Thermodynamique des complexes metalliques ternaires des amino-acides. II. Etude des systemes Ni(II)—glycine—valine Ni(II)—alanine—valine

Standard enthalpies and entropies of formation for binary and ternary Ni(II) complexes with pairs of the following amino acids as ligands: glycine, DL--alanine and DL-valine, were calorimetrically determined at 25°C in aqueous solution using 1 M ionic strength (NaClO₄).

The results are discussed according to every possible pathway for mixed ligand complex formation and also using the classical statistical methods. Temperature-dependent and temperature-independent components of the thermodynamic data are calculated. In all cases with these ligands involving identical coordination sites, the temperature-independent component of the enthalpy change is closely constant for binary as well as for ternary complexes. All the data show that the stabilization of mixed ligand complexes with respect to the parent binary complexes arises from the entropy term and is maximum for the Ni(II)—glycine—valine system.     

1,2-dihydroisoquinolines—XVIII Rearrangements—IV Dihydroisoquinoline rearrangement—15

When 1-allyl-2-methyl-1,2-dihydropapaverine is treated with hot, dilute mineral acid, rearrangement occurs to give, almost exclusively the 3-allyl-2-methyl-3,4-dihydropapaverinium salt. The previously reported rearrangement of 1-cinnamyl-2-methyl-6,7-dimethoxy-1,2-dihydroisoquinoline has been re-examined and the earlier result, that rearrangement occurs yield the 3-cinnamyl-3,4-dihydroisoquinolinium salt, confirmed.     

Einkristalle von CuPrS2 im A— und Pr2S3 im C—Typ bei Versuchen zur Synthese ternärer Kupfer(I)—Praseodym(III)—Sulfide

Single Crystals of A—type CuPrS₂ and C—type Pr₂S₃ from Attempts to Synthesize Ternary Copper(I) Praseodymium(III) Sulfides Coarse, yellowish‐green single crystals of the ternary copper(I) praseodymium(III) sulfide CuPrS₂ form within seven days at 800°C by oxidation of elemental copper and praseodymium with sulfur (molar ratio: 1:1:2) in evacuated silica tubes when equimolar quantitites of CsCl are present as flux. Attempts to synthesize CuPr₃S₅ or CuPr₅S₈ under analogous conditions always yield two‐component mixtures of CuPrS₂ and Pr₂S₃ (C type) instead of the desired target compounds. The crystal structure of CuPrS₂ (monoclinic, P2₁/c; a = 655.72(6), b = 722.49(6), c = 686.81(6)pm, β = 98.686(7)°; Z = 4) exhibits undulated layers {[Cu(S1)_3/3(S2)_1/1]^3—} parallel (100) which consist of vertex‐linked pairs of two [CuS₄]^7— tetrahedra ([Cu₂S₆]^10—) sharing a common edge. Their three‐dimensional cross‐linkage is achieved by Pr³⁺ cations in monocapped trigonal prismatic coordination of seven S^2— anions each. The metal sulfur distances in the [CuS₄] units cover with 233 (Cu—S2) and 236 (Cu—S1) as well as 247 (Cu—S1′) and 248pm (Cu—S1″) a rather broad interval, whereas those (Pr—S: 284—304 pm) within the [PrS₇] polyhedra lie relatively closer together. According to Pr_2.677□_0.333S₄ (with Z = 4), C—Pr₂S₃ crystallizes in a cation‐deficient Th₃P₄‐type structure (cubic, I4¯3d; a = 857.68(7) pm; Z = 5.333 for Pr₂S₃). In conformity with the Niggli formula {PrS_8/5.333} Pr³⁺ is surrounded trigon‐dodecahedrally by eight S^2— at distances of 287 (4×) and 307pm (4×). Neither the X‐ray single‐crystal structure refinement nor electron‐beam microprobe analyses leave any evidence for the incorporation of Cu⁺ cations into this crystal structure.     

Phosphoranes par fermeture trans-annulaire: III—Conformation—configuration—labilité

The analysis of the n.m.r. spectra of the two isomers of 1,6,6-trimethyl-3-phenyl-2,8-dioxa-5-aza-1-phospha ^vbicyclo[3.3.0]octane allows us to propose a conformation for each 5-membered ring and for the configuration of the phosphorus atom. The lability of the H? P proton, revealed by high temperature experiments and by P? H ? P? D exchange, is significantly different in the two isomers.     

Ein Calciumurannitrid — (Ca3U)N4 — mit Natriumchloridstruktur

Mixtures of calcium amide, Ca(NH₂)₂ and uranium hydride, UH₃ were reacted at temperatures between 600 °C and 1000 °C for 2d to 30d. Starting with a mixture 3 : 1 a singlephase, black, microcrystalline product is obtained. As a result of X‐ray and neutron diffraction the phase has the composition (Ca_{0, 75}U_{0, 25})N = Ca₃UN₄. It crystallizes in the space group Fm3¯m with a = 4.9398 (1) Å in the sodium chloride structure type with statistical occupation of the cation site 4a by 3Ca and 1U.