SYNTHESES AND STRUCTURES OF TRIS(TRIMETHY LSILYL) CYCLOPENTADIENYL MOLYBDENUM CYCLIC CARBENE COMPLEXES

Tris(trimethylsilyl) cyclopentadiene was treated with n - BuLi in digl yme or THF, followed by reaction with Mo(CO)(6). The corresponding lit hium salt of molybdenum anion [eta(5)- {(Me3Si)(n)C5H5-n}Mo(CO)(3)](-) Li(+)1, (n = 2, 3) was formed. Meanwhile,desilylation was observed. Th e reaction of 1 with X(CH3)(3)X 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 stru ctures of 2 similar to 5 were characterized by elemental analyses, IR, H-1 NMR and C-13 NMR spectra. The crystal structure of 4 was determin ed by X-ray crystallography. The crystal is monoclinic, with space gro up P2(1)/n, a = 1.2611(3), b = 1.2434(2), c = 1.7095(6) nm, beta = 91. 07(2)degrees, V = 2.680(2)nm(3), D-c = 1.563 g.cm(-3),Z = 4. The final deviation factor R = 0.062, R-w=0.054.