Rapid and Efficient Solid-State Mechanosynthesis of Bipyridine Metal Complexes.

2,2'-bipyridine is considered to be the most widely used chelating ligand and it has been extensively studied especially in the areas of coordination chemistry, medicine, materials, and catalysis. A mechanochemical reaction is a process that involves the application of mechanical energy and it provides a high yield in a shorter reaction time and eliminates the need for bulk solvents, typically request in solvothermal reaction. Notwithstanding the importance of the synthesis of bipyridine-metal compounds for several decades and recent advancements in the mechanochemical synthesis the development of a mechanochemical protocol for the synthesis of metal complexes bearing bipyridine remains unexplored. In this work, we extensively studied the mechanochemistry reaction of more than 10 metallic precursors of Ru, Ir, Pt, Pd, Fe, and Co with 2,2'-bipyridine in different stoichiometric ratio without utilization of bulk solvents, under ambient conditions and without air-sensitive procedures. A comparison of the yield, reaction time, temperature, frequency, green metrics (E-factor and the Effective Mass Yield (EMY)) of conventional solvothermal methodologies and mechanochemical synthesis clearly indicates that the mechanochemical approach is more sustainable and efficient. Mechanochemistry approach can be complementary to common solvothermal approach, and in the future, it will be required greater attention in the field of organometallic chemistry.