Multicenter interactions and ligand field effects in platinum( ii ) tripyrrindione radicals
Multicenter interactions and ligand field effects in platinum( ii ) tripyrrindione radicals
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铂( ii )三吡啶二酮自由基的多中心相互作用和配体场效应
DOI：
10.1039/d3dt00894k
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发表时间：
2023
影响因子：
4
通讯作者：
Ghosh, Abhik
中科院分区：
文献类型：
--
作者：
Tomat, Elisa;Curtis, Clayton J.;Astashkin, Andrei V.;Conradie, Jeanet;Ghosh, Abhik
三吡咯-1，14-二酮生物吡喃与几种天然的血红素代谢物共用，是金属配位的氧化还原活性平台。本文报道了正方形平面铂(II)三吡二酮的合成，其中生物吡咯以三齿根的形式键合，四配位被水或叔丁基异氰酸酯配体占据。这些络合物通过层析纯化和暴露在空气中是稳定的。电子顺磁共振(EPR)数据和密度泛函理论(DFT)分析证实，自旋密度主要位于三吡二酮配体上。在低温下，铂(II)三苯并二酮自由基间的煎饼键合导致了抗磁性π二聚体的形成。单齿配体的同一性(即水和异氰化物)既影响二聚的热力学参数，也影响这些络合物中基于三苯并二酮的氧化还原过程。对氧化配合物的分离和结构表征表明，在固体状态下，抗磁性的三苯并二酮类化合物堆积在一起，而在水相配合物中，则存在亲金属的铂(II)-−-铂(II)接触。总体而言，铂(II)三苯并二酮类化合物的性质，包括溶液和固体中的氧化还原电位和分子间相互作用，都是通过生物吡咯配体的氧化还原状态或单齿配体性质的容易实现的变化来调节的。
The tripyrrin-1,14-dione biopyrrin, which shares the scaffold of several naturally occurring heme metabolites, is a redox-active platform for metal coordination. We report the synthesis of square planar platinum(II) tripyrrindiones, in which the biopyrrin binds as a tridentate radical and the fourth coordination position is occupied by either aqua or tert-butyl isocyanide ligands. These complexes are stable through chromatographic purification and exposure to air. Electron paramagnetic resonance (EPR) data and density functional theory (DFT) analysis confirm that the spin density is located predominantly on the tripyrrindione ligand. Pancake bonding in solution between the Pt(II) tripyrrindione radicals leads to the formation of diamagnetic π dimers at low temperatures. The identity of the monodentate ligand (i.e., aqua vs. isocyanide) affects both the thermodynamic parameters of dimerization and the tripyrrindione-based redox processes in these complexes. Isolation and structural characterization of the oxidized complexes revealed stacking of the diamagnetic tripyrrindiones in the solid state as well as a metallophilic Pt(II)−Pt(II) contact in the case of the aqua complex. Overall, the properties of Pt(II) tripyrrindiones, including redox potentials and intermolecular interactions in solution and in the solid state, are modulated through easily accessible changes in the redox state of the biopyrrin ligand or the nature of the monodentate ligand.