Bimetallic catalysis involving dipalladium(I) and diruthenium(I) complexes

Dipalladium(I) and diruthenium(I) compounds bridged by two [{(5,7-dimethyl-1,8-naphthyridin-2-yl)amino}carbonyl]ferrocene (L) ligands have been synthesized. The X-ray structures of [Pd(2)L(2)][BF(4)](2) (1) and [Ru(2)L(2)(CO)(4)][BF(4)](2) (2) reveal dinuclear structures with short metal-metal distances. In both of these structures, naphthyridine bridges the dimetal unit, and the site trans to the metal-metal bond is occupied by weakly coordinating oxygen from the amido fragment. The catalytic utilities of these bimetallic compounds are evaluated. Compound 1 is an excellent catalyst for phosphine-free, Suzuki cross-coupling reactions of aryl bromides with arylboronic acids and provides high yields in short reaction times. Compound 1 is also found to be catalytically active for aryl chlorides, although the corresponding yields are lower. A bimetallic mechanism is proposed, which involves the oxidative addition of aryl bromide across the Pd-Pd bond and the bimetallic reductive elimination of the product. Compound 1 is also an efficient catalyst for the Heck cross-coupling of aryl bromides with styrenes. The mechanism for aldehyde olefination with ethyl diazoacetate (EDA) and PPh(3), catalyzed by 2, has been fully elucidated. It is demonstrated that 2 catalyzes the formation of phosphorane utilizing EDA and PPh(3), which subsequently reacts with aldehyde to produce a new olefin and phosphine oxide. The efficacy of bimetallic complexes in catalytic organic transformations is illustrated in this work.     

About Influence of Gravity on Heat Conductivity Process of the Planets

In the present study it is shown that the interaction of a quasi-static gravitational wave through density fluctuations give rise to a heat conductivity coefficient and hence rise in temperature. This fact is a very important characteristics needed to establish a heat equilibrium process of such massive body as the Earth and other Planets. To carry out this exercise, general mechanism has been provided, which makes a bridge between classical physics and quantum theory. The specific dependence of heat conductivity coefficient in wide region has also been calculated.     

Palladium(0)-catalyzed rearrangement of allyl enol ethers to form chiral quaternary carbon centers via asymmetric allylic alkylation

Herein we report the first palladium(0)-catalyzed asymmetric allylic alkylation (AAA) of allyl enol ether via π-allylpalladium intermediate using Trost chiral diphosphine. This unprecedented reaction produced very rare α-aryl quaternary aldehydes with multi-functional groups. The main novelty in the chemistry demonstrates that enol ethers can be used as precursors for π-allylpalladium intermediates, an observation that is certainly rare and to the best of our knowledge, perhaps without prior precedent. Chiral ligand (R,R)-L3 was found to be optimal in this Pd-AAA reaction and provided good to excellent yield (80–95%) and enantioselectivity (70–90%) with a range of analogs.     

Possible existence of wormholes in the central regions of halos

An earlier study (Rahaman, et al., 2014 and Kuhfittig, 2014) has demonstrated the possible existence of wormholes in the outer regions of the galactic halo, based on the Navarro–Frenk–White (NFW) density profile. This paper uses the Universal Rotation Curve (URC) dark matter model to obtain analogous results for the central parts of the halo. This result is an important compliment to the earlier result, thereby confirming the possible existence of wormholes in most of the spiral galaxies.     

Magnetic transitions in Ni1−xMox and Ni1−xWx disordered alloys

We present a mean-field study of the magnetic phase diagram of Ni_1−xMo_x and Ni_1−xW_x alloys. The pair energies that enter the internal energy part of the free energy are obtained from a first-principles calculation. We try to understand why spin-glass phase is not observed in these alloys.     

S-wave scattering of fermion revisited

A model where a Dirac fermion is coupled to background dilaton field is considered to study s-wave scattering of fermion by a back ground dilaton black hole. It is found that an uncomfortable situation towards information loss scenario arises when one loop correction gets involved during bosonization.     

Synthesis and structural verification of the xylomannan antifreeze substance from the freeze-tolerant Alaskan beetle Upis ceramboides

Tetra-, hexa-, and octasaccharide subunits of the [→4)-β-D-Manp-(1→4)-β-D-Xylp-(1→](n) xylomannan motif proposed as the structure of a novel nonprotein, thermal hysteresis-producing antifreeze substance from the freeze-tolerant Alaskan beetle Upis ceramboides have been accessed by total chemical synthesis. Comparison of their NMR spectral data with data of the isolate lends strong support to the proposed structure. Synthetic tetrasaccharides representing various linkage isomers considered (α- rather than β-manno, and linkage through mannose O3 rather than O4) show more significant chemical shift differences with the isolate and are therefore excluded from further consideration.     

Test particle trajectories near cosmic strings

We present a detailed analysis of the motion of test particle in the gravitational field of cosmic strings in different situations using the Hamilton-Jacobi (H-J) formalism. We have discussed the trajectories near static cosmic string, cosmic string in Brans-Dicke theory and cosmic string in dilaton gravity.     

Chiral Thirring–Wess model

The vector type of interaction of the Thirring–Wess model was replaced by the chiral type and a new model was presented which was termed as chiral Thirring–Wess model in Rahaman (2015). The model was studied there with a Faddeevian class of regularization. Few ambiguity parameters were allowed there with the apprehension that unitarity might be threatened like the chiral generation of the Schwinger model. In the present work it has been shown that no counter term containing the regularization ambiguity is needed for this model to be physically sensible. So the chiral Thirring–Wess model is studied here without the presence of any ambiguity parameter and it has been found that the model not only remains exactly solvable but also does not lose the unitarity like the chiral generation of the Schwinger model. The phase space structure and the theoretical spectrum of this new model have been determined in the present scenario. The theoretical spectrum is found to contain a massive boson with ambiguity free mass and a massless boson.     

Solid‐State Regioselective Cyclization Initiated by the Electrophilic Attack on the Double Bond by N‐Bromosuccinimide on Montmorillonite K‐10 Clay Support under Microwave Irradiation

3‐Allyl‐4‐hydroxy‐coumarins and pyrones were regioselectively cyclized with N‐bromosuccinimide (NBS) on solid phase under microwave irradiation in excellent yield. NBS on montmorillonite K‐10 clay under microwave irradiation for expeditious solvent‐free regioselective cyclization has been used for the first time.