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Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts.

ABSTRACT: We report an experimental observation of ³¹ P NMR resonances shifted by over 10 000 ppm (meaning percent range, and a new record for solutions), and similar ¹ H 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.

SUBMITTER: Ott JC

PROVIDER: S-EPMC8518043 | biostudies-literature | 2021 Oct

REPOSITORIES: biostudies-literature

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Observability of Paramagnetic NMR Signals at over 10 000 ppm Chemical Shifts.

Ott Jonas C JC Suturina Elizaveta A EA Kuprov Ilya I Nehrkorn Joscha J Schnegg Alexander A Enders Markus M Gade Lutz H LH

Angewandte Chemie (International ed. in English) 20210915 42

We report an experimental observation of 31 P NMR resonances shifted by over 10 000 ppm (meaning percent range, and a new record for solutions), and similar 1 H 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 aniso ...[more]

PMID: 34351041

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