Über Na2PrO3 und Na2TbO3

On Na₂PrO₃ and Na₂TbO₃ Using an exchange reaction of Na₂O with Li₈TbO₆ (Na : Tb = 2.1 : 1; au-tube; 750°C, 30 d) yellow-orange colored single crystals of Na₂TbO₃ could be prepared for the first time. Na₂TbO₃ crystallizes monoclinic in C2/c (Z = 8; a = 576.92(6), b = 1001.27(9), c = 1117.91(14) pm, β = 99.98(1)°). According to four-circle data the Li₂SnO₃-type of structure is adopted (PW 1100, MoKα , 1935 I₀ (hkl), R = 4.86%, R_w = 3.63% for all 928 unique reflexions). By a similar exchange reaction of Na₂O with Li₈PrO₆ for the first time single crystals of Na₂PrO₃ could be prepared, too (Na : Pr = 2.2 : 1; au-tube; 700°C; 23 d). The structure determination reveils that there is a variant of the NaCl-type of structure, which ressembles to the Li₂SnO₃-type of structure (PW 1100, MoKα , 2199 I₀ (hkl)), R = 8.88%, R_w = 5.21% for all 947 unique reflexions; C2/c, Z = 8, a = 678.78(5), b = 977.47(7), c = 1080.38(9) pm, β = 108,4(1)°. In contrast to Na₂TbO₃ there are no layers according to NaO(Na_1/3Tb_2/3)O. All octahedral intersticies are occupied systematically with Pr⁴⁺ and Na⁺ : (Na_2/3Pr_1/3)O(Na_2/3Pr_1/3)O.     

Large volume sample application by a simplified “closed” on-column injector in capillary gas chromatography

Summary A new simplified version of a closed on-column injector is introduced. Because of its design isobaric injection conditions do not have to be followed and a wide range of injection temperatures above the boiling point of the sample solvent can be chosen for on-column injections in capillary gas chromatography. Also, when following certain basic injection rules, injections of large sample volumes (20 l or more) give accurate and reproducible results without further problems.Presented at the 17th International Symposium on Chromatography, September 25–30, 1988, Vienna, Austria.     

13C-nmr of carbonyl compounds 1. Stereodynamic behaviour of acyclic and cyclic dienones

The conformational mobility of a series of conjugated dienones is investigated by low-temperature NMR- and IR-spectroscopy and interpreted in terms of substituent effects.     

Li(thf)3cyclo-(P4tBu4CH)]--synthesis, molecular structure and dynamic behaviour

[Li(thf)3cyclo-(P4tBu4CH)] (2-Li), containing the first tetraphosphacyclopentanide anion cyclo-(P4tBu4CH)- (2), was prepared, and its dynamic behaviour in solution analysed by variable-temperature 31P NMR spectroscopy.