نتایج جستجو برای: π electron delocalization

تعداد نتایج: 340883  

2009
Hakan Arslan Don VanDerveer İsmail Özdemir Nevin Gürbüz Yetkin Gök Bekir Çetinkaya

The asymmetric unit of the title compound, (C(13)H(15)N(2)S(2))[RuCl(3)(C(10)H(14))], contains a 1,3-(2-thienylmeth-yl)-4,5-dihydro-imidazolium cation and a trichlorido(η(6)-p-cymene)ruthenate(II) anion. The thio-phene rings of the cation are disordered by an 180° rotation about the thio-phene-CH(2) bonds with occupancies of 0.847 (5)/0.153 (5) and 0.700 (5)/0.300 (5), respectively. The Ru atom...

Journal: :Inorganic chemistry 2011
Philippe F Weck Alina P Sergeeva Eunja Kim Alexander I Boldyrev Kenneth R Czerwinski

Trinuclear transition-metal complexes such as Re(3)X(9) (X = Cl, Br, I), with their uniquely featured structure among metal halides, have posed intriguing questions related to multicenter electron delocalization for several decades. Here we report a comprehensive study of the technetium halide clusters [Tc(3)(μ-X)(3)X(6)](0/1-/2-) (X = F, Cl, Br, I), isomorphous with their rhenium congeners, pr...

Journal: :Chemistry 2014
Michaela K Jahn David A Dewald Montserrat Vallejo-López Emilio J Cocinero Alberto Lesarri Wenli Zou Dieter Cremer Jens-Uwe Grabow

The conformational landscape and ring-puckering properties of ε-caprolactone have been analyzed by using microwave spectroscopy and quantum chemical calculations. Two conformers were detected in a supersonic jet expansion, the most stable form being a chair containing the ester group in its rectangular flap. This conformation benefits from reduced CH2 bond eclipsing and angle strain, while π-el...

2016
Yongjun Li Zhiyu Jia Shengqiang Xiao Huibiao Liu Yuliang Li

Thermodynamic stabilization (π-electron delocalization through effective conjugation) and kinetic stabilization (blocking the most-reactive sites) are important considerations when designing stable polycyclic aromatic hydrocarbons displaying tunable optoelectronic properties. Here, we demonstrate an efficient method for preparing a series of stable two-dimensional (2D) twisted dibenzoterrylene-...

Journal: :Proceedings. Mathematical, physical, and engineering sciences 2014
Patrick W Fowler Christopher M Gibson David E Bean

Alternating partial hydrogenation of the interior region of a polycyclic aromatic hydrocarbon gives a finite model system representing systems on the pathway from graphene to the graphane modification of the graphene sheet. Calculations at the DFT and coupled Hartree-Fock levels confirm that sp2 cycles of bare carbon centres isolated by selective hydrogenation retain the essentially planar geom...

In this study, the adsorption of 4-hydroxy phenyl-azobenzene on the surface of (4, 0) zigzag open-end boron nitride nanotube (BNNT) has been investigated by quantum calculations. In order to find the preferred adsorption site, different positions and orientations were considered. The impacts of donor-acceptor electron delocalization on the structural and electronic properties and reactivity of ...

Ali Heydar Pakiari, Maryam Farrokhnia

The concept of Resonance Assisted Hydrogen Bond (RAHB), which usually occurs in b diketons, has a remarkable role in chemistry. These molecules, which contain heteroatom particularly O and N, are species with biological interest in protein folding and DNA pairing. Therefore, the amplification of hydrogen bonds strength by substituents may be important in life scie...

Journal: :Physical review letters 2010
K A Al-Hassanieh Yi-Feng Yang Ivar Martin C D Batista

We consider a periodic Anderson model (PAM) with a momentum-dependent interband hybridization that is strongly suppressed near the Fermi level. Under these conditions, we reduce the PAM to an effective low-energy Hamiltonian, H(eff), by expanding in the small parameter V0/t (V0 is the maximum interband hybridization amplitude and t is the hopping integral of the broadband). The resulting model ...

2008
B. I. Shklovskii

Statistics of many particle energy levels of a finite two-dimensional system of interacting electrons is numerically studied. It is shown that the statistics of these levels undergoes a Poisson to Wigner crossover as the strength of the disorder is decreased. This transition occurs at a similar strength of disorder as the one-electron delocalization crossover in a finite 2d system and develops ...

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