Computational (DFT) and Experimental (EXAFS) Study of the Interaction of [Ir(IMes)(H)(2)(L)(3)] with Substrates and Co-substrates Relevant for SABRE in Dilute Systems

Bram J. A. van Weerdenburg, Anthonius H. J. Engwerda, Nan Eshuis, Alessandro Longo, Dipanjan Banerjee, Marco Tessari, Celia Fonseca Guerra, Floris P. J. T. Rutjes, F. Matthias Bickelhaupt, Martin C. Feiters

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Signal amplification by reversible exchange (SABRE) is an emerging hyperpolarization method in NMR spectroscopy, in which hyperpolarization is transferred through the scalar coupling network of para-hydrogen derived hydrides in a metal complex to a reversibly bound substrate. Substrates can even be hyperpolarized at concentrations below that of the metal complex by addition of a suitable co-substrate. Here we investigate the catalytic system used for trace detection in NMR spectroscopy with [Ir(IMes)(H)2(L)3]+ (IMes=1,3-dimesitylimidazol-2-ylidene) as catalyst, pyridine as a substrate and 1-methyl-1,2,3-triazole as co-substrate in great detail. With density functional theory (DFT), validated by extended X-ray absorption fine structure (EXAFS) experiments, we provide explanations for the relative abundance of the observed metal complexes, as well as their contribution to SABRE. We have established that the interaction between iridium and ligands cis to IMes is weaker than that with the trans ligand, and that in mixed complexes with pyridine and triazole, the latter preferentially takes up the trans position.
Original languageEnglish
Pages (from-to)10482-10489
Number of pages8
JournalChemistry: A European Journal
Volume21
Issue number29
DOIs
Publication statusPublished - 13 Jul 2015

Keywords

  • density functuional calculations
  • iridium
  • ligands
  • NMR spectroscopy
  • X-ray absorption spectroscopy

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