A review of the recent coordination chemistry and catalytic applications of pyrazole and pyrazolyl transition metal complexes

The versatile coordination behavior of the pyrazolyl based ligands has given rise to a rich coordination chemistry and applications of their transition metal complexes. This diverse coordination chemistry is largely derived from the ease of fine-tuning the steric and electronic features of these pyrazolyl ligands and their resultant complexes. The pyrazolyl transition metal complexes are thus amenable to a wide range of coordination features, rendering them suitable for various applications such as catalysis, electronic and magnetic devices among others. The current review captures and analyses recent progress and reports on the syntheses, coordination chemistry of the pyrazole and pyrazolyl transition metal complexes and their applications in transition metal catalyzed oligomerization and polymerization, hydrogenation, carbonylation, carbon‑carbon coupling, and biomimetic reactions. The review also presents a critical analyses and comparisons of the current findings with other related non-pyrazolyl transition metal complexes, thus providing insights on the potential of these pyrazolyl metal complexes as catalysts in various organic transformations.