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

Six diruthenium(II,III) compounds of the formula Ru2(ap)4–(CC–C6H4-4-NCH–4′–C6H4–R) (ap as 2-anilinopyridinate, 3) and Ru2(ap)4–(CC–C6H4–3–NCH–4′–C6H4–R) (4), where R is H (a), Br (b) or CHO (c), were prepared from the condensation reactions between Ru2(ap)4(CC–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.

Reported herein is the synthesis of diruthenium compounds bearing para- or meta-imino-phenylacetylide in the axial position via on-complex Schiff base condensation, and ensuing voltammetric and structural characterization. Figure optionsDownload as PowerPoint slideHighlights
► Iminophenylacetylenes molecules are obtained by on-complex Schiff base condensation.
► CV reveals reductions due to aldehyde and imine groups stabilized by diruthenium complexes.
► Interaction of the imine functional groups with diruthenium is strongly influenced by position.