Synthesis of carboxy-pyrrole and indole Ru-Complexes and conversion of coordination from K2-(O,O) to K2-(N,O)

Organometallic compounds are playing an increasingly important role in medicinal chemistry due to their unique features, such as their ability to interact with biological molecules, showing different reactivity, and tunable electronic structures. These compounds are utilized for a variety of functions in medicinal chemistry, including use as anticancer, antibacterial, antiviral, and anti-inflammatory agents, in targeted drug delivery, imaging, and enzyme inhibition or modulation. Indole and pyrrole derivatives are particularly important ligands when coordinated to ruthenium. Their coordination helps fine-tuning of the stability, electronic properties, and biological activity of the Ruthenium complexes, a crucial aspect in designing new metal-based anticancer drugs and catalysts. Solvent ligands, such as water, alcohols, acetonitrile, and dimethyl sulfoxide (DMSO), also play a key role when coordinated to Ruthenium complexes. They can significantly influence stability, reactivity, and overall characteristics of the complexes. Solvent addition contributes to stabilization, prompts to ligand exchange and electronic tuning, increasing solubility features. In this context, indole and pyrrole-2-carboxylic acid are first coordinated to [Ru(H)2(CO)(PPh3)3], followed by a subsequent coordination of acetonitrile molecule for both complexes. Interestingly, a change in the coordination site of pyrrole and indole-2-carboxylic acid is observed, shifting the coordination from k2-(O,O) to k2-(N,O), upon acetonitrile incorporation. In the second step, these solvent-complexes react with organic ligands as the 4-picoline and 4-aminopyridine, leading to the displacement of acetonitrile. Additionally, the biologically compatible DMSO is coordinated in exchanging the acetonitrile-solvent coordination to enhance the solubility of the obtained complexes.