title: Tetranuclear Tetrapyrido[3,2-a:2',3'-c:3",2"-h:2"',3"'-j]phenazineruthenium Complex: Synthesis, Wide-Angle X-ray Scattering, and Photophysical Studies.
abstract: The tetranuclear ruthenium complex {Ru[(tpphz)Ru(bpy)(2)](3)}(8+), where tpphz is tetrapyrido[3,2-a:2',3'-c:3",2"-h:2"',3"'-j]phenazine, has been synthesized by reaction of [Ru(tpphz)(3)](2+) with [Ru(bpy)(2)Cl(2)] and by reaction of [Ru(bpy)(2)(tpphz)](2+) with [Ru(DMSO)(4)Cl(2)]. The large distance between the chiral centers allows full (1)H NMR interpretation despite the mixture of eight stereoisomers. The tetranuclear complex was further characterized by electrospray mass spectrometry and by the wide-angle X-ray scattering technique, which confirmed the starburst geometry. The photophysical properties of the tetranuclear complex in acetonitrile were studied and compared with those of [Ru(tpphz)(3)](2+) (1 x 10(-)(4) M acidic solution) and [(bpy)(2)Ru(tpphz)Ru(bpy)(2)](4+) model molecules. The tetranuclear complex gives rise to a single emission, attributed to metal-to-ligand charge-transfer states involving peripheral Ru centers and tpphz bridging ligands.
authors.affiliation: CEMES-CNRS UPR 8011, BP 4347, 29 Rue Jeanne Marvig, 31055 Toulouse, France, and Dipartimento di Chimica, Centro di Reattività e Catalisi CNR, Università di Ferrara, Via L. Borsari 46, 44100 Ferrara, Italy.
authors.forename: Eléna
authors.initials: E
authors.lastname: Ishow
authors.forename: André
authors.initials: A
authors.lastname: Gourdon
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Launay
authors.forename: Pierre
authors.initials: P
authors.lastname: Lecante
authors.forename: Marc
authors.initials: M
authors.lastname: Verelst
authors.forename: Claudio
authors.initials: C
authors.lastname: Chiorboli
authors.forename: Franco
authors.initials: F
authors.lastname: Scandola
authors.forename: Carlo-Alberto
authors.initials: CA
authors.lastname: Bignozzi