Preparation of Quaternary FeCoMoCu Metal Oxides for Oxygen Evolution Reaction

Molybdenum doping is an effective way to improve the oxygen evolution reaction(OER) properties of catalysts, which can efficiently improve the electronic conductivity, mass transport process, and intrinsic activity of transition metal oxides or hydroxides, especially for those multi-component oxides with more abundant active sites. Herein, we have prepared a quaternary FeCoMoCu metal oxide on Cu foam(FeCoMoCuO_x@Cu) as an efficient OER catalyst. As expected, FeCoMoCuO_x@Cu could exhibit a low overpotential(252 mV at the current density of 10 mA/cm²) and exceptional stability(10000 cycles of CV scans or constant electrolysis for 48 h).     

Nb3Ru5B2 – The First Fully Characterized Ternary Phase in the Nb‐Ru‐B System: Synthesis,Crystal Structure,and Bonding Analysis

The first fully characterized phase in the Nb‐Ru‐B system, Nb₃Ru₅B₂, was successfully synthesized as polycrystalline powders as well as single crystals and characterized by EDX analysis and X‐ray diffraction methods. It is the first ternary phase of the type A₃T₅B₂ adopting the Ti₃Co₅B₂ structure type and containing a group eight transition metal at the T sites. According to COHP bonding analysis the Nb–Nb interactions between two pentagonal prisms are strongly bonding and thus weaken the Nb–Ru interactions, which become significantly weaker than those found in the tetragonal prisms. Furthermore a deep pseudogap is found around the Fermi Level of the calculated DOS and the phase is predicted to be a metallic conductor as expected for this metal‐rich boride.     

Opening a New Series of Calcium Boridecarbides with Heterographene Nets by Ca1–x(B,C)6 and Ca1–x(B,C)8 – Two Members of the (CaB2)Cn Compound Series

Ca_1–xB₂C₄ (x ~ 0.08) and Ca_1–xB₂C₆ (x ~ 0.04) are two compounds containing heterographene‐B,C nets which were prepared by solid state synthesis and structurally characterized by X‐ray powder diffraction data. Both compounds crystallize in the space group P6/ mmm (No. 191). The lattice constants are a = 4.55971(5) Å and c = 4.4020(1) Å for CaB₂C₄ and a = 2.58390(5) Å, c = 4.43597(8) Å for CaB₂C₆. The calcium atoms are intercalated between the heterographene (B,C) nets. The calcium atom distribution in Ca_1–xB₂C₆ is disordered, leading to diffuse scattering. A model for this disorder was developed that matches well the observed diffuse scattering observed in the electron diffraction pattern. For Ca_1–xB₂C₆ and its decomposition products magnetic and electric properties are being reported.     

Nanosized rare-earth hexaborides: Low-temperature preparation and microstructural analysis

A versatile, rapid and easy synthesis of pure rare-earth-(RE) hexaboride powders was developed, without resorting to hazardous precursors or generating undesired, ineliminable, side products. To this purpose, we employed a metathesis reaction, typically starting from a mixture of a hydrated rare earth trichloride and MgB₂, kept at 650 °C for 1 h under vacuum. This methodology affords nanosized RE hexaborides, with average crystallite (domain) sizes down to a few nanometers, useful for tailoring the functional performances of the MgB₂ superconducting phase produced by the reactive liquid infiltration method. For the powders showing the lowest average domain sizes (YbB₆ and EuB₆), an unconventional microstructural analysis, based on Total Scattering methods and on the Debye Function Approach, was also performed, which provided the complete nanocrystal size distributions.     

Structural Study and Solution Integrity of Dioxomolybdenum(VI) Complexes with Tridentate Schiff Base and Azole Ligands

Four new molybdenum complexes [Mo^VIO₂(L¹)(Him)] ( 1 ), [Mo^VIO₂(L¹)(3‐MepzH] ( 2 ), [Mo^VIO₂(L²)(3‐MepzH)] ( 3 ), and [(Mo^VIO₂)₂(μ‐L³)(MeOH)₂] ( 4 ) were synthesized and characterized by IR, NMR, ESI‐MS, and single‐crystal structure analysis [H₂L¹ = 2‐(salicylideneamino)‐2‐methyl‐1‐propanol, H₂L² = 2‐(3‐methoxysalicylideneamino)‐2‐methyl‐1‐propanol, H₄L³ = 1, 7‐bis(salicylidene)dihydrazide malonic acid, Him = imidazole and 3‐MepzH = 3‐methylpyrazole]. In all four structures the molybdenum atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base di‐ or tetraanion (L^{1, 2})^2—/(L³)^4— and one oxo group occupying the sites of the equatorial plane. The other oxo group and the azole or methanol molecule occupy the apical sites. In 1—3 two centrosymmetrically related molecules form a hydrogen‐bonded pair through the (azole)N‐H···O(alkoxo) interaction. Additional crystal packing appears to be controlled mostly by π stacking between the aromatic rings of the salicyl moiety. ESI‐MS investigations reveal that the integrity of complexes 1—4 is largely retained in methanol solution. At the same time evidence is provided that di‐ to tetranuclear oligomers of formula [{Mo^VIO₂(L)}_x] and [{Mo^VIO₂(L)}_x(3‐MepzH)] with L = L¹, L², x = 2, 3, 4 are present simultaneously with 2 and 3 in methanol solution, respectively the tetranuclear species [{(Mo^VIO₂)₂(L³)}₂] with 4 .     

Neue Calix[4]aren‐Komplexe des vierwertigen Molybdäns

Novel Calix[4]arene Complexes of Tetravalent Molybdenum The reaction of p‐tert.‐Butylcalix[4]aren Cax(OH)₄ with [Mo(NMe₂)₄] in equimolar amounts at 80°C in toluene affords after extraction into acetonitrile a mixture of [CaxO₄Mo(NHMe₂)(NCMe)] ( 1(NCMe) ) and [(CaxO₄Mo)₂(NCMe)₂] ( 2(NCMe)₂ ). If the same reaction is carried out in acetonitrile or in mixtures of toluene and acetonitrile instead of toluene, the formation of 2(NCMe)₂ is suppressed and only 1(NCMe) has been isolated. Both compounds have been characterized by X ray crystal structure determinations. 1(NCMe) : space group: C2/c, lattice constants: a = 37, 987(8)Å, b = 13, 012(3)Å, c = 20, 271(4)Å, β = 103, 39°; 2(NCMe)₂ : space group: P2₁/n, lattice constants: a = 11, 937(2)Å, b = 21, 078(4)Å, c = 19, 620(4)Å, β = 107, 31(3)°. The molybdenum atom in 1(NCMe) is coordinated with four oxygen atoms of the calix[4]arene ligand, a nitrogen atom of the amine ligand, and the nitrogen atom of the endohedrally coordinated acetonitrile molecule in a slightly distorted octahedron. Two of these monomer units are linked via hydrogen bridges. In 2(NCMe)₂ two complex fragments [CaxO₄Mo(NCMe)] are linked via phenolate units of the calix[4]arene. The Mo‐Mo′ distance of 261.2(1)pm is in accordance with a Mo‐Mo double bond. EH‐, DFT‐, und MP2‐ calculations have been performed on model complexes [CaxO₄Mo(NH₃)(NCH)] ( 1′(NCH) ) and [(p‐H‐CaxO₄Mo)₂(NCH)₂] ( 2′(NCH)₂ ) for a closer inspection of the binding in these compounds. The results of the calculations suggest that addition of the electron rich, basic oxygen atom is the structure determining feature of 2′(NCH)₂ and not a metal metal bond.     

湿式消化-ICP-AES法测定航空润滑油中镍钛镁铬钼锡

研究采用硝酸-高氯酸混合酸湿式消化法,建立ICP-AES法同时测定航空润滑油中痕量金属元素镍、钛、镁、铬、钼、锡。样品消化完全、快速,检出限分别为(μg．L^-1)：镍4．1、钛2．1、镁4．2、铬3．2、钼3．6、锡24．4,RSD小于5％,回收率为96．0％～104．0％。     

Bildung und Struktur von [μ‐(1,2 : 2‐η‐tBu2P–P){Mo(CO)2cp′}2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXIV. Formation and Structure of [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂] [cp′Mo(CO)₂]₂ (cp′ = C₅H₄^tBu) reacts with ^tBu₂P–P=P(Me)^tBu₂ to yield the compound [μ‐(1,2 : 2‐η‐^tBu₂P–P){Mo(CO)₂cp′}₂], which crystallizes in the space group P2₁2₁2₁ with a = 1202.42(7), b = 1552.48(8), and c = 1765.3(1) pm.     

Synthesis and Structure of the Tetrameric [Cp*V(μ‐F)2]4 (Cp* = C5Me5); Preparation of the Imido Molybdenum Fluoride [(2,6‐i‐Pr2C6H3N)2MoF2] · THF and the Structural Investigation of [(2,6‐i‐Pr2C6H3N)6Mo4(μ3‐F)2Me2(μ‐O)4]

Treating [Cp*V(μ‐Cl)₂]₃ (Cp* = C₅Me₅) and [(2,6‐i‐Pr₂C₆H₃N)₂MoMe₂], respectively, with Me₃SnF afforded the title compounds [Cp*V(μ‐F)₂]₄ ( 1 ) and [(2,6‐i‐Pr₂C₆H₃N)₂MoF₂] · THF ( 2 ). 1 has a tetrameric structure, in which four V atoms can be regarded as being arranged at the vertices of a distorted tetrahedron, with four long edges bridged by one F atom and each of the other two short edges bridged by two F atoms with a mean V–F bond length of 2.00 Å. A hydrolyzed product of 2 , [(2,6‐i‐Pr₂C₆H₃N)₆Mo₄(μ₃‐F)₂Me₂(μ‐O)₄] ( 3 ) was characterized by elemental analyses and X‐ray single crystal study. The X‐ray diffraction analysis reveals that 3 has a unique tetranuclear structure, containing two five and two six coordinated Mo atoms connecting each other by four μ‐O and two μ₃‐F atoms. The geometries around the two Mo atoms can be described having distorted trigonal bipyramidal and distorted octahedral coordination spheres, respectively. The Mo–(μ‐O) bond lengths are 1.813 Å (average) for five coordinated Mo atoms and 2.030 Å (average) for those of six coordinated, respectively, indicating an additional π bonding between five coordinated Mo atoms and the μ‐O atoms. The Mo–(μ₃‐F) distances range from 2.291 to 2.352 Å.