scholarly journals Theoretical Study of the Electronic Effects in the Intramolecular Ketene-Styrene [2+2] Cycloaddition

2019 ◽  
Vol 54 (4) ◽  
Author(s):  
Manuel Fernando Rubio ◽  
Federico Jiménez-Cruz ◽  
Guillermo Ramírez-Galicia
Keyword(s):  
Transition State ◽  
Theoretical Study ◽  
Positive Charge ◽  
Ring Structure ◽  
Experimental Results ◽  
Electronic Effects ◽  
Hartree Fock ◽  
Reaction Constant ◽  
Remote Substituent

DFT (B3LYP/6-31+G*) and post-Hartree-Fock (MP2/6-31+G*//B3LYP/6-31G*) calculations were carried out in order to explain the effect of a remote substituent in the intramolecular ketene-styrene [2+2] cycloaddition of p-substituted 2-methyl-7-arylhepta- 1,6-dien-1-one which produces the bicycle[3.1.1] or the bicycle [3.2.0] heptanones according to Bèlanger experimental results. The transition state geometries were found as an asynchronous process with a three-member ring structure and an incipient positive charge development. Kinetic and thermodynamic controls were proposed at B3LYP/6-31+G* to determine which product is most likely to form in a competence reaction. In addition, the value of the ρ experimental reaction constant was reproduced, ρ ~ -1.34.

scholarly journals A Theoretical Study of the Conformational Changes in Hydrazine

1974 ◽  
Vol 52 (15) ◽  
pp. 2785-2791 ◽  
Author(s):  
John O. Jarvie ◽  
Arvi Rauk
Keyword(s):  
Dihedral Angle ◽  
Conformational Changes ◽  
Theoretical Study ◽  
Potential Surface ◽  
Experimental Results ◽  
Hartree Fock ◽  
Pyramidal Inversion ◽  
Bond Functions ◽  
Torsional Component ◽  
Substituted Hydrazines

Abinitio restricted Hartree–Fock–Roothaan l.c.a.o.–m.o.–s.c.f. calculations using a Gaussian lobe basis with bond functions have been performed to determine the characteristics of the potential surface for nuclear motions in hydrazine. It was found that in its equilibrium conformation the molecule has a dihedral angle of 95°. The barrier to pyramidal inversion at one nitrogen is 6.1 kcal/mol and the syn and anti rotational barriers are calculated to be 12.0 and 1.6 kcal/mol, respectively. There is a very slight torsional component in the inversion pathway. During rotation over the anti barrier the bond angles contract from their average equilibrium value of 109.5° to 105.3°. This contraction appears to be an important feature of the rotational potential curve. Features of the surface are used to rationalize experimental results in cyclic and acyclic substituted hydrazines.

scholarly journals Ag2O versus Cu2O in the Catalytic Isomerization of Coordinated Diaminocarbenes to Formamidines: A Theoretical Study

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 491
Author(s):  
Juan F. Van der Maelen ◽  
Javier Ruiz
Keyword(s):  
Reaction Mechanism ◽  
Nitrogen Atom ◽  
Carbon Atom ◽  
Transition State ◽  
Theoretical Study ◽  
Theoretical Calculations ◽  
Experimental Results ◽  
Similar Reaction ◽  
Isomerization Process ◽  
Catalytic Isomerization

DFT theoretical calculations for the Ag2O-induced isomerization process of diaminocarbenes to formamidines, coordinated to Mn(I), have been carried out. The reaction mechanism found involves metalation of an N-H residue of the carbene ligand by the catalyst Ag2O and the formation of a key transition state showing a μ-η2:η2 coordination of the formamidinyl ligand between manganese and silver, which allows a translocation process of Mn(I) and silver(I) ions between the carbene carbon atom and the nitrogen atom, before the formation of the formamidine ligand is completed. Calculations carried out using Cu2O as a catalyst instead of Ag2O show a similar reaction mechanism that is thermodynamically possible, but highly unfavorable kinetically and very unlikely to be observed, which fully agrees with experimental results.

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