Engineering Highly Active Single-Phosphine-Coordinated Ru Catalysts for Heterogeneous N -Alkylation without Base-Additive

Abstract N-Alkylation of amine with alcohol is an attractive route for synthesizing high-value amines. However, existing homogeneous and heterogeneous catalytic systems still suffer from limitations such as insufficient metal utilization, requirement for alkaline additives, poor recyclability, and limited intrinsic activity. Herein, we propose an alcohol-driven coordination tailoring strategy, in which the alcohol governs the transformation of pristine Ru1-3P sites into highly active Ru1-1P with a well-defined [RuH2Cl2(Ph-CHO)(PPh3)] configuration. In base-additive-free N-alkylation, the Ru1-1P/POPs catalyst delivers a TOF of 323 h–1 and an apparent activation energy of 70.1 kJ·mol–1, far outperforming the Ru1-3P/POPs (145 h–1, 103.3 kJ·mol–1) and surpassing most reported catalysts. Comprehensive characterization confirms that Ru remains atomically dispersed even after 10 cycles. Mechanistic studies reveal that different from traditional base-dependent pathways, this catalytic cycle follows a dihydride transfer mechanism. The unique Ru1-1P configuration significantly reduces the barrier of the rate-determining β-hydride elimination. This work provides a facile strategy for regulating single-atom coordination environments and deepens the understanding of structure-performance relationships at the molecular level.