Origins of dihydrogen binding to metal-inserted porphyrins: electric polarization and Kubas interaction

Junga Ryou; Gunn Kim; Suklyun Hong

doi:10.1063/1.3583813

paper

Origins of dihydrogen binding to metal-inserted porphyrins: electric polarization and Kubas interaction

arXiv:1107.3678 · doi:10.1063/1.3583813

Abstract

Using density functional theory calculations, we have investigated the interactions between hydrogen molecules and metalloporphyrins. A metal atom such as Ca or Ti is introduced for incorporation in the central N $_{4}$ cavity. Within local density approximation (generalized gradient approximation), we find that the average binding energy of H $_{2}$ to the Ca atom is about 0.25 (0.1) eV/H $_{2}$ up to four H $_{2}$ molecules, whereas that to the Ti atom is about 0.6 (0.3) eV per H $_{2}$ up to two H $_{2}$ . Our analysis of orbital hybridization between the inserted metal atom and molecular hydrogen shows that H $_{2}$ binds weakly to Ca-porphyrin through a weak electric polarization in dihydrogen, but is strongly hybridized with Ti-porphyrin through the Kubas interaction. The presence of $d$ orbitals in Ti may explain the difference in the interaction types.

12 pages, 5 figures. Selected as a front cover of the Journal of Chemical Physics

Origins of dihydrogen binding to metal-inserted porphyrins: electric polarization and Kubas interaction

Abstract

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