title: In search of molecules displaying ferromagnetic exchange: multiple-decker Ni12and Ni16complexes from the use of pyridine-2-amidoxime.
abstract: The use of pyridine-2-amidoxime (pyaoxH2) in Ni chemistry has provided access to a dodecanuclear complex and a hexadecanuclear Ni cluster, namely [Ni12(pyaox)6(pyaoxH)6(MeOH)2Cl2]Cl4·5MeOH (1·5MeOH) and [Ni16(pyaox)8(pyaoxH)8(MeOH)4](SO4)4·10H2O·26MeOH (2·10H2O·26MeOH). Complex 1·5MeOH was isolated by the reaction of NiCl2·6H2O, pyaoxH2and NaOMe in a 1 : 1 : 2 molar ratio in MeOH in 60% yield. Treatment of NiSO4·6H2O with pyaoxH2and NEt3in a 1 : 1 : 2 molar ratio in MeOH afforded 2·10H2O·26MeOH in good yield (65%). The two compounds display a multi-decker configuration based on stacked Ni4layers, {Ni4(pyaox)2(pyaoxH)2}2+x(x = 3, 1·5MeOH; x = 4, 2·10H2O·26MeOH); each deck consists of two square planar and two octahedral NiIIcentres. The number of decks observed in 1·5MeOH and 2·10H2O·26MeOH depends on the nature of the inorganic anion that is present in the reaction system, which provides elements of synthetic control towards new high nuclearity NiIIspecies. 2·10H2O·26MeOH is the first structurally characterized complex of any metal displaying a quadruple-decker configuration, being also the highest nuclearity metal cluster bearing pyaoxH2and the highest nuclearity NiIIcluster with any type of 2-pyridyl oxime. Each cluster cation displays ferromagnetic exchange between the octahedral NiIIions resulting in a spin ground state of S = 6 for 1 and S = 8 for 2. Magnetothermal studies have been performed and discussed for both clusters.
authors.affiliation: School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland. constantina.papatriantafyllopo@nuigalway.ie and Department of Chemistry, University of Patras, 26504 Patras, Greece.
authors.forename: Constantinos G
authors.initials: CG
authors.lastname: Efthymiou
authors.affiliation: REQUIMTE-LAQV, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, 4169-007 Porto, Portugal.
authors.forename: Luís
authors.initials: L
authors.lastname: Cunha-Silva
authors.affiliation: Department of Chemistry, University of Patras, 26504 Patras, Greece.
authors.forename: Spyros P
authors.initials: SP
authors.lastname: Perlepes
authors.affiliation: EastCHEM School of Chemistry, The University of Edinburgh, David Brewster Road, EH9 3FJ Edinburgh, UK. r.inglis@ed.ac.uk.
authors.forename: Euan K
authors.initials: EK
authors.lastname: Brechin
authors.affiliation: EastCHEM School of Chemistry, The University of Edinburgh, David Brewster Road, EH9 3FJ Edinburgh, UK. r.inglis@ed.ac.uk.
authors.forename: Ross
authors.initials: R
authors.lastname: Inglis
authors.affiliation: Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Departamento de Fisica de la Materia Condensada, 50009 Zaragoza, Spain. evange@unizar.es.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0002-8028-9064
authors.initials: M
authors.lastname: Evangelisti
authors.affiliation: School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland. constantina.papatriantafyllopo@nuigalway.ie.
authors.forename: Constantina
authors.initials: C
authors.lastname: Papatriantafyllopoulou