Diruthenium σ-iminophenylacetylide complexes from on-complex Schiff base condensation

Six diruthenium(II,III) compounds of the formula Ru2(ap)4–(Ctriple bond; length of mdashC–C6H4-4-Ndouble bond; length as m-dashCH–4′–C6H4–R) (ap as 2-anilinopyridinate, 3) and Ru2(ap)4–(Ctriple bond; length of mdashC–C6H4–3–Ndouble bond; length as m-dashCH–4′–C6H4–R) (4), where R is H (a), Br (b) or CHO (c), were prepared from the condensation reactions between Ru2(ap)4(Ctriple bond; length of mdashC–C6H4–4/3–NH2) (1/2) and an appropriate aldehyde. X-ray structural studies of compounds 3a and 3b revealed minimal changes upon the formation of the imine bond in the coordination sphere of the Ru2 core with respect to the parent compounds. Voltammetric measurements show that compounds 3a/b and 4a/b exhibit four one electron redox processes: an oxidation of Ru2, two reductions of Ru2, and a reduction of the imine group. Both compounds 3c and 4c also undergo a fourth reduction attributed to the aldehyde functional group.