Approximate transferability in alkanenitriles

Abstract

The atomic and bond properties of a series of alkanenitriles were calculated in order to analyze the transferability of the CN, methyl, and methylene groups. The calculations were carried out using the atoms in molecules (AIM) theory on RHF/6-31++G * * //RHF/6-31G * * wave functions obtained for compounds CN-R (R ranging from H to C 11 H 23 ). Linear correlations between L( ) and N( ) were used to establish N(CH 2 ) and N(CH 3 ) nearly transferable values. Average values and maximum differences to the mean value of several properties were used for classifying the CN group. It shows a transferable behavior along the CN-R series for R > Et. The methyl group presents specific properties when R < Pr. The methylene groups can be classified considering both their position with respect to the end of the chain and the position with respect to the CN group. The atomic energy displays a dependence on the molecular size. Although this behavior does not allow to consider this property as transferable, both the ab initio total electronic molecular energies and the experimental heats of formation can be fitted, by linear regression analysis, as a function of the number of methylene groups.

Role of functional groups in linear regression analysis of molecular properties

“…as demonstrated by the group of Mosquera. [14][15][16][17][18][19][20] The intercept E (XCH 2 | CH 3 ) may be equated to the sum of E (CH 3 |) from the n-alkane series and E (FCH 2 |) from its energy in CH 2 F | CH 2 F since, as pointed out above, E(CH 2 F | CH 3 ) equals their sum. The excellent linear correlation coefficients obtained by N&H apply equally to the fittings obtained from Eqn (3) for the same homologous series.…”

Toward universal substituent constants: Transferability of group descriptors from the quantum theory of atoms in molecules

“…When using QTAIM atomic energies to examine transferability, one should omit the scaling factor for the energy, or use the self‐consistent virial scaling 30 . The transferability of atomic and group properties in alkanes, 27 alkanols, 31,32 fluoroalkanes, 33 cyanoalkanes, 34,35 ethers, 36,37 aldehydes, and ketones, 38,39 was considered by Mosquera's group. Transferability in DNA base‐pairing has also been studied through QTAIM analysis of the total virial field 40 .…”

Toward anab initiofragment database for bioisosterism: Dependence of QCT properties on level of theory, conformation, and chemical environment

“…Breneman and coworkers25, 26 developed a database of “transferable atom equivalents” with associated QCT properties. A systematic series of QCT studies was also carried out on the transferability of the carbonyl group27 and alkyl chains28 in aldehydes and ketones, oxygen atoms in linear ethers,29 and on the approximate transferability in alkanenitriles30 and alkanols 31. This research group also studied the effects of electron correlation and conformational changes on the distortion of the charge distribution in alkyl chains,32 again using QCT.…”