Table 5.
13C‐NMR signal enhancement levels seen for the indicated carbon signals of imidazole as a function of catalyst (optimum polarisation transfer field in brackets) at 9.4 T, with and without 5 mM HCl
| Catalyst 13C signal | CA | CB | CA | CB |
|---|---|---|---|---|
| Without HCl | With HCl | |||
| IMes | 61 (90 G) | 9 (120 G) | 59 (90 G) | 40 (30 G) |
| d 22‐IMes | 243 (90 G) | — | 144 (80 G) | 149 (40 G) |
| SIMes | 446 (100 G) | 89 (100 G) | 365 (90 G) | 489 (110 G) |
| d 22‐SIMes | 274 (110 G) | — | 221 (30 G) | 322 (30 G) |
reagent concentrations were 6.5 mM (iridium), 65 mM (imidazole) and 19.5 mM (acetonitrile).