Syntheses, structures and redox properties of {Os(PPh3)2Cp}2{μ-(Ctriple bond; length of mdashC)x} (x = 2, 3, 4): Comparisons with the Ru analogues

The syntheses of {Os(PPh3)2Cp}2{μ-(Ctriple bond; length of mdashC)x} (x = 2, 3, 4) from reactions between OsBr(PPh3)2Cp* and Me3Si(Ctriple bond; length of mdashC)xSiMe3 in the presence of KF/NaBPh4 are described. The molecular structure of x = 3 has been determined by a single-crystal XRD study. Comparison of the redox properties of {M(PPh3)2Cp}2{μ-(Ctriple bond; length of mdashC)x} (M = Ru, Os) shows that the oxidation potentials of the osmium complexes are invariably lower (by between 0.16 and 0.64 V) than those of the Ru analogues.