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Characterization of H 2 ‐Splitting Products of Frustrated Lewis Pairs: Benefit of Fast Magic‐Angle Spinning
Author(s) -
Malär Alexander A.,
Dong Shunxi,
Kehr Gerald,
Erker Gerhard,
Meier Beat H.,
Wiegand Thomas
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900006
Subject(s) - frustrated lewis pair , magic angle spinning , borane , solid state nuclear magnetic resonance , chemistry , nuclear magnetic resonance spectroscopy , spectroscopy , spectral line , characterization (materials science) , catalysis , proton , dipole , spinning , magic angle , nmr spectra database , crystallography , lewis acids and bases , nuclear magnetic resonance , materials science , stereochemistry , physics , nanotechnology , organic chemistry , polymer chemistry , nuclear physics , quantum mechanics , astronomy
Proton spectroscopy in solid‐state NMR on catalytic materials offers new opportunities in structural characterization, in particular of reaction products of catalytic reactions such as hydrogenation reactions. Unfortunately, the 1 H NMR line widths in magic‐angle spinning solid‐state spectra are often broadened by an incomplete averaging of 1 H‐ 1 H dipolar couplings. We herein discuss two model compounds, namely the H 2 ‐splitting products of two phosphane‐borane Frustrated Lewis Pairs (FLPs), to study potentials and limitations of proton solid‐state NMR experiments employing magic‐angle spinning frequencies larger than 100 kHz at a static magnetic field strength of 20.0 T. The 1 H lines are homogeneously broadened as illustrated by spin‐echo decay experiments. We study two structurally similar materials which however show significant differences in 1 H line widths which we explain by differences in their 1 H‐ 1 H dipolar networks. We discuss the benefit of fast MAS experiments up to 110 kHz to detect the resonances of the H + /H − pair in the hydrogenation products of FLPs.