Synthesis and properties of N3 and CN delivery compounds and related precursors for nitride and ceramic fabrication

The simple azido and cyano compounds Cl₂AsN₃, Br₂AsN₃, (C₆H₅)SiH₂N₃, (C₆H₅)SiH₂CN and p‐(tolyl)SiH₂CN have been prepared for the first time by metathesis reactions involving the corresponding halides and NaN₃, LiN₃ and LiCN. These compounds represent a highly reactive and efficient family of delivery reagents for the preparation of N₃ and CN molecular precursors to bulk ceramics and nitride thin films. They are isolated as low volatility liquids and characterized by spectroscopic methods and chemical analysis. Ab initio simulations were used to elucidate the structural and vibrational properties of the simpler, fully inorganic Cl₂AsN₃ and Br₂AsN₃ species. This theoretical treatment was extended to include the hypothetical H₂AsN₃ and HClAsN₃ derivatives which are particularly desirable as single‐source low‐temperature As? N sources for the formation of highly sought after, metastable GaAs_1?xN_x materials for solar cell applications. The practical utility of the title molecules is also demonstrated by synthesizing several representative compounds of B, Be, Ga and Al, which are of interest for the development of open frameworks, optoelectronic nitrides and refractory B? C? N hybrids. The cyanide derivatives (C₆H₅)SiH₂CN and p‐(tolyl)SiH₂CN react readily with Be and B halides to yield crystalline Be(CN)₂ and amorphous B? C? N. The latter is crystallized upon heating to form graphite‐like polymorphs with homogeneous nanoscale morphologies. The azide derivatives Cl₂AsN₃, Br₂AsN₃ and (C₆H₅)SiH₂N₃ react readily with GaBr₃, GaCl₃ and BBr₃ to produce high yields of the previously reported Br₂GaN₃, Cl₂GaN₃ and Br₂BN₃, respectively. The latter is shown to possess a trimeric molecular structure in which the α‐nitrogen of the azide group bridges the boron atoms to form cyclohexane‐like B₃N₃ rings. Copyright © 2008 John Wiley & Sons, Ltd.     

Preparation and properties of perfluorochloromethyl-mercaptophosphoryldichlorides and -chlorophosphanes

In Arbuzov-type reactions CF_nCl_3?nSCl reacts with ROPCl₂ (R = CH₃, C₂H₅) to give CF_nCl_3?nSP(O)Cl₂ (n = 3,2,1,0). The corresponding reaction with CF₃SeX (X = Cl, Br) produces CF₃SeP(O)Cl₂ in good yields only in the presence of catalysts such as SbCl₅ or BCl₃. Reactions between P₄ and the sulfenylchlorides produce (CF_nCl_3?nS)_xPCl_3?n (n = 3,2,1 and x = 1,2). On heating CF_n′ Cl_3?n′ SP(O)Cl₂ (n′ = 2,1,0) decompose to P(O)Cl₃ and SCF_n′ Cl_2?n′. During this process fluorination of P(O)Cl₃ to P(O)F₃ by SCF₂ is observed. A Cl/Br exchange between CF_nCl_3?nSP(O)Cl₂ (n = 3,2) and PBr₃ was proved ¹⁹F? and ³¹P-NMR-spectroscopically.Chemical and physical properties of the newly synthesized compounds will be discussed.     

Dimethylphosphinato and dimethylarsinato complexes of Sb(III) and Bi(III) and their chemistry

Abstract  

The reaction of Me₂PO₂H and Me₂AsO₂H with SbCl₃, BiCl₃, and Bi(NO₃)₃·5H₂O gave the complexes Sb(Me₂PO₂)₃, Sb(Me₂AsO₂)₃, (Me₂PO₂)₂Bi-Cl, Bi(Me₂AsO₂)₃, (Me₂PO₂)₂Bi(NO₃), and (Me₂AsO₂)₂Bi(NO₃)·H₂O, respectively. The arsinato complexes did not react with the Lewis bases pyridine, Ph₃P, and Ph₃As in acetone. The compounds Sb(Me₂AsO₂)₃ and (Me₂AsO₂)₂Bi(NO₃)·H₂O reacted to a small extent with nicotinic acid in methanol but Bi(Me₂AsO₂)₃ gave (Me₂AsO₂-BiO) _x in good yields. (Me₂AsO₂)₂Bi(NO₃)·H₂O in methanol quantitatively rearranged to new complexes with the same composition, [(Me₂AsO₂)₂Bi(NO₃)·H₂O]′ and [(Me₂AsO₂)₂Bi(NO₃)·H₂O]″ in the presence of pyridine. With thiophenol in air, Sb(Me₂AsO₂)₃ gave PhSSPh and Me₂As-SPh (1:1 mol ratio), (Me₂AsO₂-SbO) _x and some Sb(Me₂AsO₂)₃ was reformed, Bi(Me₂AsO₂)₃ gave (Me₂AsO₂-BiO) _x , PhSSPh, and Me₂As-SPh (1:0.6 mol ratio), whereas (Me₂AsO₂)₂Bi(NO₃)·H₂O quantitatively gave PhSSPh, thus acting as a catalyst for the air oxidation of thiophenol.     

NMR studies of fluorocarbon diphosphines and oxy- and thio-bisphosphines

Both the diphosphine CH₃CF₃PPCH₃CF₃ and the thio-bisphosphine CH₃CF₃PSPCH₃CF₃ show ¹⁹F and ³¹P NMR spectra indicative of diastereomeric mixtures of d,l and meso isomers. The temperature-dependent reversible interconversions of the isomers have been attributed to the inversion at the phosphorus atom. The equilibrium constants for the isomerization reactions have been measured at various temperatures. The fluorine NMR spectra of the meso and d,l isomers of CD₃CF₃PSPCD₃CF₃ have been analyzed as M₃XX′M₃′ spin systems. Good agreement is found between the observed and calculated spectra. The five-bond fluorine-fluorine coupling constant of the low-field isomer is larger than that of the high-field isomer. The ¹⁹F NMR spectra of (CF₃)₂PP(CF₃)₂, (CF₃)₂POP(CF₃)₂, (CF₃)₂PSP(CF₃)₂, CH₃CF₃PPCH₃CF₃ and CH₃CF₃PSPCH₃CF₃ have been examined over a wide range of temperatures in an attempt to correlate the data to the geometries of these compounds.     

Oxidative fluorination and oxygenation of bis(trifluoromethylthio)methane and ethyltrifluoromethylsulfide

Chloride monofluoride fluorinates (CF₃S)₂CH₂ to (CF₃SF₄)₂CH₂ and CH₃SF₄CH₂F, and CF₃SC₂H₅ to trans-CF₃SF₄C₂H₅. Mono-chloroperbenzoic acid with the same reactants gives either CF₃SCH₂S(O)CF₃ or CF₃SCH₂SO₂CF₃, and CF₃S(O)C₂H₅ and CF₃SO₂C₂H₅.     

Azido- and phosphiniminato-complexes of titanium and vanadium

Summary The azido complexes [Ti( ⁵-C₅H₅Cl₂(N₃)], [Ti( ⁵-C₅H₅)₂Cl(N₃)], [TiCl(N₃)(S₂CNEt₂)₂] and [Ti(N₃)(S₂CNEt₂)₃] have been prepared from appropriate metal halides by reaction with trimethylsilylazide. The [Ti( ⁵-C₅H₅)Cl₂(N₃)] complex reacts with HC1 and MeCOCl to give HN₃ and MeNCO respectively and [Ti( ⁵-C₅H₅)Cl₃], whereas [Ti( ⁵-C₅H₅)Cl₂(NPPh₃)] is formed on reaction with PPh₃. The phosphiniminato complexes [TiCl(NPPh₃)(S₂CNEt₂)₂], [TiCl₂(NPPh₃)₂], [VOCl₂(NPPh₃)], [VOCl(NPPh₃)₂] and [VCl₃(NPPh₃)₂] have been prepared from the appropriate halido-complexes and Me₃SiN=PPh₃.     

Preparation and characterization of acrylates and polyacrylates having variable fluorine contents and distributions

Five acrylic esters having different fluorine contents and distributions in their side-groups (i.e., CH₂=CHC(O)OR, where R = ? C(CH₃)₂C₆F₄H, ? C(CH₃)₂C₆F₅, ? C(CF₃)₂C₆F₅, ? C(CF₃)₂C₆H₅, and ? C(CH₃)₂C₆H₅) have been prepared from the reactions of the lithium salts of their corresponding alcohols with acryloyl chloride. These monomers are polymerized under identical conditions by the radical initiator AIBN and five polyacrylates were prepared having the structure of ? [ ? CH₂CHC(O)OR? ]_n? . These addition polymers were compared and fully characterized by GPC, VPO, DSC, TGA, NMR, IR, and UV-visible spectroscopies, and they showed potential for practical applications. Significant differences in their thermal stabilities were found with respect to fluorine contents and distributions in these polyacrylates, and the highest stability arises from CF₃ substitutions in the side-chains of the polymers. © 1994 John Wiley & Sons, Inc.     

New Phosphides with Transition and Rare-Earth Metals and Their Crystal Structures

Abstract

The interaction between components in systems M-M′- P (M -Zr, Hf, Nb, Mo, W, Mn, Re; M′-V, Cr, Fe, Co, Ni, Cu), Ln-{Fe, Co, Ni, Cu}-P (Ln-rare-earth metals) and M-{Si, B}-P (M-Cr, Mo, W, Mn, Re, Co, Ni, Cu) have been investigated and isotermal sections for 47 ternary systems have been built. 98 new phosphides have been synthesized and the crystal structure for 76 has been determined. The structures of new compounds belong to the known structure types, such as MgCu₂, Mg₆ Cu₁₆ Si₇, TiNiSi, Zr₂ Fe₁₂P₇, Hf₂ CO₄ P₃, CeAl₂ Ga₂, ZrFe₄Si₂, Nb₄ CoSi, Mo₅ SiB₂, MgZn₂, HfCuSi₂. The structures of several phosphides represent the new types: Nb₂P, α-Ni₈P₃, Zr₂Ni_l-xP, Tb,_1?xNiP, SmNi₄P₂, Nd₃Ni₇P₅, Ni₃,₃₆Si₁,₇₆P₆, Mo₂Ni₆P₃, Re_0,6, Ni_0,4P · The obtained experimental data allowed us to make the following conclusions:     

Development and synthesis of bulk and membrane catalysts based on framework phosphates and molybdates

The scientific principles were formulated that underlie an integrated approach to development and synthesis of bulk and membrane catalysts for methanol transformation to dimethyl ether and hydrogen which are environmentally friendly fuels. The results were summarized for studies into relationships in formation of phosphates MZr₂(PO₄)₃ (M = Na, K, Rb, Cs, Mg_0.5, Ca_0.5, Sr_0.5, Ba_0.5, Zr_0.25), Cu_0.5(1+y)Fe _y Zr_2−y (Po₄)₃, molybdate phosphates Na_1−y Zr₂(Moo₄) _y (Po₄)_3−y , and molybdate Ni_0.3Cr_0.4Fe_1.4(Moo₄)₃ with the desired structure and properties controllable by variation of their chemical composition and synthesis parameters. The surface characteristics and catalytic properties of the resulting systems and the yields of the target product formed from methanol transformations in inert and oxidizing atmospheres were analyzed in relation to the catalyst synthesis condition.     

Self- and cross-disproportionation-to-combination rations for cyclopentyl and cyclohexyl radicals and their deuterated analogues

Hydrogen, cycloalkene, and bicycloalkyl were found to be the principal products which account for ≈?97% of all products formed in the gas-phase radiolysis of water vapor containing low concentrations of cycloalkanes. From the ratios of cycloalkene-to-bicycloalkyl yields extrapolated to the zero dose, the self- and cross-disproportionation-to-recombination rate constant ratios Δ = k_d/k_c were determined for the following 12 reactions: Δ(c-C₅H₉, c-C₅H₉) = 0.73; Δ(c-C₅D₉, c-C₅D₉) = 0.58; Δ(c-C₆H₁₁, cC₆H₁₁) = 0.59; Δ(c-C₆D₁₁, c-C₆D₁₁) = 0.46; Δ(c-C₅H₉, c-C₆H₁₁) = 0.28; Δ(c-C₅D₉, c-C₆H₁₁) = 0.28; Δ(c-C₅H₉, c-C₆D₁₁) = 0.24; Δ(c-C₅D₉, c-C₆D₁₁) = 0.24; Δ(c-C₆H₁₁, c-C₅H₉) = 0.33; Δ(c-C₆H₁₁, c-C₅D₉) = 0.25; Δ(c-C₆D₁₁, c-C₅H₉) = 0.35; and Δ(c-C₆D₁₁, c-C₅D₉) = 0.28, where in the case of the cross-disproportionation the symbol Δ(R₁,R₂) is used to represent k_d/k_c for the disproportionation in which radical R₁ captures a hydrogen (deuterium) atom from radial R₂. The geometrical mean rule holds in the cross-combination reactions of cyclopentyl and cyclohexyl radicals. The kinetic isotope effect in the disproportionation reaction was determined as 1.24 ± 0.06.     

Nitrosyl,nitryl and dioxygenyl hexafluoroplatinate(IV) and (V) and related compounds: Synthesis,reactions and raman spectra

The reactions of PtF₅, O₂PtF₆, PtF₆, IrF₆, NOPtF₆, NO₂PtF₆, NOIrF₆ and NO₂IrF₆ with NOF and NO₂F have been examined under a variety of conditions. The relative ease of synthesis of NOPtF₆, (NO)₂PtF₆, NOIrF₆ and NO₂IrF₆ and the conversion of NOIrF₆ to NOPtF₆ with PtF₆ confirms the order of strong oxidizing properties of Pt^VIF₆, Ir^VIF₆, Pt^VF^-₆ and Ir^VF^-₆. The NO⁺₂ ion is intrinsically unstable with respect to the elimination of oxygen in Pt (IV) and Ir (IV) fluorometallate salts and accordingly there is serious doubt about earlier claims for the synthesis of the (NO⁺)(NO⁺₂)PtF₆ salt. No evidence for the (NO₂)₂PtF₆ could be found.Raman spectral data for NOBF₄, NO₂BF₄, NO₂AsF₆, NOPtF₆, NO₂PtF₆, (NO)₂PtF₆, NOIrF₆, NO₂IrF₆ and (NO)₂IrF₆ are presented and analyzed. The NO⁺₂ ion appears to be linear in all of the compounds and the absence of the Raman forbidden ν₂ fundamental indicates little if any anion-cation interaction at least of the type that leads to a permanent distortion of the cation. In the spectra of all of the nitryl salts, including NO₂BF₄, a low frequency band at about 140 cm^-1 is clearly observed, the intensity and shape of which is a function of the anion. The band probably reflects an unknown lattice dynamic process. No such bands are evident in the spectra of NO⁺ and (NO⁺)₂ salts.     

Electrical and magnetic properties and homogeneity ranges of mixed-valence cesium-vanadium oxides

Single crystals of CsV₂O₅, Cs₂V₅O₁₃, Cs_xV₂O₅, and CsV₃O₇, grown from melts, have been subjected to electrical conductivity and magnetic susceptibility measurements. CsV₂O₅ and Cs₂V₅O₁₃ are insulators exhibiting Curie-Weiss' law behavior with p_eff close to $\text{1.73}\text{V}{}^{\mathrm{4+}}\text{ion}$. They are stoichiometric according to the X-ray studies. CsV₂O₅, which has a very limited composition range (x ≈ 0.30?;0.33), is a semiconductor with temperature-dependent paramagnetism ($\text{p}{}_{\mathrm{<mtext>eff</mtext>}}\text{=}\text{1.83}\text{V}{}^{\mathrm{4+}}\text{ion}$). Cs_xV₃O₇ (0.30 ? x ? 0.40) is antiferromagnetic with a Néel temperature of ≈230 K. The temperature variation of the lattice parameters of Cs_0.33V₃O₇ has been determined with a Bond-type diffractometer. The same crystal was used for the conductivity measurements, and together these studies indicate that the transition from the semiconducting antiferromagnetic state to the semiconducting paramagnetic state takes place stepwise. The observed properties are discussed with reference to the crystal structures of the compounds.     

Bidentate Phosphanyl- and Arsanylboranes

A new class of neutral bidentate ligands with pnictogenyl-functional sites has been obtained. The reaction of tmeda⋅(BH₂I)₂ ( 1 , tmeda=tetramethylethylendiamine) with different phosphanides yields the corresponding bidentate phosphanylboranes tmeda⋅(BH₂PH₂)₂ ( 2 a ), tmeda⋅(BH₂PPh₂)₂ ( 2 b ), and tmeda⋅(BH₂tBuPH)₂ ( 2 c ). This reaction strategy could be further extended to synthesize the first bidentate arsanylborane tmeda⋅(BH₂AsPh₂)₂ ( 3 ). Depending on the substituents on the phosphorus, these compounds form different Au^I complexes, to build either polymeric tmeda⋅(BH₂PH₂AuCl)₂ ( 4 a ), or monomeric tmeda⋅(BH₂PPh₂AuCl)₂ ( 4 b ) products. These compounds form also neutral oligomeric group 13/15 chain-like molecules by coordination to a boron moiety such as tmeda⋅(BH₂PH₂BH₃)₂ ( 5 a ) and tmeda⋅(BH₂AsPh₂BH₃)₂ ( 5 b ). DFT calculations provide insight into the differences between the syntheses of mono- and bidentate pnictogenylboranes.     

Benzylammonium,imidazolium and pyridinium polyvanadates — Synthesis and characterization

Summary From the reaction systems,B-V₂O₅-HClO₄-H₂O andB-V₂O₅-H₂O, whereB is benzylamine (Bz), imidazole (Im) or pyridine (Py), eight new compounds were synthesized: at 20°C, the metavanadate and decavanadates of composition (BzH)VO₃, (BzH)₆V₁₀O₂₈·3H₂O, (ImH)₆V₁₀O₂₈·2H₂O, (PyH)₆V₁₀O₂₈·2H₂O, (ImH)₄H₂V₁₀O₂₈·2H₂O and (PyH)₄H₂V₁₀O₂₈·3H₂O, and at 60°C, the hexavanadates of composition (ImH)₂V₆O₁₆·H₂O and (PyH)₂V₆O₁₆·H₂O. ThepH ranges of solutions the polyvanadates can be isolated from, were estimated. The compounds prepared were characterized by chemical analysis and IR spectroscopy. The synthesis of deuterated analogues allowed to assign the IR bands corresponding to vibrations of water in the spectra of deca- and dihydrogendecavanadates and to V-OH vibrations in the spectra of dihydrogendecavanadates.

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Benzylammonium-, Imidazolium- und Pyridinium-Polyvanadate. Synthese und Charakterisierung

Zusammenfassung Aus dem ReaktionssystemB-V₂O₅-HClO₄-H₂O undB-V₂O₅-H₂O [B=Benzylamin (Bz), Imidazol (Im) oder Pyridin (Py)] wurden acht neue Verbindungen synthetisiert: bei 20°C entstanden die Metavanadate und Decavanadate der Zusammensetzung (BzH)VO₃, (BzH)₆V₁₀O₂₈·3H₂O, (ImH)₆V₁₀O₂₈·2H₂O, (PyH)₆V₁₀O₂₈·2H₂O, (ImH)₄H₂V₁₀O₂₈·2H₂O und (PyH)₄H₂V₁₀O₂₈·3H₂O, bei 60°C entstanden die Hexavanadate (ImH)₂V₆O₁₆·H₂O und (PyH)₂V₆O₁₆·H₂O. DiepH-Bereiche, innerhalb derer Polyvanadate isoliert werden können, wurden abgeschätzt. Die Verbindungen wurden mittels chemischer Analyse und IR-Spektroskopie charakterisiert, wobei die Synthese deuterierter Analoga die Zuordnung von Banden unterstützte.

     

Cationic arenechromium-nitrosyls and -hydrides

Complexes Cr(CO)₂L(C₆Me_6-nH_n), n = 0-3, L = CO and PPh₃, react with NOPF₆ in methanol/toluene to give [Cr(CO)L(NO)(C₆Me_6-nH_n)] PF₆, n = 0-3, L = CO; n = 0, L = PPh₃, and these react with nucleophiles (X^-) to give cyclohexadienyl derivatives Cr(CO)₂(NO)(C₆Me_6-nH_nX); the compounds Cr(CO)₂(PhCCPh)(C₆Me_6-nH_n) react with NOPF₆ to yield [Cr(H)(CO)₂(PhCCPh)(C₆Me_6-nH_n)] PF₆, n = 0 and 1.     

Anab initio investigation of structure and inversion barrier of triisopropylamine and related amines and phosphines

Summary The equilibrium geometry and barrier to pyramidal inversion of triisopropylamine, N(CH(CH₃)₂)₃, is computed at SCF level of theory. For comparison, results for ammonia NH₃ (including a near HF calculation), trimethylamine N(CH₃)₃ and the three analogous phosphine compounds PH₃, P(CH₃)₃ and P(CH(CH₃)₂)₃ are presented as well.     

Fluorine addition to polychlorinated and polybrominated ethenes and arenes using vanadium pentafluoride

Reaction of vanadium pentafluoride with trichloroethene, tetrabromoethene, hexachlorobenzene, and octachloronaphthalene at −20 to 50 °C gave products from fluorine addition, CFCl₂CFClH, C₂Br₄F₂, C₆Cl₆F₆, and C₁₀Cl₈F₈, respectively. The fluorine addition to pentachloropyridine and hexabromobenzene was accompanied by the partial replacement of halogen atoms by fluorine and led to products C₅Cl₄F₅N and C₆Br₄F₈, respectively.     

Molecular Structure and Magnetic and Optical Properties of Endometallonitridofullerene Sc3N@Ih-C80 in Neutral,Radical Anion,and Dimeric Anionic Forms

A series of compounds with Sc₃N@I_h-C₈₀ in the neutral, monomeric, and dimeric anion states have been prepared in the crystalline form and their molecular structures and optical and magnetic properties have been studied. The neutral Sc₃N@I_h-C₈₀ ⋅ 3 C₆H₄Cl₂ ( 1 ) and (Sc₃N@I_h-C₈₀)₃(TPC)₂ ⋅ 5 C₆H₄Cl₂ ( 2 , TPC=triptycene) compounds both crystallized in a high-symmetry trigonal structure. The reduction of Sc₃N@I_h-C₈₀ to the radical anion resulted in dimerization to form diamagnetic singly bonded (Sc₃N@I_h-C₈₀⁻)₂ dimers. In contrast to {[2.2.2]cryptand(Na⁺)}₂(Sc₃N@I_h-C₈₀⁻)₂ ⋅ 2.5 C₆H₄Cl₂ ( 3 ) with strongly disordered components, we synthesized new dimeric phases {[2.2.2]cryptand- (K⁺)}₂(Sc₃N@I_h-C₈₀⁻)₂ ⋅ 2 C₆H₄Cl₂ ( 4 ) and {[2.2.2]cryptand- (Cs⁺)}₂(Sc₃N@I_h-C₈₀⁻)₂ ⋅ 2 C₆H₄Cl₂ ( 5 ) in which only one major dimer orientation was found. The thermal stability of the (Sc₃N@I_h-C₈₀⁻)₂ dimers was studied by EPR analysis of 3 to show their dissociation in the 400–460 K range producing monomeric Sc₃N@I_h-C₈₀^.− radical anions. This species shows an EPR signal with a hyperfine splitting of 5.8 mT. The energy of the intercage C−C bond was estimated to be 234±7 kJ mol⁻¹, the highest value among negatively charged fullerene dimers. The EPR spectra of crystalline (Bu₃MeP⁺)₃(Sc₃N@I_h-C₈₀^.−)₃ ⋅ C₆H₄Cl₂ ( 6 ) are presented for the first time. The salt shows an asymmetric EPR signal, which could be fitted by three lines. Two lines were attributed to Sc₃N@I_h-C₈₀^.−. Hyperfine splitting is manifested above 180 K due to the hyperfine interaction of the electron spin with the three scandium atoms (a total of 22 lines with an average splitting of 5.32 mT are observed at 220 K). Furthermore, each of the 22 lines is additionally split into six lines with an average separation of 0.82 mT. The large splitting indicates intrinsic charge and spin density transfer from the fullerene cage to the Sc₃N cluster. Both the monomeric and dimeric Sc₃N@I_h-C₈₀⁻ anions show an intrinsic shift of the IR bands attributed to the Sc₃N cluster and new bands corresponding to these species appear in the NIR range of their UV/Vis/NIR spectra, which allows these anions to be distinguished from neutral species.     

Addition and elimination of hydrogen and ligand substitution on triosmium clusters. Kinetics and mechanism

The kinetics of the reversible reaction HOs₃(μ-COMe)(CO)₁₀ + H₂ ? H₃Os₃(μ³-COMe)(CO)₉ + CO has been investigated. The reaction of HOs₃(μ-COMe)(CO)₁₀ with hydrogen involves dissociation of a CO ligand prior to the rate-determining step, which is proposed to be the oxidative addition of molecular hydrogen. The reaction of H₃Os₃(μ₃-COMe)(CO)₉ with CO involves rate-limiting hydrogen loss. The equilibrium constant and the competition ratio for hydrogen and CO for the unsaturated intermediate were determined. The mechanism of substitution by AsPh₃ on HOs₃(μ-COMe)(CO)₁₀ also involves a CO dissociative mechanism. Based upon relative rate constants for CO, AsPh₃, and hydrogen addition to HOs₃(COMe)(CO)₉, CO dissociation and hydrogen addition are proposed to occur at different metal sites.     

Superconducting LaRu2P2 and other alkaline earth and rare earth metal ruthenium and osmium phosphides and arsenides with ThCr2Si2 structure

The ThCr₂Si₂-type compounds MRu₂P₂ (M = Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb), MOs₂P₂ (M = Sr, Ba, Eu), and MRu₂As₂ (M = Ca, Sr, Ba, La, Eu) were prepared by sintering techniques and/or by reaction of the elemental components in a tin flux. The crystal structures of SrRu₂P₂ and LaRu₂P₂ were refined from single-crystal diffractometer data to residuals of R = 0.019 (224 structure factors, 11 variable parameters) and R = 0.028 (510 F's, 11 variables), respectively. LaRu₂P₂ is diamagnetic and becomes superconducting at 4.1 K. No transition to a superconducting state was observed down to 1.8 K for the compounds MFe₂P₂ (M = Ca, Sr, Ba, La), MRu₂P₂ (M = Ca, Sr, Ba, Y), and MOs₂P₂ (M = Sr, Ba).