Magneto-structural correlations in layered polymeric molecular ferromagnets based on Ni(II) and Co(II) complexes with 3-imidazoline nitroxide radicals and methanol with different substituents in the metal cycle

Ikorskiǐ, V. N.; Романенко, Г. В.; Sygurova, M. K.; Ovcharenko, V. V.; Paunthou, F. Lanfranc de; Rey, P.; Резников, В. А.; Podoplelov, A. V.; Sagdeev, R. Z.

doi:10.1007/bf02578360

Cited by 9 publications

(8 citation statements)

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“…For 3 and 4, these distances are considerably longer (Table ), which is also important to note before discussing the magnetic properties of the complexes. In conclusion we also note that the bond lengths and angles in the bischelate fragment NiL 2 in 1 - 4 are close to those in the previously investigated polymorphs of NiL 2 and NiL (Cl) 2 (CH 3 OH) 2 , where L (Cl) is an analogue of L containing a chlorine atom in the γ-position of the enaminoketone group. , …”

Section: Resultssupporting

confidence: 85%

Molecular Magnets Based on Nickel(II) Complexes with 3-Imidazoline Nitroxides and Alcohols

et al. 1998

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Crystallization of heterospin bischelate NiL(2), where L is deprotonated nitroxide 4-(3',3',3'-trifluoromethyl-2'-oxopropylidene)-2,2,5,5-tetramethyl-3-imidazoline-1-oxyl, with alcohols allows a logical assembly of layered [NiL(2)(CH(3)OH)(2) (1) and NiL(2)(C(2)H(5)OH)(2) (2)] or frame compounds [NiL(2)(HO(CH(2))(4)OH) (3) and NiL(2)(HO(CH(2))(5)OH) (4)]. The structures of complexes 1, 2, and 4 have been determined. Crystal data: 1, monoclinic, space group P2(1)/c, a = 8.929(2) Å, b = 15.773(3), c = 11.518(2), beta = 118.84(1) degrees, Z = 2; 2, monoclinic, space group P2(1)/c, a = 9.923(5) Å, b = 15.992(5) Å, c = 11.486(2) Å, beta = 120.63(3) degrees, Z = 2; 4, monoclinic, space group C2/c, a = 21.028(4) Å, b = 10.943(2), c = 14.405(3), beta = 110.61(3) degrees, Z = 4. The structure of 3 is very close to the structure of 4 and has been reported earlier. Robust H-bonding between the OH groups of the coordinated alcohols and the >N-(*)O groups of the neighboring fragments NiL(2) leads to the formation of polymeric layers in the solid. At the same time, hydrogen bonds form effective channels for magnetic interactions >N-(*)O.H-O(R)-Ni(2+)-(R)O-H.O(*)-N<. The magnetic phase transition to the weak ferromagnetic state below 7 K is inherent in 1-4. For 2 and 4, this transition is induced by the external magnetic field that correlates with the elongation of Ni-(R)O and (R)O.O(*)- distances in the exchange channels >N-(*)O.H-O(R)-Ni(2+)-(R)O-H.O(*)-N< in solids 2 and 4 compared to 1 and 3. It has been found that magnetic ordering occurs only within the polymeric layers formed due to multiple hydrogen bonds. Investigation of the anisotropy of magnetic susceptibility performed on large single crystals of 1-4 revealed an essentially different ordering of the magnetic moments of magnetic sublattices in 1, 2 and in 3, 4.

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Section: Resultssupporting

confidence: 85%

Molecular Magnets Based on Nickel(II) Complexes with 3-Imidazoline Nitroxides and Alcohols

et al. 1998

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“…A number of coordination and hydrogen-bonded architectures was designed using metal bis-chelates with deprotonated nitroxide radical derivatives L 5 −L 10 . These include α- and β-[NiL 5 2 ], β-[CoL 5 2 ], [Ni(H 2 O) 2 L 5 2 ], [Ni( n -BuOH) 2 L 5 2 ], , [Ni( i -BuOH) 2 L 5 2 ], [Co(MeOH) 2 L 6 2 ], [CoL 7 2 ] and [CuL 7 2 ], [Ni(MeOH) 2 L 5 2 ] and its Co counterpart, [Ni(MeOH) 2 L 8 2 ] and its Co counterpart, [Ni(MeOH) 2 L 9 2 ], and [Ni(MeOH) 2 L 10 2 ] . The general feature in the series is that nitroxide oxygens connect to neighboring units through either coordination to the metal center or hydrogen bonding to the alcohol hydroxy group.…”

Section: Resultsmentioning

confidence: 99%

Inclusion in Microporous β-Bis(1,1,1-trifluoro-5,5-dimethyl-5- methoxyacetylacetonato)copper(II), an Organic Zeolite Mimic

Soldatov

Ripmeester

2000

Chem. Mater.

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In this contribution, we show that the porous β-form of the title complex preserves its host lattice pore structure in the presence of more than 100 guests. Among the species that are able to promote the α-to-β transformation and that are capable of being included as guests are the gaseous and condensed hydrocarbons, their halo derivatives, alcohols, diols, aldehydes, ketones, ethers, esters, ethers of inorganic acids, acids, nitriles, and a variety of substituted aromatics. The empty β-form behaves like a microporous sponge, instantly absorbing significant quantities even of highly volatile compounds such as methane, ethane, and propane. The material demonstrates zeolite-like behavior, not only from the robustness of the empty pore structure, but also from its propensity for efficient adsorption and desorption. The thermal stability of inclusions with normal paraffins increases from 142 °C (incongruent melting) to 163.5 °C (true melting) in the series from n-C5 to n-C16, while the guest-free α-form of the complex melts at 157 °C. The interaction of the complex with alcohols illustrates competing options between chemical bonding to copper and physical sorption into the microporous β-form. Methanol and ethanol coordinate to copper, thereby taking part in building, respectively, 2-D and 1-D polymers, whereas higher alcohols induce conversion to a 3-D β-form, stabilizing this porous modification by inclusion. From the observed stoichiometry and thermal stability, the host matrix is shown to be capable of molecular recognition of alcohols that have a shape and dimensions complementary to available pore geometry. Finally, the prospects for the rational design of new 3-D microporous polymers of bis-chelate building blocks are discussed.

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“…The structural analysis of the compound allows us to select exchange interactions in the following way. 59 where each Co(II) ion interacts via OH groups of water molecules with N–O groups of two neighboring molecules. Irrespective of the method of selecting an exchange interaction, the theoretical description of its magnetic properties may be treated like a magnetic system of the Co(II) ion plus two nitroxide radicals 59 {Co(II) ion + two nitroxide radicals}.…”

Section: Resultsmentioning

confidence: 99%

“…59 where each Co(II) ion interacts via OH groups of water molecules with N–O groups of two neighboring molecules. Irrespective of the method of selecting an exchange interaction, the theoretical description of its magnetic properties may be treated like a magnetic system of the Co(II) ion plus two nitroxide radicals 59 {Co(II) ion + two nitroxide radicals}. The strict analysis of the magnetic data of Co(II) complexes needs to consider the effects of spin–orbit coupling and zero-field splitting.…”

Section: Resultsmentioning

confidence: 99%

“…The compound 2 is not coordinated with the N–O unit of the radical; however, the Co ion is coordinated through the hydrogen bonding of the water molecule (model shown below). The structural analysis of the compound allows us to select exchange interactions in the following way where each Co(II) ion interacts via OH groups of water molecules with N–O groups of two neighboring molecules.…”

Section: Resultsmentioning

confidence: 99%

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Magnetic Exchange Interaction in Nitronyl Nitroxide Radical-Based Single Crystals of 3d Metal Complexes: A Combined Experimental and Theoretical Study

et al. 2018

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Two stable nitronyl nitroxide free radicals { R 1 = 4′-methoxy-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (NNPhOMe) and R 2 = 2-(2′-thienyl)-4,4,5,5-tetramethylimidazoline 3-oxide 1-oxyl (NNT)} are successfully synthesized using Ullmann condensation. The reactions of these two radicals with 3d transition metal ions, in the form of M(hfac) 2 (where M = Co or Mn, hfac: hexafluoroacetylacetone), result in four metal–organic complexes Co(hfac) 2 (NNPhOMe) 2 , 1 ; Co(hfac) 2 (NNT) 2 ·(H 2 O), 2 ; Mn(hfac) 2 (NNPhOMe)· x (C 7 H 16 ), 3 ; and Mn(hfac) 2 (NNT) 2 , 4 . The crystal structure and magnetic properties of these complexes are investigated by single-crystal X-ray diffraction, dc magnetization, infrared, and electron paramagnetic resonance spectroscopies. The compounds 1 and 4 crystallize in the triclinic, P 1̅, space group, whereas complex 3 crystallizes in the monoclinic structure with the C 2/ c space group and forms chain-like structure along the c direction. The complex 2 crystallizes in the monoclinic symmetry with the P 2 1 / c space group in which the N–O unit of the radical coordinates with the Co ion through hydrogen bonding of a water molecule. All compounds exhibit antiferromagnetic interactions between the transition metal ions and nitronyl nitroxide radicals. The magnetic exchange interactions ( J / K B ) are derived using isotropic spin Hamiltonian H = −2 J ∑( S metal S radical ) for the model fitting to the magnetic susceptibility data for 1 , 2 , 3 , and 4 . The exchange interaction strengths are found to be −328, −1.25, −248, and −256 K, for the 1 , 2 , 3 , and 4 metal–organic complexes, respectively. Quantum chemical density functional theory (DFT) computations are carried out on several models of the metal–radical complexes to elucidate the magnetic interactions at the molecular level. The calculations show that a small part of the inorganic spins are delocalized over the oxygens from hfac {∼0.03 for Co(II) and ∼0.015 for Mn(II)}, whereas a m...

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Magneto-structural correlations in layered polymeric molecular ferromagnets based on Ni(II) and Co(II) complexes with 3-imidazoline nitroxide radicals and methanol with different substituents in the metal cycle

Cited by 9 publications

References 2 publications

Molecular Magnets Based on Nickel(II) Complexes with 3-Imidazoline Nitroxides and Alcohols

Molecular Magnets Based on Nickel(II) Complexes with 3-Imidazoline Nitroxides and Alcohols

Inclusion in Microporous β-Bis(1,1,1-trifluoro-5,5-dimethyl-5- methoxyacetylacetonato)copper(II), an Organic Zeolite Mimic

Magnetic Exchange Interaction in Nitronyl Nitroxide Radical-Based Single Crystals of 3d Metal Complexes: A Combined Experimental and Theoretical Study

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