Investigation of Manganese-based Catalysts for Carbonyl Hydrosilylation

Since its discovery in the late 1940s, hydrosilylation reactions have become crucial in both industrial and laboratory settings to form silicon-carbon and silicon-oxygen bonds.^1,2 Since Speier's exploration into chloroplatinic acid catalyzed olefin hydrosilylation, precious metal catalysts have been widely implemented for the production of silicon products including adhesives and rubber.² It is estimated that the silicon industry worldwide consumes around 5,600 kilograms of platinum each year.³ Given the cost, toxicity, and low abundance of these precious metal catalysts, there has been interest in synthesizing sustainable alternatives.^4,5 While iron, cobalt and nickel were at the forefront of this initiative, manganese has shown to be promising, and researchers have sought to unlock its potential.⁴ This has led to the development of manganese-based catalysts that explore different ligand systems to mediate hydrosilylation reactions. In this talk, pyridine diimine (PDI), N-phosphinoamidinate and bis-N-heterocyclic carbene ligand systems are investigated and their reactivity with various carbonyl containing compounds are tested to evaluate their activity and stability.^2,4,5,6 In addition to calculating turn over frequencies and/or turn over numbers for some of the catalysts, mechanistic pathways were investigated for select catalysts. These findings have established breakthroughs for manganese catalysts and shed light on mechanistic pathways which further aid in understanding and developing future hydrosilylation catalysts.^2,4

1. Ojima, I. Organic Silicon Compounds. 1989, 1479.

2. Trovitch, R.J. et al., J. Am. Chem. Soc. 2017, 139, 4901.

3. A. J. Holwell, Platinum Met. Rev. 2008, 52, 243– 246.

4. Trovitch, R.J. et al., Acc. Chem. Res. 2017, 50, 2842.

5. Turculet, L. et al., Angew. Chem. Int. Ed. 2017, 56, 15901.

6. Royo, B. et al., ChemCatChem. 2018, 10, 2734.