Synthese und ungewöhnliche Reaktivität eines Cyclotrisilans

Reductive coupling of dichlorosilane 1 with magnesium yields the stable, highly moisture sensitive cyclotrisilane 2a. The hydrolysis products, 1,3-siloxanediol 3 and disilane 4 corroborate the proposed structure of 2a. The reaction with typical silylene trapping agents like benzyl, benzophenone or 2,2′-bipyridyl results in cleavage of all three endocyclic bonds of 2a, yielding the formal silylene addition products 8, 9 and 10.     

Diskrete polynukleare Metall-Komplexe aus Polysulfid-Lösungen: [Cu6S17]2−, ein ungewöhnlicher binärer CuI-Komplex mit verschiedenen bemerkenswerten strukturellen Eigenschaften

Discrete Polynuclear Metal Complexes from Polysulfide Solutions: [Cu₆S₁₇]^2?, a Novel Binary Polynuclear Cu^I Complex with Several Remarkable Structural Features The complex [Cu₆S₁₇]^2?, obtained from Cu(acac)₂ and an ethanolic polysulfide solution, contains an unusual arrangement of the metal atoms and novel types of ligand coordination, particularly of polysulfido (S₄^2? and S₅^2?) ions. The relevance of the synthesis with respect to the “dilemma of transporting metals together with sulfur” for the process of metal sulfide rock formation is evidenced. (PPh₄)₂[Cu₆S₁₇] crystallizes in the space group C2/c with Z = 4 (for further details see Inhaltsübersicht).     

Gitterschwingungsspektren. LXIII. Be(lO3)2 · 4 H2O,ein Hydrat mit ungewöhnlicher Bindungsstruktur und Gitterdynamik

Lattice Vibration Spectra. LXIII. Be(IO₃)₂ · 4 H₂O, a Hydrate with Unusual Bonding and Lattice Dynamics The IR and Raman spectra (4000–50 cm^?1) of Be(IO₃)₂ · 4 H₂O and of deuterated specimens are recorded at 90 and 300 K and discussed in terms of the unusual relations of the masses of the atoms involved and the large polarization power of the beryllium ions. Thus, the translatory modes of the Be²⁺ ions (BeO₄ skeleton vibrations), the librations of the H₂O molecules, and the internal vibrations of the IO₃^? ions in the spectral regions of 300–400 and 600–1000 cm^?1 couple and coincide producing unusual v_H/v_D isotopic ratios of partly < 1. The H-bond donor strengths of the water molecules is so much increased (due to the very large ionic potential of Be²⁺ ions, viz. 49 e nm^?1) (synergetic effect) that the H-bonds formed are similar in strength as those in hydrates of hydroxides with the very strong H-bond acceptor group OH^? (v_OD of matrix isolated HDO molecules 2 074 and 2 244 (H₂O I) and 2 206 and 2 349 cm^?1 (H₂O II))     

Er2S[SiO4]: Ein Erbiumsulfid‐ortho‐Oxosilicat mit ungewöhnlicher Sulfidionen‐Koordination

During the reaction of cadmium sulfide with erbium and sulfur in evacuated silica ampoules pink lath‐shaped crystals of Er₂S[SiO₄] occur as by‐product which were characterized by X‐ray single crystal structure analysis. The title compound crystallizes orthorhombically in the space group Cmce (a = 1070.02(8), b = 1235.48(9), c = 683.64(6) pm) with eight formula units per unit cell. Besides isolated ortho‐oxosilicate units [SiO₄]^4?, the crystal structure contains two crystallographically independent Er³⁺ cations which are both eightfold coordinated by six oxygen and two sulfur atoms. The sulfide anions are surrounded by four erbium cations each in the shape of very distorted tetrahedra. These excentric [SEr₄]¹⁰⁺ tetrahedra build up layers according to by vertex‐ and edge‐connection. They are piled parallel to (010) and separated by the isolated ortho‐oxosilicate tetrahedra.     

NO2−-Komplexe von Kupfer(II) mit ungewöhnlicher Koordination

NO₂^? Complexes of Copper(II) with Unusual Coordination The structures and spectroscopic properties of various new alkali nitro(nitrito) complexes of copper(II) are reported. Cs₄KCu₃(NO₂)_11-x(OH)_x (OH₂) [x ≈ 1] crystallizes in a cubic perovskite-analogous structure with a square-planar coordination of Cu²⁺ by the nitrogen ligator atoms, which is considerably disordered, however. The K⁺ substitution by a further Cs⁺ cation leads to a monoclinic distortion of the unit cell. The Cu(NO₂)₅^3? polyhedra in the compound Cs₃Cu(NO₂)₅, which is also of the perovskite-type with respect to the metal ion positions, are (distorted) axially compressed trigonal bipyramids. The groundstate is predominantly d — as expected. The NO₂- anions are partly nitro- and partly nitrito-bonded to Cu²⁺ and additionally disordered with respect to this bonding isomerism in the equatorial plane. Further compounds of the two structural types with different alkali cations were prepared.