Low-dimensional compounds containing cyanido groups. XXIX. Crystal structures, spectral and magnetic properties of five [Cu(L) 2 X]C(CN) 3 complexes (L 5 2,2 0 -bipyridine or 1, 10-phenanthroline; X 5 Cl 2 , Br 2 or CH 3 COO 2 ) Abstract Five new ionic [Cu(L) 2 X]C(CN) 3 (L = 2,2 0 -bipyridine (bpy) or 1,10-phenanthroline (phen), X = Cl -, (4) and [Cu(phen) 2 Br 0.7 (CH 3 COO) 0.3 ]C(CN) 3 Á0.5H 2 O (5), have been synthesized and characterized by IR and UV-Vis spectroscopy. X-ray structural analysis revealed that the structures of all discussed compounds consist of [Cu(L) 2-X] ? complex cations and uncoordinated C(CN) 3 -counteranions; water molecules were found in 2, 3, 4 and 5; a molecule of ethanol was found in 4, too. The shapes of coordination polyhedra around the copper atoms, which are pentacoordinated by two bidentate bpy or phen molecules and Cl -, Br -or CH 3 COO -ligands monodentately coordinated in the equatorial plane, are distorted trigonal bipyramids. Structures of 1-5 are stabilized by weak p-p interactions and by hydrogen bonds. Magnetic properties of complexes 1-4 are characterized by the presence of weak antiferromagnetic exchange couplings.

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Magnetothermal properties of the compound NiCl2(bipy), where bipy = 4,4 -bipyridine, were studied. The single-ion anisotropy of Ni(II) ions was estimated and its influence on magnetocaloric effect in NiCl2(bipy) was investigated. Above the metamagnetic transition a maximum in the isothermal change of the magnetic entropy is reached near 11 K at field change from 0 T to 7 T with peak value −∆S = 6 J K −1 kg −1 . The temperature dependence of ∆S above 7 K agrees with the assumed easy-axis type of single-ion anisotropy. The inverse magnetocaloric effect, typical for ordered antiferromagnets, was observed in the ordered state of NiCl2(bipy) only for isothermal magnetization in small fields up to 2 T.

The crystals of trCupbapaqs3rCrpCNq6s2un ¤ 6nH2O (bapa = bis(3-aminopropyl)amine) are formed by infinite Cu(II)-Cr(III) antiparallel chains, which are connected into the third direction by additive [Cu(bapa)] moieties. The onset of long-range magnetic order at 3.2 K was observed by AC susceptibility. The study of the magnetocaloric effect from magnetization measurements yields a large entropy change ¡∆SM 13.65 J K ¡1 mol ¡1 (¡∆SM 12.25 J kg ¡1 K ¡1 ) at the field change from 0 T to 3 T at temperature 4 K. The analysis of the critical behavior of ¡∆SM suggests the value of critical exponent n 0.577 at the ordering temperature characteristic for threedimensional magnets with Ising anisotropy.