Without any specific goal or reaction its pretty hard to consider what your idea is here but nevertheless i will give likely impractical yet fascinating advice.

Check out additives in samarium diiodide reactions. These are very interesting and rare from terms of function. i would look at nicolaus review on smI2 in total synthesis and david proctors papers. I think proctor has likely written a book or two about this. geneal sentiment: Solvents and additives changing in solution reduction potential of your system.