title: Strong Exchange Coupling in a Trimetallic Radical-Bridged Cobalt(II)-Hexaazatrinaphthylene Complex.
abstract: Reducing hexaazatrinaphthylene (HAN) with potassium in the presence of 18-c-6 produces [{K(18-c-6)}HAN], which contains the S=1/2 radical [HAN](.-) . The [HAN](.-) radical can be transferred to the cobalt(II) amide [Co{N(SiMe3 )2 }2 ], forming [K(18-c-6)][(HAN){Co(N'')2 }3 ]; magnetic measurements on this compound reveal an S=4 spin system with strong cobalt-ligand antiferromagnetic exchange and J≈-290 cm(-1) (-2 J formalism). In contrast, the Co(II) centres in the unreduced analogue [(HAN){Co(N'')2 }3 ] are weakly coupled (J≈-4.4 cm(-1) ). The finding that [HAN](.-) can be synthesized as a stable salt and transferred to cobalt introduces potential new routes to magnetic materials based on strongly coupled, triangular HAN building blocks.
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.|Department of Chemistry, University of Jyvaskala, P.O. Box 35, 40014, Jyvaskala, Finland.
authors.forename: Jani O
authors.initials: JO
authors.lastname: Moilanen
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: Nicholas F
authors.initials: NF
authors.lastname: Chilton
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Day
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Pugh
authors.affiliation: School of Chemistry, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK. Richard.Layfield@manchester.ac.uk.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Layfield
keywords: cobalt; hexaazatrinaphthylene; magnetism; non-innocent ligands; radicals