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In the title compound, catena-poly[[[triaquacopper(II)]- micro -acetylenedicarboxylato-kappa(2)O:O"] hydrate], [[Cu(C(4)O(4))(H(2)O)(3)].H(2)O](n), the Cu(II) ion is coordinated by two monodentate carboxylate groups in trans positions and three water molecules, thus forming a fivefold coordination polyhedron that can be described as a distorted square pyramid. All atoms are located on general sites. The polyhedra are connected by bifunctional acetylenedicarboxylate ligands, to form almost linear chains parallel to [001]. Hydrogen bonds involving the non-coordinated water molecule connect these chains to form a three-dimensional framework.

From a solution of Ni(CH3COO)2 ∙ 4 H2O and acetylenedicarboxylic acid in deionized water single crystals of Ni(C2(COO)2)(H2O)4 ∙ 2 H2O(P21/a, Z = 2, isotypic to Co(C2(COO)2)(H2O)4 ∙ 2 H2O) were obtained by slow evaporation of the solvent. In the solid state structure nickel is octahedrally surrounded by four water molecules and two oxygen atoms of the carboxylate anions. These octahedra are connected to chains by the dicarboxylates. Heating the hexahydrate to 100 °C in a stream of argon leads to Ni(C2(COO)2)(H2O)2 (C2/c, Z = 4, isotypic to Mn[C2(COO)2] ∙ 2 H2O). Here, the NiO6 octahedron is built by two water molecules and four oxygen atoms of the dicarboxylate ligands, which connect the Ni octahedra to a three-dimensional network. Thermoanalytical investigations show another mass loss at about 200 °C, which leads to non-crystalline products. Finally, at about 400 °C NiO is formed. Measurements of the magnetic susceptibilities result in the expected behaviour for Ni2+ in an octahedral co-ordination (3A2 ground state). The effective magnetic moment at room temperature is μeff = 3.20 μB.

Single crystals of Ba

Inhaltsübersicht. [Ba(Benzo-15-Krone-5) 2 ](I 3 ) 2 und [Ba(Benzo-15-Krone-5) 2 ](I 7 ) 2 lassen sich durch Umsetzung von Benzo-15-Krone-5 (C 14 H 20 O 5 ), Bariumiodid (BaI 2 ) und Iod (I 2 ) in Ethanol/Dichlormethan in kristalliner Form gewinnen. Das Triiodid besteht aus einem sandwichartigen Kation [Ba(Benzo-15-Krone-5) 2 ] 2ϩ und einem linear symmetrischen Anion I 3 Ϫ , das als isolierte Einheit vorliegt. Das ungewöhnliche I 7 Ϫ -Anion im Heptaiodid entspricht in [Ba(benzo-15-crown-5) 2 ](I n ) 2 : Synthesis and Crystal Structure of a Triiodide (n ‫؍‬ 3) and a Heptaiodide (n ‫؍‬ 7) Abstract. [Ba(benzo-15-crown-5) 2 ](I 3 ) 2 and [Ba(benzo-15-crown-5) 2 ](I 7 ) 2 can be obtained in crystalline form by reacting benzo-15-crown-5 (C 14 H 20 O 5 ), barium iodide (BaI 2 ), and iodine (I 2 ) in ethanole /dichloromethane. The triiodide consists of a sandwich-like cation [Ba(benzo-15-crown-5) 2 ] 2ϩ and an isolated symmetrically linear I 3Ϫ anion. The unusual I 7 Ϫ anion in the heptaiodide can be described as a V-shaped pentaiodide unit, which is connected with a Einleitung

Results of measurements of the temperature dependence of the specific conductivity of a triethylamine(TEA)/water mixture of critical composition (xc(TEA) = 0.0777; mole fraction of TEA) as well as of mixtures of non-critical composition are reported. They are analysed by fitting the function; 7&: visually determined critical temperature; 0: critical exponents; theoretical value A = 0.5) to the experimental data, For the analysis the critical exponent 0 is fixed at values predicted by different models (0 = 0.65, 0 = 0.89). T, is fixed at the value determined visually for each mixture studied. The analysis of the data shows that in a triethylamine/water mixture of critical composition an anomalous decrease of the electrical conductivity as a function of temperature can be detected as the critical temperature is approached. The reproducibility of the conductivity data is limited by the chemical instability of the system. Therefore it is not possible to decide unequivocally which of the proposed values of the critical exponent 0 is consistent with the data.

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