Ultra-low temperature structure determination of a Mn12 single-molecule magnet and the interplay between lattice solvent and structural disorder

Farrell, Andrew R.; Coome, J. A.; Probert, Michael R.; Goeta, Andrés E.; Howard, Judith A. K.; Lemée-Cailleau, Marie–Hélène; Parsons, Simon; Murrie, Mark

doi:10.1039/c3ce00042g

Cited by 10 publications

(4 citation statements)

References 45 publications

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“…A similar behaviour has been later reported also in lanthanide based complexes. 55,56,68,69 In the present case, the heterodinuclear structural unit of 2 form a 3D network with water molecules from crystallization: 49 it can then be suggested that when the sample was pressed in a pellet this resulted in a partial loss of solvent. This is of peculiar importance, since the water molecules in the lattice generate an extended network of hydrogen bonds, which might be able to transmit weak exchange coupling interactions.…”

Section: Discussion On Ageingmentioning

confidence: 68%

Tm(iii) complexes undergoing slow relaxation of magnetization: exchange coupling and aging effects

2017

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The present study focuses on the dynamic magnetic behaviour of exchange coupled 3d-4f complexes containing the scarcely investigated non-Kramers Tm center, the 3d metal ions being either the low-spin Fe (1) or the diamagnetic Co (2) ion. Both complexes display field-induced slow relaxation of magnetization. The field and temperature dependences of the relaxation rate provided indication of relevant contributions from quantum tunnelling, direct, Orbach and Raman processes, with only minor effects from exchange coupling interactions. Furthermore, the aged sample of 2 exhibited an additional relaxation process, possibly due to structural modifications accompanied by solvent loss, highlighting the importance of a careful consideration of this factor when analysing the magnetization dynamics in solvated systems.

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Section: Discussion On Ageingmentioning

confidence: 68%

Tm(iii) complexes undergoing slow relaxation of magnetization: exchange coupling and aging effects

2017

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“…104 Accordingly, we set S Z ¼ 10 as a constraint on the GAUSSIAN 09 and VASP electron and spin distributions we computed. In VASP, we optimized the atomic positions and used the experimental lattice parameters of Farrell et al 105 (Cambridge Structural Database ID BESXAA). In GAUSSIAN 09, we used an isolated molecule and optimized the atomic positions.…”

Section: Collinear and Non-collinear Magnetic Materialsmentioning

confidence: 99%

Introducing DDEC6 atomic population analysis: part 2. Computed results for a wide range of periodic and nonperiodic materials

2016

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Net atomic charges (NACs) are widely used throughout the chemical sciences to concisely summarize key information about charge transfer between atoms in materials. The vast majority of NAC definitions proposed to date are unsuitable for describing the wide range of material types encountered across the chemical sciences. In this article, we show the DDEC6 method reproduces important chemical, theoretical, and experimental properties across an extremely broad range of material types including small and large molecules, organometallics, nanoclusters, porous solids, nonporous solids, and solid surfaces. Some important comparisons we make are: (a) correlations between various NAC models and spectroscopically measured core-electron binding energy shifts for Ti-, Fe-, and Mo-containing solids, (b) comparisons between DDEC6 and experimentally extracted NACs for formamide and natrolite, (c) comparisons of accuracy of different NAC methods for reproducing the electrostatic potential surrounding a material across one and multiple system conformations, (d) comparisons between calculated and chemically expected electron transfer trends for atoms in numerous dense solids, solid surfaces, and molecules, (e) an assessment of NAC transferability between three crystal phases of the diisopropylammonium bromide organic ferroelectric, and (f) comparisons between DDEC6 and polarized neutron diffraction atomic spin moments for the Mn 12 -acetate single-molecule magnet. We find the DDEC6 NACs are ideally suited for constructing flexible force-fields and give reasonable agreement with force-fields commonly used to simulate biomolecules and water. We find the DDEC6 method is more accurate than the DDEC3 method for analyzing a broad range of materials. This broad applicability to periodic and non-periodic materials irrespective of the basis set type makes the DDEC6 method suited for use as a default atomic population analysis method in quantum chemistry programs. † Electronic supplementary information (ESI) available: Tables listing spectroscopically measured core electron energies and Bader, CM5, DDEC3, DDEC6, HD NACs for Ti-and Mo-containing solids; plot comparing DDEC6 to DDEC3 NACs for 14 systems comprised almost entirely of surface atoms; DDEC6 and DDEC3 NACs for Mo 2 C(110) surface with K adatom and NaF (001) surface; DDEC6 and DDEC3 NACs, atomic dipoles, and atomic quadrupoles for SrTiO 3 (100) surface and bulk crystal; DDEC6, DDEC3, Bader, and IH NACs for NaF and SrTiO 3 bulk crystals; xyz les (which can be read using any text editor or the free Jmol visualization program downloadable from jmol.sourceforge.net) containing geometries, NACs, atomic dipoles and quadrupoles, tted tail decay exponents, and ASMs. See

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“…However, in order to understand the magnetic anisotropy in Co(II) mononuclear complexes, which tends to dictate the resulting magnetic properties, a thorough understanding of the geometrical environment of the Co(II) is required . In particular, where low temperature magnetic measurements are used to confirm certain properties, it is also important to be certain of the structure in the temperature range at which the measurement is carried out (typically < 10 K) …”

Section: Introductionmentioning

confidence: 99%

“…28 In particular, where low temperature magnetic measurements are used to confirm certain properties, it is also important to be certain of the structure in the temperature range at which the measurement is carried out (typically < 10 K). 29 We present herein a systematic variable temperature single crystal X-ray diffraction study of [Co II (NO 3 ) 3 (H 2 O)-(HDABCO)] (1), 30 evidencing a disorder-to-order, singlecrystal to single-crystal phase transition accompanied by a clear coordination switch from a 5-to a 7-coordinate complex below 140 K. The magnetic studies of 1 confirm slow relaxation of the magnetization under an applied dc field, originating from a large easy-plane magnetic anisotropy. We stress the merits of thorough low temperature crystallographic investigations of single-ion magnets, especially where the ligands involved can display a variety of coordination modes.…”

Section: ■ Introductionmentioning

confidence: 99%

Trigonal to Pentagonal Bipyramidal Coordination Switching in a Co(II) Single-Ion Magnet

et al. 2019

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In molecular magnetism and single-ion magnets in particular, the observation of slow relaxation of the magnetization is intimately linked to the coordination environment of the metal center. Such systems typically have blocking temperatures well below that of liquid nitrogen, and therefore detailed magnetic characterization is usually carried out at very low temperatures. Despite this, there has been little advantage taken of ultralow temperature single-crystal X-ray diffraction techniques that could provide a full understanding of the crystal structure in the same temperature regime where slow magnetic relaxation occurs. Here, we present a systematic variable temperature single crystal X-ray diffraction study of [CoII(NO3)3(H2O)(HDABCO)] (1) {DABCO = 1,4-diazabicyclo[2.2.2]octane} conducted between 295 to 4 K. A reversible and robust disorder-to-order, single-crystal to single-crystal phase transition was identified, which accompanied a switching of the coordination geometry around the central Co(II) from 5- to 7-coordinate below 140 K. The magnetic properties were investigated, revealing slow relaxation of the magnetization arising from a large easy-plane magnetic anisotropy (+D) in the Co(II) pentagonal bipyramidal environment observed at low temperatures. This study highlights the importance of conducting thorough low temperature crystallographic studies, particularly where magnetic characterization is carried out at such low temperatures.

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Ultra-low temperature structure determination of a Mn12 single-molecule magnet and the interplay between lattice solvent and structural disorder

Abstract: Ultra-low temperature structure determination of a Mn 12 single-molecule magnet and the interplay between lattice solvent and structural disorder3{

Cited by 10 publications

References 45 publications

Tm(iii) complexes undergoing slow relaxation of magnetization: exchange coupling and aging effects

Tm(iii) complexes undergoing slow relaxation of magnetization: exchange coupling and aging effects

Introducing DDEC6 atomic population analysis: part 2. Computed results for a wide range of periodic and nonperiodic materials

Trigonal to Pentagonal Bipyramidal Coordination Switching in a Co(II) Single-Ion Magnet

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