Mechanochemistry for sustainable organometallic synthesis: A review across the d-block

Mechanochemistry has emerged as a powerful and increasingly mature approach for the synthesis of coordination and organometallic compounds, offering access to reaction pathways and products that differ fundamentally from those observed under conventional solution-based conditions. This review provides a critical overview of recent developments in the mechanochemical synthesis of d-block coordination complexes, with emphasis on studies published over the last decade and on contemporary contributions that reflect current advances in structural control, mechanistic understanding, and sustainability assessment. Focusing on molecular, structurally characterized species rather than extended frameworks, the review surveys mechanochemical reactivity across early-, middle-, and late-transition metals, highlighting how solvent-free or minimally solvated conditions influence metal-ligand interactions, coordination geometries and product selectivity. Particular attention is devoted to comparisons between mechanochemical and solution-based approaches, addressing when the two converge, and when mechanochemistry enables qualitatively different outcomes. Beyond synthetic efficiency, mechanochemical methodologies are analyzed through the combined lens of green chemistry metrics, reaction rates, yields, product distributions and apparatus-dependent effects. By integrating recent experimental advances with critical analysis, this contribution positions mechanochemistry as a complementary and conceptually distinct field within modern coordination and organometallic chemistry, rather than as a universal replacement for solution-based synthesis.