Controlled Dimerization and Bonding Scheme of Icosahedral M@Au 12 (M=Pd, Pt) Superatoms

2020 ◽  
Vol 133 (2) ◽  
pp. 655-659
Author(s):  
Emi Ito ◽  
Shinjiro Takano ◽  
Toshikazu Nakamura ◽  
Tatsuya Tsukuda
Keyword(s):  
Bonding Scheme

Formation of H -Addition Radicals in Adenine Derivatives

1976 ◽  
Vol 31 (5-6) ◽  
pp. 225-231 ◽  
Author(s):  
H. Zehner ◽  
W. Flossmann ◽  
E. Westhof
Keyword(s):  
Esr Spectroscopy ◽  
Coupling Constants ◽  
Molecular Orbital Calculations ◽  
X Rays ◽  
Hydrogen Atoms ◽  
Indo Calculations ◽  
Differential Stability ◽  
Purine Ring ◽  
Bonding Scheme ◽  
Adenine Derivatives

The formation of H-aduition radicals in monocrystals of 9-methyl adenine, deoxyadenosine monohydrate, and adenosine hydrochloride by irradiation with X-rays has been studied using ESR spectroscopy. In 9-methyl adenine and adenosine-HCl, hydrogen atoms add exclusively to position C8 of the imidazole part of the purine ring. On the other hand, in deoxyadenosine · H2O crystals, H-addition radicals at position C2 of the pyrimidine part of the purine ring occur together with H-addition radicals at position C8. Both radicals could be isolated by using their differential stability under warming or illumination with light. The C8-addition radical is characterized by two equivalent β-protons of 38.0 ± 0.5 G and the C2-addition radical by two non-equivalent β-protons of 34.0 ±1.0 and 50.0 ± 1.0 G. The nitrogen splittings perpendicular to the purine ring are 27.0 and 6.6 G for the C2-addition radical and 20.5 and 9.2 G for the C2-addition radical. The coupling constants of both radicals are in agreement with INDO calculations. It is further shown that the added hydrogen atom comes partly from the hydrogen bonding scheme and partly from the non­exchangeable hydrogens for the C8-addition radical. Together with additional experiments on polycrystalline samples, these results lead to the conclusion that hydrogen atoms add non-selectively to C2 and C8 of the neutral molecules, whereas protons add predominantly to C8 of anion radicals. This is supported by Hückel molecular orbital calculations.

The electronic properties of three popular high spin complexes [TM(acac)3, TM = Cr, Mn, and Fe] revisited: an experimental and theoretical study

2017 ◽  
Vol 19 (36) ◽  
pp. 24840-24854 ◽  
Author(s):  
S. Carlotto ◽  
L. Floreano ◽  
A. Cossaro ◽  
M. Dominguez ◽  
M. Rancan ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Structural Properties ◽  
High Spin ◽  
Spectroscopic Data ◽  
Theoretical Study ◽  
Combined Use ◽  
Electronic And Structural Properties ◽  
Bonding Scheme

The combined use of NEXAFS spectroscopic data and DFT results on TM(acac)3(TM = Cr, Mn, Fe) allowed us to look into the TM–ligand bonding scheme and to rationalize the peculiar electronic and structural properties of the title complexes.

Triple 1D1D superatomic bonding. Au22(dppo)6 as a Π4- and Δ2-triply bonded cluster based on Au11 assembled units

2020 ◽  
Vol 22 (3) ◽  
pp. 1422-1426 ◽  
Author(s):  
Alvaro Muñoz-Castro
Keyword(s):  
Valence Electron ◽  
Bonding Scheme

Our analysis reveals the Au22(dppo)6 cluster as a triple-bonded 22-valence electron (ve) supermolecule, featuring a bonding scheme based on 1D + 1D shell combinations, which largely contrasts with the developed bonding of [Au13]5+ core derivatives.

H-bonding scheme in allactite: a combined single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, FTIR and EPMA-WDS study

2016 ◽  
Vol 80 (5) ◽  
pp. 719-732 ◽  
Author(s):  
G. Diego Gatta ◽  
Ferdinando Bosi ◽  
Maria Teresa Fernandez Diaz ◽  
Ulf Hålenius
Keyword(s):  
Neutron Diffraction ◽  
Optical Absorption ◽  
Single Crystal ◽  
Absorption Spectroscopy ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Optical Absorption Spectroscopy ◽  
Hydroxyl Groups ◽  
X Ray ◽  
Bonding Scheme

AbsatractThe crystal chemistry of allactite from Långban, Värmland (Sweden) was investigated by single-crystal X-ray and neutron diffraction, optical absorption spectroscopy, Fourier-transform infra-red spectroscopy (FTIR) and electron microprobe analysis by wavelength-dispersive spectroscopy (EPMA-WDS). The optical spectra indicate the presence of Mn in valence state 2+ only. Assuming 16 O atoms per formula unit, arsenic as As5+and the (OH) content calculated by charge balance, the resulting formula based on the EPMA-WDS data is (Mn2+6.73Ca0.13Mg0.12Zn0.02)∑7.00(As5+)2.00O16H8, very close to the ideal composition Mn7(AsO4)2(OH)8. In the unpolarized FTIR spectrum of allactite, fundamental (OH)-stretching bands are observed at 3236, 3288, 3387, 3446, 3484, 3562 and 3570 cm–1, suggesting that a number of OH environments, with different hydrogen bond strengths, occur in the structure. The neutron structure refinement shows that four independent H sites occur in allactite with full site occupancy, all as members of hydroxyl groups. The complex hydrogen-bonding scheme in the allactite structure is now well defined, with at least nine hydrogen bonds energetically favourable with mono-, bi- and trifurcated configurations.

scholarly journals N-Heterocyclic carbenes on close-packed coinage metal surfaces: bis-carbene metal adatom bonding scheme of monolayer films on Au, Ag and Cu

2017 ◽  
Vol 8 (12) ◽  
pp. 8301-8308 ◽  
Author(s):  
Li Jiang ◽  
Bodong Zhang ◽  
Guillaume Médard ◽  
Ari Paavo Seitsonen ◽  
Felix Haag ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Metal Surfaces ◽  
Heterocyclic Carbenes ◽  
Solid Surfaces ◽  
Monolayer Films ◽  
Coinage Metal ◽  
Bonding Scheme ◽  
Group 11 Metals

N-Heterocyclic carbenes wet the solid surfaces of group 11 metals with energetically favourable electron donating biscarbene metal complexes.

Refinement of the layered titanosilicate AM-1 from single-crystal X-ray diffraction data

2007 ◽  
Vol 63 (11) ◽  
pp. i186-i186 ◽  
Author(s):  
Stanislav Ferdov ◽  
Uwe Kolitsch ◽  
Christian Lengauer ◽  
Ekkehart Tillmanns ◽  
Zhi Lin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time ◽  
Ir And Raman ◽  
Bonding Scheme

The structure of the layered noncentrosymmetric titanosilicate AM-1 (also known as JDF-L1, disodium titanium tetrasilicate dihydrate), Na4Ti2Si8O22·4H2O, grown as small single crystals without the use of organics, has been refined from single-crystal X-ray diffraction data. The H atom has been located for the first time, and the hydrogen-bonding scheme is also characterized by IR and Raman spectroscopy. All atoms are in general positions except for the Na, the Ti, one Ti-bound O, one Si-bound O and the water O atoms (site symmetries 2, 4, 4, 2 and 2, respectively).

Engineering the bonding scheme in C–S–H: The iono-covalent framework

2008 ◽  
Vol 38 (2) ◽  
pp. 159-174 ◽  
Author(s):  
R.J.-M. Pellenq ◽  
N. Lequeux ◽  
H. van Damme
Keyword(s):  
Bonding Scheme

The X-ray crystal structure of N-(1-octyl)-d-talonamide and a consideration of its hydrogen-bonding scheme

1993 ◽  
Vol 240 ◽  
pp. 47-56 ◽  
Author(s):  
Christoph André ◽  
Peter Luger ◽  
Sönke Svenson ◽  
Jürgen-Hinrich Fuhrhop
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
X Ray ◽  
Bonding Scheme
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