SYNTHESIS, CHARACTERIZATION AND REACTIVITY OF THE FIRST HEPTAMETHYLINDENYL-MOLYBDENUM COMPLEXES - CRYSTAL-STRUCTURES OF [MO(CO)(ETA(2)-MEC-CME)(2)(ETA(5)-C9ME7)]BF4 AND [MO(CO)(2)(ETA(3)-C3H5)(ETA(5)-C9ME7)]

The synthesis and characterisation of the first (eta(5)-heptamethylind enyl)molybdenum complexes are reported. Reaction of Li[C9Me7] with Mo( CO)(6) in refluxing THF readily forms Li[Mo(CO)(3)(eta(5)-C9Me7)], whi ch is shown to be a useful precursor in the formation of (carbonyl)(et a(5)-heptamethylindenyl)molybdenum complexes. The compounds [MoI(CO)(3 )(eta(5)-C9Me7)] 3, [Mo(Me)(CO)(3)(eta(5)-C9Me7)] 4 and [Mo(CO)(2)(eta (3)-C3H5)(eta(5)-C9Me7)] 5 have been prepared from this intermediate a nd characterised. Treatment of 3 with AgBF4 and MeC=CMe affords [Mo(CO )(MeC=CMe)(2)(eta(5)-C9Me7)]BF4 6a; for this and the indenyl analogue, a new route to carbonyl-bis(alkyne)-molybdenum derivatives is demonst rated. Reaction of 3 with TIPF6 in MeCN forms the complex [Mo(MeCN)(2) (CO)(2)(eta(5)- C9Me7)]PF6 7. Protonation of 5 in the presence of MeC= CMe, or reaction of 7 with the same acetylene, also yields 6 with appr opriate counter anions. Single crystal X-ray diffraction studies of co mpounds 5 and 6a are reported.