This invention also provides a dihalosilane represented by the general formula (7): ##STR8## wherein Y represents a chlorine atom, a bromine atom or an iodine atom; R1 represents a substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl group; X is an atom having an unpaired electron or a group containing an atom having an unpaired electron, and represents an oxygen atom, a sulfur atom or