Molecular Engineering of Redox Rich Diruthenium Compounds: Further Investigation of Ru<Subscript>2</Subscript>(Y<Emphasis Type="Italic">ap</Emphasis>)<Subscript>4</Subscript>X Type Compounds

Three new diruthenium compounds, Ru₂(L1)₄Cl (1), Ru₂(L2)₄Cl (2) and Ru₂(ap)₄F (3) were synthesized and characterized, where L1, L2, and ap are 2-(3-methoxyanilino)pyridinate, 2-(3-propoxyanilino)pyridinate, and 2-anilinopyridinate, respectively. Structural study revealed the Ru–Ru bond lengths of 2. 2816(7) Å (1) and 2. 2785(6) Å (3). All three compounds are S = 3/2 molecules. Each of three diruthenium compounds displays two reversible one electron couples, an oxidation and a reduction, and the potential data appear to indicate that the axial fluoro ligand is a much stronger donor than the chloro ligand.     

Synthesis and crystal structure of two complexes [Cu<Subscript>2</Subscript>(NiL)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>] and [Cd<Subscript>2</Subscript>(CuL)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]

Macrocyclic and supermolecular complexes [Cu₂(NiL)₂Cl₄] (I) and [Cd₂(CuL)₂Cl₄] (II) (H₂L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-diene) have been synthesized and structurally determined by X-ray diffraction and IR spectrum. Complex I crystallizes in the monoclinic system with P2₁/n group, a = 10.9019(15), b = 14.3589(19), c = 12.4748(17) 0A, β = 108.645(2)°, Z = 4. Complex II crystallizes in the monoclinic system with P2₁/n group, a = 10.9784(16), b = 14.580(2), c = 12.8904(18) Å, β = 109.339(2)°, Z = 4.     

Synthesis of ammonia from natural gas at atmospheric pressure with doped ceria–Ca<Subscript>3</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript>–K<Subscript>3</Subscript>PO<Subscript>4</Subscript> composite electrolyte and its proton conductivity at intermediate temperature

A new type of oxide–salt composite electrolyte, yttrium doped ceria YDC–Ca₃(PO₄)₂–K₃PO₄, was developed and demonstrated for its promising use for ammonia synthesis. Using this composite electrolyte, ammonia was synthesized from nitrogen and natural gas at atmospheric pressure in the solid-state proton conducting cell reactor, and the optimal condition for ammonia production was determined . The evolved rate of ammonia is up to 6.95×10⁻⁹ mol s⁻¹ cm⁻².     

Fabrication and characterization of TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> composite nanoparticles and polyurethane/(TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript>) nanocomposite films

TiO₂–SiO₂ composite nanoparticles were prepared by a sol–gel process. To obtain the assembly of TiO₂–SiO₂ composite nanoparticles, different molar ratios of Ti/Si were investigated. Polyurethane (PU)/(TiO₂–SiO₂) hybrid films were synthesized using the “grafting from” technique by incorporation of modified TiO₂–SiO₂ composite nanoparticles building blocks into PU matrix. Firstly, 3-aminopropyltriethysilane was employed to encapsulate TiO₂–SiO₂ composite nanoparticles’ surface. Secondly, the PU shell was tethered to the TiO₂–SiO₂ core surface via surface functionalized reaction. The particle size of TiO₂–SiO₂ composite sol was performed on dynamic light scattering, and the microstructure was characterized by X-ray diffraction and Fourier transform infrared. Thermogravimetric analysis and transmission electron microscopy (TEM) employed to study the hybrid films. The average particle size of the TiO₂–SiO₂ composite particles is about 38 nm when the molar ratio of Ti/Si reaches to1:1. The TEM image indicates that TiO₂–SiO₂ composite nanoparticles are well dispersed in the PU matrix.     

Reaction of Methyl Diazoacetate with Amines Catalyzed by Ru<Subscript>2</Subscript>(OAc)<Subscript>4</Subscript>Cl

Reactions of primary and secondary amines with methyl diazoacetate in the presence of Ru₂(OAc)₄Cl gave the corresponding N-substituted glycine methyl esters in almost quantitative yield. Catalytic decomposition of methyl diazoacetate generates methoxycarbonylcarbene which is inserted into the N-H bond of amines with high regioselectivity.     

Dissymmetrization of crystal structures of grossular-andradite garnets Ca<Subscript>3</Subscript>(Al,Fe)<Subscript>2</Subscript>(SiO<Subscript>4</Subscript>)<Subscript>3</Subscript>

The crystal structures of three birefringent grossular-andradite natural garnets Ca₃(Al,Fe)₂(SiO₄)₃ were investigated using single-crystal X-ray diffraction data (MoK_α, number of reflections measured 8065, 10619, 9213; R = 2.81, 2.74, 3.26%). According to the values of unit cell constants, inconsistent intensities of reflections and appearance of additional (forbidden) reflections explored garnets have different symmetry: cubic, sp. gr. (Fe/(Fe + Al) = 0.078, Δn = 0.0002); orthorhombic, sp. gr. Fddd (Fe/(Fe + Al) = 0.58, Δn = 0.0089); triclinic, sp. gr. or I1 and pseudo-orthorhombic (Fe/(Fe + Al) = 0.23, Δn = 0.0066). Careful refinement of all crystal structures in space groups , Fddd and has confirmed the symmetry reduction detected on the diffraction patterns and shown that dissymmetrization of cubic garnets connects with partial ordering of trivalent cations over Y-sites. Direct linear relationship between Fe-occupancy, an average Y–O bond lengths and octahedral O–O edges has been revealed. Cluster models of dissymmetrization have been regarded. Evidence for the “growth dissymmetrization” phenomena (kinetic phase transformations) as the reasons of the symmetry reduction of cubic garnets has been discussed. The reasonable assumption that the garnets crystal structures described as orthorhombic are triclinic, but the deviations from the orthorhombic symmetry so small, that cannot be manifested by of X-ray diffraction study has been taken.     

Ammonia gas sensor based on a spinel semiconductor,Co<Subscript>0.8</Subscript>Ni<Subscript>0.2</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanomaterial

Thick film of nanocrystalline Co_0.8Ni_0.2Fe₂O₄ was obtained by sol–gel citrate method for gas sensing application. The synthesized powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy. The XRD pattern shows spinel type structure of Co_0.8Ni_0.2Fe₂O₄. XRD of Co_0.8Ni_0.2Fe₂O₄ revels formation of solid solution with average grain size of about 30 nm. From gas sensing properties it observed that nickel doping improves the sensor response and selectivity towards ammonia gas and very low response to LPG, CO, and H₂S at 280 °C. Furthermore, incorporation of Pd improves the sensor response and stability of ammonia gas and reduced the operating temperature upto 210 °C. The sensor is a promising candidate for practical detector of ammonia.     

Alum (KAl(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 12H<Subscript>2</Subscript>O) Catalyzed One-Pot Synthesis of Coumarins under Solvent-Free Conditions

Summary. Alum (KAl(SO₄)₂ · 12H₂O) is used as an efficient catalyst in the Pechmann condensation of phenol derivatives with β-keto esters leading to the formation of coumarins in excellent yields under solvent-free conditions. This methodology offers significant improvements for the synthesis of coumarins with regard to the yield of products, simplicity in operation, and green aspects by avoiding toxic catalysts and solvents.     

Formation of Composites Based on CsHSO<Subscript>4</Subscript> and Cs<Subscript>5</Subscript>H<Subscript>3</Subscript>(SO<Subscript>4</Subscript>)<Subscript>4</Subscript> and Mechanism of Their Protonic Conduction

Vibrational spectra of finely divided amorphous CsHSO₄,Cs₅H₃(SO₄)₄ · H₂O, and composites based on these are measured and analyzed. An analysis of the spectra indicates the occurrence of substantial changes in the system of hydrogen bonds and in the spectral range of the sulfate group of acid sulfates in the composites. Structural dynamics of the SO₄ tetrahedrons is in full conformance with protonic conduction and the data of x-ray diffraction analyses accompanied by differential scanning calorimetry. It is shown that mobility of protons in the composites increases. A mechanism of the formation of the composites and their conduction is proposed.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 640–645.Original Russian Text Copyright © 2005 by Ponomareva, Lavrova, Burgina.     

Synthesis,structure, and NO-donor activity of the paramagnetic complex [Fe<Subscript>2</Subscript>(SC<Subscript>3</Subscript>H<Subscript>5</Subscript>N<Subscript>2</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>] as a model of nitrosyl [2FE-2S] proteins

The neutral dinuclear iron nitrosyl complex [Fe₂(SC₃H₅N₂)₂(NO)₄] (1) of the “g = 2.03” family with a ligand analogous to natural mercaptohistidine was synthesized by the metathesis reaction of the thiosulfate ligands in the [Fe₂(S₂O₃)₂(NO)₄]²⁻ anion with imidazolidine-2-thiolate ligands. The electrochemical determination of nitrogen oxide in solution showed that compound 1 has a lower NO-donor ability compared to the iron complexes with 1-methylimidazole-2-thiol and imidazole-2-thiol synthesized earlier. Study of the magnetic properties of polycrystals of 1 demonstrated that the effective magnetic moment at room temperature is ca. 2.45 μ_B and corresponds to a molecule containing a pair of the noninteracting spins S = 1/2. This is evidence that each iron coordination unit in complex 1 contains one unpaired electron, and the iron atom is in the low-spin state. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 28–34, January, 2007.     

Laser assisted selective chemical metalization of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> films

Thick aluminum oxide films are prepared on Al plates by anodizing. On the ceramic surface thus obtained a very thin Ag film is deposited via vacuum thermal evaporation. The Ag/Al₂O₃/Al samples prepared are irradiated by Nd:YAG laser through a suitable metal mask in order to remove the top metal film in the exposed areas. Thus, a negative silver image of the copied mask is obtained. Further, the samples are processed in Ni electroless chemical bath activated by the rest of silver. All processing steps are studied by scanning electron microscopy (SEM). EDS X-ray mapping is applied to study the final distribution of Al and Ni in the processed areas. In addition, the DC conductivity of the fabricated Ni wires obtained is measured. The proposed new method for selective chemical deposition of electroconductive Ni onto laser microstructured Ag/Al₂O₃/Al samples is simple, versatile and not restricted to the metal/ceramic system studied as well as to the electroless deposited metal.     

Synthesis of isomeric 2-oxazolidinones from (1<Emphasis Type="Italic">R</Emphasis>,2<Emphasis Type="Italic">R</Emphasis>)-and (1<Emphasis Type="Italic">S</Emphasis>,2<Emphasis Type="Italic">S</Emphasis>)-2-amino-1-(4-nitrophenyl)-1,3-propanediols

A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds was studied. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007.     

Investigation into the formation of heteronuclear clusters of formula [{Ru<Subscript>6</Subscript>C(CO)<Subscript>16</Subscript>Ag<Subscript>2</Subscript>X}<Subscript>2</Subscript>]<Superscript>2−</Superscript> (X = Cl,Br or I)

Reaction of [Ru₆C(CO)₁₆]²⁻ with an excess of AgX (X = Cl, Br or I) affords heteronuclear clusters of formula [{Ru₆C(CO)₁₆Ag₂X}₂]²⁻ in 80% yield, which for X = I and X = Br/Cl were crystallographically characterised. The formation of the cluster was followed in solution using electrospray ionisation mass spectrometry (ESI-MS), which revealed the presence of a wide range of clusters with the general formula [{Ru₆C(CO)₁₆} _x Ag _y X _z ]^{(2x−y+z)−} where x = 1 or 2, y = 1, 2, 3 or 4 and z = 0, 1 or 2. The high yield of the product despite the evident complicated solution speciation is attributed to selective crystallisation of the observed compound driving the equilibrium toward this product.     

Starch Derivatives of High Degree of Functionalization 11: Studies on Alternative Acylation of Starch with Long-chain Fatty Acids Homogeneously in <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl acetamide/LiCl

Starch materials of different amylose content were allowed to react with saturated and unsaturated fatty acids of varying chain length from C₁₄ to C₁₈ under homogeneous conditions applying the solvent N,N-dimethyl acetamide in combination with LiCl. As reagent the corresponding acid chlorides and, alternatively, carboxylic acids in situ activated with toluene-4-sulfonyl chloride and N,N′-carbonyldiimidazole (CDI) were studied. Using fatty acid chlorides (FACl) and toluene-4-sulfonyl chloride-activated acids an almost complete substitution of the starch occurs. By in situ activation of the fatty acids with CDI, products with a degree of substitution up to 2 were obtained, which, in particular, represents a simple and very mild procedure.     

The group-theoretical structure of the atomic g shell: connection with the alternating group <Emphasis Type="Italic">A</Emphasis><Subscript>6</Subscript> as <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript>(9)

The special projective linear groups PSL(2ℓ + 1) or L ₂(2ℓ + 1) of order 2ℓ(2ℓ + 1)(ℓ + 1) can be used to study atomic shells of electrons with angular momentum quantum number ℓ corresponding to the atomic p, d, f, and g shells for ℓ = 1, 2, 3, 4, respectively. For the atomic g shell the group L ₂(9) is isomorphic with the alternating group A ₆ on six objects of order 360 or the symmetry group of the 5-dimensional simplex, a 5-dimensional analogue of the tetrahedron with 6 vertices and 15 edges. This leads to the subgroup chain SO(9) ⊃ SO(5) ⊃ L ₂(9) for the atomic g shell analogous to the subgroup chain SO(7) ⊃ G ₂ ⊃ L ₂(7) ≈⁷ O for the atomic f shell. In the L ₂(9) group only the representations of spherical harmonics or sums thereof, Γ(Y_ℓ), with dimensions dim Γ(Y_ℓ) or dim Γ(Y_ℓ) ± 1 divisible by 9 are found to be individually reducible to irreducible representations (irreps) or sums of irreps of L ₂(9). This leads to term groupings such as S, PD, G, PF, DH, L, PK, DI, FH, M, FI, PO, DN, HK, R, etc., of increasing total dimension for the irreps of SO(9) for various g ⁿ configurations in the atomic g shell.     

Features of interlayer electron transport in quasi-two-dimensional organic metal (ET)<Subscript>4</Subscript>HgBr<Subscript>4</Subscript>(C<Subscript>6</Subscript>H<Subscript>4</Subscript>Cl<Subscript>2</Subscript>)

Angular dependences of the interlayer magnetoresistance in quasi-two-dimensional organic metal (ET)₄HgBr₄(C₆H₄Cl₂) (ET is bis(ethylenedithio)tetrathiafulvalene) in magnetic fields up to 15 T in the temperature range 1.5–4.2 K were studied. Interlayer charge transport in this metal can be described within the framework of the model of almost noninteracting metal layers.     

An exact expression for the wiener index of a TUC<Subscript>4</Subscript>C<Subscript>8</Subscript>(R) nanotorus

The Wiener index of a graph G is defined as , where V(G) is the set of all vertices of G and for denotes the length of a minimal path between x and y. A C ₄ C ₈ net is a trivalent decoration made by alternating squares C ₄ and octagons C ₈. It can cover either a cylinder or a torus. In this paper, an algorithm for computing the distance matrix of a C ₄ C ₈(R) nanotorus T = T[p,q] is given. Using this matrix, the Wiener index of T is computed.     

Spectroscopic investigation of structure and mechanism of proton conductivity CsHSO<Subscript>4</Subscript> and composites CsHSO<Subscript>4</Subscript>/SiO<Subscript>2</Subscript>

IR and RS spectra, structural, thermodynamical and transport properties of CsHSO₄ and CsHSO₄/SiO₂ composites have been investigated. It is shown that CsHSO₄ is stabilized in composites in phase II (monoclinic modification), which turns into amorphous state with increasing silicon dioxide content. A formation of disordered highly conducting states of CsHSO₄ in composites at the temperatures noticeably lower than superionic phase transition was stated. Bond length equalization in sulfate-ions, weakening of hydrogen bond system, and as a result easier proton transfer in composites in comparison with pure salt take place in these conducting states. Mechanism for formation of composites and their proton conductivity is proposed.     

Synthesis characterization and catalytic evaluation of Ni/ZrO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> aerogels catalysts

The Ni/ZrO₂/SiO₂ aerogels catalysts were synthesized via three different routes: (i) impregnation ZrO₂–SiO₂ composite aerogels with a aqueous solution of Ni(NO₃)₂, (ii) impregnation SiO₂ aerogels with a mixed aqueous solution of Ni(NO₃)₂ and ZrO(NO₃)₂ · 2H₂O, (iii) one-pot sol–gel procedure from precursors Ni(NO₃)₂/ZrO(NO₃)₂ · 2H₂O/Si(OC₂H₅)₄. These catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), ammonia temperature-programmed desorption (NH₃-TPD), N₂ adsorption–desorption isotherms and Fourier transform infrared (FT-IR). The Liquid-phase hydrogenation of maleic anhydride (MA) was performed over these catalysts. The results revealed that the different preparation routes result in a difference between the obtained samples, concerning the crystal structure and composition, surface acidity, mixed level of each component, texture, and catalytic selectivity.     

Synthesis and characterization of the [Ru<Subscript>3</Subscript>O(CH<Subscript>3</Subscript>COO)<Subscript>6</Subscript>(py)<Subscript>2</Subscript>(BPE)Ru(bpy)<Subscript>2</Subscript>Cl](PF<Subscript>6</Subscript>)<Subscript>2</Subscript> dimer

The polymetallic [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl](PF₆)₂ complex (bpy = 2,2′-bipyridine, BPE = trans-1,2-bis(4-pyridil)ethylene and py = pyridine) was assembled by the combination of an electroactive [Ru₃O] moiety with a [Ru(bpy)₂(BPE)Cl] photoactive centre, and its structure was determined using positive ion electrospray (ESI-MS) and tandem mass (ESI-MS/MS) spectrometry. The [Ru₃O(CH₃COO)₆(py)₂(BPE)Ru(bpy)₂Cl]²⁺ doubly charged ion of m/z 732 was mass-selected and subject to 15 eV collision-induced dissociation, leading to a specific dissociation pattern, diagnostic of the complex structure. The electronic spectra display broad bands at 409, 491 and 692 nm ascribed to the [Ru(bpy)₂(BPE)] charge-transfer bands and to the [Ru₃O] internal cluster transitions. The cyclic voltammetry shows five reversible waves at −1.07 V, 0.13 V, 1.17 V, 2.91 V and −1.29 V (vs SHE) assigned to the [Ru₃O]^{−1/0/+1/+2/+3} and to the bpy^0/−1 redox processes; also a wave is observed at 0.96 V, assigned to the Ru^+2/+3 pair. Despite the conjugated BPE bridge, the electrochemical and spectroelectrochemical results indicate only a weak coupling through the π-system, and preliminary photophysical essays showed the compound decomposes under visible light irradiation.