223759-14-6Relevant articles and documents
Unexpected Competition between Vanadium and Zinc in the Synthesis of Sterically Bulky Metallocenes
Overby, Jason S.,Jayaratne, Kumudini C.,Schoell, Nathan J.,Hanusa, Timothy P.
, p. 1663 - 1667 (1999)
Attempts to form (Cp3i)2V and (Cp4i)2V (Cpni = C5(iPr)nH5-n) from the reaction of zinc-reduced VCl3 and K[Cpni] in THF at room temperature produces the corresponding zincocenes (Cp3i)2Zn and (Cp4i)2Zn instead. In refluxing THF, the same reactions generate the expected (Cpni)2V vanadocenes. The latter are also formed from the reaction of aluminum-reduced VCl3 with K[Cpni] at room temperature. Reaction of 3 equiv of K[Cp3i] or K[C5Ph4H] with VCl3 in THF produces (Cp3i)2V and (C5Ph4H)2V, respectively, whereas the equivalent reaction with K[Cp4i] generates (Cp4i)2VCl. These experiments suggest that zincocenes are intermediates whenever vanadocenes are synthesized from zinc-reduced VCl3 but that zinc complexes will be isolated only when certain cyclopentadienyl rings and temperature conditions are used. A single-crystal X-ray diffraction study of (Cp3i)2V found the metal to reside on a crystallographically imposed inversion center, with an average V-C(ring) distance of 2.274-(9) A?; the isopropyl groups orient themselves to minimize unfavorable steric interactions between the rings.
