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A Binuclear 1,1′‐Bis(boratabenzene) Complex: Unprecedented Intramolecular Metal–Metal Communication through a B−B Bond
Author(s) -
Braunschweig Holger,
Demeshko Serhiy,
Ewing William C.,
Krummenacher Ivo,
Macha Bret B.,
Mattock James D.,
Meyer Franc,
Mies Jan,
Schäfer Marius,
Vargas Alfredo
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201603437
Subject(s) - cobaltocene , intramolecular force , chemistry , bimetallic strip , moiety , crystallography , density functional theory , cobalt , agostic interaction , metal , photochemistry , stereochemistry , inorganic chemistry , computational chemistry , polymerization , metallocene , organic chemistry , polymer
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 ‐C 5 H 5 )Co} 2 {μ:η 6 ,η 6 ‐(BC 5 H 5 ) 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.