with the titanacyclopentadiene. In the reaction of 2 under analogous conditions a zirconacyclopentadiene Cp₂Zr–CH=CH–C(SiMe₃)=C(SiMe₃) ( 5 ) and the dimeric complex [Cp₂Zr(C(SiMe₃)=CH(SiMe₃)]₂[μ-σ(1,2)-C≡C] ( 6 ) were observed. Whereas 5 decomposes to a mixture of unidentified paramagnetic species, 6 was isolated and investigated by NMR spectroscopy and X-ray analysis. In the reaction of rac-(ebthi)Zr(η²-Me₃SiC₂SiMe₃) (ebthi = ethylenbistetrahydroindenyl) with 2-ethynyl-pyridine the complex rac-(ebthi)ZrC(SiMe₃)=CH(SiMe₃)](σ-C≡CPy) 7 was obtained, which was investigated by an X-ray analysis.     

Mild Hydrogenation of Amides to Amines over a Platinum‐Vanadium Bimetallic Catalyst

Hydrogenation of amides to amines is an important reaction, but the need for high temperatures and H₂ pressures is a problem. Catalysts that are effective under mild reaction conditions, that is, lower than 30 bar H₂ and 70 °C, have not yet been reported. Here, the mild hydrogenation of amides was achieved for the first time by using a Pt‐V bimetallic catalyst. Amide hydrogenation, at either 1 bar H₂ at 70 °C or 5 bar H₂ at room temperature was achieved using the bimetallic catalyst. The mild reaction conditions enable highly selective hydrogenation of various amides to the corresponding amines, while inhibiting arene hydrogenation. Catalyst characterization showed that the origin of the catalytic activity for the bimetallic catalyst is the oxophilic V‐decorated Pt nanoparticles, which are 2 nm in diameter.     

Beiträge zum thermischen Verhalten von Sulfaten. II. Zur thermischen Dehydratisierung des ZnSO4 · 7 H2O und zum Hochtemperaturverhalten von wasserfreiem ZnSO4

Contributions to the Thermal Behaviour of Sulfates. II. On the Thermal Dehydration of ZnSO₄ · 7 H₂O and the Effect of High Temperature upon Anhydrous ZnSO₄ The dehydration of ZnSO₄ · 7 H₂O and effect of high temperature upon unhydrous ZnSO₄ was examined by means of continous high temperature Guinier photographs. On heating in air ZnSO₄ · 7 H₂O decomposes stepwise to ZnSO₄ · 6 H₂O, to an unknown hydrate, to the monohydrate and finally to N? ZnSO₄, which is the thermodynamically stable modification at S.T.P. At about 700°C a reversible transformation to H-ZnSO₄ can be observed which can start from N? ZnSO₄ or H-ZnSO₄, proceeds to the oxide sulfate Zn₃O(SO₄)₂ and finally to ZnO. ZnSO₄ · 6 H₂O crystallizes monoclinically in the hexahydrite structure with a_25°C = 9.981 Å, b_25°C = 7.250 Å, c_25°C = 24.280 Å, β_25°C = 98.45°, Z = 8, space group: C 2/c. Cubic H-ZnSO₄ is the first A²⁺B⁶⁺O₄ compound of H-Cristobalit structure; probable space group F 4 3 m with a_700°C = 7.18 Å, Z =4, N-Zn₃O(SO₄)₂ is monoclinic probable space group B 2 with a_25°c=13.987 Å, b_25°c=6.706 Å, c_25°c =7.379 Å β_25°c=90.69°, Z=4, Above 420°C N-Zn₃(SO₄)₂ becomes orthorhombic where at first of all H′-Zn₃O(SO₄)₂ which has a reversible transformation point to H-Zn₃O(SO₄)₂ at 655°C is formed. The probable space group of H-Zn₂O(SO₄)₂ is C 222₁ with a _850°C = 7.36 Å, b_350°C = 13.96 Å, c_850°C = 6.79 Å Z = 4, The solid solution N? Cu_1,5Zn_1,5O(SO₄)₂ is isotypic with N? Zn₃O(SO₄)₂ and has the lattice constants a_25°C = 14.03 Å, b_25°C = 6.62 Å, c_25°C = 7.33 Å, β_25°C = 90.58°, Transoformations into the non quenchable high temperature modifications H-ZnSO₄, H′-Zn₃O(SO₄)₂ and H-Zn₃O(SO₄)₂ are displacive. The thermal expansion of N-ZnSO₄ and H-ZnSO₄ and H-ZnSO₄ has been exa-mined.     

Dynamic and controlled rate thermal analysis of halotrichite

Three halotrichites namely halotrichite Fe²⁺SO₄·Al₂(SO₄)₃·22H₂O, apjohnite Mn²⁺SO₄·Al₂(SO₄)₃·22H₂O and dietrichite ZnSO₄·Al₂(SO₄)₃·22H₂O, were analysed by both dynamic, controlled rate thermogravimetric and differential thermogravimetric analysis. Because of the time limitation in the controlled rate experiment of 900 min, two experiments were undertaken (a) from ambient to 430 °C and (b) from 430 to 980 °C. For halotrichite in the dynamic experiment mass losses due to dehydration were observed at 80, 102, 319 and 343 °C. Three higher temperature mass losses occurred at 621, 750 and 805 °C. In the controlled rate thermal analysis experiment two isothermal dehydration steps are observed at 82 and 97 °C followed by a non-isothermal dehydration step at 328 °C. For apjohnite in the dynamic experiment mass losses due to dehydration were observed at 99, 116, 256, 271 and 304 °C. Two higher temperature mass losses occurred at 781 and 922 °C. In the controlled rate thermal analysis experiment three isothermal dehydration steps are observed at 57, 77 and 183 °C followed by a non-isothermal dehydration step at 294 °C. For dietrichite in the dynamic experiment mass losses due to dehydration were observed at 115, 173, 251, 276 and 342 °C. One higher temperature mass loss occurred at 746 °C. In the controlled rate thermal analysis experiment two isothermal dehydration steps are observed at 78 and 102 °C followed by three non-isothermal dehydration steps at 228, 243 and 323 °C. In the CRTA experiment a long isothermal step at 636 °C attributed to de-sulphation is observed.     

Beiträge zur Chemie des Phosphors. 236. Über einige physikalische und chemische Eigenschaften von Diphosphan(4)

Contributions to the Chemistry of Phosphorus. 236. On Several Physical and Chemical Properties of Diphosphane(4) The density of diphosphane(4) has been measured between ?78°C and +18°C and the value d₄²⁰ = 1.014 · 0.002 extrapolated. The refractive index of P₂H₄ was determined to be n²⁰ = 1.66 ± 0.01. The surface tension at 0°C and ?50°C was measured to be σ = 34 and 42 dyn · cm^?1, respectively. In the UV absorption spectrum, gaseous P₂H₄ exhibits a broad absorption band at λ_max = 2 220 Å, in n-hexane solution, this band is shifted somewhat to shorter wave-lengths. The molar extinction coefficient was determined to be ? ≈? 900 1 · mol^?1 · cm^?1. As a result of photolytic decomposition, absorptions for PH₃ and more phosphorus-rich hydrides also occur. The solubility behavior of P₂H₄ in various organic solvents and the stabilities of the resultant solutions have been investigated. At 0°C, the solubility of diphosphane(4) in water was found to be ± 035 ± 0.003 g P₂H₄/100 g solution and that of water in diphosphane(4) to be 43.2 ± 1.6 g H₂O/100 g solution. The system diphosphane(4)/methanol also exhibits a miscibility anomaly. The IR spectra of liquid P₂H₄ and of its solutions in various solvents revealed, in accord with the results of nuclear magnetic resonance spectroscopy [7], that diphosphane(4) is practically not associated. Weak interactions through hydrogen bridging bonds occur with pyridine and methanol in which P₂H₄ serves as the proton donor and, in the latter case, also as proton acceptor. For the thermolysis of diphosphane(4), it has been found that the primary step comprises a disproportionation with inter-molecular elimination of PH₃ and formation of triphosphane(5). With further progress of the thermolysis, in dependence on the reaction conditions, mixtures of various phosphanes of differing composition are formed. Photolysis gives rise to phosphane mixtures having similar compositions. With aqueous silver salt and iodine solutions, diphosphane(4) reacts as a reducing agent; with sodium hydroxide solution, it reacts by a slow disproportionation as well as by formation and degradation of the subsequently formed polyphosphides. On reaction with triphenylmethyl, triphenylmethane and a yellow solid of varying composition are formed. The reaction of diazomethane with diphosphane(4) leads to the preferential insertion of the carbene in the P? P bond and formation of methylenebis(phosphane).