Observation and Analysis of Large Dynamic Frequency Shifts in the 1H NMR Signals of H-D in Deuterium-Substituted Dihydrogen Complexes

Ryan Gilbert-Wilson; Biswanath Das; Dejan Mizdrak; Leslie D Field; Graham E Ball

doi:10.1021/acs.inorgchem.0c02082

Observation and Analysis of Large Dynamic Frequency Shifts in the ¹H NMR Signals of H-D in Deuterium-Substituted Dihydrogen Complexes

Inorg Chem. 2020 Nov 2;59(21):15570-15573. doi: 10.1021/acs.inorgchem.0c02082. Epub 2020 Oct 19.

Authors

Ryan Gilbert-Wilson¹, Biswanath Das¹, Dejan Mizdrak¹, Leslie D Field¹, Graham E Ball¹

Affiliation

¹ School of Chemistry, University of New South Wales (UNSW), Sydney, New South Wales 2052, Australia.

PMID: 33073977
DOI: 10.1021/acs.inorgchem.0c02082

Abstract

A dynamic frequency shift (DFS) in the ¹H NMR resonance of the HD unit of the deuterium-labeled dihydrogen complex [Ru(D)(η²-HD)(P³P₃^ⁱPr)][BPh₄] [P³P₃^ⁱPr = P(CH₂CH₂CH₂PⁱPr₂)₃] has been observed and analyzed. To the best of our knowledge, this is the first demonstration of the DFS for a H-D pair. The observed DFS of the center line relative to the outside lines in the H-D triplet is large, up to ∼11 Hz, because of the short H-D distance encountered in dihydrogen complexes. Analysis of the DFS as a function of the temperature, combined with density-functional-theory-calculated or least-squares-fitted electric-field-gradient (EFG) parameters, suggests an H-D bond length of 0.92-0.94 Å. A DFS was also observed in trans-[Fe(η²-HD)(H)(dppe)₂]⁺, suggesting the DFS will be commonplace in dihydrogen complexes if appropriate conditions are employed for its observation. Possible applications of the DFS as a probe of the bond lengths, EFGs, and molecular motion, particularly in inorganic systems, are discussed.