Arsen(III)‐, Antimon(III)‐ und Bismuth(III)‐halogenid‐Komplexe des [2.2.2]Paracyclophans: Vom lockeren van‐der‐Waals‐Addukt zu stark gerichteten π‐Komplexen mit zwei‐ und dreifacher externer η<sup>6</sup>‐Koordination

Probst, Thomas; Steigelmann, Oliver; Riede, Jürgen; Schmidbaur, Hubert

doi:10.1002/cber.19911240516

Cited by 43 publications

(40 citation statements)

References 22 publications

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“…[16][17][18] To analyze this attractive interaction, DFT calculations were performed on the AsCl 3 -benzene dimer. [19] These studies revealed a lower limit for the binding energy of 7.4 kcal mol À1 for the arsenic-arene interaction, with CÀAs distances of 3.2-3.4 .…”

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confidence: 99%

Arsenic–π Interactions Stabilize a Self‐Assembled As₂L₃ Supramolecular Complex

2004

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The self-assembly of supramolecular coordination compounds has resulted in structures with a diverse range of properties, shapes, sizes, and stoichiometries, including helicates (M 2 L 2 , M 2 L 3 , etc.), triangles (M 3 L 3 ), squares (M 4 L 4 ), rings (e.g., M 6 L 6 ), and polyhedra (M 4 L 4 , M 4 L 6 , M 6 L 6 , M 8 L 12 , etc.).[1] These assemblies almost exclusively contain metals with square-planar, tetrahedral or octahedral coordination geometries. Metals that can exhibit more peculiar coordination geometries have typically been avoided as components for a supramolecular design strategy, [2] most likely because of their variable coordination spheres. Herein we describe a supramolecular design strategy for forming arsenic-based assemblies, which relies on the self-assembly of arsenic(iii) with thiol ligands-and hence the reversibility and lability of arsenic-sulfur bonds-and we report the first member of this class, [As 2 L 3 ] (H 2 L = a,a'-dimercapto-para-xylene). The design strategy incorporates the unusual, yet predictable trigonal-pyramidal coordination geometry of As III featuring a stereochemically active lone pair when coordinated by sulfurbased ligands (Figure 1 a). [3][4][5][6] We selected arsenic(iii) as a design component because of its unusual coordination geometry and a general lack of specific and powerful chelators for this highly toxic ion. [7] Arsenic compounds are legendary for their toxicity, and hydrated As III is recognized as a known human carcinogen. Arsenic is abundant in the earths crust and is all-toofrequently present as an environmental health hazard; [8][9][10] however, specific chelators for environmental and in vivo remediation and sensing applications are lacking. Furthermore, the stereochemically active lone pair of As III adds a novel feature to the targeted supramolecular assemblies: for instance, lone pairs directed into the cavity would provide a unique soft, Lewis-basic cavity environment (Figure 1 b). [11] Figure 1 illustrates the design strategy for forming C 3h -symmetric [As 2 L 3 ] assemblies, which is based on rigid, twofold symmetric dithiols capable of acting as bridging ligands. Dithiol ligand H 2 L[12] (Scheme 1) was the initial bridging ligand investigated, because it is easily prepared and thiolates show a well-known affinity for As III .[12] Using a ligand such as H 2 L allows for two possible orientations of the arsenic lone pairs: into or out of the cavity of the complex. Molecular models (CAChe, MM3) indicated that the lone pairs would be directed into the cavity with an AsÀAs distance of about 6 . [13] H 2 L, synthesized by a literature procedure, [12] forms a yellowish white solid in 52 % yield when treated with stoichiometric amounts of AsCl 3 and KOH in THF/methanol mixtures. The product has very simple 1 H and 13 C NMR spectra, indicative of formation of the desired high-symmetry C 3h complex, and the parent ion peak [H{As 2 L 3 }] + is present in the electrospray ionization mass spectrum. Interestingly, [As 2 L 3 ] also forms in the absence of any...

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confidence: 99%

Arsenic–π Interactions Stabilize a Self‐Assembled As₂L₃ Supramolecular Complex

2004

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“…Previous work by Schmidbaur et al has shown that As III and other heavier main group elements with stereochemically active lone pairs can form close contacts with arene rings in the solid state 16–18. To analyze this attractive interaction, DFT calculations were performed on the AsCl 3 –benzene dimer 19.…”

Section: Methodsmentioning

confidence: 99%

P28.08: 2‐ or 3‐dimensional ultrasonography: What is the best predictor of pulmonary hypoplasia in complicated pregnancies?

Vergani

Andreani

Greco

et al. 2008

Ultrasound in Obstet & Gyne

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Ein As2L3‐Metallocryptant wurde mithilfe einer prädiktablen Designstrategie für den Aufbau selbstorganisierter supramolekularer Arsenkomplexe erhalten. Der Komplex ist gegen eine Reihe von kompetitiven Metallionen, starke Säuren und überschüssigen Ligand erstaunlich stabil. Röntgenstrukturanalyse und Dichtefunktionalrechnungen sprechen für eine starke Arsen‐π‐Wechselwirkung als einen Grund für diese Stabilität.

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“…16 During the same period (mid to late 1980s), Schmidbaur and coworkers reported the groundbreaking complexes of pCp with some of the main-group metals. [17][18][19] Despite these contributions in synthesis of metallacyclophanes of pCp and Dp, a lot of effort is still required to explore the bonding properties of these complexes to make use of these promising p-donating ligands on industrial scale.…”

Section: Introductionmentioning

confidence: 99%