Zusammenfassung
The reaction of [(Cp2NbTe2H)-Nb-#] (1(#); Cp-# = Cp* (C5Me5) or Cp-x (C5Me4Et)) with two equivalents of [Co-2(CO)(8)] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [(Cp2NbTe2Co3)-Nb-#(CO)(7)] (2(#)) and [Co4Te2(CO)(10)] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of ...
Zusammenfassung
The reaction of [(Cp2NbTe2H)-Nb-#] (1(#); Cp-# = Cp* (C5Me5) or Cp-x (C5Me4Et)) with two equivalents of [Co-2(CO)(8)] gives a series of cobalt carbonyl telluride clusters that contain different types of niobocene carbonyl fragments. At 0 degrees C, [(Cp2NbTe2Co3)-Nb-#(CO)(7)] (2(#)) and [Co4Te2(CO)(10)] (3) are formed which disappear at higher temperatures: in boiling toluene a mixture of [cat(2)][Co9Te6(CO)(8)] (5(#)) (cat = [(Cp2Nb)-Nb-#(CO)(2)](+)) and [cat(2)][Co11Te7(CO)(10)] (6(#)) is formed along with [cat][Co(CO)(4)] (4(#)). Complexes 6(#) transform into [cat][Co11Te7(CO)(10)] (7(#)) upon interaction with HPF6 or wet SiO2. The molecular structures of 2(Cp-x), 4(Cp-x), 5(Cp*), 6(Cp*) and 7(Cp*) have been determined by X-ray crystallography. The structure of the neutral 2(Cp-x) consists of a [Co-3(CO)(6)Te-2] bipyramid which is connected to a [(C5Me4Et)(2)Nb(CO)] fragment through a mu(4)-Te bridge. The ionic structures of 4(Cp-x), 5(Cp*), 6(Cp*) and 7(Cp*) each contain one (4, 7) or two (5, 6) [(Cp2Nb)-Nb-#(CO)(2)](+) cations. Apart from 4, the anionic counterparts each contain an interstitial Co atom and are hexacapped cubic cluster anions [Co9Te6(CO)(8)](2-) (5) or heptacapped pentagonal prismatic cluster anions [Co11Te7(CO)(10)](n-) (n = 2: [6](2-), n = 1: [7](-)), respectively. Electrochemical studies established a reversible electron transfer between the anionic clusters [Co11Te7(CO)(10)](-) and [Co11Te7(CO)(10)](2-) in 6# and 7# and provided evidence for the existence of species containing [Co11Te7(CO)(10)] and [Co11Te7(CO)(10)](3-). The electronic structures of the new clusters and their relative stabilities are examined by means of DFT calculations.
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