“…The dianion of cyclooctatetraene has been used successfully to prepare COT complexes of primarily the early transition metals (e.g., Ti(»;8-C8H8)(? ;4-C8H8), ref 9), metals in the actinide series (e.g., U(t;8-CsH8)2, ref lc), and metals in the iron triad (e.g., Ru-(bicyclo[2.2.1 ]hepta-2,5-diene)(7j6-C8H8), ref 10). This technique is cleaner and more predictable than that employing reducing agents such as aluminum alkyls in the presence of COT and seemed particularly suitable for preparation of Nb and Ta COT complexes.…”