Ferro- or antiferromagnetism? Heisenberg chains in the crystal structures of verdazyl radicals

2018 ◽  
Vol 20 (35) ◽  
pp. 22902-22908 ◽  
Author(s):  
Steffen Eusterwiemann ◽  
Carsten Doerenkamp ◽  
Thomas Dresselhaus ◽  
Oliver Janka ◽  
Constantin G. Daniliuc ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Exchange Coupling ◽  
Verdazyl Radicals ◽  
Verdazyl Radical ◽  
Heisenberg Chains

Quantum chemically calculated exchange-coupling maps are employed to design verdazyl radical crystals with either ferromagnetic or antiferromagnetic behaviour.

Strong Ferromagnetic and Antiferromagnetic Exchange Coupling between Transition Metals and Coordinated Verdazyl Radicals

2000 ◽  
Vol 122 (33) ◽  
pp. 8077-8078 ◽  
Author(s):  
Robin G. Hicks ◽  
Martin T. Lemaire ◽  
Laurence K. Thompson ◽  
Tosha M. Barclay
Keyword(s):  
Transition Metals ◽  
Exchange Coupling ◽  
Antiferromagnetic Exchange ◽  
Verdazyl Radicals

Exploiting verdazyl radicals to assemble 2p–3d–4f one-dimensional chains

2015 ◽  
Vol 44 (12) ◽  
pp. 5364-5368 ◽  
Author(s):  
Chao Wang ◽  
Shuang-Yan Lin ◽  
Wei Shi ◽  
Peng Cheng ◽  
Jinkui Tang
Keyword(s):  
Transition Metal ◽  
One Dimensional ◽  
Efficient Approach ◽  
Verdazyl Radicals ◽  
Verdazyl Radical

Exploiting the coordination abilities of an isopropyl substituted verdazyl radical to transition metal and lanthanide(iii) ions represents an efficient approach to produce a system incorporating 2p, 3d and 4f spin carriers.

Crystal structures, magnetic properties, and absorption spectra of nickel(II) thiocyanato complexes: a comparison of different coordination geometries

2003 ◽  
Vol 81 (11) ◽  
pp. 1168-1179 ◽  
Author(s):  
Bruno Larue ◽  
Lan-Tâm Tran ◽  
Dominique Luneau ◽  
Christian Reber
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Absorption Spectra ◽  
Exchange Coupling ◽  
Molecular Magnetism ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Space Group ◽  
Trigonal Bipyramidal ◽  
Ferromagnetic Interactions

Thiocyanatonickel(II) compounds with composition {(AsPh4)2[Ni(NCS)4]} 1, {(Cat)[Ni(NCS)4]} 2, {(AsPh4)4 [Ni2(NCS)8]} 3, {(Cat)2[Ni2(NCS)8]·2CH3NO2} 4, and {(Et4N)4[Ni(NCS)6]} 5 (Cat2+ = (p-xylylenebis(triphenyphosphonium))2+) were prepared. The crystal structures of compounds 1, 3, and 4 were determined. Compound 1 crystallizes in the monoclinic C2/c space group with a = 22.761(2) Å, b = 15.055(1) Å, c = 15.054(1) Å, β = 108.915(1)°, V = 4879.9(6) Å3, and Z = 4. Compound 3 crystallizes in the triclinic P–1 space group with a = 11.2183(6) Å, b = 14.2551(8) Å, c = 16.629(1) Å, α = 79.326(1)°, β = 73.605(1)°, γ = 75.496(1)°, V = 2451.0(2) Å3, Z = 2. Compound 4 crystallizes in the monoclinic P21/n space group with a = 13.1148(9) Å, b = 27.128(2) Å, c = 14.882(1) Å, β = 114.056(2)°, V = 4834.8(6) Å3, Z = 4. The magnetic properties of compounds 1-4 were studied over the 2–300 K temperature range. Compounds 1 and 2 with monometallic [Ni(NCS)4]2– complex units have similar magnetic properties, in agreement with nickel(II) ions in pseudo-tetrahedral environments. Compounds 3 and 4 with bimetallic [Ni2(NCS)8]4– complex units exhibit magnetic properties, which are indicative of Ni(II)–Ni(II) ferromagnetic interactions with zero-field splitting effects caused by the pseudo-square-pyramidal or pseudo-trigonal-bipyramidal coordination environments of the nickel(II) ion in compounds 3 and 4, respectively. The structures and magnetic results for all compounds are correlated with NIR–UV–vis absorption spectra.Key words: nickel(II) thiocyanato complexes, crystal structures, paramagnetism, molecular magnetism, exchange coupling, absorption spectroscopy.

scholarly journals Syntheses, spectroscopy, and crystal structures of 3-(4-bromophenyl)-1,5-diphenylformazan and the 3-(4-bromophenyl)-1,5-diphenylverdazyl radical and the crystal structure of the by-product 5-anilino-3-(4-bromophenyl)-1-phenyl-1H-1,2,4-triazole

2018 ◽  
Vol 74 (3) ◽  
pp. 292-297 ◽  
Author(s):  
Gregor Schnakenburg ◽  
Andreas Meyer
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Organic Compounds ◽  
Spectroscopic Data ◽  
Structural Data ◽  
The Other ◽  
Side Product ◽  
Axis Direction ◽  
Verdazyl Radical ◽  
First Time

The title compounds, C19H15BrN4, C20H16BrN4and C20H15BrN4, are nitrogen-rich organic compounds that are related by their synthesis. The verdazyl radical, in which stacking leads to antiferromagnetic interactions, was reported previously [Iwaseet al.(2013).Phys. Rev. B,88, 184431]. For this compound, improved structural data and spectroscopic data are presented. The other two compounds have been crystallized for the first time and form stacks of dimers, roughly along thea-axis direction of the crystal. The formazan molecule shows signs of rapid intramolecular H-atom exchange typical for this class of compounds and spectroscopic data are provided in addition to the crystal structure. The triazole compound appears to be a side-product of the verdazyl synthesis.

scholarly journals Bis(triphenylphosphine)iminium Salts of Dioxothiadiazole Radical Anions: Preparation, Crystal Structures, and Magnetic Properties

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 30 ◽  
Author(s):  
Paweł Pakulski ◽  
Mirosław Arczyński ◽  
Dawid Pinkowicz
Keyword(s):  
Magnetic Properties ◽  
Crystal Structures ◽  
Magnetic Materials ◽  
Exchange Coupling ◽  
Crystal Packing ◽  
Stable Radical ◽  
Radical Anions ◽  
Iminium Salts ◽  
Redox Active ◽  
Derivatives Of

Phenanthroline dioxothiadiazoles are redox active molecules that form stable radical anions suitable for the construction of supramolecular magnetic materials. Herein, the preparation, structures and magnetic properties of bis(triphenylphosphine)iminium (PPN) salts of [1,2,5]thiadiazole[3,4-f][1,10]phenanthroline 1,1-dioxide (L), [1,2,5]thiadiazole[3,4-f][4,7]phenanthroline 1,1-dioxide (4,7-L), 5-bromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (BrL), and 5,10-dibromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (diBrL) are reported. The preparation of new bromo derivatives of the L: 5-bromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (BrL) and 5,10-dibromo-[1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 2,2-dioxide (diBrL)—suitable starting materials for further derivatization—are described starting from a commercially available and cheap 1,10-phenanthroline. All PPN salts show antiferromagnetic interactions between the pairs of radical anions, which in the case of PPN(diBrL) are very strong (−116 cm−1; using Ĥ = −2JSS type of exchange coupling Hamiltonian) due to a different crystal packing of the anion radicals as compared to PPN(L), PPN(4,7-L), and PPN(BrL).

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