Molecular structure, natural bond analysis, vibrational, and electronic spectra of aspartateguanidoacetatenickel(II), [Ni(Asp)(GAA)]·H2O: DFT quantum mechanical calculations

2012 ◽  
Vol 97 ◽  
pp. 1041-1051 ◽  
Author(s):  
J.M. Ramos ◽  
M.T. de M. Cruz ◽  
A.C. Costa ◽  
G.F. Ondar ◽  
Glaucio B. Ferreira ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Electronic Spectra ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations

pKa-Werte von Ethidiumbromid und 7-Amino-9-phenyl-10- äthyl-phenanthridinium-bromid / pKa-Values of Ethidiumbromide and 7-Amino-9-phenyl-10-ethyl-phenanthridinium- bromide

1976 ◽  
Vol 31 (11-12) ◽  
pp. 656-660 ◽  
Author(s):  
Ingfried Zimmermann ◽  
Herbert Zimmermann
Keyword(s):  
Electronic Spectra ◽  
Water Solution ◽  
Ph Dependence ◽  
Quantum Mechanical ◽  
Amino Group ◽  
Quantum Mechanical Calculations ◽  
Acidic Water ◽  
Amino Groups ◽  
Electronic Density ◽  
Decreasing Ph

Abstract Ethidiumbromide (1) has two amino groups in 2-and 7-position which are protonated in acidic water solution. Both pKa-values of 1 are determined at 20 °C by means of the pH-dependence of the electronic spectra using a iterative calculating procedure, pKa1 = 0.713, pKa2 = 2.43. Acetylation of 1 and quantum mechanical calculations lead to the conclusion that the electronic density at the 7-amino group is greater than in 2-position. Therefore with decreasing pH preferably the 7-amino group is protonated (pKa2). followed by the protonation of the 2-amino group (pKa1). The pKa of 7-amino-9-phenyl-10-ethyl-phenanthridinium-bromide in water solution at 20 °C is determined to pKa= 1 .2 5 .

scholarly journals Report on the Real Structure of Benzene Molecules and the Thickness of Graphene

2021 ◽  
Author(s):  
Ning Wang ◽  
Dulun Wang
Keyword(s):  
Molecular Structure ◽  
Layer Structure ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Quantum Mechanical ◽  
Ultraviolet Spectroscopy ◽  
Quantum Mechanical Calculations ◽  
Covalent Bonds ◽  
Wide Range ◽  
Long Time

Abstract The problem of the benzene molecular structure has not been solved for a long time. This research proposes a new concept of covalent bonds based on the existing theory: each electron shared by the nucleus corresponds to a half-valent bond, and a half-valent bond can be formed between interval carbon atoms of the benzene ring. A new theory was established. Quantum mechanical calculations results can quantitatively explain experimental results, such as the hydrogenation heat and ultraviolet spectroscopy of benzene. It has solved more than one hundred years of difficult problems. The design of the new structural forms of benzene molecules shows half-valent bonds with dotted lines, which have a wide range of adaptability, and shows the structural forms and reaction formulas of more than dozens of benzene homologs and derivatives. Under the guidance of the new theory, the stacked three-dimensional structure of benzene was explored. The thickness of the three-layer benzene tube is calculated to be almost equal to the thickness of the graphene. Therefore, it is speculated that graphene may be a three layer structure.

Molecular structure of Hf(BH4)4 investigated by quantum mechanical calculations and gas-phase electron diffraction

2004 ◽  
pp. 967 ◽  
Author(s):  
Konstantin B. Borisenko ◽  
Anthony J. Downs ◽  
Heather E. Robertson ◽  
David W. H. Rankin ◽  
Christina Y. Tang
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Gas Phase Electron Diffraction

scholarly journals Are the program packages for molecular structure calculations really black boxes?

2007 ◽  
Vol 72 (12) ◽  
pp. 1329-1341
Author(s):  
Ana Mrakovic ◽  
Milica Drvendzija ◽  
Aleksandra Samolov ◽  
Milena Petkovic ◽  
Miljenko Peric
Keyword(s):  
Molecular Structure ◽  
Quantum Chemistry ◽  
Periodic Table ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Dissociation Energies ◽  
Black Boxes ◽  
Homonuclear Diatomic Molecules ◽  
Gaussian Program ◽  
Structure Calculations

In this communication it is shown that the widely held opinion that compact program packages for quantum-mechanical calculations of molecular structure can safely be used as black boxes is completely wrong. In order to illustrate this, the results of computations of equilibrium bond lengths, vibrational frequencies and dissociation energies for all homonuclear diatomic molecules involving the atoms from the first two rows of the Periodic Table, performed using the Gaussian program package are presented. It is demonstrated that the sensible use of the program requires a solid knowledge of quantum chemistry.

scholarly journals Substituent and structural effects on the kinetics of the reaction of N-(substituted phenylmethylene)-m- and -p-aminobenzoic acids with diazodiphenylmethane

2007 ◽  
Vol 72 (12) ◽  
pp. 1191-1200 ◽  
Author(s):  
Bratislav Jovanovic ◽  
Aleksandar Marinkovic ◽  
Zeljko Vitnik ◽  
Ivan Juranic
Keyword(s):  
Molecular Structure ◽  
Rate Constants ◽  
Experimental Results ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Structural Effects ◽  
Electronic Effects ◽  
Aminobenzoic Acids ◽  
Kinetics Of ◽  
Insight Into

The rate constants for the reaction of twenty-two N-(substituted phenylmethylene)- m- and -p-aminobenzoic acids with diazodiphenylmethane were determined in absolute ethanol at 30 ?C. The effects of substituents on the reactivity of the investigated compounds were interpreted by correlation of the rate constants with LFER equations. The results of quantum mechanical calculations of the molecular structure together with experimental results gave a better insight into the effects of structure on the transmission of electronic effects of the substituents. New ? constants for substituted benzylideneamino group were calculated.

The molecular structure of Mg(acac)2 determined by gas-phase electron diffraction and quantum mechanical calculations

2004 ◽  
Vol 701 (1-3) ◽  
pp. 1-8 ◽  
Author(s):  
Alexander V. Zakharov ◽  
Marwan Dakkouri ◽  
Alexander V. Krasnov ◽  
Georgiy V. Girichev ◽  
Irina G. Zaitzeva
Keyword(s):  
Molecular Structure ◽  
Electron Diffraction ◽  
Gas Phase ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Gas Phase Electron Diffraction

scholarly journals Real Structure of Benzene Molecule and the Thickness of Graphene

2021 ◽  
Author(s):  
Dulun Wang
Keyword(s):  
Molecular Structure ◽  
Chemical Reaction ◽  
Layer Structure ◽  
Covalent Bond ◽  
Benzene Molecule ◽  
Ultraviolet Spectrum ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Wide Range ◽  
Benzene Rings

Abstract The problem of benzene molecular structure has not been solved for more than 100 years. This research proposes a new concept of covalent bond based on the existing theory: each electron shared by multiple atom nuclei corresponds to a half-valent bond. The half-valent bond can be formed between the spacer carbon atoms of the benzene ring. In this way, a new theory was established. Quantum mechanical calculations can quantitatively explain experimental results, such as the hydrogenation heat and ultraviolet spectrum of benzene. Using the dotted line to indicate the half-valent bond, benzene molecular structural forms and chemical reaction formulas as will as its dozens of homologues and derivatives are designed easily. The method not only has a wide range of adaptability, but can also record the chemical reaction process. If several stacked benzene rings can form a benzene tube under the guidance of the new theory, calculated thickness of the three-layer benzene tube is very close to the thickness of graphene. Therefore, referring to other characteristics of graphene, it is considered to be more like a three-layer structure.

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