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arXiv · 1107.3678

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

Junga Ryou·Gunn Kim·Suklyun Hong
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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.

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Junga Ryou, Gunn Kim, Suklyun Hong. 2011-07-19. Origins of dihydrogen binding to metal-inserted porphyrins: electric polarization and Kubas interaction. https://doi.org/10.1063/1.3583813

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