Synthetic Utility of Stable Phosphanylcarbenes: Synthesis and Crystal Structure of an α‐(Lithiomethylene)phosphorane

The first crystallographically characterized phosphonium yldiide 2 was obtained in a simple reaction by addition of n‐butyllithium to the stable phosphanyl(silyl)carbene 1 . R=cHex₂N.     

Selective metal sensor phthalocyanines bearing non-peripheral functionalities: Synthesis,spectroscopy, electrochemistry and spectroelectrochemistry

A novel alcohol-soluble ionophore ligand and its non-peripherally tetrasubstituted functional 1,8,15,22-tetrakis(6-hydroxyhexylsulfanyl) metallophthalocyanines M[Pc(α-SC₆H₁₂OH)₄] (M = Cu(II), Zn(II), Co(II); Pc = phthalocyanine) are reported. The aggregation and cation binding behaviors of the phthalocyanine compounds in the presence of soft Ag^I and Pd^II metal ions were investigated by using UV–Vis spectroscopy. The new compounds have been characterized by elemental analysis, IR, ¹H, ¹³C NMR, UV/Vis spectroscopy, ESI and MALDI–TOF–MS mass spectra. Voltammetric and in-situ spectroelectrochemical studies show that while copper and zinc phthalocyanine complexes give well-defined ring-based reduction and oxidation processes, the cobalt phthalocyanine gives both metal-based and ring-based redox processes which have reversible and diffusion controlled character.     

Rate constant for the reaction C2H5 + HBr → C2H6 + Br

RRKM theory has been employed to analyze the kinetics of the title reaction, in particular, the once-controversial negative activation energy. Stationary points along the reaction coordinate were characterized with coupled cluster theory combined with basis set extrapolation to the complete basis set limit. A shallow minimum, bound by 9.7 kJ?mol(-1) relative to C(2)H(5) + HBr, was located, with a very small energy barrier to dissociation to Br + C(2)H(6). The transition state is tight compared to the adduct. The influence of vibrational anharmonicity on the kinetics and thermochemistry of the title reaction were explored quantitatively. With adjustment of the adduct binding energy by ～4 kJ?mol(-1), the computed rate constants may be brought into agreement with most experimental data in the literature, including new room-temperature results described here. There are indications that at temperatures above those studied experimentally, the activation energy may switch from negative to positive.     

Adsorption of the guanine molecule over the pristine,Nb-, and Au-doped boron nitride nanosheets: a DFT study

Structural Chemistry - A theoretical study has been conducted onto the pristine, Nb-, and Au-doped boron nitride (BN) nanosheets using DFT calculations with the B3LYP-D3 method in order to evaluate...     

ChemInform Abstract: Exploring the Optoelectronic Structure and Thermoelectricity of Recent Photoconductive Chalcogenides Compounds,CsCdInQ3 (Q: Se,Te).

CsCdInQ₃ (Q: Se, Te), potential materials for hard Xray and γ‐ray detection, are investigated by a DFT‐based full potential linearized augmented plane wave method.     

Global attractor for the regularized Bénard problem

In this paper, we study the asymptotic behaviour of weak solutions for the regularized Bénard problem. We establish the global existence and uniqueness of weak solutions of this problem and give a proof for the existence of global attractor in the three-dimensional case for this system.     

Synthesis, H- or J-type aggregations,electrochemistry and in situ spectroelectrochemistry of metal ion sensing lead(II) phthalocyanines

We report, in this study, peripherally 3- and 4-substituted functionalized ionophore ligands (1–3) and their α- and β-tetra polyalcohol substituted lead(II) phthalocyanines M{Pc[S–CH(C₃H₇)(C₂H₅OH)]₄} (7, 9 and 11) and M{Pc[S–C₆H₁₂(OH)]₄} (8, 10 and 12) which are a mixture of different isomers. The complexes have been fully characterized by elemental analysis, FT-IR, ¹H NMR, ¹³C NMR, MS (MALDI-TOF) and UV–Vis spectral data. These complexes induced H-type (face-to-face fashion) or J-aggregate (edge-to-edge) dimers when titrated with AgNO₃ or Na₂PdCl₄ in a THF–MeOH solution. Cyclic and square wave voltammetry studies showed that the complexes gave three one-electron ligand-based reductions and two one-electron oxidation couples having diffusion controlled mass transfer character. Assignments of these redox couples were confirmed by spectroelectrochemical measurements. The observation of split Q bands, which are characteristic spectral behavior of metal-free phthalocyanines, indicates demetallization of the complexes during the spectroelectrochemical measurement under the applied potentials. The types of the substituents on the ring of the phthalocyanines affect the demetallization process of the complexes.     

Reaction kinetics of the addition of atomic sulfur to nitric oxide

The reaction of S((3)P(J)) with NO ((2)Pi) in an Ar bath gas has been studied by the laser photolysis-resonance fluorescence technique over 300-810 K at pressures from 60 to 800 mbar. The observed second-order rate constants are close to the low-pressure limit. Fitting of Troe's formalism to experiment, with an estimated F(cent) = 0.78 exp(-T/7445) and k(infinity) given subsequently, yields k(0) = (6.2+/-0.6) x 10(-33) exp(+ (940+/-40)/T) cm(6) molecule(-2) s(-1). Error limits are +/-25%. A theoretical analysis of this value suggests that the average energy transferred during collisions between Ar and the excited intermediate is DeltaE = -360(-160) (+90) cm(-1). Over 300-800 K, the high-pressure limit is predicted to be k(infinity) = 2.2 x 10(-10) (T/300)(0.24) cm(3) molecule(-1) s(-1). Doublet and quartet adducts between S and NO were characterized via CBS-QB3 theory. The kinetic data can be rationalized with SNO ((2)A(')) as the major product, and an ab initio estimate of Delta(f)H(298) for SNO is 176+/-8 kJ mol(-1).