Compensated Silicon doped with elements of transition group reveals a number of unique properties which strongly depend on the concentration of electric active atoms concentration. The paper is devoted to investigation of interaction among impurity manganese and silicon atoms. Investigation results showed that in the temperature range of 1200-13000 0C manganese atoms form electric neutral molecules with oxygen. Formation of such molecules in silicon provides not only electric neutrality, but also decreases participation of oxygen atoms in formation of other complexes which are responsible for generation of thermodonors and aggravation of electric and physical parameters of semiconductor devices.