The present study utilizes rapid mixing techniques together with fast optical spectroscopy to probe the assembly of [Cu-2(5-OH-bdC)(2)L-2](12) formation in methanol, The data reveal five distinct kinetic steps involved in the formation of the Cu-nanoball in methanol with lifetimes of < 15 ms, 26 ms, 310 ms, 4 s, and 45 s. From these results two possible mechanistic pathways are proposed based upon fragment isomerization followed by condensation. Both mechanisms involve fast building unit assembly (<15 ms) followed by either concerted or sequential fragment isomerization (activation controlled) coupled with condensation.