A series of biseyclopentadienyl tetraearbonyl di-iron complexes

[cp’Fe(CO)2]2(Cp’=C5H5

C9H7

C5HMe4

Me3SiC5

C5HPh4

t-BuC5H4)

were employedforthe radical polymerization of styreneintoluene using Me2CBrCO2Et as initiator．It was found that the polymerization was uncontrollable for systems of [C5H5Fe(CO)2]2 and[C9H7Fe(CO)2]2．When the bulky substituents were introduced to the cyclopentadienyl rings

the polymerization rates became much slower When [C5HPh

Fe(CO)2]2 was used to catalyze the bulk polymerization of styrene

although the molecular weight distribution was somewhat broad

the molecular weisht Mn increased linearly with the converisou rate and the measured Mn values were very close to the thoretical values

indicating that the molecularweight is controllable．For the system of [(t-BuC5H4)Fe(CO)2]2

the molecular weight Mn increased linearly with the converison rate and the molecular weight distribution decreased with convemion increasing

indicating the polymerization system is controllable.