Accurate nuclear quadrupole moment of ruthenium from the molecular method

Abstract

The nuclear electric quadrupole moment (NQM) of ruthenium was reevaluated by means of the molecular method. Therefore, four-component relativistic electronic structure calculations of the electric field gradient at the Ru nucleus in ruthenium monocarbide, which were done with the coupled cluster methodology and carefully augmented large basis sets, were combined with the respective nuclear quadrupole coupling constant from experiments. This provided a recommended NQM value of (425 ± 13) mbarn for 101Ru.

Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

“…[5] An analogous approach has been developed when only the quadrupolar parameters are determined via NQR being termed 'NQR crystallography'. [6,22] 2.1 | Hardware and referencing 2.1.1 | Applied magnetic fields More widespread NMR observation of solids using MAS (e.g., 13 C, 29 Si and 27 Al) starting in the mid-to late-1980s was predominantly on wide-bore 7.05 or 9.4 T magnets. The resulting low frequencies for low-γ nuclei (i) meant there were few probes available to observe them, (ii) did not help with the intrinsically weak signals, (iii) had larger second-order quadrupolar effects than at higher magnetic fields and (iv) suffered from some experimental complexities at such low frequencies (e.g., probe ringing [14,23] ).…”

“…[57] Increasing the bandwidth of pulses continues to be an active area of research to make more nuclei accessible, with an important addition being broadband adiabatic inversion (BRAIN) pulses to help with cross-polarisation. [58] More detailed reference to the development of such sequences including the manipulation of satellite transition intensity is given in previous works, [12,13] as well as in several of the reviews in Table 3 listed in Section 3. On many occasions, the linewidths still exceed the extended bandwidth from such approaches and frequency-offsetting is still necessary, usually in combination with improved bandwidth excitation.…”

“…In recent developments rather than rely on the effects listed above in (iii) to bring about the polarisation transfer, a more direct equivalent to CP is being examined. [103] As for conventional NMR, DNP studies have been dominated to date by 1 H and 13 C, with few applications to low-γ nuclei. However, examples do exist such as for 35 Cl in active pharmaceutical ingredients.…”

“…There is no doubt that the use of such calculations has added an important dimension to NMR methodology, with often real new insight provided about materials. The bulk of this work has been applied to 1 H and 13 C but is also making a very important contribution to the study of inorganic materials. There are still limited examples of such calculations from the nuclei reviewed here.…”

“…Although this is an absolute quantity, a better understanding is provided when the receptivity is quoted relative to a commonly studied nucleus. Often 1 H or 13 C are quoted as references; however, for inorganic materials, one of the most commonly studied spin-½ nuclei is 29 Si, which is used as the reference point here (Table 1). The great power of NMR spectroscopy to understand molecules and materials comes from the fact that within the spectral resolution available, the range of local interactions present can provide a lot of information about the local surroundings (i.e., the immediate coordination up to intermediate length scales).…”