Sterically-directed disassembly of diruthenium(II,III) tetraacetate using substituted and unsubstituted 2,2′-bipyridines and 1,10-phenanthrolines

A novel synthetic methodology that involves the “disassembly” of diruthenium(II,III) tetracarboxylates using the modestly π-acidic bidentate 2,2′-bipyridine and 1,10-phenanthroline ligands and their substituted derivatives as disassembling agents was exploited to generate, in high yield, heteroleptic bis-diamine-mono-carboxylate-Ru(II) complexes. The reactions proceed so that these heteroleptic complexes are only formed when steric hindrance is introduced directly adjacent to the binding nitrogen atoms otherwise the homoleptic tris-diamine Ru(II) complexes are formed exclusively. Two novel heteroleptic complexes have been synthesized in high yield, namely [Ru(η2-O2CCH3)(6,6′-Me2-2,2′-bipy)2](PF6) 4 and [Ru(η2-O2CCH3)(2,9-Me2-1,10-phen)2](PF6) 6. Both complexes have been characterized using X-ray crystallography, elemental analysis, IR, NMR and UV–visible spectroscopy and cyclic voltammetry.

Graphical abstractA novel “disassembly” reaction of [Ru2(μ-O2CCH3)4(H2O)2]+ is achieved using bidentate 2,2′-bipyridine and 1,10-phenanthroline-type ligands as disassembling agents. Reactions proceed in such a way that heteroleptic bis-diamine-mono-carboxylate-Ru(II) complexes are only formed when steric hindrance is located directly adjacent to the binding nitrogen atoms, otherwise the homoleptic tris-diamine-Ru(II) complexes are produced.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► [Ru2(μ-O2CCH3)4(H2O)2]+ was disassembled using various heterocyclic diamines. ► Nature of product depends on steric crowding next to coordinating nitrogens. ► Heteroleptic products show lower redox potentials than homoleptic products.