A Copper(II)‐Nitrite Complex Hydrogen‐Bonded to a Protonated Amine in the Second‐Coordination‐Sphere
A Copper(II)‐Nitrite Complex Hydrogen‐Bonded to a Protonated Amine in the Second‐Coordination‐Sphere
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铜 (II) - 亚硝酸盐络合物氢 - 在第二配位 - 球体中与质子化胺键合
DOI：
10.1002/ejic.202200105
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发表时间：
2022
影响因子：
2.3
通讯作者：
Kundu, Subrata
中科院分区：
文献类型：
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作者：
Gupta, Shourya;Arora, Sumangla;Mondal, Aditesh;Stieber, S. Chantal E.;Gupta, Puneet;Kundu, Subrata
亚硝酸（HONO）在与地球化学、大气化学和哺乳动物生理学相关的各种无金属和金属介导的途径中起着关键作用。虽然HONO的亚稳态性质阻碍了对其在过渡金属位点的反应性的详细研究，但本文中的报告利用了异位铜（II）穴状化合物[oC] CuII，其特征在于位于离[CuII]（ONO）核心适当距离处的质子响应性第二配位层，从而能够分离[CuII]（κ1-ONO H+）络合物（2 H-NO2）。一组关于2 H-NO2及其15 N-同位素异构体（2 H-15 NO2）的补充分析研究（UV-维斯，14 N/15 N FTIR，15 N NMR，HRMS，EPR和CHN）揭示了2 H-NO2的分子式为{[oCH]CuII（κ1-ONO）}（ClO 4）2。基于对{[oCH]CuII（κ1-ONO）}2+的约化密度梯度（RDG）分析的非共价相互作用指数（NCI）揭示了顶端3°铵位点与结合至铜（II）位点的亚硝酸根阴离子之间的氢键相互作用。[CuII]（κ1-ONO膦酰基H+）物种（2 H-NO2）的FTIR光谱显示，由于与亚硝酸根的氢键相互作用，铵NH振动特征向较低波数移动。[CuII]（κ1-ONO膦酰基H+）物种（2 H-NO2）对取代苯酚（2，4-DTBP）的厌氧硝化的反应性特征与密切相关的三脚架[CuII]-亚硝酸根络合物（1-NO2/3-NO2/4-NO2）的反应性特征明显不同。
Nitrous acid (HONO) plays pivotal roles in various metal‐free as well as metal‐mediated routes relevant to biogeochemistry, atmospheric chemistry, and mammalian physiology. While the metastable nature of HONO hinders the detailed investigations into its reactivity at a transition metal site, this report herein utilizes a heteroditopic copper(II) cryptate [oC]CuIIfeaturing a proton‐responsive second‐coordination‐sphere located at a suitable distance from a [CuII](ONO) core, thereby enabling isolation of a [CuII](κ1‐ONO⋅⋅⋅H+) complex (2H‐NO2). A set of complementary analytical studies (UV‐vis,14N/15N FTIR,15N NMR, HRMS, EPR, and CHN) on2H‐NO2and its15N‐isotopomer (2H‐15NO2) reveals the formulation of2H‐NO2as {[oCH]CuII(κ1‐ONO)}(ClO4)2. Non‐covalent interaction index (NCI) based on reduced density gradient (RDG) analysis on {[oCH]CuII(κ1‐ONO)}2+discloses a H‐bonding interaction between the apical 3° ammonium site and the nitrite anion bound to the copper(II) site. The FTIR spectra of [CuII](κ1‐ONO⋅⋅⋅H+) species (2H‐NO2) shows a shift of ammonium NH vibrational feature to a lower wavenumber due to the H‐bonding interaction with nitrite. The reactivity profile of [CuII](κ1‐ONO⋅⋅⋅H+) species (2H‐NO2) towards anaerobic nitration of substituted phenol (2,4‐DTBP) is distinctly different relative to that of the closely related tripodal [CuII]‐nitrite complexes (1‐NO2/3‐NO2/4‐NO2).