Preparation, structure and reactivity of the nonbonded organoditantalum(IV) complexes (. eta. -C sub 5 Me sub 4 Ta sub 2 (. mu. -X) sub 4 ) (R = Me, Et; X = Cl, Br), precursors to the doubly bonded organoditantalum(III) complexes (. eta. -C sub 5 Me sub 4 R) sub 2 Ta sub 2 (. mu. -X) sub 4

It is reported that a dinuclear organoditantalum(IV) complex is an isolable intermediate in the reductive dimerization of the mononuclear (peralkylcyclopentadienyl)-tantalum(V) complexes ({eta} -C{sub 5}Me{sub 4}R)TaX{sub 4} where R=Me, Et; X=Cl, Br to the doubly bonded organoditantalum(III) complexes ({eta}-C{sub 5}Me{sub 4}R{sub 2})Ta({mu}-x){sub 4}. This intermediate compound was found to be paramagnetic in solution and to have a solid-state structure with two bridging halogen atoms and no tantalum-tantalum bonding interaction. The reactivity of this intermediate complex should render it very useful for the preparation of other Ta(IV) complexes and, through oxidative addition, Ta(V) organometallics. 4 tabs., 1 fig., 21 refs.