Synthesis and Crystal Structure Determination of Dimeric Co(II) and Ni(II) with Pyridine 2,6-Dicarboxylic Acid

Abstract  

Two new dimeric complexes of Ni and Co with pyridine 2,6-dicarboxylic acid were synthesized, the structure of both these complexes were determined by single crystal X-ray crystallography and was characterized spectrally with the help of IR and UV spectrometers and the magnetic moments of both the reported complexes were recorded. Both of these complexes crystallize in the monoclinic space group P 2₁/c1. For the dimeric cobalt complex, formula C₁₄ H₂₁ Co₂ N₂ O₁₅; a = 8.3950(3) ?; α = 90°, b = 27.3702(8) ?; β = 98.211(2)°, c = 9.6235(3) ?; γ = 90° and Z = 3. For the dimeric Nickel complex, formula C₁₄ H₂₁ Ni₂ N₂ O₁₅, a = 8.330(10) A; α = 90°, b = 27.266(5) A; β = 98.61(10)^o, c = 9.653(10) A; γ = 90° and Z = 4. Both the dimeric complexes were observed to be hexa-coordinated with two different types of donor atoms (nitrogen and oxygen). Details of the synthesis, structures and spectroscopic properties have been discussed.     

Acetanilide palladacycle: an efficient catalyst for room‐temperature Suzuki–Miyaura cross‐coupling reaction

The catalytic activity of three acetanilide palladacycles derived from easily accessible and commercially available acetanilide derivatives, viz. N‐phenylacetamide ( L1 ), N‐(4‐chlorophenyl)acetamide ( L2 ) and N‐(4‐methylphenyl)acetamide ( L3 ) has been examined in Pd‐catalyzed Suzuki–Miyaura reaction of arylboronic acid with aryl bromides at room temperature. The complex 1L3 exhibited efficient activity in the Suzuki–Miyaura reaction (up to 99% isolated yield) under mild reaction conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

RF breakdown by toroidal helicons

Bounded whistlers are well-known for their efficient plasma production capabilities in thin cylindrical tubes. In this paper we shall present their radio frequency (RF) breakdown and discharge sustaining capabilities in toroidal systems. Pulsed RF power in the electronmagnetohydrodynamic (EMHD) frequency regime is fed to the neutral background medium. After the breakdown stage, discharge is sustained by toroidal bounded whistlers. In these pulsed experiments the behaviour of the time evolution of the discharge could be studied in four distinct phases of RF breakdown, steady state attainment, decay and afterglow. In the steady state average electron density of ≈10¹² per cc and average electron temperature of ≈20 eV are obtained at 10⁻³ mbar of argon filling pressure. Experimental results on toroidal mode structure, background effects and time evolution of the electron distribution function will be presented and their implications in understanding the breakdown mechanism are discussed.     

Effect of radio frequency field on toroidal plasma parameters

Low temperature plasma parameters in a toroidal magnetic field are measured. The effect of an externally applied perpendicular electric field on the plasma parameters is studied. The lifetime of the plasma is measured in the presence and absence of the RF electric field. Decrease in the plasma lifetime in the presence of RF field is attributed to detrapping of the primary electrons to a larger volume. Plasma lifetime increases when a small vertical magnetic field is added to the toroidal magnetic field.     

Tetrakis(μ‐benzoato‐κ2O:O)bis{[4‐(dimethylamino)pyridine‐κN1]copper(II)}

The title compound, [Cu₂(C₇H₅O₂)₄(C₇H₁₀N₂)₂], is a crystallographically centrosymmetric binuclear complex, with Cu atoms [Cu...Cu = 2.6982 (4) Å] bridged by four benzoate ligands. Each of the Cu atoms in this bunuclear copper(II) acetate hydrate analogue is present in an approximately square‐pyramidal environment, with four O atoms in a plane and the pyridine N atom at the apical site. Selected geometric parameters are compared with values for related tetrabenzoate complexes of copper(II).     

Coordination compounds of imidazoles with rhodium halides

Summary Compounds of the types [RhL₆](BF₄)₃, [RhL₅X](BF₄)₂ (L=1-methylimidazole), [RhL₄X₂]X (L=1-methylimidazole, 1-nbutylimidazole, 1-vinylimidazole, 1-vinyl-2-methylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-ethyl-4(5)-methylimidazole; X=Cl or Br) and [RhL₄X₂]BF₄ (L = 1-n-butylimidazole, 1-vinylimidazole, 1-vinyl-2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole and 1,2-dimethylimidazole) have been prepared and characterized by conductivity measurements, i.r. and¹H n.m.r. spectral studies. Analytical data agree with the monodentate nature of the ligands while a strongv(Rh-X) frequency reveals that the halogens aretrans to each other. The compounds also reveal d-d transition bands atca. 24000–22000 cm^–1 in the visible region.     

Modular relations for the nonic analogues of the Rogers-Ramanujan functions with applications to partitions

We define the nonic Rogers-Ramanujan-type functions D(q), E(q) and F(q) and establish several modular relations involving these functions, which are analogous to Ramanujan's well known forty identities for the Rogers-Ramanujan functions. We also extract partition theoretic results from some of these relations.     

Synthesis of substituted 1,2,4‐oxadiazoles from substituted acid chlorides and amidoximes under mild conditions

Substituted amidoximes have been synthesized, isolated and converted into substituted oxadiazoles as a novel heterocyclic compounds under mild conditions in good to excellent yield.     

PLS-DA - Docking Optimized Combined Energetic Terms (PLSDA-DOCET) protocol: a brief evaluation

Docking studies have become popular approaches in drug design, where the binding energy of the ligand in the active site of the protein is estimated by a scoring function. Many promising techniques were developed to enhance the performance of scoring functions including the fusion of multiple scoring functions outcomes into a so-called consensus scoring function. Hereby, we evaluated the target oriented consensus technique using the energetic terms of several scoring functions. The approach was denoted PLSDA-DOCET. Optimization strategies for consensus energetic terms and scoring functions based on ROC metric were compared to classical rigid docking and to ligand-based similarity search methods comprising 2D fingerprints and ROCS. The ROCS results indicate large performance variations depending on the biological target. The AUC-based strategy of PLSDA-DOCET outperformed the other docking approaches regarding simple retrieval and scaffold-hopping. The superior performance of PLSDA-DOCET protocol relative to single and combined scoring functions was validated on an external test set. We found a relative low mean correlation of the ranks of the chemotypes retrieved by the PLSDA-DOCET protocol and all the other methods employed here.