Catalytic Effects of Ruthenocene Bimetallic Compounds Derived from Fused Aromatic Ring Ligands on the Main Oxidizing Agent for Solid Rocket Motor

We report the catalytic effect of three ruthenocene bimetallic compounds derived from fused aromatic rings of general formula [{Cp*Ru}2L], with Cp*: pentamethylcyclopentadiene and L = pentalene (1), 2,6-diethyl-4,8-dimethyl-s-indacene (2), and 2,7-diethyl-as-indacene (3), on the thermal decomposition of ammonium perchlorate (AP). The new compound 3 was characterized by a combination of multinuclear magnetic resonance (NMR) spectroscopy and elemental analysis. The differential scanning calorimetry (DSC) analysis of compound 3 shows a decrease in the decomposition temperature of AP to 347 ºC, increases the energy release to 2048 J g-1 and, consequently, leads to the lowest activation energy (42.9 kJ mol−1). These results are comparable to the typically used metallocene (catocene: 347 ºC and 2472 J g-1), suggesting a suitable and competitive alternative to be used as a modifier for composite solid propellants.

Practical Approbation of Thermodynamic Criteria for the Consolidation of Bimetallic and Functionally Gradient Materials

This study concerns the key problem of determining the conditions for the consolidation or fracture of bimetallic compounds and high-gradient materials with different coefficients of thermal expansion. The well-known approach to determining the strength is based on the assessment of the critical energy release rates during fracture, depending on the conditions of loading (the portion of shear loading). Unfortunately, most of the experimental results cannot be used directly to select suitable fracture toughness criteria before such a connection is made. This especially applies to the region of interphase interaction, when it is required to estimate the internal energy of destruction accumulated during the preparation of the joint in the adhesion layer within the range of 20–50 μm. Hence, criteria for the adhesive consolidation of bimetallic compound layers were obtained on the basis of the thermodynamics of nonequilibrium processes. The analysis of the quality of the joint using the obtained criteria was carried out on the basis of the calculation of isochoric and isobaric heat capacities and coefficients of thermal expansion of multiphase layers. The applicability of the criteria for the qualitative assessment of the adhesion of layers is demonstrated in the example of bimetallic joints of steel 316L—aluminum alloy AlSi10Mg obtained by the SLM method at various fusion modes.

Crystal structures of [Cu(phen)(H2O)3(MF6)]·H2O (M = Ti, Zr, Hf) and [Cu(phen)(H2O)2F]2[HfF6]·H2O

The crystal structures of three bridged bimetallic molecular compounds, namely, triaqua-2κ3 O-μ-fluorido-pentafluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N′)copper(II)titanium(IV) monohydrate, [Cu(TiF6)(phen)(H2O)3]·H2O (phen is 1,10-phenanthroline, C12H8N2), (I), triaqua-2κ3 O-μ-fluorido-pentafluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N′)copper(II)zirconium(IV) monohydrate, [Cu(ZrF6)(phen)(H2O)3]·H2O, (II), and triaqua-2κ3 O-μ-fluorido-pentafluorido-1κ5 F-(1,10-phenanthroline-2κ2 N,N′)copper(II)hafnium(IV) monohydrate, [Cu(HfF6)(phen)(H2O)3]·H2O, (III), and one molecular salt, bis[diaquafluorido(1,10-phenanthroline-κ2 N,N′)copper(II)] hexafluoridohafnate(IV) dihydrate, [CuF(phen)(H2O)2]2[HfF6]·2H2O, (IV), are reported. The bridged bimetallic compounds adopt Λ-shaped configurations, with the octahedrally coordinated copper(II) center linked to the fluorinated early transition metal via a fluoride linkage. The extended structures of these Λ-shaped compounds are organized through both intra- and intermolecular hydrogen bonds and intermolecular π–π stacking. The salt compound [Cu(phen)(H2O)2F]2[HfF6]·H2O displays an isolated square-pyramidal Cu(phen)(H2O)2F+ complex linked to other cationic complexes and isolated HfF6 2− anions through intermolecular hydrogen-bonding interactions.

On the Performances of Density Functionals for Open Shell First-Row Transition Metal Compounds

<p>The selection of density functional is the key to obtain useful results in a computational work. Due to their complexity in terms of electronic structures, open-shell first-row transition metal complexes are difficult to be correctly described by most functionals. In this work, totally 19 reactions involving V, Cr, Mn, Fe, Co, Ni complexes, either monometallic or bimetallic, were used as testing set for 18 functionals ranging from generalized gradient approximation (GGA) to doubly-hybrid functionals, with experimental electron affinities and ligand association energies as standard. It is shown that for monometallic complexes PBE0-D3BJ and B3LYP-D3BJ perform the best, whereas MN15 and MN15L are the optimal functionals for bimetallic compounds. On the other hand, the accuracy of DLPNO-CCSD(T) is not significantly better than the best-performing functionals, and the use of doubly-hybrid functionals is risky.</p>

On the Performances of Density Functionals for Open Shell First-Row Transition Metal Compounds

<p>The selection of density functional is the key to obtain useful results in a computational work. Due to their complexity in terms of electronic structures, open-shell first-row transition metal complexes are difficult to be correctly described by most functionals. In this work, totally 19 reactions involving V, Cr, Mn, Fe, Co, Ni complexes, either monometallic or bimetallic, were used as testing set for 18 functionals ranging from generalized gradient approximation (GGA) to doubly-hybrid functionals, with experimental electron affinities and ligand association energies as standard. It is shown that for monometallic complexes PBE0-D3BJ and B3LYP-D3BJ perform the best, whereas MN15 and MN15L are the optimal functionals for bimetallic compounds. On the other hand, the accuracy of DLPNO-CCSD(T) is not significantly better than the best-performing functionals, and the use of doubly-hybrid functionals is risky.</p>

On the Performances of Density Functionals for Open Shell First-Row Transition Metal Compounds

<p>The selection of density functional is the key to obtain useful results in a computational work. Due to their complexity in terms of electronic structures, open-shell first-row transition metal complexes are difficult to be correctly described by most functionals. In this work, totally 19 reactions involving V, Cr, Mn, Fe, Co, Ni complexes, either monometallic or bimetallic, were used as testing set for 18 functionals ranging from generalized gradient approximation (GGA) to doubly-hybrid functionals, with experimental electron affinities and ligand association energies as standard. It is shown that for monometallic complexes PBE0-D3BJ and B3LYP-D3BJ perform the best, whereas MN15 and MN15L are the optimal functionals for bimetallic compounds. On the other hand, the accuracy of DLPNO-CCSD(T) is not significantly better than the best-performing functionals, and the use of doubly-hybrid functionals is risky.</p>

Reactions of In–Zn bonds with organic azides: products that result from hetero- and homo-bimetallic behaviour

Bimetallic compounds with indium–zinc bonds react with organic azides to give products consistent with hetero- and homo-bimetallic behaviour.

Composition dependence of magnetic relaxation for CoIIxNiII1−x chain-based compounds with mixed double azide–tetrazolate bridges

A series of isomorphous random bimetallic compounds based on CoIIxNiII1−x (0 ≤ x ≤ 1) chains with simultaneous azide–tetrazolate bridges exhibit composition-dependent magnetic relaxation were investigated.