Silicon-based products such as oil, grease, rubbers, resin, etc. are widely used in the industrial, agricultural, medicinal, and other areas. The above-mentioned are not naturally substances, and organosilicon compounds as the effective component are manufactured artificially. The hydrosilylation of olefins is one of the most straightforward and atom-economical methods for the generation of versatile silicon-containing intermediates in silicon chemistry. Also the catalysts are very necessary. Transition metal complexes are confirmed to have high activity and selectivity. The Pt-based complexes, such as Karstedts and Speiers catalysts, are most widely used in the past. Over the past years, the transition-metal-based catalysts such as Pd, Rh, Ru, Zr, etc. have been reported to be efficient in the alkene hydrosilylation reaction. In this paper, we mainly introduce the advances in new reaction mechanisms of olefin hydrosilylation catalyzed by several transition metal complexes. In particular, we highlight the new mechanistic pathways from the experimental studies and quantum mechanics calculations. Not only a summary of previous works is given, but also some ideas and inspirations are provided for future research.

Contents
1 Introduction
2 Mechanisms of olefin hydrosilylation catalyzed by late transition metal complexes
2.1 Platinum complexes catalysts
2.2 Reaction mechanism catalyzed by platinum complexes
2.3 Ruthenium complexes catalysts and reaction mechanisms of olefin hydrosilylation
3 Mechanisms of olefin hydrosilylation catalyzed by middle transition metal complexes
3.1 Family of chromium (Cr、Mo、W) complexes catalysts and reaction mechanism
3.2 Family of manganese (Mn、Tc、Re) complexes catalysts and reaction mechanism
4 The mechanism of olefin hydrosilylation catalyzed by early transition metal (Zr、Ti、Hf) complexes
5 Conclusion and outlook