Silva Adilson Luís Pereira, de Almeida Luciano Farias, Marques Aldaléa Lopes Brandes, Costa Hawbertt Rocha, Tanaka Auro Atsushi, da Silva Albérico Borges Ferreira, de Jesus Gomes Varela Jaldyr
Universidade Federal da Paraíba, 58051-900, João Pessoa, PB, Brazil.
J Mol Model. 2014 Mar;20(3):2131. doi: 10.1007/s00894-014-2131-x. Epub 2014 Feb 25.
Density functional theory (DFT) was used to examine the interaction between molecular oxygen (O₂) and macrocyclic iron complexes of the type FeN₄ during the formation of FeN₄--O₂ adducts. In order to understand how this interaction is affected by different macrocyclic ligands, O₂ was bonded to iron-tetraaza[14]annulene (FeTAA), iron-tetramethyl-tetraaza[14]annulene (FeTMTAA), iron-hexamethyl-tetraaza[14]annulene (FeHMTAA), iron dibenzotetraaza[14]annulene (FeDBTAA), and two iron-tetramethyl-dibenzotetraaza[14]annulene complexes (FeTMDBTAA1, FeTMDBTAA2). The ground state for FeN₄-O₂ adducts was the open-shell singlet. Analysis of the factors influencing the O₂ bonding process showed that different macrocyclic ligands yielded adducts with differences in O--O and Fe--O₂ bond lengths, total charge over the O₂ fragment, O--O vibrational frequency, and spin density in the O₂ fragment. A smaller energy gap between the α-HOMO of the FeN₄ complexes and the β-LUMO of O₂ increased the interaction between the complex and the O₂ molecule. The order of activity was FeDBTAA < FeTMDBTAA2 < FeTMDBTAA1 < FeTAA < FeTMTAA < FeHMTAA.
采用密度泛函理论（DFT）研究了分子氧（O₂）与FeN₄型大环铁配合物在形成FeN₄--O₂加合物过程中的相互作用。为了理解这种相互作用如何受不同大环配体的影响，将O₂与铁-四氮杂[14]轮烯（FeTAA）、铁-四甲基-四氮杂[14]轮烯（FeTMTAA）、铁-六甲基-四氮杂[14]轮烯（FeHMTAA）、铁二苯并四氮杂[14]轮烯（FeDBTAA）以及两种铁-四甲基-二苯并四氮杂[14]轮烯配合物（FeTMDBTAA1、FeTMDBTAA2）进行键合。FeN₄-O₂加合物的基态为开壳单重态。对影响O₂键合过程的因素分析表明，不同的大环配体产生的加合物在O--O和Fe--O₂键长、O₂片段上的总电荷、O--O振动频率以及O₂片段中的自旋密度方面存在差异。FeN₄配合物的α-最高占据分子轨道（α-HOMO）与O₂的β-最低未占分子轨道（β-LUMO）之间较小的能隙增加了配合物与O₂分子之间的相互作用。活性顺序为FeDBTAA ＜ FeTMDBTAA2 ＜ FeTMDBTAA1 ＜ FeTAA ＜ FeTMTAA ＜ FeHMTAA。
