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Isolation and characterization of a covalent Ce^IV-Aryl complex with an anomalous ¹³C chemical shift.

ABSTRACT: The synthesis of bona fide organometallic Ce^IV complexes is a formidable challenge given the typically oxidizing properties of the Ce^IV cation and reducing tendencies of carbanions. Herein, we report a pair of compounds comprising a Ce^IV - C_aryl bond [Li(THF)₄][Ce^IV(κ²-ortho-oxa)(MBP)₂] (3-THF) and [Li(DME)₃][Ce^IV(κ²-ortho-oxa)(MBP)₂] (3-DME), ortho-oxa = dihydro-dimethyl-2-[4-(trifluoromethyl)phenyl]-oxazolide, MBP^2- = 2,2'-methylenebis(6-tert-butyl-4-methylphenolate), which exhibit Ce^IV - C_aryl bond lengths of 2.571(7) - 2.5806(19) Å and strongly-deshielded, Ce^IV - C_ipso ¹³C{¹H} NMR resonances at 255.6 ppm. Computational analyses reveal the Ce contribution to the Ce^IV - C_aryl bond of 3-THF is ~12%, indicating appreciable metal-ligand covalency. Computations also reproduce the characteristic ¹³C{¹H} resonance, and show a strong influence from spin-orbit coupling (SOC) effects on the chemical shift. The results demonstrate that SOC-driven deshielding is present for Ce^IV - C_ipso ¹³C{¹H} resonances and not just for diamagnetic actinide compounds.

SUBMITTER: Panetti GB

PROVIDER: S-EPMC7969749 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeA multiecho, field of view (FOV)-oversampled k-t spiral acquisition and direct iterative decomposition of water and fat with echo asymmetry and least-squares estimation reconstruction is demonstrated to improve the stability of hyperpolarized 13 C magnetic resonance spectroscopic imaging (MRSI) in the presence of signal ambiguities attributed to low-SNR (signal-to-noise-ratio) species, local uncertainties in metabolite peaks, and echo-to-echo signal inconsistencies.Theoryk-t spiral acquisitions redistribute readout points to be more densely spaced radially in k-space by acquiring an FOV and matrix that are oversampled by η. These more densely spaced spiral turns constitute effective intraspiral echoes and can supplement conventional interspiral echoes to improve spectral separation and reduce spectral cross-talk to better resolve 13 C-labeled species for spectroscopic imaging.MethodsDigital simulations and imaging phantom experiments were performed for a range of interspiral echo spacings and η using multiecho, k-t spiral acquisitions. Image spectral cross-talk artifacts were evaluated both qualitatively and quantitatively as the percent error in measured metabolite ratios. In vivo murine experiments evaluated the feasibility of multiecho, k-t spiral [1-13 C]pyruvate MRSI to reduce spectral cross-talk for 3 scenarios of different expected reconstruction stability.ResultsDigital simulations and imaging phantom experiments both demonstrated reduced or comparable image spectral cross-talk and percent errors in measured metabolite ratios with increasing η and better choices of echo spacings. In vivo images displayed markedly reduced spectral cross-talk in lactate images acquired with η = 7 versus η = 1.ConclusionThe precision of hyperpolarized 13 C metabolic imaging and quantification in the presence of low-SNR species, local uncertainties in metabolite resonances, and echo-to-echo signal inconsistencies can be improved with the use of FOV-oversampled k-t spiral acquisitions.

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Isolation and characterization of a covalent Ce^IV-Aryl complex with an anomalous ¹³C chemical shift.

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Dataset Information

Isolation and characterization of a covalent CeIV-Aryl complex with an anomalous 13C chemical shift.

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Isolation and characterization of a covalent Ce^IV-Aryl complex with an anomalous ¹³C chemical shift.