Coordination and electronic characteristics of a nitrogen heterocycle pincer ligand
Coordination and electronic characteristics of a nitrogen heterocycle pincer ligand
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DOI：
10.1016/j.ica.2016.07.011
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发表时间：
2016-09-01
影响因子：
2.8
通讯作者：
Caulton, Kenneth G.
中科院分区：
文献类型：
--
作者：
Cook, Brian J.;Chen, Chun-Hsing;Caulton, Kenneth G.
研究了在吡唑氮上同时具有质子或甲基取代基的双（吡唑-3-基）吡啶配体的Fe（II）配位化学，包括配体发生氧化还原变化的意愿。吡唑氮上的质子促进分子间氢键形成，导致氧化还原不可逆性；这些氮的甲基化消除了分子间的相互作用，导致了可逆的外球还原。所得到的n -甲基化配体的阴离子自由基在吡啶部分比在吡唑基钳形配体臂中具有更大的自旋，但也可检测到离域到吸电子的吡唑基钳形配体臂中；EPR和密度泛函计算有助于表征配体自由基阴离子，如其钾络合物。(C) 2016年Elsevier B.V.出版
The Fe(II) coordination chemistry of bis(pyrazole-3-yl)pyridine ligands with both proton or methyl substituents on pyrazole nitrogen are investigated, including the willingness of the ligand to undergo redox change. Protons on the pyrazole nitrogen promote intermolecular hydrogen bonding and lead to redox irreversibility; N methylation of those nitrogens eliminates those intermolecular interactions and leads to reversible outer-sphere reducibility. The resulting anion radical of the N-methylated ligand has more spin in the pyridine moiety than in the pyrazolyl pincer ligand arms, but also detectably delocalized into the electron withdrawing pyrazolyl pincer ligand arms; EPR and density functional calculations assist in characterizing the ligand radical anion, as its potassium complex. (C) 2016 Published by Elsevier B.V.