Anna Mašlejová

Limiting negative zero-field splitting in tetrakis(imidazole)bis(acetato) nickel(II) complex

Abstract Magnetic properties of bis(acetato-O)tetrakis(imidazole-N3)nickel(II) have been investigated by low-temperature magnetic susceptibility as well as high-field magnetisation and subjected to theoretical analysis. A simultaneous fitting of susceptibility and magnetisation gave the following set of magnetic parameters: g z =2.181, g x =2.039, and D / hc =−22.3 cm −1 . Thanks to the magnetisation measurements the sign of the axial zero-field splitting parameter is fixed unambiguously. The negative value of the D -parameter, unexpected for the geometry of an elongated tetragonal bipyramid, is understandable by introducing different orbital reduction factors for axial (acetate) and equatorial (imidazole) ligands.

Structure and zero-field splitting in bis(1,2-dimethylimidazole) bis(acetato)nickel(II) molecular complex

Abstract A new neutral mononuclear nickel(II) complex of the composition [Ni(Me2iz)2(ac)2] was prepared and characterised (Me2iz=1,2-dimethylimidazole, ac=acetate). The X-ray structure analysis shows that the carboxylato group coordinates as a bidentate ligand with a low O–Ni–O angle of 62°. Therefore an enhanced magnetic anisotropy is expected and confirmed by the magnetic susceptibility measurements. The set of magnetic parameters is gx,gy=2.175, gz=2.263, D/hc=−14.30 cm −1 , and χ TIP =2.04×10 −9 m 3 mol −1 . The axial zero-field splitting parameter D spans the interval of large values owing to a combined effect of the ligand field and angular momentum anisotropy.

Copper oxalate complexes: synthesis and structural characterisation

Six copper(II) oxalate complexes, namely {K2[Cu(ox)2]}n (1), {(Hiz)2[Cu(ox)2]}n (2), {[Cu(ox) (N-Bzliz)2]}n (3), (HMeiz)2[Cu(ox)2] (4), {[Cu(ox)(Meiz)2]}n (5), and [Cu(Hox)2(H2O)2](N-Bzliz) (6) where ox = oxalate ion, iz = imidazole, N-Bzliz = N-benzylimidazole, Meiz = 2-methylimidazole, were synthesised and characterised by single crystal X-ray diffraction (complexes 1–5) or powder X-ray diffraction (compound 6). The three-dimensional crystal packing structures of 2, 4, and 5 are consolidated by intermolecular hydrogen bonds linking the oxygen atom of the oxalate group and the amine or imine group of the imidazole-based part into chains. The molecules of complex 6 are held together by intermolecular hydrogen bonds between the oxygen atoms of the oxalate group and coordinated water molecules.