2,5-Di(trimethylsilyl)-1-methylcyclopentadiene (1) was prepared by two similar reaction steps from methyl cyclopentadiene. The reaction of 1 and Fe(CO)5 gave the expected dinuclear product [η^5-{Me3Si)2MeC5H2}Fe(CO)]2-(μ-CO)2, (2). 2 reacted with iodine to yield the Fe-Fe bond cleaved iron iodide 4.2 was reduced by Na-Hg to form the Fe-Fe bond cleaved iron anion. The anion reacted respectively with some halides to afford the substituted iron derivatives η ^5-[(Me3Si)2MeC5H2]Fe(CO)2R (R=PhCH2, 5; CH2COOC2H5, 6; Ph3Sn, 7; Ph2SnCl, 8). The crystal structure of 4 was determined by X-ray crystallography. The crystal is monoclinic, space group P21/c with a=0.7333(1), b=2.0089(3), c=1.3323(4)nm; β=92.02(2)°, V=1.962(1)nm^3, Z=4, Dc=1.57g.cm^-^1.

Key words: INFRARED SPECTROPHOTOMETRY, CRYSTAL STRUCTURE, CYCLOPENTADIENE P, IRON COMPLEX, PROTON MAGNETIC RESONANCE SPECTROMETRY, TRIMETHYLSILANES