Zur Struktur zweier Arsen- und Antimontricarboxylate

Zusammenfassung Arsen-tris(2,2-dimethylpropionat) (1) kristallisiert monoklin in der Raumgruppe P2₁/n mita=926.2,b=2158.6,c=983.7 pm, =94.92° undZ=4. As hat gegenüber O die Koordinationszahl 3+3. Antimontripropionat (2) kristallisiert monoklin in der Raumgruppe P2₁/c mita=930.2,b=863.0,c=1575.2 pm, =90.27 undZ=4. Die Moleküle sind intermolekular zu Ketten verknüpft, wodurch Sb die Koordinationszahl 3+3 (+3) erreicht.

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Structure of arsen(III) and antimony(III) carboxylates

Summary Arsen-tris(2,2-dimethylpropionate) (1) crystallizes monoclinic in the space group P2₁/n witha=926.2,b=2158.6,c=983.7 pm, =94.92°, andZ=4. As has a coordination number of 3+3. Antimony tripropionate (2) crystallizes monoclinic in the space group P2₁/c witha=930.2,b=863.0,c=1575.2 pm, =90.27, andZ=4. The molecules are bridged to chains; therefore, Sb reaches the coordination number 3+3 (+3).

     

(CH3)2SBr2 – einige Reaktionen und Strukturen

(CH₃)₂SBr₂ – Reactions and Structures (CH₃)₂SBr₂ ( 1 ) is a donor acceptor complex (8-S-3 + 10-Br-2) which reacts with (CH₃)₂S(?O)NSi(CH₃)₃ to yield [(CH₃)₂S(O)?N? S(CH₃)₂]⁺Br^? ( 2 ). With SbBr₃ (CH₃)₂SBr⁺SbBr₄^? ( 3 ) can be isolated. 1 crystallizes monoclinic in the space group P2₁/c with a = 733.8, b = 734.2, c = 1132.7 pm, β = 92.8° and Z = 4. 2 crystallizes in the orthorhombic space group Pnma with a = 967.2, b = 793.3, c = 1168.3 pm and Z = 4. The SBr and BrBr force constants of 1 are compared with those of S₂Br₂, 3 and Br₂ resp. The nmr and mass spectra of 1 and 2 are communicated.     

Base-freie Tris(trimethylsilyl)methyl-Derivate des Lithiums,Aluminiums, Galliums und Indiums

Base-free Tris(trimethylsilyl)methyl Derivatives of Lithium, Aluminium, Gallium, and Indium Base-free LiR* (R*=-C(SiMe₃)₃) has been prepared from R*Cl and Li-metal in toluene at 85?90°C and used to synthesize the metallanes R*MMe₂ with M = Al, Ga and In, respectively. The NMR (¹H, ¹³C, ²⁹Si) and the vibrational spectra of these trisyl compounds have been discussed. AlCl₃ and LiR*(ratio 1 : 1) forms the metallate metallate Li[R*AlCl₃]. The triclinic unit cell (space group P1 ) consists of a centrosymmetric assoziate, formed by four Li[R*AlCl₃]- units with Al? Cl…?Li bridges, two pairs of Li-atoms differing in their chlorine-coordination and two disordered toluene molecules, inserted in the crystal lattice (R₁wR₂ =0,0444/0,1072). The reaction of GaCl₃ with LiR* (I :1) gives the unusual sesquichloride (R*Ga(Cl_1,33)Me_0,67)₃ in moderate yield. The X-ray structure determination shows a Ga₃Cl₃-skeleton with chairconformation and disordered, terminal gallium ligands (R₁/wR₂= 0,0646/0,2270).     

Determination of the rare earth elements in natural waters by isotope-dilution mass spectrometry

A method is described for the determination of ten rare earth elements (La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb, Lu) in natural waters by isotope-dilution mass spectrometry. A 1-l sample is used for sea water, and proportionately less for other natural waters. The rare earth elements are extracted by co-precipitation with hydrated iron (III) oxide and purified on a single cation-exchange column, with hydrochloric and nitric acids as eluents. Final measurements are from a triple Re/ Ta filament in the mass spectrometer, run automatically under computer control. Relative standard deviations are better than 4% for the analysis of standard solutions, with accuracy in the same range. The analytical blank is low ( <0.03 pmol, 4 pg, for Nd) producing a sample/blank concentration ratio greater than 100 for all ten rare earth elements when determined in a 1-l seawater sample. Concentration depth profiles are given for an ocean water and normalised abundance patterns for three natural waters.     

Spectroscopic studies of the stability of monolayers of 2-docosylamino-5-nitropyridine at the air/water interface

Monolayers of 2-docosylamino-5-nitropyridine (DCANP) at the air/water interface were investigated by UV/Vis spectroscopy. The combination of this method with the classic constant-area relaxation technique yields insight into the longtime stability and the collapse behavior of monolayers. We have demonstrated that monolayers of DCANP are certainly stable under standard deposition conditions. At surface pressures above 20 mN/m monolayer instabilities lead to the formation of a three-dimensional head-to-head multilayered structure.