The story of a mechanism-based solution to an irreproducible synthesis resulting in an unexpected closed-system requirement for the LiBEt3H-based reduction: The case of the novel subnanometer cluster, [Ir(1,5-COD)(μ-H)]4, and the resulting improved, inde

Reproducibility issues in the synthesis of the novel sub-nanometer cluster [Ir(1,5-COD)(μ-H)]4 are investigated; only after the “paper mechanism” shown was written down was a prediction-and then experimental verification-of the missing detail required for a repeatable, reliable synthesis discovered: namely the need to employ a closed reaction system for reduction of the Ir-Cl in [(1,5-COD)IrCl]2 by LiBEt3H, a previously hidden insight with broader implications for other metal-halide reductions by boron-hydride reagents that can proceed by electron transfer mechanisms, the formation of HBEt3, its cage escape, disproportionation 2 HBEt3 → H2 + 2 BEt3, and then volatile H2 loss if the system is not a closed system.