Investigation of Oxidative Behaviour and Structural Insights of (3,4,5-Trimethoxyphenyl)Porphyrin Ni(II) Complex: Experimental and Theoretical Study

IF 1.8 3区化学 Q3 CHEMISTRY, INORGANIC & NUCLEAR

Russian Journal of Inorganic Chemistry Pub Date : 2024-08-29 DOI:10.1134/s0036023624601521

I. U. Muzaddadi, A. Murugan, M. Hemamalini, M. N. Tahir, N. Raman, B. Bezbaruah, B. Ahmed, A. Manohar, A. Kulandaisamy, M. F. Hussain, T. Rajkumar

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Abstract

Meso 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl)porphyrin [H₂T(3,4,5-OCH₃)PP] and its Ni complex [T(3,4,5-OCH₃)PP Ni] (complex 1) have been prepared. Its oxidation characteristics were examined using diverse analytical techniques, such as UV-visible spectrophotometry (UV-Vis), electron paramagnetic resonance (EPR), cyclic voltammetry (CV), and nuclear magnetic resonance (NMR) with antimony pentachloride (SbCl₅) or trifluoroacetic acid (TFA). The structure of the titled compound has been confirmed by single-crystal analysis. Cyclic voltammetry study of complex 1 provides that Ni^II is converted to Ni^III porphyrin through π-cation radical formation which is further EPR supported by IR spectrum peaks at 1276 cm^–1 with the addition of SbCl₅. The confirmation of formation of the π-cation radical has been established by the emergence of a novel peak at 649.5 nm in the UV-visible spectrum. This peak, indicative of oxidation, was observed at the central Ni ion, distinguishing it from the porphyrin macrocycle. Additionally, the EPR spectrum informed the formation of Ni(III) from Ni(II) porphyrin which is oxidized with SbCl₅ or CF₃COOH (TFA) as \(d_{z}^{2}\) orbital has a single electron with high spin, S = 3/2 ground state in complex 1. Crystallographic analysis and Hirshfeld surface analysis, show hydrogen bonding and molecular packing in the crystal lattice. DFT calculation and experimental HOMO–LUMO gap in solvent closely align with the theoretically determined HOMO–LUMO energy difference (0.92 eV) for complex 1.

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(3,4,5-三甲氧基苯基)卟啉镍(II)配合物的氧化行为调查与结构洞察：实验与理论研究

摘要制备了 5,10,15,20-四(3,4,5-三甲氧基苯基)卟啉[H2T(3,4,5-OCH3)PP]及其镍络合物[T(3,4,5-OCH3)PP Ni]（络合物 1）。利用多种分析技术，如紫外-可见分光光度法（UV-Vis）、电子顺磁共振（EPR）、循环伏安法（CV）以及五氯化锑（SbCl5）或三氟乙酸（TFA）核磁共振（NMR），对其氧化特性进行了研究。单晶分析证实了标题化合物的结构。对复合物 1 的循环伏安法研究表明，NiII 通过形成 π-阳离子自由基而转化为 NiIII卟啉，加入 SbCl5 后，红外光谱在 1276 cm-1 处的峰值进一步证实了这一点。紫外可见光谱在 649.5 纳米处出现了一个新的峰值，从而证实了 π-阳离子自由基的形成。该峰值在中心镍离子上观察到，表明了氧化作用，从而将其与卟啉大环区分开来。此外，由于复合物 1 中的\(d_{z}^{2}\) 轨道有一个高自旋的单电子，即 S = 3/2 基态，因此通过 EPR 光谱可以发现卟啉中的 Ni(II) 被 SbCl5 或 CF3COOH (TFA) 氧化后形成了 Ni(III)。晶体分析和 Hirshfeld 表面分析表明，在晶格中存在氢键和分子堆积。DFT 计算和溶剂中的实验 HOMO-LUMO 间隙与理论测定的复合物 1 的 HOMO-LUMO 能量差（0.92 eV）非常吻合。

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来源期刊

Russian Journal of Inorganic Chemistry 化学-无机化学与核化学

CiteScore

3.10

自引率

38.10%

发文量

237

审稿时长

3 months

期刊介绍： Russian Journal of Inorganic Chemistry is a monthly periodical that covers the following topics of research: the synthesis and properties of inorganic compounds, coordination compounds, physicochemical analysis of inorganic systems, theoretical inorganic chemistry, physical methods of investigation, chemistry of solutions, inorganic materials, and nanomaterials.