Irene Brüdgam

Homoleptic carbene complexes VI. Bis{1,1′-methylene-3,3′-dialkyl-diimidazolin-2,2′-diylidene}palladium chelate complexes by the free carbene route

Abstract 1,1′-Methylene-3,3′-dialkyldiimidazolium salts have been deprotonated with n -butylithium in the presence of palladium(II) iodide to give the percarbene complexes 1 (alkyl=Me) and 2 (alkyl=Et), each containing two bidentate 1,1′-methylene-3,3′-dialkyldiimidazolin-2,2′-diylidene chelate ligands. The X-ray structure analysis of 1 reveals a stereochemistry in which the two spiro-linked six-membered metallacycles adopt boat-like conformations strongly bending out of the PdC 4 coordination plane in opposite directions. The carbenoid imidazole rings, which are rotated by +42 and −43°, respectively, relative to this plane, break down into two tightly bound π-systems (N4C4N, CC) connected by long CN bonds.

Synthesis and Spectroscopic Properties of Arene-Substituted Pyrene Derivatives as Model Compounds for Fluorescent Polarity Probes

In this paper, the syntheses of a variety of substituted phenyl pyrenes 5a−n by Suzuki cross-coupling and of two decoupled analogues 10 and 17 are reported. These compounds have been investigated by fluorescence spectroscopy. The solvatochromism of their emission bands (Stokes shift) and the quantum yields in methylcyclohexane and acetonitrile have been determined. Furthermore, the crystal structure of a pyrenyl-tris(2,2′-bipyridine)ruthenium(II) complex 19 is presented.

Solvothermal Synthesis of a 24-Nuclear, Cube-Shaped Squarato-oxovanadium(IV) Framework: [N(nBu)4]8[V24O24(C4O4)12(OCH3)32]

Polydentate bridging ligands can be used to link small polyoxo-alkoxo-metalate units to form supramolecular clusters. In the title compound, twelve μ4 -bridging squarato groups connect eight trinuclear methoxo-oxo-vanadate units to form a tetradodecanuclear cubic framework, in whose cavity six n-butyl groups of the tetra-n-butylammonium cations are anchored.

Two New Isopolyoxotungstates(VI) with the Empirical Composition Cs2W2O7⋅2 H2O and Na2W2O7⋅H2O: An Icosatetratungstate and a Polymeric Compound

The largest isopolyoxotunstate ion known to date, W24 O8424- (structure shown in the picture), isolated as the cesium salt, and a chainlike polyoxotungstate ion made up of planar W4 O16 units, isolated as the sodium salt, hide behind the simple empirical formulas of the title compounds.

Complex stabilization of sesquifulvalene derivatives

Template syntheses of sesquifulvalenes ( 1 ) and ( 2 ) lead to air-stable complexes [( 1 )Mn(CO) 3 ]BF 4 ( 6 ) and [( 2 )Mn(CO) 3 ]BF 4 ( 9 ) as potential candidates for non-linear optical applications; the X-ray structure of 6 is reported.

Trinuclear thiocyanate-bridged compounds of the type [ML]2[Mn(NCS)4](ClO4)2 (where M = Cu(II), Ni(II); L = N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene)

The complexes of general formula [ML]2[Mn(NCS)4](ClO4)2 (where M = Cu(II), Ni(II); L = N-dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) were obtained and the crystal structures of both heteronuclear compounds were determined at 173 K. Complex [CuL]2[Mn(NCS)4](ClO4)2 (1) crystallizes in a monoclinic space group, C2/c, with a = 41.297(9) A, b = 7.571(2) A, c = 16.417(4) A, beta = 96.97(15) degrees, Z = 8, whereas complex [NiL]2[Mn(NCS)4](ClO4)2.H2O (2) crystallizes in a monoclinic space group, P2/c, with a = 21.018(5) A, b = 7.627(2) A, c = 16.295(4) A, beta = 104.47(1) degrees, Z = 4. The magnetic behaviour of (1) and (2) has been investigated over the temperature range 1.8-300 K. Complex (1) displays ferromagnetic coupling inside the trinuclear core of CuMnCu and compound (2) behaves like a mononuclear Mn(II) system. The magnetic properties of the second compound (2) with a similar trinuclear structure shows that Ni(II) ions have a diamagnetic character and a rather weak zero-field splitting at the central Mn(II) ion occurs. Finally, the magnitudes of the Cu(II)-M(II) interactions with M = Ni and Mn have been compared and qualitatively justified.

Synthese und kristallstrukturuntersuchung von bis[dicarbonyl(μ-trifluormethylisocyanid)-(η-pentamethylcyclopentadienyl)molybdän)], [Mo(CO)2(μ-CNCF3)(η-Cp★)]2 und dessen isomerisierung zu Cp★(CO)2Mo(μ-F3CNCCNCF3)Mo(CO)2Cp★

Abstract Trifluoromethyl isocyanide adds to the metal—metal triple bond of bis[dicarbonyl(η-pentamethylcyclopentadienyl)molybdenum] forming Mo 2 Cp 2 ★ (CO) 4 (η 2 -μ-CNCF 3 ) as the first isolated product. Further addition of trifluoromethyl isocyanide at 0°C leads to the formation of [Mo(CO) 2 (μ-CNCF 3 )(η-Cp ★ )] 2 , which according to crystal structure analysis contains two bridging CF 3 NC ligands. During the isomerization of this compound in dichloromethane solution at room temperature or in the solid state above 110°C molybdenum—molybdenum bond cleavage and carbon—carbon bond formation occurs, leading to Cp ★ (CO) 2 Mo(μ-F 3 CNCCNCF 3 )Mo(CO) 2 Cp ★ , which contains 1,1,1,6,6,6-hexafluoro-2,5-diaza-2,3,4-hexatriene as bridging ligand.

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

Summary A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also influenced by the structural features of the substrates. This systematic study reveals that steric and electronic factors exhibited by the alkene and ketone subunits are of high importance for the outcome of these cyclization reactions leading to highly substituted benzannulated cyclooctanol derivatives. In exceptional cases, 7-exo-trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process.

Synthese und Strukturuntersuchungen von Iodocupraten(I) X. [Co(cp)2]2[CuI3] und [Co(cp)2][Cu2I3] = 1/9{[Co(C(cp)2]9[Cu6I11]∞2[(Cu6I8)2]} [1] / Syntheses and Structure Analyses of Iodocuprates(I) X. [Co(cp)2]2[CuI3] and [Co(cp)2][Cu2I3] = 1/9{[Co(cp)2]9[Cu6I11]∞2[(Cu6I8)2]} [1]

Bis-(cobalticenium)triiodocuprate(I), [Co(cp)2]2[CuI3]≡(1) and cobalticenium-triiododicuprate(I), [Co(cp)2][Cu2I3]=1/9{[Co(cp)2]9[Cu6I11] ∞2[(Cu6I8)2]}=(2) were obtained by reacting [Co(cp)2]I with CuI in acetone 1 and acetonitrile 2, respectively. The crystal structure of 1 exists of cobalticenium cations and mononuclear planar anions CuI32-. The crystal structure of 2 contains cobalticenium cations and two different types of iodocuprate(I) anions: an isolated hexa-nuclear ion Cu6I115- built up by 6 edge sharing CuI4 tetrahedra and polymeric layers ∞2 [Cu6I8]2-. In the latter anion Cu6I11 components are two-dimensionally connected via 3 common edges and Cu(I) ions are distributed over two kinds of tetrahedral sites.

Synthese und Strukturuntersuchungen von Iodocupraten(I) VI. Iodocuprate(I) mit zweikernigen Anionen [CU2I4]2- und [Cu2I6]4-/ Syntheses and Structure Analyses of Iodocuprates(I) VI. Iodocuprates(I) with Dinuclear Anions [Cu2I4]2- and [Cu2I6]4-

Abstract Bis(dipyridiniomethan)-di-μ-iodotetraiododicuprate(I), [Py2CH2]2[Cu2I6] and two modifications of bis(tetraphenylphosphonium )-di-μ-iodo-diiododicuprate(I) were obtained by reacting Cu with I2 and [Py2CH2]I2 or [PPh4]I in acetone. The crystal structures of these com pounds are built up by the cations and the binuclear anions: edge sharing Cul4-tetrahedra in [Cu2I6]4- and edge sharing, nearly trigonal planar Cul3-units in [Cu2I4]2-. Whereas the Cu2I4 anions (-A ) are centrosymmetric and almost planar, the anions (-B) are folded about the bridging I···I contact. The anions [Cu2I6] are in intimate contact with the cations via short intermolecular I···N and I···C interactions.