Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts,Angewandte Chemie International Edition

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Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts
Angewandte Chemie International Edition ( IF 16.1 ) Pub Date : 2021-08-05 , DOI: 10.1002/anie.202107944
Jonas C Ott ₁ , Elizaveta A Suturina ₂ , Ilya Kuprov ₃ , Joscha Nehrkorn ₄ , Alexander Schnegg ₄ , Markus Enders ₁ , Lutz H Gade ₁

Affiliation

We report an experimental observation of ³¹P NMR resonances shifted by over 10 000 ppm (meaning percent range, and a new record for solutions), and similar ¹H chemical shifts, in an intermediate-spin square planar ferrous complex [^tBu(PNP)Fe-H], where PNP is a carbazole-based pincer ligand. Using a combination of electronic structure theory, nuclear magnetic resonance, magnetometry, and terahertz electron paramagnetic resonance, the influence of magnetic anisotropy and zero-field splitting on the paramagnetic shift and relaxation enhancement is investigated. Detailed spin dynamics simulations indicate that, even with relatively slow electron spin relaxation (T₁ ≈10⁻¹¹ s), it remains possible to observe NMR signals of directly metal-bonded atoms because pronounced rhombicity in the electron zero-field splitting reduces nuclear paramagnetic relaxation enhancement.

中文翻译：

超过 10 000 ppm 化学位移的顺磁 NMR 信号的可观测性

我们报告了在中间自旋方形平面亚铁配合物 [ ^{t Bu} (PNP) 中³¹ P NMR 共振位移超过 10 000 ppm（意味着百分比范围，并且是溶液的新记录）以及类似的¹ H 化学位移的实验观察结果)Fe-H]，其中 PNP 是咔唑基钳配体。结合电子结构理论、核磁共振、磁力测量和太赫兹电子顺磁共振，研究了磁各向异性和零场分裂对顺磁位移和弛豫增强的影响。详细的自旋动力学模拟表明，即使电子自旋弛豫相对较慢（ T ₁ ≈10 ^-11 s），仍然可以观察到直接金属键合原子的核磁共振信号，因为电子零场分裂中明显的菱形减少了核顺磁性放松增强。

更新日期：2021-10-04

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