Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F16%3A33161050" target="_blank" >RIV/61989592:15310/16:33161050 - isvavai.cz</a>

Výsledek na webu

<a href="http://pubs.acs.org/doi/pdf/10.1021/acs.inorgchem.6b00415" target="_blank" >http://pubs.acs.org/doi/pdf/10.1021/acs.inorgchem.6b00415</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.inorgchem.6b00415" target="_blank" >10.1021/acs.inorgchem.6b00415</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound

Popis výsledku v původním jazyce

The 2-pyridylmethyl N-pendant-armed heptadentate macro cyclic ligand {3,12-bis(2-methylpyridine)-3,12,18-triaza-6,9-dioxabicydo [12.3.1] octadeca-1,14,16-triene = L} and [M(L)] (ClO4), complexes, where M = Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), and Cu(II) (5), were prepared and thoroughly characterized, including elucidation of X-ray structures of all the compounds studied. The complexes 1-5 crystallize in non-centrosymmetric Sohncke space groups as racemic compounds. The coordination numbers of 7, 6 + 1, and 5 were found in complexes 1-3, 4, and 5, respectively, with a distorted pentagonal bipyramidal (1-4) or square pyramidal (5) geometry. On the basis of the magnetic susceptibility experiments, a large axial zero-field splitting (ZFS) was found for 2, 3, and 4 (D(Fe) =-7.4(2) cm(-1), D(Co) = 34(1) cm(-1), and D(Ni) =-12.8(1) cm(-1), respectively) together with a rhombic ZFS (E/D = 0.136(3)) for 4. Despite the easy plane anisotropy (D > 0, E/D = 0) in 3, the slow relaxation of the magnetization below 8 K was observed and analyzed either with Orbach relaxation mechanism (the relaxation time To = 9.90 x 10(-10) s and spin reversal barrier Ueff = 24.3 K (16.9 cm(-1))) or with Raman relaxation mechanism (C = 2.12 x 10-8 and n = 2.84). Therefore, compound 3 enlarges the small family of field-induced single-molecule magnets with pentagonalbipyramidal chromophore. The cyclic voltammetry in acetonitrile revealed reversible redox processes in 1-3 and 5, except for the Ni(II) complex 4, where a quasi-reversible process was dominantly observed. Presence of the two 2-pyridylmethyl pendant arms in L with a stronger o--donor/7c-acceptor ability had a great impact on the properties of all the complexes (1-5), concretely: (i) strong pyridine-metal bonds provided slight axial compression of the coordination sphere, (ii) substantial changes in magnetic anisotropy, and (iii) stabilization of lower oxidation states.

Název v anglickém jazyce

Late First-Row Transition-Metal Complexes Containing a 2-Pyridylmethyl Pendant-Armed 15-Membered Macrocyclic Ligand. Field-Induced Slow Magnetic Relaxation in a Seven-Coordinate Cobalt(II) Compound

Popis výsledku anglicky

The 2-pyridylmethyl N-pendant-armed heptadentate macro cyclic ligand {3,12-bis(2-methylpyridine)-3,12,18-triaza-6,9-dioxabicydo [12.3.1] octadeca-1,14,16-triene = L} and [M(L)] (ClO4), complexes, where M = Mn(II) (1), Fe(II) (2), Co(II) (3), Ni(II) (4), and Cu(II) (5), were prepared and thoroughly characterized, including elucidation of X-ray structures of all the compounds studied. The complexes 1-5 crystallize in non-centrosymmetric Sohncke space groups as racemic compounds. The coordination numbers of 7, 6 + 1, and 5 were found in complexes 1-3, 4, and 5, respectively, with a distorted pentagonal bipyramidal (1-4) or square pyramidal (5) geometry. On the basis of the magnetic susceptibility experiments, a large axial zero-field splitting (ZFS) was found for 2, 3, and 4 (D(Fe) =-7.4(2) cm(-1), D(Co) = 34(1) cm(-1), and D(Ni) =-12.8(1) cm(-1), respectively) together with a rhombic ZFS (E/D = 0.136(3)) for 4. Despite the easy plane anisotropy (D > 0, E/D = 0) in 3, the slow relaxation of the magnetization below 8 K was observed and analyzed either with Orbach relaxation mechanism (the relaxation time To = 9.90 x 10(-10) s and spin reversal barrier Ueff = 24.3 K (16.9 cm(-1))) or with Raman relaxation mechanism (C = 2.12 x 10-8 and n = 2.84). Therefore, compound 3 enlarges the small family of field-induced single-molecule magnets with pentagonalbipyramidal chromophore. The cyclic voltammetry in acetonitrile revealed reversible redox processes in 1-3 and 5, except for the Ni(II) complex 4, where a quasi-reversible process was dominantly observed. Presence of the two 2-pyridylmethyl pendant arms in L with a stronger o--donor/7c-acceptor ability had a great impact on the properties of all the complexes (1-5), concretely: (i) strong pyridine-metal bonds provided slight axial compression of the coordination sphere, (ii) substantial changes in magnetic anisotropy, and (iii) stabilization of lower oxidation states.

Druh

J_x - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)

CEP obor

CA - Anorganická chemie

OECD FORD obor

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Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2016

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Inorganic Chemistry

ISSN

0020-1669

e-ISSN

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Svazek periodika

55

Číslo periodika v rámci svazku

12

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

16

Strana od-do

5957-5972

Kód UT WoS článku

000378369900031

EID výsledku v databázi Scopus

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