Cp* as a removable protecting group: low valent Zn(I) compounds by reductive elimination, protolytic and oxidative cleavage of Zn-Cp*.

Zn-Cp* bond cleavage reactions leading to novel monovalent cationic zinc species are presented (Cp* = pentamethylcyclopentadienyl). The treatment of [Zn2Cp2] with two equiv. of [H(Et2O)2][BAr4(F)] (BAr4(F) = B{C6H3(CF3)2}4) yields the triple-decker complex [Cp3Zn4(Et2O)2][BAr4(F)] (1) via protolytic removal of a Cp* ligand as CpH, whereas the reaction with an equimolar amount of [FeCp2][BAr4(F)] (Cp = cyclopentadienyl) results in the formation of [CpZn2(Et2O)3][BAr4(F)] (2) under oxidative cleavage of a Cp* ring giving decamethylfulvalene, (Cp*)2, and [FeCp2] as by-products. The molecular structures of compounds 1 and 2 are established by single-crystal X-ray diffraction studies. A new synthetic pathway for the formation of [Zn2Cp2] based on the reductive elimination of CpH from in situ formed Cp*ZnH is presented.