Scalable and Robust Synthesis of CpRu(MeCN)3PF6 via Continuous Flow Photochemistry

The preparation of CpRu(MeCN)(3)PF6 using an easily assembled continuous flow reactor is described. This scalable, reproducible method provides the title compound in excellent yield and purity, and eliminates the need for any purification steps. Under our optimized conditions, the residence time required for complete conversion was only 5 min at an initial substrate concentration of 0.06 M, as compared to a reaction time of 12-36 h for the batch process at 0.02 M. This threefold increase in concentration and significant decrease in reaction time increases the throughput and efficiency of the synthesis. Using the simple laboratory equipment described herein, ruthenium catalyst of >99% purity was produced with a throughput of 1.56 g/h (5 mL reactor), which is 10 times the highest reported throughput for the batch process.