Synthesis, structure and spectroelectrochemistry of bis(η6-1,4-tri-tert-butyl-benzene)chromium(0) and bis(η5-1,2,4-tri-tert-butyl-cyclopentadienyl)cobalt(II). Dia- and paramagnetic sandwich complexes derived from sterically highly demanding π-ligands

Abstract

Metal atom synthesis gives access to the bis(arene)chromium sandwich of 1,4 di-tert-butyl-benzene (5). 5 displays an axial sandwich structure with a linear arene-chromium-arene axis and a Cr-arene distance of 1.64 Å. Reduction of [{(η5-1,2,4 tri-tert-butyl-Cp)CoCl}2] with the trianion of decacyclene in THF produces the cobaltocene sandwich [(η5-1,2,4 tri-tert-butyl Cp)2Co] 2 as black crystals in 65% yield. Electrochemistry shows that the monocations 2+ and 5+ are able to support reversibly the one-electron reduction to their corresponding neutral congeners. © 1999 Elsevier Science S.A.