Effect of metals on the electronic communication through a molecular wire model

Two triosmium complexes of 1,4-bis(ferrocenyl)-1,3-butadiyne, Os-3(CO)(10)( mu(3)-FcC(4)Fc) (2) and Os-3- (CO)(11)(mu(3)-FcC(4)Fc) (3) (Fc = (C5H5)Fe(C 5H4)), have been prepared and structurally characterized. In 2 one of the t riple bonds of the butadiyne grouping is coordinated as a triple bridge to a triangle of three osmium atoms. In 3 the triosmium cluster is opened and is coordinated as a Linear chain to both triple bonds. The electronic commu nication measured via redox potentials of the ferrocenyl groups indicates t hat the metal atoms increase the electronic communication in 3 and decrease it in 2.