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首页> 外文期刊>RSC Advances >Theoretical view on a linear end-on manganese–dioxygen complex bearing a calix[4]arene ligand
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Theoretical view on a linear end-on manganese–dioxygen complex bearing a calix[4]arene ligand

机译：轴承座胶层[4]芳烃配体的线性端部锰 - 二氧化络合物的理论观点

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By taking a Mn–dioxygen complex supported by a zwitterionic calix[4]arene ligand ([MnL(O _(2) )(H _(2) O)](PF _(6) ) _(2) ; H _(4) L = [5,11,17,23-tetrakis(trimethylammonium)-25,26,27,28-tetrahydroxycalix[4]arene], CSD refcode: CAGVAJ) as a model system, we investigated the geometric and electronic structures of [MnL(O _(2) )(H _(2) O)] ~(2+) through density functional theory (DFT) calculations without and with the presence of additional waters. It was found that the ground-state structure of [MnL(O _(2) )(H _(2) O)] ~(2+) possesses a typical bent end-on binding mode (Mn–O–O angle at around 130° and dioxygen bond length at ～1.32 ?) within a sextet state ( S = 5/2) irrespective of calculated methodologies. The experimently proposed linear end-on structure (Mn–O–O angle at ～180°) and the side-on structure (Mn–O–O angle ～75°) are shown to be transition-state structures in the process of dioxygen flipping from one bent-end-on structure to another. By the inclusion of water solvation effect via both the explicit water-cluster model ([MnL(O _(2) )(H _(2) O)] ~(2+) – n H _(2) O, n = 1, 4, 6, 8) and implicit CPCM solvation model, a good correlation was concluded: the more additional waters and the more contracted O _(e) square benefit the larger Mn–O–O angle, indicating a water solvation effect and a ligand size effect. Inspired by the relationship of linear end-on mode with bent end-on mode and the consistence of the projected dioxygen bond length of [MnL(O _(2) )(H _(2) O)] ~(2+) –8H _(2) O in the CPCM model along the Mn–O bond direction ( d _(O1–O2) (p) = 1.240 ?) with the experimental dioxygen bond length (1.249 ?), we concluded that the linear Mn–O–O arrangement fitted by experimentalists should be a result of the flipping motion of dioxygen rotating about the Mn–O bond in solid-state structures of the [MnL(O _(2) )(H _(2) O)](PF _(6) ) _(2) complex based on analyses of the crystallographic data. Natural bond orbital (NBO) analyses show the sextet [MnL(O _(2) )(H _(2) O)] ~(2+) – n H _(2) O ( n = 0, 1, 4, 6, 8) have a Mn( III )-superoxo nature, consistent with experimental observations. The differences in the bonding structures of the three binding modes were discussed by the second-order perturbation energies Δ E _( i → j ) from the superoxo lone pair (LP) orbitals to Mn( III ) 3d orbitals in β electron space. It can also give clues about the instability of the linear end-on binding mode and the increased Mn–O–O angle in the presence of water solvents.
机译：通过取双倍离子胶体支持的Mn-DiOxygen络合物[4]芳烃配体（[MnL（O _（2））（H _（2））]（PF _（6））_（2）; H _ （4）L = [5,11,17,23-四（三甲基铵）-25,26,27,28-四羟基碱[4]芳烃]，CSD Refcode：Cagvaj）作为模型系统，我们调查了几何和电子通过密度泛函理论（DFT）计算的[Mn1（O _（2））（H _（2））]〜（2+），没有额外的水的存在。发现[MNL（O _（2））（H _（2））]〜（2+）的地态结构具有典型的弯曲端接绑定模式（MN-O-O角无论计算方法如何，在六号状态（S = 5/2）内约为130°和二氧化键长度在〜1.32？）。实验所提出的线性端部结构（〜180°的Mn-O-O角）和侧面结构（Mn-O-O角度〜75°）被示出为Dioxygen过程中的过渡状态结构从一个弯曲的端接结构翻转到另一个结构。通过通过显式水簇模型（H _（2））（H _（2））]〜（2+） - N H _（2）O，N =）通过含水溶剂化效应1,4,6,8）和隐含的CPCM溶剂化模型，得出了良好的相关性：越多的水域和较少的o _（e）方形越大，较大的Mn-O-O角度，表明水溶性效应和配体尺寸效果。灵感来自线性端部模式与弯曲的端部模式的关系和[MnL（O _（2））（H _（2））]〜（2+）的突出二恶英键长度的一致性 - 8h _（2）o在CPCM模型中，沿Mn-O键方向（D _（O1-O2）（P）= 1.240？），具有实验性Dioxygen键长（1.249？），我们得出结论，线性MN-由实验主义者安装的O-O布置应该是[MnL（2））（H _（2））的固态结构中的Mn-O键旋转的二恶英旋转的运动的结果（基于晶体数据分析的PF _（6））_（2）复杂。天然键轨道（NBO）分析显示SEXTET [MNL（O _（2））（H _（2））]〜（2+） - N H _（2）O（n = 0,1,4， 6,8）具有Mn（III）-Superoxo性质，与实验观察一致。通过从超脂孤独对（LP）轨道（LP）轨道到β电子空间中的Mn（III）3D轨道的二阶扰动能量δe_（I→j）讨论了三种结合模式的粘合结构的差异。它还可以给出关于线性端部结合模式的不稳定性的线索和水溶液存在下的增加的MN-O-O角度。

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