The kinetics of the reduction of 2-methyl-(7) and 2-(Z-benzyl)-5-nitroisoquinolinium cations (2) by 1-(X-benzyl)-l, 4-dihydronicotinamides (1) to give the corresponding 1, 2-dihydro-5- nitroisoquinohes have been studied in 20% acetonitrile-80% water (v/v) at pH 7.0, 25 OC, and an ionic strength of 1.0. Deuterium labeling studies indicated direct hydrogen transfer from C-4 of 1 to C-1 of 2 or 7 without exchange with solvent protons. In the presence of ...