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Fatila E.M.,University of Guelph | Rouzieires M.,CNRS Paul Pascal Research Center | Jennings M.C.,FreeLance Crystallography | Lough A.J.,University of Toronto | And 2 more authors.
Journal of the American Chemical Society

A supramolecular species composed of a pair of nonequivalent Dy(III)-radical complexes exhibits single-molecule magnet (SMM) properties. The weak effective antiferromagnetic coupling between the Dy(III) ions can be compensated by application of a small (700 Oe) dc field, revealing the relaxation mode of the two distinct SMMs. These unique results illustrate how the dynamics of a supramolecular [Dy-Radical]2 SMM can be fine-tuned by the exchange-bias and an applied magnetic field. © 2013 American Chemical Society. Source

Fatila E.M.,University of Guelph | Clerac R.,CNRS Paul Pascal Research Center | Rouzieres M.,CNRS Paul Pascal Research Center | Soldatov D.V.,University of Guelph | And 2 more authors.
Chemical Communications

The first coordination polymer of a bridging radical 1,2,3,5-dithiadiazolyl ligand is reported. Upon coordination with the La(hfac)3 fragment, the paramagnetic 4-(benzoxazol-2′-yl)-1,2,3,5-dithiadiazolyl (boaDTDA) ligand forms a one-dimensional (1D) alternating -[La(hfac)3-boaDTDA] n- polymer exhibiting ferromagnetic (FM) coupling between the radicals, mediated through the diamagnetic LaIII ion (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato). © 2013 The Royal Society of Chemistry. Source

Fatila E.M.,University of Guelph | Clerac R.,CNRS Paul Pascal Research Center | Jennings M.,FreeLance Crystallography | Preuss K.E.,University of Guelph
Chemical Communications

The coordination complex of Ni(hfac)2 (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato) and the 4-(benzoxazol-2′-yl)-1,2,3, 5-dithiadiazolyl (boaDTDA) neutral radical π-stacks in a one-dimensional "staircase" arrangement. This particular packing aligns regions of α and β spin densities on neighbouring NiII(hfac) 2(boaDTDA) molecules. This complex exemplifies a McConnell I type mechanism, giving rise to intermolecular ferromagnetic exchange observed for the first time between metal-thiazyl complexes. © 2013 The Royal Society of Chemistry. Source

Fatila E.M.,University of Guelph | Mayo R.A.,University of Guelph | Rouzieres M.,CNRS Paul Pascal Research Center | Jennings M.C.,FreeLance Crystallography | And 6 more authors.
Chemistry of Materials

π-π radical interactions have exacting geometry requirements, significantly more stringent than those of a hydrogen bond or a van der Waals interaction. Here, supramolecular synthons based on such radical-radical recognition are employed to generate switchable structural and magnetic properties. Interactions between neighboring paramagnetic ligands of the La(hfac)3(pyDTDA)2 coordination complex cause a rare re-entrant phase transition (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-; pyDTDA = 4-(2'-pyridyl)-1,2,3,5-dithiadiazolyl). Below 100 K, the complex is diamagnetic in the solid state, consistent with an f0 lanthanum(III) ion and "pancake bonding" of the π-radical ligands. Upon heating, the supramolecular one-dimensional arrangement undergoes two sequential structural phase transitions, observed at ca. 160 and 310 K, successively involving the rupture of half and then the totality of the "pancake bonds" and generating stepwise increases in the paramagnetic susceptibility. We use the structural and magnetic data to develop a theoretical model that clearly predicts the unprecedented re-entrant behavior of this radical-La(III)-radical complex. Moreover, this microscopic free-energy model demonstrates that any system with essentially noninteracting "dimers" contains within itself the possibility of a distortion associated with re-entrant phase transitions if the lattice is "soft" enough (i.e., low rigidity). © 2015 American Chemical Society. Source

Smithson C.S.,University of Guelph | Macdonald D.J.,University of Guelph | Matt Letvenuk T.,University of Guelph | Carello C.E.,University of Guelph | And 5 more authors.
Dalton Transactions

Under aprotic conditions, the reaction of 4-amino-1,2-naphthoquinone with excess S2Cl2 generates 4,5-dioxo-naphtho[1,2-d][1,2,3]dithiazol-2-ium chloride in a typical Herz condensation. By contrast, prior literature reports an imine (NH) product, 4,5-dioxo-1H-naphtho[1,2-d][1,2,3]dithiazole, for the same reaction performed in acetic acid. Herein, the cation product is isolated with four different counter-anions (Cl-, GaCl4 -, FeCl4 - and OTf-). Reduction of the cation generates a neutral radical 1,2,3-dithiazolyl-o-naphthoquinone, with potential ligand properties. Further reduction generates a closed shell anion, isolated as a water-stable Li+ complex and exhibiting O,O-bidentate chelation. The hydroxy (OH) isomer of the original imine (NH) product is reported, and this can be readily deprotonated and acylated (OAc). All species are structurally characterized. Solution redox behaviour and EPR are discussed where appropriate. © 2016 The Royal Society of Chemistry. Source

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