The project focuses on research of enzymatic and synthetic polynuclear clusters FenSn (n=2,4) mainly on their redox and acid-base properties and their influence on the barrier for the transfer of hydrogen atom. This study will be based on a new concept of asynchronicity that we have developed (Proc Natl Acad Sci USA, 2018, accepted manuscript). Results are expected to contribute significantly to a general understanding of the properties of FeS-dependent radical enzymes (including understanding their selectivity).