Dirk Hinz

Lanthanide(III) Dodecanoates: Structure, Thermal Behaviour, and Ion-Size Effects on the Mesomorphism

Rare-earth salts of dodecanoic acid (lauric acid) have been prepared and characterized. The compounds have the stoichiometry Ln(C11H23COO)3, where Ln = Y, La, Ce-Lu (except Pm). The thermal behaviour of these rare-earth dodecanoates has been investigated by hot-stage polarized optical microscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and high-temperature X-ray diffraction analysis. The compounds have a lamellar bilayer structure in the solid state, with the alkyl chains in an all-trans conformation normal to the ionic sublayer. The size of the

Thermal behaviour of lanthanum(III) alkanoates

The mesophase behaviour of the lanthanum(III) alkanoates [La(CxH2x+1COO)3] (x =3-19) has been investigated by hot-stage polarizing optical microscopy, differential scanning calorimetry and high-temperature X-ray diffraction. Lanthanum(III) butyrate monohydrate shows no mesomorphism, whereas for the remaining short chain homologues (x = 4-9) a highly viscous mesophase M and a smectic A phase were observed. The longer chain lanthanum(III) soaps (x = 10-19) exhibit only a smectic A phase. However, the chain length has a pronounced effect on the transition temperatures. The thermal behaviour of lanthanum(III) alkanoates is compared with that of other lanthanide(III) alkanoates.

Rare-earth complexes of mesomorphic Schiff's base ligands

Rare-earth complexes of mesomorphic Schiff s bases, 4-[(alkylimino)methyl]-3-hydroxyphenyl 4-alkyloxybenzoates, were synthesized. Whereas the ligands LH display a nematic and/or a smectic C phase, the metal complexes show a viscous smectic A phase and decompose at the clearing point. The mesophase was investigated by hot-stage polarizing optical microscopy, by differential scanning calorimetry and by high temperature X-ray diffraction. Two types of complex were found, [Ln(LH)3 (NO3)3] and [Ln(LH)2L(NO3)2], depending on the ligand or the central metal ion. The first coordination sphere of the rare-earth ion in these metallomesogens is comparable to that in the structure of complexes with 4-alkoxy-N-alkyl2-hydroxybenzaldimine ligands.

Mesomorphic behaviour of praseodymium(III) alkanoates

In this paper, we describe the synthesis, characterization and thermal behaviour of praseodymium(III) alkanoates. The compounds have the stoichiometry [Pr(C x H2x+1COO)3], where x = 5-19, and were characterized by elemental analysis and infrared spectroscopy. The thermal behaviour was investigated by hot-stage polarizing optical microscopy, DSC and high temperature X-ray diffraction. A highly viscous mesophase M and a smectic A phase were observed for the shorter chain compounds (x = 5-8), whereas only a smectic A phase was observed for the longer chain compounds of this type of metallomesogens. The chain length has a pronounced effect on the transition temperatures.

Mesomorphic behaviour of cerium(III) alkanoates

Ž. In this paper, we describe the synthesis, characterisation and thermal behaviour of cerium III alkanoates. The compounds have the w Ž. x stoichiometry Ce C H COO , where xs 5-17, and were characterised by elemental analysis and infrared spectroscopy. The x 2 xq 13 Ž. thermal behaviour was investigated by hot-stage polarised optical microscopy, by differential scanning calorimetry DSC and by Ž. high-temperature X-ray diffraction XRD . A highly viscous mesophase M and a smectic A phase were observed for the shorter Ž. compounds xs 5-9 , whereas only a smectic A phase was observed for the longer compounds of these kind of metallomesogens. The chain length has a pronounced effect on the transition temperatures. q 2001 Elsevier Science B.V. All rights reserved. Ž.

Über die komplexen Hydroxide des Chroms: Na9[Cr(OH)6]2(OH)3 · 6 H2O und Na4[Cr(OH)6]X · H2O (X = Cl, (S2)1/2) – Synthese, Kristallstruktur und thermisches Verhalten

Aus einer heis gesattigten Losung von CrIII in konzentrierter NaOH-Losung (50 Gew.%) kristallisiert beim langsamen Abkuhlen auf Raumtemperatur Na9[Cr(OH)6]2(OH)3 · 6 H2O (triklin, P1, a = 872,9(1) pm, b = 1142,0(1) pm, c = 1166,0(1) pm, α = 74,27(1)°, β = 87,54(1)°, γ = 70,69(1)°) in Form von tiefgrunen plattchen- bis lattenformigen Kristallen aus. Bei Gegenwart von Chlorid- bzw. Disulfidionen entstehen unter gleichen Bedingungen grune prismen- bzw. lattenformige Kristalle von Na4[Cr(OH)6]Cl · H2O (monoklin, C2/c, a = 1138,8(2) pm, b = 1360,4(1) pm, c = 583,20(7) pm, β = 105,9(1)°) bzw. Na4[Cr(OH)6](S2)1/2 · H2O (monoklin, P21/c, a = 580,8(1) pm, b = 1366,5(3) pm, c = 1115,0(2) pm, β = 103,71(2)°). Die Kristallstrukturen der beiden letztgenannten Verbindungen sind einander sehr ahnlich. In den drei Verbindungen bilden die Anionen zusammen mit den Kristallwassermolekulen eine verzerrt kubisch-dichteste Kugelpackung aus, in der die Kationen geordnet Oktaederlucken besetzen. Das thermische Verhalten der Verbindungen wurde durch DTA/TG- bzw. DSC/TG- und Hochtemperatur-Pulverdiffraktometermessungen untersucht. Als Abbauprodukt entsteht im letzten Schritt jeweils NaCrO2. Complex Hydroxides of Chromium: Na9[Cr(OH)6]2(OH)3 · 6 H2O and Na4[Cr(OH)6]X · H2O (X = Cl, (S2)1/2) – Synthesis, Crystal Structure, and Thermal Behaviour Green plate-like crystals of Na9[Cr(OH)6]2(OH)3 · 6 H2O (triclinic, P1, a = 872.9(1) pm, b = 1142.0(1) pm, c = 1166.0(1) pm, α = 74.27(1)°, β = 87.54(1)°, γ = 70.69(1)°) are obtained upon slow cooling of a hot saturated solution of CrIII in conc. NaOH (50 wt%) at room temperature. In the presence of chloride or disulfide the reaction yields green prismatic crystals of Na4[Cr(OH)6]Cl · H2O (monoclinic, C2/c, a = 1138.8(2) pm, b = 1360.4(1) pm, c = 583.20(7) pm, β = 105.9(1)°) or green elongated plates of Na4[Cr(OH)6](S2)1/2 · H2O (monoclinic, P21/c, a = 580.8(1) pm, b = 1366.5(3) pm, c = 1115.0(2) pm, β = 103.71(2)°), respectively. The latter compounds crystallize in related structures. All compounds can be described as distorted cubic closest packings of the anions and the crystal water molecules with the cations occupying octahedral sites in an ordered way. The thermal decomposition of the compounds was investigated by DSC/TG or DTA/TG and high temperature X-ray powder diffraction measurements. In all cases the final decomposition product is NaCrO2.

Synthesis and crystal structure of the first titanium halide with isolated octahedral clusters, [Ti6C]Cl14

[Ti6C]Cl14 is obtained as black, single crystals through metallothermic reduction of titanium(III) chloride with sodium in the presence of a carbon source and crystallizes isostructurally with [Zr6C]Cl14 and [Nb6□]Cl14.