نتایج جستجو برای: alkaline earth metals

تعداد نتایج: 193458  

Journal: :Dalton Transactions 2021

The phosphido-bis(borane) complexes 2–4 crystallise with remarkably similar structures, in spite of the progressively increasing ionic radii metal centres.

Journal: :Organic letters 2002
Daniel Collado Ezequiel Perez-Inestrosa Rafael Suau Jean-Pierre Desvergne Henri Bouas-Laurent

[structure: see text] A new type of donor-spacer-acceptor podand system has been synthesized and proved as an efficient dual channel fluorosensor for Li+, Mg2+, and Ca2+. The known ability for the N-oxide function to bind Lewis acids is the key step in the appearance of a new emitting charge-transfer (CT) excited state. The occurrence of this CT state for alkaline earth (Mg2+ and Ca2+) and not ...

Amir Hossein Hakimyoun Hadi Bharifar Mohammad Ail Zarinfard Reza Ghiasi Simzar Hosseinzade

The structural and electronic properties of C24-2nBn Nn and M@ C24-2nBn Nn (M= alkaline and earth alkaline metals; n=3 and 6) molecules are studied using the Density Functional Theory (DFT). It was found that the most interaction is in M@ C24-2nBn Nn complexes (M=Be, Mg; n=3 and 6). The negative nucleus-independent chemical shifts confirm that C24-2nBn Nn (n=3 and 6) cages exhibit aromatic char...

2014
Gavin M. Mudd Mohan Yellishetty Barbara K. Reck T. E. Graedel

The long-term availability of mineral resources is crucial in underpinning human society, technology, and economic activity, and in managing anthropogenic environmental impacts. This is increasingly true for metals that do not generally form the primary product of mines (“host” metals), such as copper or iron, but are recovered as by-products (or sometimes co-products during the processing of p...

Journal: :Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2010
Arndt Simon

Solid-state chemistry of cluster compounds with metals in the left part of the periodic table is described. As a function of the metal valence electron concentration (VEC), characteristic changes occur with stepwise changing features. Strongly metal-metal-bonded and ligand-encapsulated clusters exist for large values of VEC. At decreased values, endohedral atoms stabilize the clusters, and with...

Journal: :Dalton transactions 2012
Tao Yang Xiang Zhao Qian Xu Hong Zheng Wei-Wei Wang Sheng-Tao Li

By means of density functional theory and statistical mechanics, we investigate the geometric and electronic structures, thermodynamic stability and infrared (IR) vibrational frequencies of alkaline earth metal endohedral fullerenes, M@C(76) (M = Ca, Sr, and Ba). The results reveal that M@C(1)(17,459)-C(76) possesses the lowest energy followed by M@C(2v)(19,138)-C(76) with a very small energy d...

Journal: :The Journal of chemical physics 2011
Wirawan Purwanto Henry Krakauer Yudistira Virgus Shiwei Zhang

Weak H(2) physisorption energies present a significant challenge to even the best correlated theoretical many-body methods. We use the phaseless auxiliary-field quantum Monte Carlo method to accurately predict the binding energy of Ca(+)-4H(2). Attention has recently focused on this model chemistry to test the reliability of electronic structure methods for H(2) binding on dispersed alkaline ea...

Journal: :Chemical communications 2014
Kirsten Reuter Carsten von Hänisch

The synthesis of the thermally stable bicyclic diphosphasilirane O(SiiPr2P)2SiiPr2 (4) was achieved via oxidation of the alkaline earth metal substituted cyclic diphosphanide 3 with 1,2-dibromoethane. Nonetheless, during extended storage at low temperature, impurity induced rearrangement in favour of the dimeric species [O(SiiPr2P)2SiiPr2]2 (5) is observed.

Journal: :Environmental science & technology 2011
Travis S Schmidt William H Clements Robert E Zuellig Katharine A Mitchell Stanley E Church Richard B Wanty Carma A San Juan Monique Adams Paul J Lamothe

Whole body Zn concentrations in individuals (n = 825) from three aquatic insect taxa (mayflies Rhithrogena spp. and Drunella spp. and the caddisfly Arctopsyche grandis) were used to predict effects on populations and communities (n = 149 samples). Both mayflies accumulated significantly more Zn than the caddisfly. The presence/absence of Drunella spp. most reliably distinguished sites with low ...

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