Department of Physics, Graphene Research Institute and Institute of Fundamental Physics, Sejong University, Seoul 143-747, Korea.
J Chem Phys. 2011 Jun 21;134(23):234701. doi: 10.1063/1.3583813.
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) molecules. 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.
使用密度泛函理论计算，我们研究了氢分子和金属卟啉之间的相互作用。引入一个金属原子，如 Ca 或 Ti，以嵌入中央 N(4)腔中。在局域密度近似（广义梯度近似）下，我们发现 H(2)与 Ca 原子的平均结合能约为 0.25（0.1）eV/H(2)，最多可容纳四个 H(2)分子，而与 Ti 原子的结合能约为 0.6（0.3）eV/H(2)，最多可容纳两个 H(2)分子。我们对插入金属原子和分子氢之间的轨道杂化的分析表明，H(2)通过弱二氢键与 Ca-卟啉弱结合，但通过库巴斯相互作用与 Ti-卟啉强烈杂化。Ti 中 d 轨道的存在可能解释了相互作用类型的差异。
