Dihalodicarbonylruthenium(II)-bis(tertiaryphosphine chalcogenide) complexes

Summary Reactions of 1,1-methylene bis(diphenylphosphine oxide or sulphide) (dpmO₂ or dpmS₂) and 1-(diphenylphosphinoethyl)-2-diphenylphosphine sulphide (dpePS) with dihalodicarbonylruthenium(II) in EtOH gave 1:1 (L:M) complexes of stoichiometry: Ru(CO)₂X₂L₂ (L = dpmO₂, dpmS₂ or dpePS; X = Cl or Br), which were characterized by elemental analysis and i.r. spectroscopy. The spectra reveal that: (a) the carbonyls occupy octahedral cis-positions, and (b) dpmS₂ shows a higher coordination shift than does dpePS, probably due to the better Lewis basicity of the Ph₂P moiety as compared to the Ph₂P(S) moiety in the ligands. Cis-octahedral geometries are inferred from these studies.     

Electrical transport properties of pristine and iodine doped polyetherimides

Electrical conduction behavior of pristine and iodine doped polyetherimides(PEI) has been investigated under both transient and steady state conditions in the operating temperature range 50-200℃at various electric fields of 12-60 kV/cm.The transient currents show the hyperbolic decay character,and the decay exponent p(a measure of current decay rate) decreases with temperature(7) and doping concentration.The origin of transient currents has been attributed to the dipolar nature of carbonyl((?)C=O) groups...     

Analysis of gas flow dynamics in hollow core photonic crystal fibre based gas cell

Gas flow dynamics in hollow core photonic crystal fibre (HC-PCF) is a trivial problem to study the gas filling time in HC-PCF gas sensor and other gas filled HC-PCF devices. This article analyzes the pressure dependence of gas diffusion coefficient in core and cladding holes of HC-PCF under the same condition of temperature and pressure during filling of methane and acetylene gas. An analytical model has been proposed to study the gas flow dynamics in core and cladding of HC-PCF. Due to gas filling, as the pressure varies inside the HC-PCF, at each increment of time, this model computes the change in pressure and respective gas diffusion coefficient. Using incremental gas diffusion coefficient, this model computes the gas filling time in a process similar to practical scenario. The gas filling time inside the core and cladding holes of HC-PCF for both methane and acetylene gas has been analyzed in this article. The results obtained can be utilized for HC-PCF based gas cell design.     

Synthesis and electrochemical studies of phenylazo substituted tetraaza macrocyclic complexes of Ni(II)

Synthesis and characterization of some phenyl azo substituted tetraaza macrocyclic complexes of Ni(II) are reported. Electrochemical behaviour of these macrocyclic complexes has been examined using polarographic, voltammetric and spectroscopic techniques. These studies show that both the ligand and the metal are electrochemically active. The electrochemical behaviour of the azo function has been shown to occur through a single four-electron process. When a nitro group is also present, the nitro function of the azo moiety is reduced in a six-electron cathodic wave.     

The Adomian decomposition method with Green’s function for solving nonlinear singular boundary value problems

In this paper, we present an efficient numerical algorithm for solving a general class of nonlinear singular boundary value problems. This present algorithm is based on the Adomian decomposition method (ADM) and Green’s function. The method depends on constructing Green’s function before establishing the recursive scheme. In contrast to the existing recursive schemes based on ADM, the proposed numerical algorithm avoids solving a sequence of transcendental equations for the undetermined coefficients. The approximate series solution is calculated in the form of series with easily computable components. Moreover, the convergence analysis and error estimation of the proposed method is given. Furthermore, the numerical examples are included to demonstrate the accuracy, applicability, and generality of the proposed scheme. The numerical results reveal that the proposed method is very effective.     

Numerical solution of singular boundary value problems using Green’s function and improved decomposition method

In this work, an effective technique for solving a class of singular two point boundary value problems is proposed. This technique is based on the Adomian decomposition method (ADM) and Green’s function. The technique relies on constructing Green’s function before establishing the recursive scheme for the solution components. In contrast to the existing recursive schemes based on ADM, the proposed recursive scheme avoids solving a sequence of nonlinear algebraic or transcendental equations for the undetermined coefficients. The approximate solution is obtained in the form of series with easily calculable components. For the completeness, the convergence and error analysis of the proposed scheme is supplemented. Moreover, the numerical examples are included to demonstrate the accuracy, applicability, and generality of the proposed scheme. The results reveal that the method is very effective, straightforward, and simple.     

The chemistry of pyridine thiols and related ligands,Part 6. The crystal and molecular structure of [1,3–bis(diphenylphosphino)-propane][bis(pyridine-2–thiolato)]ruthenium(II). A comparison with solution phase behaviour

Reaction of cis-RuCl2(dppp)2 with pyridine-2–thiol (HpyS) in the presence of Et3N in dry benzene replaces both the chloro groups and a diphosphine molecule to form Ru(dppp)(pyS)2 (1) [dppp=Ph2P(CH2)3PPh2], whose crystal and molecular structure has been determined with the help of single crystal X-ray crystallography. The discrete molecules of (1) adopt a distorted octahedral structure containing chelating pyridine-2–thiolato and dppp ligands with trans-S, cis-N and cis-P atom dispositions. The important interatomic parameters are: Ru-S, 2.443(2), 2.339(2); Ru-N, 2.133(5), 2.129(5); Ru-P, 2.274(2), 2.279(2)Å; trans-bond angles, S-Ru-S, 153.89(6); N-Ru-P, 172.76(13), 163.51(14)°; bite angles: P-Ru-P, 90.71(6); N-Ru-S, 67.18(14), 67.72(14)°. The n.m.r. spectra (1H, 13C, 31P) of (1) are also reported in order to compare solution phase behaviour with the solid state structure. The 13C-n.m.r. spectrum of the complex shows the presence of non-equivalent phenyls in the Ph2P-moiety.