Cs[Er10(C2)2]I18 und [Er10(C2)2]Br18: zwei neue Beispiele für „reduzierte”︁ Halogenide der Lanthanide mit isolierten [M10(C2)2]-Clustern

Cs[Er₁₀(C₂)₂]I₁₈ and [Er₁₀(C₂)₂]Br₁₈: Two New Examples for Reduced Halides of the Lanthanides with Isolated [M₁₀(C₂)₂] Clusters Cs[Er₁₀(C₂)₂]I₁₈ is obtained from the reaction of ErI₃ with caesium and carbon in sealed tantalum containers at 700°C and [Er₁₀(C₂)₂]Br₁₈ through the metallothermic reduction of ErBr₃ with rubidium in the presence of carbon at 750°C in sealed niobium containers. The crystal structures {Cs[Er₁₀(C₂)₂]I₁₈: triclinic, P1 ; a = 1 105.2(8) pm, b = 1 112.0(7) pm; c = 1 122.9(8) pm; α = 66.91(3)°, β = 87.14(3)°; γ = 60.80(3)°; Z = 1; R = 0.049, R_w = 0.043; [Er₁₀(C₂)₂]Br₁₈: monoclinic, P2₁/n, a = 971.8(6) pm, b = 1 623.4(9) pm, c = 1 163.8(6) pm, β = 104.00(6)°; Z = 2; R = 0.077, R_w = 0.057} contain isolated dimeric [Er₁₀(C₂)₂] clusters. Due to the inclusion of C₂ units, the octahedra are elongated in the direction of the pseudo C₄ axis. The connecting edges of the two octahedra are exceptionally short (316.7 pm and 314.8 pm respectively). The dimeric units are connected via X^i?a and X^a?i (X = Br, I) bridges according to [Er₁₀(C₂)₂XX]X. Cs⁺ is surrounded by a cuboctahedron of iodide ions in Cs[Er₁₀(C₂)₂]I₁₈.     

[(1,4,8,11‐Tetraazacyclotetradeca‐1,4,8,11‐tetrayl)tetraacetamide‐κ6N1,N4,N8,N11,O1,O8]copper(II) sulfate 4.5‐hydrate

The crystal structure of the title copper(II) complex, [Cu(C₁₈H₃₆N₈O₄)]SO₄·4.5H₂O, formed with the tetra­amide cyclam derivative 2‐(4,8,11‐triscarbamoyl­methyl‐1,4,8,11‐tetra­aza­cyclo­tetradec‐1‐yl)­acet­amide (TETAM), is described. The macrocycle lies on an inversion centre occupied by the hexacoordinated Cu atom. The four macrocyclic tertiary amines form the equatorial plane of an axially Jahn–Teller elongated octahedron. Two O atoms belonging to two diagonally opposite amide groups occupy the apical positions, giving rise to a trans‐III stereochemistry, while both the remaining pendant side arms extend outwards from the macrocyclic cavity and are engaged in hydrogen bonds with sulfate anions and co‐crystallized water mol­ecules.     

The mono-, sesqui-, and dibromides of indium: InBr,In2Br3, and InBr2

Of the four reduced indium bromides, InBr, In₂Br₃, InBr₂, and In₄Br₇, synthesis, crystal growth and structure determination of the first three is reported. InBr (orthorhombic), Cmcm, Z = 4, a = 446.6(1), b = 1236.8(2), c = 473.9(1) pm, V_m = 39.42(1) cm³ mol^?1) crystallizes with the TlI-type structure. In₂Br₃ (orthorhombic, Pnma, Z = 16, a = 1300.6(5), b = 1649.8(5), c = 1289.7(9) pm, V_m = 104.16(9) cm³ mol ^?1), isotypic with Ga₂Br₃, is according to In₂[In₂Br₆] a mixed-valence In^I–In^II-bromid with eclipsed [In₂Br₆]^2? groups with d(In–In) = 268.8 and 271.6 pm, respectively. InBr₂(?In[InBr₄]) is a mixed-valence In^I? In^III bromide with the GaCl₂-type structure (orthorhombic, Pnna, Z = 8, a = 798.6(2), b = 1038.5(2), c = 1042.5(5) pm, V_m = 65.09(4) cm³ mol^?1).     

Procedure for the quantification of rider peaks.

Rider peaks are small peaks which are not well resolved from a large and asymmetrical neighbour but sit on its trailing side. The usual case is a large, tailed peak which is eluted just in front of the small peak, although the opposite situation can also occur (a small peak in front of a large peak with fronting). The common integration techniques. i.e. separating the peaks by vertical drop or by a tangent and determining area or height, give erroneous results. We propose a method for their quantification with low error. It is necessary to set up a "two-dimensional" calibration by varying both concentrations, i.e. of the large peak and of the rider. This leads to a series of linear equations which describe the rider size, as found by the integrator, as a function of the size of the large peak. The y-axis intercepts i of these equations show a linear relationship with the concentration x of the rider analyte, whereas the slopes s follow a quadratic relationship. These equations can be used to solve the equation y = s(x) x z + i(x) for x (y and z are the integrated peak size of the rider and the large peak, respectively). The procedure was tested with computer-generated peak pairs as well as with HPLC separations of 2,3-dimethylaniline (large tailing peak) and 2,3-dimethylphenol (symmetrical rider peak).     

Anil-Synthese 22. Mitteilung über die Herstellung von Styryl-und Distyryl-Derivaten des Pyridins

Preparation of Styryl and Distyryl Derivatives of Pyridine 2,4-, 2,5- and 2,6-Dimethylpyridines react with anils of aromatic aldehydes in the presence of dimethylformamide and potassium hydroxide to yield the corresponding distyrylpyridines (‘anil synthesis’). Under the same reaction conditions (4-methylstyryl)pyridines are converted to (stilbenylvinyl)pyridines. Similarly, the Schiff's base derived from pyridine-3-carbaldehyde and p-chloroaniline on treatment with methyl- and p-tolyl-substituted aromatic heterocycles gives the corresponding (heteroaryl-styryl)pyridines, whereas with the Schiff's bases derived from pyridine-2- and -4-carbaldehyde side reactions, such as dimerization followed by disproportionation predominate.     

Zur Kenntnis von CsLiCl2

On CsLiCl₂ CsLiCl₂ crystallizes with a = 492.35(9), c = 950.0(3) pm (Guinier data), tetragonal, P4/nmm, Z = 2. The crystal structure was determined and refined from single crystal data (R = 5.2, R_w = 4.0%). It is essentially that proposed earlier for KCoO₂ which is isotypic with CsLuO₂. In CsLiCl₂ Cs⁺ has C.N. = 9 (d? = 363 pm), Li⁺ C.N. = 5 (tetragonal pyramid) with d(Li? Cl) = 231 and 4 × 260 pm, respectively.     

Dissipation of electronic excitation energy within a C60 [6:0]-hexaadduct carrying 12 pyropheophorbide a moieties

The synthesis and photophysical studies of a fullerene [6:0]-hexaadduct that carries 12 pyropheophorbide a units are reported. The synthesis started with the malonate 1, which was coupled under template conditions to C(60)() to give the hexaadduct 2. After removal of the protecting group with acid the dodecakis amino-substituted precursor compound 3 was generated. 3 was not isolated but directly reacted with the N-succinimid ester 4 of pyropheophorbide a (5), which delivered the desired fullerene [6:0]-hexaadduct 6 in excellent yield. The photophysical properties of 6 were studied and compared with those of the fullerene [5:1]-hexaadduct 7 with six pyropheophorbide a groups and the bispyropheophorbide a-fullerene [5:1]-hexaadduct 8. The pyropheophorbide a units in 6 undergo after light absorption very efficient energy transfer as well as partly excitonic interaction. The last process results in formation of energy traps, which could be resolved experimentally. Compared to the reference compounds 7 and 8, 6 has a higher probability of trap formation due to a higher local concentration of dye molecules and shorter distances between them. As a consequence, the excitation energy is delivered rapidly (within 23 ps) to the traps, resulting in decreases of the fluorescence, intersystem crossing, and singlet oxygen quantum yields in comparison with the values of the reference compounds.     

Synthesis and crystal structure of tetraethylammonium-μ-trichloro-heptachloro-diaqua-trirhenate(III)-dihydrate,NEt4[Re3Cl10(H2O)2] · 2 H2O

NEt₄[Re₃Cl₁₀(H₂O)₂] · 2 H₂O ( 1 ) was obtained from hydrochloric acid solutions of ReCl₃ and tetraethylammonium chloride, NEt₄Cl, by isothermal evaporation as dark red crystals. 1 crystallizes in the orthorhombic crystal system, space group Pnma, Z = 4, with a = 1838,7(2), b = 1456.9(1), c = 972.08(7) pm, V_m = 391.81(6) cm³ · mol^?l. The crystal structure consists of [Re₃Cl₁₀(H₂O)₂]^? anions that are arranged in the fashion of a hexagonal closest-packing of spheres. These are held together by partially disordered NEt₄⁺ cations and are bound into a hydrogen bonding system with the crystal water.     

Über die Identität eines sogenannten Ammoniumcarbonat‐Präparates

On the Identity of a so‐called Ammonium Carbonate Sample Commercial samples of so‐called “ammionum carbonate” are shown to contain ammonium carbamate rather than ammonium carbonate. In fact samples may contain varying quantities of α‐ and β‐(NH₄)(CO₂NH₂), of which only the α‐phase is reported in the literature. Mixtures of both phases tend to leak the volatile α‐phase and to react with moisture to form (NH₄)(HCO₃). The crystal structure of the new β‐(NH₄)(CO₂NH₂) is refined from X‐ray powder data.