نتایج جستجو برای: transition metal atoms

تعداد نتایج: 486890  

2006
M. A. Laguna-Marco J. Chaboy C. Piquer H. Maruyama N. Ishimatsu

We report on a transition metal contribution to the rare-earth L2-edge XMCD spectrum of intermetallic rareearth transition metal compounds (R-T). The shape and location of this contribution is independent on both the specific rare-earth and the specific 3d metal in the compound. The evolution of the signal with the 3d content indicates that the signal is proportional to the number of T neighbor...

2016
Congqing Zhu Caixia Yang Yongheng Wang Gan Lin Yuhui Yang Xiaoyong Wang Jun Zhu Xiaoyuan Chen Xin Lu Gang Liu Haiping Xia

The coordinating atoms in polydentate chelates are primarily heteroatoms. We present the first examples of pentadentate chelates with all binding atoms of the chelating agent being carbon atoms, denoted as CCCCC chelates. Having up to five metal-carbon bonds in the equatorial plane has not been previously observed in transition metal chemistry. Density functional theory calculations showed that...

Journal: :polyolefins journal 1999
giovanni ricci giuseppe leone

the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

Herein, a theoretical study on the stability of some vic-dioxime complexes of Ni(II), Pd(II) and Pt(II) in gas and aqueous phases is reported. The DFT/M06/SDD and DFT/M06/6-31G+(d,p) levels of theory were adopted for the metal ions and for every other element respectively. Structural analyses of investigated complexes have revealed square planar geometries stabilized by two O–H⋯Cl hydrogen bond...

2017
Swayamprabha Behera

STABILITY AND SPECTROSCOPIC PROPERTIES OF NEGATIVE IONS By Swayamprabha Behera, M.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, at Virginia Commonwealth University Virginia Commonwealth University, 2011. Major Director: Dr. Purusottam Jena, Distinguished Professor, Department of Physics Negative ions play an important role in chemistry as ...

Journal: :The journal of physical chemistry. A 2005
Kevin D Nielson Adri C T van Duin Jonas Oxgaard Wei-Qiao Deng William A Goddard

With the aim of developing a computationally inexpensive method for modeling the high-temperature reaction dynamics of transition metal catalyzed reactions we have developed a ReaxFF reactive force field in which the parameters are fitted to a substantial quantum mechanics (QM) training set, containing full reaction pathways for relevant reactions. In this paper we apply this approach to reacti...

2002
Donald J. Siegel Louis G. Hector James B. Adams

We have performed density functional calculations to investigate the adhesion and electronic structure at interfaces between Al and the refractory transition metal nitrides/carbides VN and VC in order to understand the significance of the ceramic’s metalloid component upon interfacial properties. We find that for both systems the preferred bonding site places the metal interfacial atoms above t...

2016
Bennett J. Eleazer Mark D. Smith Alexey A. Popov Dmitry V. Peryshkov

The first example of a transition metal (BB)-carboryne complex containing two boron atoms of the icosahedral cage connected to a single exohedral metal center (POBBOP)Ru(CO)2 (POBBOP = 1,7-OP(i-Pr)2-2,6-dehydro-m-carborane) was synthesized by double B-H activation within the strained m-carboranyl pincer framework. Theoretical calculations revealed that the unique three-membered (BB)>Ru metalacy...

Journal: :Journal of computational chemistry 2003
Mikhail B. Darkhovskii Igor V. Pletnev Andreì L. Tchougréeff

A computational method targeted to Werner-type complexes is developed on the basis of quantum mechanical effective Hamiltonian crystal field (EHCF) methodology (previously proposed for describing electronic structure of transition metal complexes) combined with the Gillespie-Kepert version of molecular mechanics (MM). It is a special version of the hybrid quantum/MM approach. The MM part is res...

2014
Hao Hu Zhengfei Wang Feng Liu

Two-dimensional (2D) hexagonal organometallic framework (HOMF) made of triphenyl-metal molecules bridged by metal atoms has been recently shown to exhibit exotic electronic properties, such as half-metallic and topological insulating states. Here, using first-principles calculations, we investigate systematically the structural, electronic, and magnetic properties of such HOMFs containing 3d tr...

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