Mobility of the dppm ligand in dinuclear RuRh complexes: formation of trinuclear RuRh2 and RuRhCu derivatives,and X-ray structure of a new heterobimetallic hydrido-bridged complex

Protonation of RuRhH₂Cl(COD)(dppm)₂ (1) (COD = 1,5 cyclooctadiene, dppm = bisdiphenylphosphinomethane) with HBF₄ · Et₂O gives [RuRhHCl(COD)-(dppm)₂]BF₄ (2), which has been shown to contain two chelating dppm ligands on ruthenium and a bridging hydride (RuH 2.08(7) Å; RhH 1.64(8) Å). Complex 2 reacts with CO to give [RuRhHCl(CO)₃(dppm)₂]BF₄ (3) containing two bridging dppm groups. Reaction of 1 with 0.5 molar equivalents of [RhCl(COD)]₂ at 80°C affords the trinuclear RuRh₂H₂Cl(PhPCH₂PPh₂)(COD)₂(dppm) (4) in low yield (25%), and that with CuCl at room temperature gives RuRhCuH₂Cl₂ (COD)(dppm)₂ (5) in high yield. Complex 5 is not very stable in solution and is converted into RuCuH₂Cl(dppm)₂ (6), a typical adduct between a Lewis acid and a hydride complex, which can be more easily obtained from RuH₂(dppm)₂ and CuCl in toluene at 80°C.     

Fluorination behaviors of the complexes of RbFUF4 and CsFUF4 systems

The reaction behaviors between some complex fluorides of MFUF₄ system (M = Rb or Cs) and fluorine were investigated. In all the cases, uranium was oxidized to hexa-valent state at the temperatures between 300 and 500°C and M₂UF₈ type complex was formed, except for the cases of 3MF·UF₄ type complexes. In the fluorinations of 3MF·UF₄, products with the composition of M₃UF₉ were formed. A change in the stability of RbFUF₆ systems with RbF/UF₆ ratio was also investigated.     

Effect of the nature of the phosphido bridge on the Co labilisation in heterobimetallic η-phosphido complexes

In contrast to their μ-PPh₂ analgoues, the compounds (OC)₅M(μ-PRH)Pt(H)(PPh₃)₂ M  Cr, Mo, W; R  Ph or cyclohexyl) do not rearrange to form (OC)₄M(μ-PRH)(μ-H)Pt(PPh₃)₂.     

Comparison of the magnetic properties of MmFeband NdFeB compounds

NdFeB and corresponding MmFeB compounds were studied, the high field magnetization at 4.2 K, the a.c. susceptibility (4.2 < T < 300 K) and the anisotropy field were measured using the singular point detection technique (77 < T < 570 K). At room temperature the anisotropy field of the MmFeB is about 3T, whereas that of NdFeB compounds is about 7T. The MmFeB compounds showed effects due to the cerium (lowering the Curie temperature) as well as due to the neodymium (spin reorientation at low temperatures).     

Calorimetric studies of CeCu AND CeMgCu alloys

Using different calorimeters, the following measurements have been carried out.

• 1.(i) The integral enthalpies of mixing of CeCu binary and some CeMgCu ternary liquid alloys,
• 2.(ii) The enthalpy of formation and the enthalpy of melting of the intermetallic compound CeCu₂.
• 3.(iii) The heat content of solid and liquid CeCu₂.

The observed concentration and temperature dependence of the measured values of the enthalpies of mixing as well as the glass-forming abilities of these alloys are explained on the basis of an association model.     

Thermodynamics of the URuC system

Thermodynamic measurements by the electromotive force method were made on the binary intermetallic phases URu₃ and U₃Ru₅ and on the ternary carbides URu₃C_0.7 and U₂RuC₂ of the URu and the URuC systems between 950 and 1200 K using galvanic cells with CaF₂ single crystal electrolytes: U, UF₃¦CaF₂¦UF₃, URu₃, Ru; U, UF₃¦CaF₂¦UF₃, U₃Ru₅, URu₃; Ru, URu₃, UF₃¦CaF₂¦UF₃, URu₃C_0.7, Ru, C; U, UF₃¦CaF₂¦UF₃, URu₃C_0.7, U₂RuC₂, C. The Gibbs energies of formation of URu₃, U₃Ru₅, URu₃C_0.7 and U₂RuC₂ were evaluated from the measured electromotive force which give ^fΔG^o〈URu₃〉 = −199 100 + 35.9 T J mol^−1fΔG^o〈U₃Ru₅〉 = −398 600 + 43.6 T J mol^−1fΔG^o〈URu₃C_0.7〉 = −192 600 + 2.5 T J mol^−1fΔG^o〈U₂RuC₂〉 = −380 200 + 52.5 T J mol⁻¹ The implications of these thermodynamic data for the behaviour of the fission product ruthenium in irradiated carbide fuels are discussed.     

The excess enthalpies of liquid GaGeTe and GaSnTe alloys

The excess enthalpies of the liquid alloys GaGeTe and GaSnTe were measured in a heat-flow calorimeter at 1203 K. The enthalpy surface in the ternary space in both systems is characterized by a valley stretching from the exothermic minimum in the GaTe system to the minima of the GeTe and SnTe systems. The minima in the ternary systems were found in this valley, i.e. on the sections Ga₂Te₃-GeTe and Ga₂Te₃-SnTe. A comparison of the experimental data with those calculated from the excess enthalpies of the constituent binaries with the aid of the Bonnier model, reveals only small deviations. A preliminary investigation was made into the ternary phase diagram of GaSnTe. This system contains the two quasibinary sections Ga₂Te₃-SnTe, GaTe-SnTe and the ternary compound Ga₆SnTe₁₀. The previously reported compounds Ga₂SnTe₃ and GaSnTe₂ do not exist.     

Ab initio quantum chemical studies of the electronic properties of the hydrogen bonded N2HF,N2HCl, (HCN)2 and NH3HCN complexes

The results of ab initio self-consistent field (SCF) and configuration interaction (CI) calculations on the hydrogen bonded N₂HF, N₂HCl, (HCN)₂ and NH₃HCN complexes, using basis sets that range from double-zeta plus polarization to triple-zeta plus double polarization, are reported. The primary objective of this work has been to calculate the changes in the dipole moments and the electric field gradients (EFGs) at the quadrupolar ¹⁴N, ²H and ³⁵Cl nuclei that are induced by H-bonding. Since the interpretation of the H-bond induced shifts requires a knowledge of the molecular dynamics in weakly H-bonded molecular complexes such as those studied in the present work, we have taken into account the effects of vibrational averaging on both the EFGs and dipole moments utilizing harmonic intermolecular force fields that were generated using ab initio SCF methods. The results of these calculations are compared with the corresponding experimental quantities that are obtained from the microwave spectra of these complexes.     

Allyldialkyl complexes of ruthenium(IV): Preparation and reductive CC bond formation followed by CH bond activation

New η³-allyldimethyl complexes Ru(η⁵-C₅R₅)(η³-C₃H₅)(CH₃)₂, where R = H or CH₃, are prepared from Ru(η⁵-C₅R₅)(η³-C₃H₅)Br₂ by alkylation with trimethyl-aluminium. The Ru^IV dimethyl complex is thermally converted to the Ru^II 1-methylallyl compound, Ru(η⁵-C₅R₅)(η³-CH₂CHCHCH₃)L, where L = CO or t-C₄H₉NC, with evolution of methane. Kinetic and deuteration studies on the reductive process are also discussed.     

Phase equilibrium diagram of the system MnCrO

A hypothetical oxygen pressure-composition phase diagram and a projection of the oxygen pressure-temperature-composition diagram on the composition triangle were constructed from phase equilibria in the system MnCrO on the basis of the data available in literature. The temperature-composition phase equilibrium diagram of this same system in air was specified. Isomorphism of solid solutions with spinel and hausmannite structure and their intertransformation was studied. Two chemical compounds, MnCr₂O₄ and Cr₄Mn₂₈O₄₈, are supposed to exist in the system.     

Mercury-rare gas van der Waals complexes: From the lightest HgHe to the heaviest HgXe

Mercury helium and mercury xenon van der Waals complexes have been observed in a supersonic free jet expansion by laser-induced fluorescence in the vicinity of the Hg(³P₁¹S₀) transition. The helium complex very weakly bonded in the ground state (D₀ = 8 ± 1 cm⁻¹) exhibited a simple rotational structure. The strongly bonded xenon complex has shown a clear example of isotopic broadening in its vibronic spectra.     

Bubble-point pressures of the H2COCO2 system

Bubble-point pressures of the H₂COCO₂ system were measured at temperatures from 253.15 to 303.15 K and pressures up to 9 MPa. Multiple bubble-points were observed within certain limits of hydrogen compositions. The data have been compared with the calculated results by the Redlich-Kwong and the Peng-Robinson equations of state.     

Molecular complexes of cyclophanes—XIII. Charge-transfer complexes of cyclophanes with fluoranil

The charge-transfer (CT) complexes of some methylated [2.2]para-, multibridged cyclo- and [2.2]indenophanes as π-donors with fluoranil (TFQ) as π-acceptor have been studied spectrophotometrically. The role of the molecular structure of the donors on their Lewis basicities and stability of their CT complexes with TFQ are discussed. Eight pure crystalline complexes were prepared. Their i.r. spectra indicate an increase of the electron density in the TFQ part of the CT complex.     

Stepwise TiCl,TiCH3, and TiC6H5 bond dissociation enthalpies in bis(pentamethylcyclopentadienyl)titanium complexes

Reaction-solution calorimetric studies involving the complexes Ti[η⁵-C₅(CH₃)₅]₂-(CH₃)₂, Ti[η⁵-C₅(CH₃)₅]₂(CH₃), Ti[η⁵-C₅(CH₃)₅]₂(C₆H₅), Ti[η⁵-C₅(CH₃)₅]₂Cl₂, and Ti[η⁵-C₅(CH₃)₅]₂Cl, have enabled derivation of titaniumcarbon and titaniumchlorine stepwise bond dissociation enthalpies in these species.