Gold-Stickstoff-Heterocyclen. 3. Synthese,Eigenschaften und Struktur von trimerem Amido-dimethylgold(III), [(CH3)2 AuNH2]3

Gold Nitrogen Heterocycles. 3. Synthesis, Properties, and Structure of Amido Dimethyl Gold(III), [(CH₃)₂ AuNH₂]₃ The reaction of [(CH₃)₂AuI]₂ with KNH₂ in liquid NH₃ yields tetrameric and trimeric amido dimethyl gold(III). The tetrameric form transforms at ambient temperature easily in the more stable trimeric complex. [(CH₃)₂AuNH₂]₃ forms air-stable, colorless crystals, which are sensitive against irridiation with light. It crystallizes in the orthorhombic space group Ama2 with the lattice constants a = 1653.4, b = 1844.4, c = 448.1 pm, Z = 4. In the trimeric complex the Au(CH₃)₂ groups are linked together by symmetrical amido bridges forming a six membered Au? N heterocycle in the chair conformation. The Au atoms exhibit a square-planar coordination of two CH₃ groups (Au? C = 203 pm) and two N atoms (Au? N = 215 pm) in a cis arrangement. The symmetry C_3v was confirmed for the complex in solution and in the solid state. The vibrational spectra as well as the H-NMR and mass spectra are discussed.     

Die Kristallstrukturen von Triphenylarsin-p-toluolsulfonylimin und seines Donor-Akzeptorkomplexes [ZrCl4(Ph3AsNSO2Tol)]2

The Crystal Structures of Triphenylarsin-p-toluene Sulfonylimine and of its Donor-Acceptor Complex [ZrCl₄(Ph₃AsNSO₂Tol)]₂ The molecular structures of the title compounds are reported. In the donor-acceptor complex [ZrCl₄(Ph₃AsNSO₂Tol)]₂ the zirconium atoms are bridged by the oxygen atoms of the triphenylarsin-p-toluene sulfonylimine molecules, forming a centrosymmetric dimer with a puckered Zr₂O₄S₂ eight-membered ring in the chair conformation. Ph₃AsNSO₂Tol: Space group P1 , Z = 2, structure determination with 4 010 observed unique reflections, R = 0.036. Lattice dimensions at 19°C: a = 897.52(4), b = 1 071.82(6), c = 1 337,49(5) pm, α = 110.280(4)°, β = 98.814(4)°, γ = 109.872(4)°. [ZrCl₄(Ph₃AsNSO₂Tol)]₂: Space group P2₁/n, Z = 4, structure determination with 3 762 observed unique reflections, R = 0.078. Lattice dimensions at ?60°C: a = 1 387.3(4), b = 1 434.9(2), c = 1 404.7(4) pm, β = 92.71(1)°.     

New copper-mediated O-arylations of phenols with arylstannanes

A novel method for the synthesis of diaryl ethers with phenols and arylstannanes under mild conditions is described. This copper-mediated O-arylation is feasible using DMAP in acetonitrile and is complementary to the use of boronic acids as aryl donors. The reaction is tolerant of a wide range of substituents and sterically hindered coupling partners.     

Controlled Uptake and Release of Metal Cations by Vanadium Oxide Nanotubes

Vanadium oxide nanotubes (C_n‐VO_x‐NTs) contain α‐monoamines (C_nH_2n+1NH₂ with 4≤n≤22) as templates intercalated between crystalline VO_x layers comprising multilayer tube walls. The present study reveals that a large proportion of the amines can easily be exchanged by metal cations. The tubular morphology is not affected by this reaction, but the distance between the VO_x layers, i.e., 2.8 nm in C₁₂‐VO_xNTs, decreases in the reaction product to 0.9 – 1.2 nm, depending on the metal salt actually applied. Alkali (Na⁺, K⁺), alkaline‐earth (Mg²⁺, Ca²⁺, Sr²⁺), and transition‐metal salts (Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺) have successfully been intercalated. This reaction is partly reversible since intercalated sodium cations can be resubstituted by dodecylamine. This exchange produces again C₁₂‐VO_x‐NTs with the original inter‐layer spacing. However, this release is successful only when sodium is complexed by a crown ether. Under these reaction conditions, even a cyclic uptake and release of Na⁺ and amine, respectively, accompanied by a corresponding shrinkage and widening of the inter‐layer distance, is observed while the tubular structure is widely preserved. Furthermore, a distinct selectivity of the metal‐cation exchange has been observed.     

Darstellung,Eigenschaften und Molekülstrukturen von chiralen Dimethylaluminium-aminoalkoxiden

Preparation, Properties, and Molecular Structures of Chiral Dimethylaluminum Amino Alkoxides Dimethylaluminium-2-piperidylmethoxide ( 1 ), N-methyl-3-piperidyloxide ( 2 ), R(–)-2-aminobutoxide ( 3 ) and cis-1 R, 2 S-2-N-benzylaminocyclohexyl-1-methoxide ( 4 ) were obtained by reaction of Me₃Al with the corresponding aminoalkohols in n-pentane. The compounds were characterized by ¹H, ¹³C, and ²⁷Al n.m.r. spectroscopy. The molecular structures of 1 , 3 , and 4 were determined by X-ray diffraction. The compounds form oxygen-bridged dimers and in consequence of an Al–N interaction two additional chelate rings. The bond distances of the central Al₂O₂ ring correspond with 1.9 Å to those of known dialkylaluminumalkoxides. The Al–N bond distances run to 2.18 Å which indicates a strong EDA interaction.