Zusammenfassung
Tetranuclear (PiPr3)2(CO)ClRu(μ-CH:CHpy)RuCl(CO)(PPh3)22(m-CH:CHC6H4CH:CH-1,4) (3a; py = pyridin-4-yl) and (PiPr3)2(CO)ClRu(μ-CH:CHpy)RuCl(CO)(PPh3)22(m-CH:CHC6H4CH:CH-1,3) (3b), which contain vinylpyridine ligands that connect peripheral Ru(PiPr3)2(CO)Cl units to a central divinylphenylene-bridged diruthenium core, were prepd. and studied. These complexes, in various oxidn. states up to the tetracation level, were characterized by std. electrochem. and spectroelectrochem. techniques, including IR, UV/visible/NIR and ESR spectroscopy. A comparison with the results for the vinylpyridine-bridged dinuclear complex (PiPr3)2(CO)ClRu(m-CH:CHpy)RuCl(CO)(PPh3)2(CH:CHPh) (6) and the divinylphenylene-bridged complexes (EtOOCpy)(CO)Cl(PPh3)2Ru2(m-CH:CHC6H4CH:CH-1,4) (8a) and (EtOOCpy)(CO)Cl(PPh3)2Ru2(m-CH:CHC6H4CH:CH-1,3) (8b), which represent the outer sections (6) or the inner core (8a,b) of complexes 3a,b, and with mononuclear (EtOOCpy)(CO)(PPh3)2RuCl(CH:CHPh) (7) indicate that every accessible oxidn. process is primarily centered on one of the vinyl ligands, with smaller contributions from the metal centers. The exptl. results and quantum chem. calcns. indicate charge- and spin-delocalization across the central divinylphenylenediruthenium part of 3a,b or the styrylruthenium unit of 6, but not beyond. The energy gap between the higher lying styryl- or divinylphenylenediruthenium-based and the lower occupied vinylpyridineruthenium-based orbitals increases in the order 6 \textless 3b \textless 3a and thus follows the conjugation within the non-heteroatom-substituted arom. vinyl ligand. on SciFinder(R)
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