摘要:
Reduction of Zr(IV) metallocenium cations with sodium amalgam (NaHg) produces EPR signals assignable to Zr(III) metallocene complexes. The chloro-bridged heterodinuclear ansa-zirconocenium cation [(SBI)Zr(mu-Cl)(2)AlMe2](+) (SBI = rac-dimethylsilylbis(1-indenyl)), present in toluene solution as its B(C6F5)(4)(-) salt, thus gives rise to an EPR signal assignable to the complex (SBI)Zr-III(mu-Cl)(2)AlMe2, while (SBI)Zr-III-Me and (SBI)Zr-III(mu-H)(2)(AlBu2)-Bu-i are formed by reduction of [(SBI)Zr(mu-Me)(2)AlMe2](+) B(C6F5)(4)(-) and [(SBI)Zr(mu-H)(3)((AlBu2)-Bu-i)(2)](+) B(C6F5)(4)(-), respectively. These products can also be accessed, along with (SBI)Zr-III-Bu-i and [(SBI)Zr-III](+) AlR4-, when (SBI)ZrMe2 is allowed to react with (HAlBu2)-Bu-i, eliminating isobutane en route to the Zr(III) complex. Further studies concern interconversion reactions between these and other (SBI)Zr(III) complexes and reaction mechanisms involved in their formation.