Conformational energy barriers in methyl acetate – Ethanol solutions: A temperature-dependent ultrasonic relaxation study and molecular orbital calculations

2020 ◽  
Vol 302 ◽  
pp. 112519 ◽  
Author(s):  
Georgios Stogiannidis ◽  
Stefanos Tsigoias ◽  
Angelos G. Kalampounias
Keyword(s):  
Molecular Orbital ◽  
Methyl Acetate ◽  
Conformational Energy ◽  
Molecular Orbital Calculations ◽  
Temperature Dependent ◽  
Energy Barriers ◽  
Relaxation Study ◽  
Ultrasonic Relaxation

Decomposition Mechanism of 1,2-Dioxetane

1974 ◽  
Vol 52 (23) ◽  
pp. 3837-3843 ◽  
Author(s):  
Gene Barnett
Keyword(s):  
Thermal Decomposition ◽  
Molecular Orbital ◽  
Equilibrium Structure ◽  
Decomposition Mechanism ◽  
Correlation Diagram ◽  
Molecular Orbital Calculations ◽  
Temperature Dependent ◽  
Planar Configuration ◽  
Orbital Correlation

An orbital correlation diagram was constructed for the thermal decomposition of 1,2-dioxetane into products that allow chemiluminescence. A decomposition mechanism is proposed that gives a temperature dependent rupture of the OO bond, thus allowing ring twisting which is followed by the rupture of the CC bond. This mechanism is consistent with results of the thermochemical analysis for this type of reaction. The equilibrium structure of 1,2-dioxetane was determined from the molecular orbital calculations and gave a planar configuration for the COOC ring.

Information from stereospecific spin–spin couplings about the relative absorptivities of the hydroxyl stretching bands in 2-iodophenol solutions

1981 ◽  
Vol 59 (21) ◽  
pp. 3021-3025 ◽  
Author(s):  
Ted Schaefer ◽  
Rudy Sebastian ◽  
Timothy A. Wildman
Keyword(s):  
Free Energy ◽  
Molecular Orbital ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Temperature Dependent ◽  
Hydroxyl Proton ◽  
Spin Coupling Constants ◽  
Cis And Trans ◽  
Spin Spin Coupling

The stereospecific spin–spin coupling constants between the hydroxyl proton and the ring protons for 2-iodophenol in various solvents yield some free energy differences between the cis and trans conformations of this molecule at 305 K. Comparison with areas of the hydroxyl stretching bands in the same or similar solvents shows that the ratio of the absorptivity coefficients for the two conformers is sensitive to solvent. It is suggested that this ratio is temperature dependent and therefore apparent enthalpy differences must be considered tentative for at least some solutions. Molecular orbital calculations are consistent with the arguments concerning the absorptivity coefficients.

scholarly journals Super-Exchange Interaction in a Chair-Piperazine Bridged Dicopper(II/II) Complex: Synthesis, Crystal Structure, Magnetic Properties and Molecular Orbital Calculations

2006 ◽  
Vol 61 (3) ◽  
pp. 237-242 ◽  
Author(s):  
C. T. Zeyrek ◽  
A. Elmali ◽  
Y. Elerman
Keyword(s):  
Molecular Orbital ◽  
Exchange Coupling ◽  
Binuclear Complex ◽  
Tridentate Ligand ◽  
Molecular Orbital Calculations ◽  
Inversion Symmetry ◽  
Coupling Constant ◽  
Temperature Dependent ◽  
Semi Empirical ◽  
Super Exchange Interaction

Abstract Reaction of the /i-bis(tridentate) ligand H3L' (L' = 1,3-bis[N-(5-cliloro-2-hydroxybenzylidene)- 2-ainiiioetliylene]-2-(5-cliloro-2-hydroxy!phenyl)iniidazoliduie) with eopper(II) chlonde diliydrate gives the chair-piperazine bridged complex [Cu2(μ-L)Cl2]. The halves of the binuclear complex are related by crystallographic inversion symmetry. The intramolecular Cu ・・・Cu separation is 6.954(3) Å. Temperature-dependent magnetic susceptibility measurements of the complex show a weak intramolecular antiferromagnetic eouphng. The super-exchange coupling constant (J) is - 10.5 cm-1. Semi-empirical extended Huckel molecular orbital (EHMO) calculations have been performed in order to gain msight into the molecular orbitals that participate in the super-exchange pathway.

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