title: A Binuclear 1,1'-Bis(boratabenzene) Complex: Unprecedented Intramolecular Metal-Metal Communication through a B-B Bond.
abstract: We report the synthesis of the first 1,1'-bis(boratabenzene) species by tetrabromodiborane(4)-induced ring-expansion reactions of cobaltocene. Six equivalents of cobaltocene are required as the species plays the dual role of reagent and reductant to yield [{(η(5) -C5 H5 )Co}2 {μ:η(6) ,η(6) -(BC5 H5 )2 }]. The formally dianionic bis(boratabenzene) moiety with a boron-boron single bond can be viewed as a symmetric dimer of the parent boratabenzene anion as well as the first example of a diboron analogue of biphenyl. The solution electrochemistry of the bimetallic complex shows four stepwise redox events, indicating significant intramolecular interaction between the cobalt ions across the 1,1'-bis(boratabenzene) unit. The magnetic properties, as investigated by variable-temperature SQUID magnetometry, reveal weak intramolecular antiferromagnetic interactions. Density functional theory calculations support the experimental results and add insight into the various electronic states of the complex.
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany. h.braunschweig@uni-wuerzburg.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Braunschweig
authors.affiliation: Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077, Göttingen, Germany.
authors.forename: Serhiy
authors.initials: S
authors.lastname: Demeshko
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: William C
authors.initials: WC
authors.lastname: Ewing
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Ivo
authors.initials: I
authors.lastname: Krummenacher
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Bret B
authors.initials: BB
authors.lastname: Macha
authors.affiliation: Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, BN1 9QJ, Sussex, UK.
authors.forename: James D
authors.initials: JD
authors.lastname: Mattock
authors.affiliation: Institut für Anorganische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 4, 37077, Göttingen, Germany.
authors.forename: Franc
authors.initials: F
authors.lastname: Meyer
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Mies
authors.affiliation: Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
authors.forename: Marius
authors.initials: M
authors.lastname: Schäfer
authors.affiliation: Department of Chemistry, School of Life Sciences, University of Sussex, Brighton, BN1 9QJ, Sussex, UK.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Vargas
keywords: borabenzene; boron; heterocycles; metal-metal interactions; π interactions