Constructing Homodesmic Reactions for Calculating the Enthalpies of Formation of Organic Compounds

Interplay of the Ring and Steric Strains in the Highly Substituted Cyclopropanes

“…It was previously shown that the heat effect of an ideal HDR is close to zero because all energy effects are mutually compensated in its reactants and products, i.e., thermal balance is added to the above-mentioned balances. In this case, the structures under study become undemanding to the level of quantum–chemical calculations . In contrast, investigation of the molecular energetics of strained cycles requires highly accurate DFT or ab initio methods as the heat effects of HDR are large.…”

“…In this case, the structures under study become undemanding to the level of quantum−chemical calculations. 14 In contrast, investigation of the molecular energetics of strained cycles requires highly accurate DFT or ab initio methods as the heat effects of HDR are large. In the recent work, 13 71 cyclic compounds were tested and it was shown that composite methods G3 and G4 lead to similar results, which are in good agreement with the most reliable empirical and theoretical estimates of the cycle strain energies of the test compounds.…”

“…The molecular energetics of the substituted cyclopropanes was investigated using our original methodology based on the construction of the complete set of homodesmotic reactions for the compounds under study. The complete set of HDRs was constructed within the framework of the graph theory approach described in ref .…”

A molecular electron density theory study of Diels‐Alder reaction between Danishefsky's diene and (2E)‐3‐phenyl‐2‐(trifluoromethyl) acrylonitrile

“…Due to superiority of the Minnesota M06-2X hybrid metadensity functional over other density functional hybrids such as B3LYP functional, the M06-2X exchangecorrelation functional conjuncted with the standard 6-31G(d,p) basis set was used to perform the DFT calculations for investigating on main-group thermochemistry, thermochemical kinetics, and noncovalent interactions of the DA reaction. [27][28][29][30][31][32][33] Berny analytical gradient optimization method was applied to accomplish optimization calculations, and the nature of the optimized stationary points was characterized by frequency calculations at the same computational level. [34] In this sense, all reactants and CA products have no any imaginary frequency, while TSs display only one imaginary frequency, such that atomic movements along this imaginary frequency be able to appropriately portray formation of CA from separate reactants.…”

“…Due to superiority of the Minnesota M06‐2X hybrid meta‐density functional over other density functional hybrids such as B3LYP functional , the M06‐2X exchange‐correlation functional conjuncted with the standard 6‐31G(d,p) basis set was used to perform the DFT calculations for investigating on main‐group thermochemistry, thermochemical kinetics, and noncovalent interactions of the DA reaction . Berny analytical gradient optimization method was applied to accomplish optimization calculations, and the nature of the optimized stationary points was characterized by frequency calculations at the same computational level .…”