Dinitrogen complexation and reduction at low-valent calcium

Science ◽  
2021 ◽  
Vol 371 (6534) ◽  
pp. 1125-1128
Author(s):  
B. Rösch ◽  
T. X. Gentner ◽  
J. Langer ◽  
C. Färber ◽  
J. Eyselein ◽  
...  
Keyword(s):  
Electron Donor ◽  
Low Valent ◽  
D Orbitals

Here we report that attempted preparation of low-valent CaI complexes in the form of LCa-CaL (where L is a bulky β-diketiminate ligand) under dinitrogen (N2) atmosphere led to isolation of LCa(N2)CaL, which was characterized crystallographically. The N22ˉ anion in this complex reacted in most cases as a very potent two-electron donor. Therefore, LCa(N2)CaL acts as a synthon for the low-valent CaI complex LCa-CaL, which was the target of our studies. The N22ˉ anion could also be protonated to diazene (N2H2) that disproportionated to hydrazine and N2. The role of Ca d orbitals for N2 activation is discussed.

Preponderant role of pentafluorophenyl moieties for tuning the electronic properties of extended benzodifuran-azomethine derivatives

2021 ◽  
Author(s):  
Chady Moussallem ◽  
Magali Allain ◽  
Frédéric Gohier ◽  
Pierre Frere
Keyword(s):  
Electronic Properties ◽  
Electron Donor ◽  
Electron Acceptor

From a central 3,7-bis(perfluorophenyl)-BDF unit, the extension performed with electron acceptor perfluorophenyl groups and/or electron donor N,N-dimethylamino groups via an imine link leads to symmetrical AAA and DAD or dissymmetrical...

Synthesis and properties of a new second-order NLO chromophore containing the benzo[b]furan moiety for electro-optical materials

RSC Advances ◽  
2014 ◽  
Vol 4 (63) ◽  
pp. 33312-33318 ◽  
Author(s):  
Maolin Zhang ◽  
Guowei Deng ◽  
Airui Zhang ◽  
Huajun Xu ◽  
Heyan Huang ◽  
...  
Keyword(s):  
Electron Donor ◽  
Optical Materials ◽  
Furan Ring ◽  
Second Order ◽  
Donor Group ◽  
Nlo Chromophores ◽  
Furan Moiety

We have designed and synthesized a new chromophore having a 1,1,7,7-tetramethyljulolidine fused furan ring as the electron donor group to systematically investigate the role of the benzo[b]furan ring in NLO chromophores.

scholarly journals Детерминизм локального атомного упорядочения в монослоях золота в формировании их электронной структуры

2022 ◽  
Vol 64 (3) ◽  
pp. 303
Author(s):  
В.Л. Карбовский ◽  
А.А. Романский ◽  
Л.И. Карбовская ◽  
В.В. Стонис
Keyword(s):  
Coordination Sphere ◽  
Electronic States ◽  
Mutual Arrangement ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
The Third ◽  
Long Range Interactions ◽  
Valence Bands ◽  
D Orbitals

The total and partial densities of electronic states of gold monolayer structures of different symmetry are calculated by the quantum mechanical calculations methods in the DFT approximation. It is shown that the first coordination sphere is determinant in the formation of the fine structure and the extent of the valence bands of the monolayer gold structures under study. The peaks splitting of the TDOS curve, which leads to its finer structure, is influenced not only by the lengths of interatomic bonds but also by the mutual arrangement of atoms. The influence of long-range interactions on the electronic structure of gold monolayers has been established. For example, for the (110) plane, a change in the atomic ordering in the third coordination sphere as a result of the introduction of a vacancy leads to noticeable changes in the TDOS curve, which indicates either a significant role of the atoms of the third coordination sphere or a significant redistribution of the interaction of d-orbitals of different symmetries of close neighbours. A correlation between the packing density, as well as the number of neighbours in the first coordination sphere, and the width of the energy band of gold monolayers has been established.

scholarly journals Potential forMethanosarcinato contribute to uranium reduction during acetate-promoted groundwater bioremediation

2017 ◽  
Author(s):  
Dawn E Holmes ◽  
Roberto Orelana ◽  
Ludovic Giloteaux ◽  
Li-Ying Wang ◽  
Pravin Shrestha ◽  
...  
Keyword(s):  
Field Experiment ◽  
Electron Donor ◽  
Enrichment Culture ◽  
Cell Suspensions ◽  
Contaminated Groundwater ◽  
Subunit A ◽  
Sedimentary Environments

AbstractPrevious studies ofin situbioremediation of uranium-contaminated groundwater with acetate injections have focused on the role ofGeobacterspecies in U(VI) reduction because of a lack of other abundant known U(VI)-reducing microorganisms. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field experiment demonstrated that acetoclastic methanogens from the genusMethanosarcinawere enriched after 40 days of acetate amendment. The increased abundance ofMethanosarcinacorresponded with an accumulation of methane in the groundwater. An enrichment culture dominated by aMethanosarcinaspecies with the sameMethanosarcina mcrAsequence that predominated in the field experiment could effectively convert acetate to methane. In order to determine whetherMethanosarcinaspecies could be participating in U(VI) reduction in the subsurface, cell suspensions ofM. barkeriwere incubated in the presence of U(VI) with acetate provided as the electron donor. U(VI) was reduced by metabolically activeM. barkericells, however, no U(VI) reduction was observed in inactive controls. These results demonstrate thatMethanosarcinaspecies could play an important role in the long-term bioremediation of uranium-contaminated aquifers after depletion of Fe(III) oxides limits the growth ofGeobacterspecies. The results also suggest thatMethanosarcinahave the potential to influence uranium geochemistry in a diversity of anaerobic sedimentary environments.

d Orbitals in the noble-gas dihalides

1970 ◽  
Vol 48 (17) ◽  
pp. 2695-2701 ◽  
Author(s):  
R. C. Catton ◽  
K. A. R. Mitchell
Keyword(s):  
Noble Gas ◽  
Valence Bond ◽  
Ionic Character ◽  
Orbital Exponent ◽  
Covalent Bonds ◽  
Model Calculations ◽  
Pair Bonds ◽  
Electron Repulsion Integrals ◽  
D Orbitals

Model calculations are reported for ArF2, KrF2, XeF2, ArCl2, KrCl2, and XeCl2. The approach is to compare the energies of a number of valence-bond structures for each molecule. The calculations use Slater-type radial functions and simplify the electron repulsion integrals with the Mulliken approximation. Energies are optimized by varying the d orbital exponent and a parameter which governs the ionic character of the covalent bonds. For all the molecules it is found that the structures such as (X—M+X− + X−M+—X) and X−M2+X−, which maintain the octet rule and exclude the use of d orbitals, are less stable than the structure X—M—X which implies localized electron-pair bonds based on pd hybrids at the noble-gas atom M.Approximate molecular wave functions are obtained from a configuration interaction calculation, and the general conclusion is that the valence-bond structures incorporating d orbitals become more important as the atomic number of the central atom increases. A preliminary study of the role of the [Formula: see text] orbital is also presented, but it seems this orbital contributes mainly as a polarization effect.

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