First Row Transition Metals in Olefin Metathesis: The Role of Iron and Manganese

Abstract

Olefin metathesis has traditionally been dominated by molybdenum and ruthenium-based catalysts, but the pursuit of sustainable and earth-abundant alternatives has driven interest in first-row transition metals particularly iron. While iron is an attractive candidate due to its abundance, low toxicity, and cost-effectiveness, significant challenges hinder its successful implementation in metathesis reactions. This review examines the electronic and structural properties of iron that contribute to its catalytic limitations, including high-spin configurations, weak metal-alkylidene interactions, and a pronounced tendency toward cyclopropanation. Computational and experimental efforts to overcome these obstacles are discussed, focusing on ligand design strategies and mechanistic insights. Additionally, the potential of manganese as an alternative to iron is explored. This work underscores the complexities of first-row transition metal catalysts in olefin metathesis and highlights future directions for achieving practical, efficient iron-based systems. Future research should focus on refining ligand architectures to stabilize key intermediates, leveraging computational insights to predict reactivity trends, and further investigating the role of metal oxidation states in metathesis activity. While the transition to first-row transition metals remains a challenge, ongoing advancements continue to push the boundaries of sustainable catalysis, bringing the dream of practical iron- or manganese-based olefin metathesis closer to reality