Synthesis and Crystal Structure of a Bixbyite‐Type Solid Solution Zr0.43Er0.57O1.07N0.43

A powder of the composition 40 mol‐% Er₂O₃ and 60 mol‐% ZrO₂ has been prepared. The anion deficient fluorite related compound Zr₃Er₄O₁₂ [R\bar{3} : a = 971.79(7) pm and c = 907.976(0) pm] was produced. This precursor was treated with gaseous ammonia at temperatures between 25 and 1200 °C. The reaction was followed in situ by X‐ray diffraction in a high temperature reaction chamber under a constant flow of ammonia. The nitridation of Zr₃Er₄O₁₂ led to a nitride oxide of the solid‐solution‐type with an apparent composition Zr_0.43Er_0.57O_1.07N_0.43 The compound crystallizes isostructural to bixbyite due to vacancy ordering [Ia\bar{3} : a = 1036.37(4) pm]. The reoxidation of the nitride oxide was monitored in DTA/TG experiments exhibiting an almost complete reoxidation to the starting composition except for some inclusions of dinitrogen.     

Kreisplatten auf elastischer Bettung bei nicht rotationssymmetrischer Belastung

Übersicht Veranlaßt durch die Bedürfnisse der Praxis wird die Lösung für die Kreisplatte auf elastischer Bettung mit rotationssymmetrischer Last auf den Fall beliebiger Randbelastung erweitert.Besondere Berücksichtigung findet dabei eine antimetrische Belastung, wie sie sich für Gründungsplatten von turmartigen Bauwerken unter Windlast ergibt.

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Summary Due to the needs of practical engineering the well known solution for circular plates on elastic foundation with axially symmetrical load has been extended to cases with arbitrary edge loading.Special consideration has been given to the case of antimetric loading which e.g. occurs at the base plates of towerlike structures under wind loads.

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Der Verfasser dankt Herrn Dipl.-Ing. G. Kobler für die geführten Diskussionen und die Durchsicht des Manuskripts.     

Molecular Structures of Mononuclear Rhodium Complexes Containing the Polydentate Ligand Tri(1‐cyclohepta‐2,4,6‐trienyl)phosphane,P(C7H7)3. Classification according to the 31P Chemical Shifts

The olefinic phosphane P(C₇H₇)₃ ( 5 ) behaves as a tetradentate tripod ligand in [RhCl{P(η²‐C₇H₇)₃}] ( 6 ), using all 3 cyclohepta‐2,4,6‐trienyl substituents as η²‐coordinating side‐arms. Nucleophilic displacement of the one‐electron chloro ligand by halides or pseudohalides to give [RhX{P(η²‐C₇H₇)₃}] (X = Br ( 7a ), I ( 7b ), N₃ ( 7c ), NCO ( 7d )) leaves the basket‐like framework [Rh{P(η²‐C₇H₇)₃}] intact. Reactions of 6 with three‐electron ligands result in decomplexation of one cyclohepta‐2,4,6‐trienyl ring and formation of [Rh(L³){P(C₇H₇)(η²‐C₇H₇)₂}] (L³ = acetylacetonate ( 8 ), 2‐carboethoxy cyclopentanonate ( 8a )), reactions of 6 with five‐electron ligands such as η⁵‐C₅H₅ cause decomplexation of two olefinic side‐arms to give [Rh(L⁵){P(C₇H₇)₂(η²‐C₇H₇)}] (L⁵ = η⁵‐C₅H₅ (Cp) ( 9 ), η⁵‐C₅H₄^tBu ( 9a )). The last remaining chelate ring in 9 is opened by pressure‐carbonylation to give the adduct [Rh(Cp)(CO){P(C₇H₇)₃}] ( 10 ) or by oxidative addition of halogens to form [Rh(Cp)X₂{P(C₇H₇)₃}] (X = Br, I). The full set of ¹H, ¹³C, ³¹P, and ¹⁰³Rh NMR data is given for the prototype complexes 7a , 8 , 9 , and 10 , and the molecular geometries of the [Rh{P(C₇H₇)₃}] fragments are compared on the basis of the X‐ray structural determinations of 6 , 8 , 8a , 9 , 9a , and 10 . The chemical shifts δ(³¹P) provide a reliable parameter for the prediction of the molecular structures of the rhodium complexes in solution.     

Correlation of the Rates of Solvolysis of the Benzhydryldimethylsulfonium Ion. Application of the Aromatic Ring Parameter(1)

Values for the specific rates of solvolysis of the benzhydryldimethylsulfonium ion in 34 solvents have been analyzed using various forms of the extended Grunwald-Winstein equation. The specific rates are insensitive toward changes in solvent nucleophilicity (N(T)) values, and they correlate best against a combination of Y(+) values (based on the solvolyses of the 1-adamantyldimethylsulfonium ion) and aromatic ring parameter (I) values. Common-molecule return is observed, being especially powerful in solvents rich in fluoro alcohol; the logarithm of the associated mass law constant correlates inversely with the solvent N(T) values. The product selectivities in ethanol-water mixtures are also consistent with an S(N)1 mechanism for the solvolyses.