Mono-, di-, and trimetallic complexes of the nonalternating polycondensed pi-perimeter decacyclene, C36H18: Synthesis, structure, and spectroelectrochemistry of [{(eta(5)-Me4EtC5)Co}(2)(mu-eta(5):eta(4)-C36H18)]

Reaction of the half-sandwich complexes [(eta (5)-Me4RC5)M(eta (2):O-acac)] (M = Co, Ni; R = Me or Et) with di- and trianions of the polycondensed pi -hydrocarbon decacyclene results in formation of the first Co and Ni triple -decker complexes of this hydrocarbon. For the title compound NMR spectra a s well as a crystal structure analysis reveal an antarafacial coordination of two {(eta (5)-Me4EtC5)Co] fragments at the central six-membered ring and one of the neighboring five-membered rings of decacyclene. The bridging pi -perimeter decacyclene displays a bowl-shaped topology. In the case of Ni, coordination of two {(eta (5)-Me5C5)Ni} fragments at the central six-membe red ring of decacyclene is observed, based on the results of H-1 and C-13 N MR studies. This coordination mode is without precedent for nickel organome tallic compounds reported so far. The cobalt complex shows a rich spectroel ectrochemistry. Results of cyclic voltammetry and coupled ESR experiments r eveal a strong interaction of both metal centers in the mixed-valent monoca tion of [{(eta (5)-Me4EtC5)-Co}(2)(mu-eta (5):eta (4)-C36H18)]. This catego rizes the title compound into Robin Day class III.