Speaker: Pan-Pan Zhou

Beijing Computational Science Research Center    

Abstract: One of the chemical explanations about the origin of red-shifted hydrogen bond has been attributed to the charge transfer from the proton acceptor Y to the σ* antibonding orbital of the X–H proton donor, which leads to the increase of its electron density, thus weakens and elongates the X–H bond. On the contrary, the decrease of electron density in the X–H antibonding orbital is an important factor responsible for the contracted X–H bond and its blue shift. These viewpoints qualitatively interpret various hydrogen-bonded complexes either red-shifted or blue-shifted. However, it should be noted that the previous work rarely considers the effect of electron density variation in the σ bonding orbital of the X–H bond, while the electron density for a bond involves both its bonding and antibonding orbitals, they are closely related to the bond length. Therefore, in this talk, I will introduce a method based on the theoretical principle about the relationship between electron density and bond length, in which it takes both the bonding and antibonding orbitals into account. The results suggest that the electron density in the σ bonding orbital is important, and its variation is an indispensable factor in explaining the X–H bond length change. This method can explain the significant role of hyperconjugation on the X–H bond length change in the red- or blue-shifted hydrogen bond from a quantitative point of view.

Date&Time: November 2, 2012 (Friday), 14:30–15:30
Location: 606 Conference Room