Naslov
Periodic trends in bond dissociation energies. A theoretical study

Autori
Mo, Otilia ; Yanez, Manuel ; Eckert-Maksić, Mirjana ; Maksić, Zvonimir ; Alkorta, Ibon ; Elguero, Jose

Izvornik
The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory (1089-5639) 109 (2005); 4359-4365

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Bond dissociation energy; periodic properties; theoretical calculations

Sažetak
Bond dissociation energies (BDEs) of all possible A-X single bonds involving the first and second row atoms, from Li to Cl, where the free valences are saturated by hydrogens, have been estimated through the use of the G3-theory and at the B3LYP/6- 311+G(3df, 2pd)//B3LYP/6-31G(2df, p) DFT level of theory. BDEs exhibit a periodical behavior. The A-X (A = Li, Be, B, Na, Mg, Al and Si) BDEs show a steady increase along the first and the second row of the periodic table as a function of the atomic number Z(X). For A-X bonds involving electronegative atoms (A = C, N, O, F, P, S, and Cl) the bond energies achieve a maximum around Z(X) = 5. The same behavior is observed when BDEs are plotted against the electronegativity of the atom X. Thus, for A-X bonds (A = Li, Be, B, Na, Mg, Al, Si), the BDEs for a fixed A increases, grosso modo, as the electronegativity difference between X and A increases, with some exceptions, which reflect the differences in the relaxation energies of the radicals produced upon the bond cleavage. A similar trend, albeit less pronounced, is found for single A-X bonds, where A = C, N, O, F, P, S, and Cl. However, there is an additional feature embodied in the enhancement of the strength of the A-Boron bonds due to the ability of boron to act as a strong electron acceptor. The trends in bond lengths and charge densities at the bond critical points are in line with the aforementioned behavior.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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