TY - JOUR

T1 - Inherent and transferable stabilization energies of carbon- and heteroatom-centred radicals on the same relative scale and their applications

AU - Coote, Michelle L.

AU - Lin, Ching Yeh

AU - Zavitsas, Andreas A.

PY - 2014

Y1 - 2014

N2 - Accurate G3(MP2)-RAD calculations are used to predict 264 R-H, R-CH 3, R-Cl and R-R bond dissociation energies for a wide-ranging test set of carbon and non-carbon centred R• radicals. The data are used to calculate a set of inherent and transferrable radical stabilization energies, denoted RSEEt, which ranks the inherent stability of the 66 radicals studied on the same relative scale, irrespective of the nature of the radical centre. The Pauling electronegativity parameter for each radical is also calculated from the same data, along with the radical's inherent bonding ability D[R-R]calc. This latter quantity is defined as the R-R bond dissociation energy expected in the absence of direct steric or resonance interactions that are present in R-R but absent in R-CH3 and R-Cl. We show that the differences between D[R-R] and D[R-R]calc are typically very small except when R is sterically bulky, or there is a chain of (hyper)conjugation across the R-R bond. In such cases the difference between D[R-R] and D[R-R]calc provides a convenient means of quantifying the stabilization or destabilization of R-R due to these interactions. The predictability of the scheme is demonstrated by using these radical stabilities to calculate R-R′ bond dissociation energies for 234 combinations of the 66 radicals studied, chosen to exclude steric or resonance interactions in the R-R′ bond. The predicted bond energies lie within an average of 1.6 kcal mol-1 from directly measured or calculated literature values.

AB - Accurate G3(MP2)-RAD calculations are used to predict 264 R-H, R-CH 3, R-Cl and R-R bond dissociation energies for a wide-ranging test set of carbon and non-carbon centred R• radicals. The data are used to calculate a set of inherent and transferrable radical stabilization energies, denoted RSEEt, which ranks the inherent stability of the 66 radicals studied on the same relative scale, irrespective of the nature of the radical centre. The Pauling electronegativity parameter for each radical is also calculated from the same data, along with the radical's inherent bonding ability D[R-R]calc. This latter quantity is defined as the R-R bond dissociation energy expected in the absence of direct steric or resonance interactions that are present in R-R but absent in R-CH3 and R-Cl. We show that the differences between D[R-R] and D[R-R]calc are typically very small except when R is sterically bulky, or there is a chain of (hyper)conjugation across the R-R bond. In such cases the difference between D[R-R] and D[R-R]calc provides a convenient means of quantifying the stabilization or destabilization of R-R due to these interactions. The predictability of the scheme is demonstrated by using these radical stabilities to calculate R-R′ bond dissociation energies for 234 combinations of the 66 radicals studied, chosen to exclude steric or resonance interactions in the R-R′ bond. The predicted bond energies lie within an average of 1.6 kcal mol-1 from directly measured or calculated literature values.

UR - http://www.scopus.com/inward/record.url?scp=84898465421&partnerID=8YFLogxK

U2 - 10.1039/c4cp00537f

DO - 10.1039/c4cp00537f

M3 - Article

C2 - 24675783

AN - SCOPUS:84898465421

SN - 1463-9076

VL - 16

SP - 8686

EP - 8696

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

IS - 18

ER -