Tris (trimethylsilyl) cyclopentadiene was treated with n-BuLi in diglyme or THF, followed by reaction with Mo(CO)6. The corresponding lithium salt of molybdenum anion [η^5-{(Me3Si)nC5H5-n}Mo^-(CO)3]Li^+, 1, (n=2, 3) was formed. Meanwhile, desilylation was observed. The reaction of 1 with X(CH2)3X was carried out in diglyme, either X=I or Br, all gave the title complexes [X=I: n=3(2), n=2(3); X=Br: n=3(4), n=2(5)]. If the same reaction was carried out in THF, only when X=I, the cylic carbene complexes could be formed. The structures of 2-5 were characterized by elemental analyses, IR, 1H NMR and 13C NMR spectra. The crystal structure of 4 was determined X-ray crystallography. The crystal is monoclinic, with space group P21/n, a=1.2611(3), b=1.2434(2), c=1.7095(6)nm, β=91.07(2)°, V=2.680(2)nm^3, Dc=1.563g.cm^-^3, Z=4. The final deviation factor R=0.062, Rw=0.054.

Key words: INFRARED SPECTROPHOTOMETRY, ELEMENTAL ANALYSIS, CRYSTAL STRUCTURE, X-RAY DIFFRACTION ANALYSIS, C13 NMR SPECTROMETRY, CYCLOPENTADIENE P, CARBENE, PROTON MAGNETIC RESONANCE SPECTROMETRY, MOLYBDENUM COMPLEX