Sybille Franken

Darstellung und struktur von di-t-butylgermaniumdi-hydroxid und di-t-butylgermaniumoxid

Abstract Hydrolysis of di-t-butylgermanium dichloride yields di-t-butylgermanium dihy-droxide which could be isolated as a crystalline solid. X-ray structure determination shows t-Bu 2 Ge(OH) 2 tetrahedra held together by hydrogen bonds and thus forming continuous double chains. Di-t-butylgermanium oxide has been prepared by dehydration of the dihydroxide. The structure consists of trimeric molecules (t-Bu 2 GeO) 3 with planar germanium-oxygen rings.

Asymmetric Michael addition/lactamization via samp-/ramp-hydrazonesenantioselective synthesis of substituted tetrahydro-2,5(1H,3H)-quinolinediones ☆

Abstract An efficient and highly diastereo- and enantioselective annulation of cyclic 1.3-diketones to tetrahydro-quinolinediones of type 4 and 5 in good overall yields is described. The key step is the Michael addition of the corresponding lithiated SAMP-/RAMP-hydrazones to arylidenemalonates followed by lactamization with virtually complete asymmetric induction (de,ee≧98%).

Large oligocyclic cavities for strong cation complexation

Abstract The syntheses of oligocyclic large cavities containing two or three catechol subunits are described. The X-ray analysis of a heptacyclic molecule composed of three triply clamped dimethyl catechol ether units demonstrates the size and shape of the cavity formed by this skeleton. Properties of the Fe3+- and Ga3+-complexes are elucidated by 1H-NMR, IR, UV/Vis spectra, and by competition experiments with an open-chained reference ligand.

Zur chalkogenolyse von monoorganyl-germanium-trichloriden I. Halogenhaltige verbindungen

Abstract New organylgermanium sesquichlorochalcogenides (RGe)2nY3n−1Cl2 (n = 3, R = t-Bu, Y=O; n = 2, R = t-Bu, Y = S; n = 2, R = t-Bu, Y=Se; n = 1, R = Mes, Y = S; n = 1, R = t-Bu, Y = Se) have been prepared by reaction of t-butyl or mesityl germanium trichloride with sodium hydroxide or sodium chalcogenides. In contrast to the sesquichalcogenides in these compounds one chalcogen atom is formally replaced by two chlorine atoms. X-ray analysis confirms that these sesquichlorochalcogenides cannot be converted into the corresponding sesquichalcogenides by replacement of the chlorine atoms owing to steric factors.

Hexa-(t-butylgermanium-sesquioxid), ein neuartiges käfigmolekül

Abstract Hydrolysis of t-butylgermanium trichloride gives hexakis(t-butylgermanium sesquioxide), (t_Buge)6O9. Among the organic Group IV sesquichalcogenides (RM)2nY3n (M=Si, Ge, Sn; Y= O, S, Se, Te) this compound is the first example with n= 3. Two six-membered and three eight-membered germanium-oxygen rings are linked together forming a new type of a cage-like molecule.

Zur Chalkogenolyse von Monoorganyl-germanium-trichloriden: II. Sesquioxide☆

Abstract Three new organylgermanium sesquioxides (RGe) 6 O 9 (R = mesityl, i-propyl, cyclohexyl) have been prepared by hydrolysis of the corresponding organylgermanium trichlorides. An X-ray study reveals that they form cage-like molecules consisting of six- and eight-membered rings like the analogous t-butyl compound.

Exploring the inclusion properties of new clathrate hosts derived from tartaric acid. X-ray structural characterization of the free ligands and their selective interaction modes with alkylamine guests

A new host 4,5-bis(hydroxydiphenylmethyl)-2,2-dimethyl-1,3-dioxolane (1) was found to form very selectively crystalline complexes with simple alkylamines. Crystals of the three different stereochemical species of this host, optically resolved (1a), racemic (1b), and meso(1c), as well as of the inclusion complexes formed by (1a) and (1b) with PrnNH2, Prn2NH, and Prn3N have been studied by X-ray diffraction. The clathrate inclusion behaviour of (1) is related to structure, and patterns of molecular recognition between this host and the amine guests are characterized. The three different hosts (1a), (1b), and (1c) contain an intramolecular hydrogen bond and are rather rigid; they dimerize in the solid by hydrogen bonding through their hydroxy groups, forming eight-membered (OH)4 rings. Circular motifs of 2 : 1 (which involve ten-membered rings of H-bonded –OH and –NH moieties) and 2 : 2 (involving 12-membered circles) co-ordination between host and guest have also been observed in the inclusion complexes of (1a) with Prn2NH and of (1b) with PrnNH2, respectively. Crystals of the other inclusion complexes between (1a) and the primary and tertiary amines, and between (1b) and the secondary and tertiary amines are characterized by localized 1 : 1 co-ordination between the complexing partners. It appears that preferential co-ordination of a given host with an amine guest is associated mainly with the formation of larger clusters of H-bonded molecules. The host–guest binding patterns are discussed in detail, in relation to those found in related systems of co-ordination-assisted clathrates.

Inclusion of water by a crown amide. First crystal structure of a respective host-guest combination

Crown amide (1) forms a stoicheiometric 1:1 inclusion complex with water, the X-ray crystal structure of which is reported. Crystals of1 · H2O are triclinic, space groupP1, witha=7.503(1),b=11.394(3),c=13.443(2) Å, α=107.066(18), β=96.627(10), γ=106.377(14)°, andZ=2.RF=0.039 for 1697 MoKα reflections [I>3σ(I)] measured at 24°C. The structure features a hydrogen bonded hostguest relationship with concrete1 · H2O units. Hydrogen bonds are between the water oxygen and O(4), N(4), respectively. The crystal packing shows a cavity arrangement of four ligands around each water molecule.

Struktur des trimeren Di-t-butylgermaniumoxids

Abstract Di-t-butylgermanium oxide has been synthesized and investigated by X-ray analysis. The germanium and oxygen atoms form a planar six-membered ring.

Enclave inclusion of nitromethane by a new crown host. X-Ray crystal structure of the inclusion complex and host selectivity properties

A 21-membered macroring (1) incorporating as characteristic building blocks a 2,6-bridged pyridino site and three adjacent catechol moieties is shown to form selectively an inclusion complex with nitromethane, the crystal structure of which demonstrates a completely encapsulated guest molecule.