Onium-boronium cations

Hypercoordinate Onium-Carbonium Dications and Isoelectronic Onium-Boronium Cations... 

In general, a broad correlation was found between the calculated NMR chemical shifts of onium-carbonium dications and the calculated B NMR chemical shifts of the corresponding isoelectronic onium-boronium cation analogs (Fig. 5.16). However, the correlation line for Figure 5.16 [Eq. (5.37)] has a slope of 0.45 contrast 0.33 for Equation (5.36) ... 

Figure 5.16. Correlation between the calculated NMR chemical shifts of onium-boronium cations and the calculated NMR chemical shifts of onium-carbonium dications (259-268, Scheme 5.17).

Shielding calculations using inexpensive computer resources routinely support the assignment of structure via NMR spectroscopy. We mention some examples here. In this reporting period, calculations of chemical shifts in specific systems have been used to support identification of species in solution, such as for B in diphenylboron cation, in boronium-onium cations, and in proposed transient intermediates, Al in alonium-onium cations, Si in siliconium-onium dications, and C in carbonium-onium dications, and in substituted vinyl cations. Structural assignments of products of reactions are assisted by calculations of C (and also H) chemical shifts, for... 

---