Professor Ulrich Mu È ller zum 60. Geburtstag gewidmet Inhaltsu È bersicht. Die Kristallstrukturen der Oxidnitride SrTaO 2 N, LaTaON 2 und CaTaO 2 N wurden mit Blick auf eine eventuell vorhandene Ordnung in der anionischen Teilstruktur mit Hilfe von Rietveld-Analysen auf Grundlage von Ro È ntgen-und Neutronenpulverdiffraktometerdaten aufgekla È rt. Die Ro È ntgen-und Neutronenpulverdiffraktogramme wurden zuna È chst individuell verfeinert, um dann durch ¹Joint-Refinementsª zusa È tzlich u È berpru È ft und abgesichert zu werden. Zumindest zwei der drei vermessenen Verbindungen haben eine vollsta È ndig geordnete anionische Teilstruktur. Die Kristallstruktur von SrTaO 2 N wurde in der Raumgruppe I4/mcm (a = 5.7049(3) A Ê , c = 8.0499 (5) A Ê , R p = 0.0706, R wp = 0.0904, Reflexe: 70 (Neutronen) /36 (Ro È ntgen), R(F 2 )(N) = 0.147, R(F 2 )(Ro È ) = 0.0952) mit einer geordneten anionischen Teilstruktur gelo È st. LaTaON 2 kristallisiert monoklin (C2/m, a = 8.0922(3) A Ê , b = 8.0603(2) A Ê , c = 5.7118(2) A Ê , b = 134.815(1)°, R p = 0.0592, R wp = 0.0766, Reflexe 235(N)/113(Ro È ), R(F 2 )(N) = 0.0944, R(F 2 )(Ro È ) = 0.165) und zeigt ebenfalls eine vollsta È ndige Ausordnung der Anionen. Im Falle von CaTaO 2 N (Pnma, a = 5.6239(3) A Ê , b = 7.8954(4) A Ê , c = 5.5473(3) A Ê , R p = 0.0503, R wp = 0.0656, Reflexe 206(N)/110(Ro È ), R(F 2 )(N) = 0.0985, R(F 2 )(Ro È ) = 0.0405) deuten leicht unausgewogene Temperaturparameter (Neutronendaten, Modell mit geordneter O/N-Verteilung) einen partiellen O/N-Austausch an.Abstract. The crystal structures of the perovskite related oxidenitrides SrTaO 2 N, LaTaON 2 and CaTaO 2 N have been determined with special regard to the structures of the respective anionic partial structure. The structure refinements were performed by individual Rietveld analyses of both X-ray and neutron powder diffractograms and in addition by joint refinements in order to confirm the results. Both refinement methods yield consistent structure solutions. At least the first two compounds have fully ordered anionic sublattices. The crystal structure of SrTaO 2 N has been solved in the space group I4/mcm (a = 5.7049(3) A Ê , c = 8.0499(5) A Ê , R p = 0.0706, R wp = 0.0904, reflections: 70 (neutrons)/36 (X-ray), R(F 2 )(n) = 0.147, R(F 2 )(X) = 0.0952), with an ordered anionic partial structure. LaTaON 2 crystallizes monoclinic (C2/m, a = 8.0922(3) A Ê , b = 8.0603(2) A Ê , c = 5.7118(2) A Ê , b = 134.815(1)°, R p = 0.0592, R wp = 0.0766, reflections: 235(n)/ 113(X), R(F 2 )(n) = 0.0944, R(F 2 )(X) = 0.165) and also shows a totally ordered distribution of the anions. In the case of CaTaO 2 N (Pnma, a = 5.6239(3) A Ê , b = 7.8954(4) A Ê , c = 5.5473(3) A Ê , R p = 0.0503, R wp = 0.0656, reflections 206(n)/ 110(X), R(F 2 )(n) = 0.0985, R(F 2 )(X) = 0.0405) slightly unbalanced displacement parameters (neutron data, ordered O/N distribution model) hint at a partial exchange of oxygen and nitrogen.

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A 21-year-old man was hospitalized with repeated bleeding from the gastrointestinal tract, the cause of which could not be detected by gastroscopy, colonoscopy or arteriography. After the third surgical intervention he died of uncontrollable bleeding. At autopsy, marked and partly ulcerated duodenal varices were found to be the cause of the bleeding. They were part of a collateral circulation that had developed from chronic obstruction of the inferior vena cava, where thrombosis had arisen in association with neonatal renal vein thrombosis. There was consecutive renal infarction which had required a left nephrectomy on the 2nd day after birth.

Wasserfreies Dimethylformamid reagiert mit Kupfer(I)‐cyanid in Gegenwart von Acetylchlorid und Luftsauerstoff zum 1,4‐Dimethyl‐2,2,3,3‐piperazintetracarbonitril (1). In 1 reagieren je 2 vicinale Nitrilgruppen an C‐2 und C‐3 mit methanolischem Ammoniak zu 2′,5′‐Diiminopyrrolidiniringen (2). Die Verseifung von 1 mit Natriumäthylat zu 3 wird beschrieben.