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A new complex, bis[4-(2-oxido-1-butenyl)-2,2,5,5-tetramethylimidazolidine-1-oxyl]copper(II) (CuLEt2), has been synthesized. The synthesis, characterization, and magnetic properties as well as the crystal structure of CuLEt2 have been studied. The layered solid of the complex possesses a metamagnetic phase transition at 4.5 K and shows strong anisotropy of magnetic properties below the ordering temperature. The easy magnetization axis lies along the b axis. The hard magnetization axis is orthogonal to the polymeric layers. Effective anisotropy fields have been estimated (H⟂ = 1390 Oe, H∥ = 420 Oe). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Two new isostructural complexes, dibromobis(1-ethyltetrazole)copper(II) (1) and dibromobis(1-hexyltetrazole)copper(II) (2), have been synthesised. Each bromine atom in the crystal structure of 1 and 2 is bonded to two copper atoms to give rise to a polymeric corrugated network. The polymeric layers are distinctly separated by tetrazole ligands. Both solids exhibit a phase transition to the ferromagnetic state with Curie temperatures of 8.5 K and 8.9 K for 1 and 2, respectively, and a strong anisotropy of the magnetic susceptibility below the ordering temperature. The easy magnetisation axis lies along the monoclinic axis, and the hard magnetisation axis is orthogonal to the polymeric layers. Effective anisotropy fields were estimated as (720–3020 Oe). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Methods for the synthesis of a new family of nitronylnitroxides, iminonitroxides, and their precursors with 2-hydroxyphenyl or 3-hydroxypyridin-2-yl substituents in the side chain have been developed. Five heterospin chelates of Cu(II) with deprotonated iminonitroxides have been isolated. Their structure and magnetic properties have been studied. In all complexes, ferromagnetic intramolecular exchange interactions take place (J∼40–350 cm−1).

Metal complexes with stable radicals form a continuous series of solid solutions Ni x Co 1− x L 2 (CH 3 OH) 2 , Ni x Co 1− x L 2 (C 2 H 5 OH) 2, and Ni x Co 1− x L 2 (HO(CH 2 ) 4 OH), where L is a deprotonated enaminoketone derivative of 3-imidazoline nitroxide. Variation of x does not affect the structural parameters of layered polymeric Ni x Co 1− x L 2 (CH 3 OH) 2 and Ni x Co 1− x L 2 (C 2 H 5 OH) 2 and framework Ni x Co 1− x L 2 (HO(CH 2 ) 4 OH) but leads to smooth variation of the magnetic transition temperature and effective magnetic moment. Spontaneous magnetization is anomalous in the range x ∼0.8–0.9, where it tends to zero because the spontaneous magnetic moment of the ‘nickel sublattice’ is compensated by the spontaneous moment of the ‘cobalt sublattice’.

The chelates of the nitrile-substituted 3-imidazoline nitroxides with copper(II), cobalt(II), and nickel(II) have been synthesized and studied with X-ray diffraction and magnetic susceptibility measurements. The influence of the nitrile substituent on structural and magnetic features of the complexes are discussed.

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 theN-(*)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 interactionsN-(*)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 channelsN-(*)O.H-O(R)-Ni(2+)-(R)O-H.O(*)-Nin 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.