title: Carborane Substituents Promote Direct Electrophilic Insertion over Reduction-Metalation Reactions.
abstract: Two-electron reduction of 1,1'-bis(o-carborane) followed by reaction with [Ru(η-mes)Cl2 ]2 affords [8-(1'-1',2'-closo-C2 B10 H11 )-4-(η-mes)-4,1,8-closo-RuC2 B10 H11 ]. Subsequent two-electron reduction of this species and treatment with [Ru(η-arene)Cl2 ]2 results in the 14-vertex/12-vertex species [1-(η-mes)-9-(1'-1',2'-closo-C2 B10 H11 )-13-(η-arene)-1,13,2,9-closo-Ru2 C2 B10 H11 ] by direct electrophilic insertion, promoted by the carborane substituent in the 13-vertex/12-vertex precursor. When arene=mesitylene (mes), the diruthenium species is fluxional in solution at room temperature in a process that makes the metal-ligand fragments equivalent. A unique mechanism for this fluxionality is proposed and is shown to be fully consistent with the observed fluxionality or nonfluxionality of a series of previously reported 14-vertex dicobaltacarboranes.
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: Wing Y
authors.initials: WY
authors.lastname: Man
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: David
authors.initials: D
authors.lastname: Ellis
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Rosair
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. a.j.welch@hw.ac.uk.
authors.forename: Alan J
authors.identifier: http://orcid.org/0000-0003-4236-2475
authors.initials: AJ
authors.lastname: Welch
keywords: bis(carboranes); fluxionality; metalation; metallacarboranes; two-electron reduction