Molecular Dynamics in Paramagnetic Materials as Studied by Magic-Angle Spinning ²H NMR Spectra

Abstract

A magic-angle spinning (MAS) 2H NMR experiment was applied to study the molecular motion in paramagnetic compounds. The temperature dependences of 2H MAS NMR spectra were measured for paramagnetic [M(H2O)6][SiF6] (M=Ni2+, Mn2+, Co2+) and diamagnetic [Zn(H2O)6][SiF6]. The paramagnetic compounds exhibited an asymmetric line shape in 2H MAS NMR spectra because of the electron-nuclear dipolar coupling. The drastic changes in the shape of spinning sideband patterns and in the line width of spinning sidebands due to the 180 degrees flip of water molecules and the reorientation of [M(H2O)6]2+ about its C3 axis were observed. In the paramagnetic compounds, paramagnetic spin-spin relaxation and anisotropic g-factor result in additional linebroadening of each of the spinning sidebands. The spectral simulation of MAS 2H NMR, including the effects of paramagnetic shift and anisotropic spin-spin relaxation due to electron-nuclear dipolar coupling and anisotropic g-factor, was performed for several molecular motions. Information about molecular motions in the dynamic range of 10(2) s(-1)<or=k<or=10(8) s(-1) can be obtained for the paramagnetic compounds from the analysis of 2H MAS NMR spectra when these paramagnetic effects are taken into account.

19F/119Sn/207Pb NMR Studies on Ion Dynamics in Tetragonal PbSnF4: Spectroscopic Evidence for Defect-Driven Conductivity

“…Simulated 119 Sn NMR spectra were produced with FORTRAN original programs. , Some details are given in the Supporting Information.…”

Electron Localization of Polyoxomolybdates with ε-Keggin Structure Studied by Solid-State 95Mo NMR and DFT Calculation

“…Numerical calculations for the 95 Mo NMR signals were carried out by a home-written Fortran90 program. Hamiltonian used for the calculation was scriptH = scriptH Q false( 1 false) + scriptH Q false( 2 false) + scriptH S + scriptH 1 . ,− Here, scriptH normalQ false( 1 false) and scriptH normalQ false( 2 false) are the first and second order quadrupole interactions, respectively. scriptH normalQ false( 1 false) that is irrelevant for the spectral line shape of the |1/2⟩ ↔ |−1/2⟩ central transition of the HIQN is needed, because it affects nutation behavior of the magnetization of 95 Mo.…”

Rotational Motion of Ligand-Cysteine on CdSe Magic-Sized Clusters

“…The dynamics of ligands have been examined by various NMR experiments. ,,,− Among them, solid-state 2 H NMR spectroscopy is a powerful method to characterize segment motion of ligands in solid samples. The shape of resonance lines in 2 H quadrupolar echo spectra sensitively reflects molecular motion with a motional rate k ranging from 10 3 to 10 7 s –1 , and thus analysis of the temperature dependence of the line shape gives information on the local dynamic structure. − In 2 H quadrupolar Carr–Purcell–Meiboom–Gill (QCPMG) spectra having a wide spikelet pattern, both the overall spectral shape and the spike width and height is sensitive to motion with k = 10 2 to 10 8 s –1 . , In this work, we synthesized CdSe-Cys with the deuterated methanediyl group (CdSe-[CD 2 ]­Cys) and studied solid-state 2 H QCPMG and quadrupolar-echo NMR of CdSe-(CD 2 )­Cys. The 2 H QCPMG spectra suggested the presence of molecular motion of monodentate ligand-cysteine.…”

“…31−34 In 2 H quadrupolar Carr−Purcell− Meiboom−Gill (QCPMG) spectra having a wide spikelet pattern, both the overall spectral shape and the spike width and height is sensitive to motion with k = 10 2 to 10 8 s −1 . 35,36 In this work, we synthesized CdSe-Cys with the deuterated methanediyl group (CdSe-[CD 2 ]Cys) and studied solid-state 2 H QCPMG and quadrupolar-echo NMR of CdSe-(CD 2 )Cys. The 2 H QCPMG spectra suggested the presence of molecular motion of monodentate ligand-cysteine.…”