title: C7 and C9 carbon-rich bridges in diruthenium systems: synthesis, spectroscopic, and theoretical investigations of different oxidation States.
abstract: Two methodologies of C-C bond formation to achieve organometallic complexes with 7 or 9 conjugated carbon atoms are described. A C7 annelated trans-[Cl(dppe)2Ru=C=C=C-CH=C(CH2)-C[triple bond]C-Ru(dppe)2Cl][X] (X = PF6, OTf) complex is obtained from the diyne trans-[Cl(dppe)2Ru-(C[triple bond]C)2-R] (R = H, SiMe3) in the presence of [FeCp2][PF6] or HOTf, and C7 or C9 complexes trans-[Cl(dppe)2Ru-(C[triple bond]C)n-C(CH3)=C(R1)-C(R2)=C=C=Ru(dppe)2Cl][X] (n = 1, 2; R1 = Me, Ph, R2 = H, Me; X = BF4, OTf) are formed in the presence of a polyyne trans-[Cl(dppe)2Ru-(C[triple bond]C)n-R] (n = 2, 3; R = H, SiMe3) with a ruthenium allenylidene trans-[Cl(dppe)2Ru=C=C=C(CH2R1)R2][X]. These reactions proceed under mild conditions and involve cumulenic intermediates [M+]=(C=)nCHR (n = 3, 5), including a hexapentaenylidene. A combination of chemical, electrochemical, spectroscopic (UV-vis, IR, NIR, EPR), and theoretical (DFT) techniques is used to show the influence of the nature and conformation of the bridge on the properties of the complexes and to give a picture of the electron delocalization in the reduced and oxidized states. These studies demonstrate that the C7 bridging ligand spanning the metal centers by almost 12 angstroms is implicated in both redox processes and serves as a molecular wire to convey the unpaired electron with no tendency for spin localization on one of the halves of the molecules. The reactivity of the C7 complexes toward protonation and deprotonation led to original bis(acetylides), vinylidene-allenylidene, or carbyne-vinylidene species such as trans-[Cl(dppe)2Ru[triple bond]C-CH=C(CH3)-CH=C(CH3)-HC=C=Ru(dppe)2Cl][BF4]3.
authors.affiliation: UMR 6226 CNRS--Université de Rennes 1, Sciences Chimiques de Rennes, Campus de Beaulieu, F-35042 Rennes Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Rigaut
authors.forename: Céline
authors.initials: C
authors.lastname: Olivier
authors.forename: Karine
authors.initials: K
authors.lastname: Costuas
authors.forename: Sylvie
authors.initials: S
authors.lastname: Choua
authors.forename: Omrane
authors.initials: O
authors.lastname: Fadhel
authors.forename: Julien
authors.initials: J
authors.lastname: Massue
authors.forename: Philippe
authors.initials: P
authors.lastname: Turek
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Saillard
authors.forename: Pierre H
authors.initials: PH
authors.lastname: Dixneuf
authors.forename: Daniel
authors.initials: D
authors.lastname: Touchard
mesh_terms: D002244:Carbon / Q000737:chemistry*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D002244:Carbon; D012428:Ruthenium