Table 3.

Indicated proton signal enhancement levels achieved at 298 K, with a PTF of 80 G, when measured at 9.4 T, by the action of the precatalysts 1a and 1b on imidazole, with and without HCl, where the concentrations are 6.5 mM iridium, 65 mM indazole and 19.5 mM acetonitrile

	1H signal enhancement (fold)
Resonance (without HCl)	IMes	d 22‐IMes	SIMes	d 22‐SIMes
H‐2 H‐4 and H‐5	−830	−198	−517	−280
	−606	−300	−197	−206
CD3OH	1.5	10	1.4	1.2
CHD2OD	2.5	45	7.5	0.5
NCMe	−35	−30	−4	0
Resonance (with 5 mM HCl)	IMes	d 22‐IMes	SIMes	d 22‐SIMes
H‐2 H‐4 and H‐5	−571	−210	−647	−225
	−456	−153	−562	−251
CD3OH	−22	−13	−7	−31
CHD2OD	2	0.2	1.5	−0.5
NCMe	−16	−168	−12	11