Synthesis, structure and electrochemistry of cationic diruthenium complexes of the type [(N∩N) 2Ru 2(CO) 2(μ-CO) 2(μ-OOCFc)] + containing a ferrocenecarboxylato bridge and two chelating aromatic diimine ligands

Abstract

The dinuclear bis(ferrocenecarboxylato) complex Ru 2(CO) 4(μ-OOCFc) 2(py) 2 (Fc = ferrocenyl, py = pyridine) was found to react with aromatic diimines (2,2′-dipyridyl, 4,4′-dimethyl-2,2′-dipyridyl, 1,10-phenanthroline, 5-nitro-1,10-phenanthroline, and 5-amino-1,10-phenanthroline) in methanol to give the cationic diruthenium complexes [(N∩N) 2Ru 2(CO) 2(μ-CO) 2(μ-OOCFc)] + ( 1: N∩N = 2,2′-dipyridyl, 2: N∩N = 4,4′-dimethyl-2,2′-dipyridyl, 3: N∩N = 1,10-phenanthroline, 4: N∩N = 5-nitro-1,10-phenanthroline, 5: N∩N = 5-amino-1,10-phenanthroline), which have been isolated as the hexafluorophosphate salts. The molecular structure of 3, solved by single-crystal X-ray analysis of the tetraphenylborate salt [ 3][BPh 4], shows a diruthenium backbone bridged by two carbonyl and by one ferrocenecarboxylato ligand, the two 1,10-phenanthroline ligands being in the axial positions. Cyclic voltammetry in dichloromethane reveals for all compounds two successive oxidations due to ferrocene/ferrocenium redox couple and oxidation of the diruthenium core.