HIGH-FIELD SOLID-STATE 35Cl NMR IN SELENIUM(IV) AND TELLURIUM(IV) HEXACHLORIDES

35Cl NMR 35Cl NQR selenium tellurium hexachloride DFT calculations CASTEP NMR.

МОДЕЛЬ С. П. ГАБУДЫ УСРЕДНЕНИЯ ЛОКАЛЬНЫХ МАГНИТНЫХ ПОЛЕЙ В ЯМР ТВЕРДОГО ТЕЛА. ПОДВИЖНОСТЬ АТОМОВ И МОЛЕКУЛ, РАСЧЕТ СТЫКОВКИ НАНОКРИСТАЛЛИЧЕСКИХ БЛОКОВ ПО ГРАНИ (111) В НИЗКОТЕМПЕРАТУРНЫХ МЕТАСТАБИЛЬНЫХ ОКСИДАХ АЛЮМИНИЯ, ...

The CQ(35Cl) quadrupole coupling constants in the three compounds were found to be 41.40.1 MHz, 30.30.1 MHz and 30.30.1 MHz, respectively, some of the largest CQ(35Cl) quadrupole coupling constants ever measured in polycrystalline powdered solids directly via 35Cl NMR spectroscopy. <...> The 35Cl EFG tensors are axial in all three cases reflecting the C4v point group symmetry of the chlorine sites. 35Cl NMR experiments in these compounds were only made possible by employing the WURST-QCPMG pulse sequence in the ultrahigh magnetic field of 21.1 T. 35Cl NMR results agree with the earlier reported 35Cl NQR values and with the complementary plane-wave DFT calculations. <...> The origin of the very large CQ(35Cl) quadrupole coupling constants in these and other main-group chlorides lies in the covalent-type chlorine bonding. <...> The ionic bonding in the ionic chlorides results in significantly reduced CQ(35Cl) values as illustrated with triphenyltellurium chloride Ph3TeCl. <...> While the higher magnetic fields benefit NMR in general, it has been found particularly advantageous for solid-state applications when dealing with quadrupolar nuclei. <...> In ionic and mostly organic salts, i.e. hydrochlorides in particular, CQ(35Cl) quadrupole couplings are found in a convenient range of below 10 MHz, which allows for reasonably straightforward recording of the spectral data and its subsequent analysis [16—19 ]. <...> In several transition metal organometallic complexes containing chlorine ligands the 35Cl EFG tensor parameters measured via 35Cl NMR were found to be sensitive to the chlorine bonding environment [21—23 ], which allowed the differentiation between bridging, terminal-axial and terminal-equatorial chlorine sites. <...> The tour-de-force solid-state 35,37Cl NMR study of covalent organic chlorides, the first study of its kind, was published very recently [ 26 ]. 35Cl and 37Cl NMR spectra recorded for several solid organic chlorides with the use of the WURST-QCPMG pulse sequence were in excess of 6—7 MHz broad, which is quite remarkable even at 21.1 T. Such strong 35,37Cl EFG interactions necessitated the exact treatment of the Zeeman-quadrupolar (ZQ) interaction in modeling the experimental spectra, since the second-order perturbation theory was no longer valid [ 27 ]. <...> In practice <...>

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