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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
Author(s) -
van Weerdenburg Bram J. A.,
Engwerda Anthonius H. J.,
Eshuis Nan,
Longo Alessandro,
Banerjee Dipanjan,
Tessari Marco,
Guerra Célia Fonseca,
Rutjes Floris P. J. T.,
Bickelhaupt F. Matthias,
Feiters Martin C.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201500714
Subject(s) - imes , iridium , chemistry , density functional theory , substrate (aquarium) , extended x ray absorption fine structure , pyridine , spectroscopy , spin isomers of hydrogen , hyperpolarization (physics) , catalysis , nuclear magnetic resonance spectroscopy , absorption spectroscopy , hydrogen , stereochemistry , computational chemistry , carbene , medicinal chemistry , organic chemistry , physics , oceanography , quantum mechanics , geology
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.