Electronic Structure of Manganese Complexes of the Redox-Non-innocent Tetrazene Ligand and Evidence for the Metal-Azide/Imido Cycloaddition Intermediate

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• 作者：Dr. Shivaiah Vaddypally ; Ian G. McKendry ; Warren Tomlinson ; Dr. Joseph P. Hooper and Dr. Michael J. Zdilla
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：July 18, 2016
• 年：2016
• 卷：22
• 期：30
• 页码：10548-10557
• 全文大小：3169K
• ISSN：1521-3765

文摘

The first synthetic manganese tetrazene complexes are described as a redox pair comprising anionic [Mn(N₄Ad₂)₂]⁻ (1) and neutral Mn(N₄Ad₂)₂ (2) complexes (N₄Ad₂=[Ad-N−N=N−N-Ad]²⁻). Compound 1 is obtained in two forms as lithium salts, one as a cationic Li₂Mn cluster, and one as a Mn–Li 1D ionic polymer. Compound 1 is electronically described as a Mn^III center with two [N₄Ad₂]²⁻ ligands. The one-electron oxidized 2 is crystalized in two morphologies, one as pure 2 and one as an acetonitrile adduct. Despite similar composition, the behavior of 2 differs in the two morphologies. Compound 2-MeCN is relatively air and temperature stable. Crystalline 2, on the other hand, exhibits a compositional, dynamic disorder wherein the tetrazene metallacycle ring-opens into a metal imide/azide complex detectable by X-ray crystallography and FTIR spectroscopy. Electronic structure of 2 was examined by EPR and XPS spectroscopies and DFT calculations, which indicate 2 is best described as a Mn^III ion with an anion radical delocalized across the two ligands through spin-polarization effects.