Molecule: 2-alkyl-benzimidazole

Red spectrum: regular 13C

Blue spectrum: 13C with Cr(acac)3 using the setup procedure described in this blog entry.

Both were run at ca. -24degC. Both took ca. 45 min.

Cr(acac)3 is especially powerful in speeding up the T1 relaxation of unprotonated 13C.