Solid‐state nuclear magnetic resonance and nuclear quadrupole resonance as complementary tools to study quadrupolar nuclei in solids

Abstract

Solid-state nuclear magnetic resonance (SSNMR) spectroscopy has largely overtaken nuclear quadrupole resonance (NQR) spectroscopy for the study of quadrupolar nuclei. In addition to information on the electric field gradient, SSNMR spectra may offer additional information concerning other NMR interactions such as magnetic shielding. With continued technological advances contributing to developments such as higher magnetic fields, SSNMR boasts several practical advantages over NQR. However, NQR is still a relevant technique, as it may often be the most practical approach in cases of extremely large quadrupolar coupling constants. Here, we discuss the advantages and disadvantages of SSNMR and NQR spectroscopies, with the quadrupolar halogens serving as examples. The purpose of this article is to serve as a guide on using SSNMR and NQR as complementary tools, covering some of their practicalities, limitations, and experimental challenges. K E Y W O R D S nuclear quadrupole resonance, quadrupolar halogens, quadrupolar nuclei, solid-state nuclear magnetic resonance

Rapid Identification of Halogen Bonds in Co‐Crystalline Powders via 127I Nuclear Quadrupole Resonance Spectroscopy

“…As ar esult, the quadrupolar coupling yields information on the electronic structure,which can be used to refine crystal structures [42] and learn more about chemical bonding.The reader is referred to an article detailing the interpretation of the quadrupolarcoupling tensor in terms of structure and bonding. [44] Rather than broad line shapes as seen in NMR (on the order of several to tens of MHz), however, pure NQR yields relatively sharp resonances (on the order of tens of kHz in this work;s ee Supporting Information), the frequencies of which relate to the quadrupolar interaction. Fortunately,n uclear quadrupole resonance (NQR) spectroscopy is well-suited to study nuclei subject to large quadrupole couplings,which is the case for quadrupolar halogens,and can be performed using the same radiofrequencye quipment included with aS SNMR spectrometer but in the absence of am agnetic field.…”

“…Fortunately,n uclear quadrupole resonance (NQR) spectroscopy is well-suited to study nuclei subject to large quadrupole couplings,which is the case for quadrupolar halogens,and can be performed using the same radiofrequencye quipment included with aS SNMR spectrometer but in the absence of am agnetic field. [44] Rather than broad line shapes as seen in NMR (on the order of several to tens of MHz), however, pure NQR yields relatively sharp resonances (on the order of tens of kHz in this work;s ee Supporting Information), the frequencies of which relate to the quadrupolar interaction. While spin-3/2 nuclei have asingle transition (1/2!3/2), spin-5/2 nuclei exhibit two possible single-quantum transitions (1/2!3/2 &3 /2!5/2).…”

Magnetic Resonance for Challenging Quadrupolar Halide Spins in Perovskites

“…NQR is suited for spins with large quadrupolar interactions. 7 The authors also demonstrated, for the first time, the 35 Cl and 79 Br NMR of bulk and nanocrystalline CsPbX 3 collected with the special WURST-CPMG sequence. 8 In the main text and Supporting Information, the authors provided introductory tutorials of NMR and NQR for halide spins.…”

Rapid Identification of Halogen Bonds in Co‐Crystalline Powders via 127I Nuclear Quadrupole Resonance Spectroscopy

“…Despite the availability of higher applied magnetic fields for NMR spectroscopy, the covalently bonded quadrupolar halogens, including 35/37 Cl (spin I =3/2), 79/81 Br (spin I =3/2), and 127 I (spin I =5/2), remain challenging or unamenable to SSNMR due to substantial quadrupolar spectral broadening. Fortunately, nuclear quadrupole resonance (NQR) spectroscopy is well‐suited to study nuclei subject to large quadrupole couplings, which is the case for quadrupolar halogens, and can be performed using the same radiofrequency equipment included with a SSNMR spectrometer but in the absence of a magnetic field . Rather than broad line shapes as seen in NMR (on the order of several to tens of MHz), however, pure NQR yields relatively sharp resonances (on the order of tens of kHz in this work; see Supporting Information), the frequencies of which relate to the quadrupolar interaction.…”