Untitled

Abstract

Sind α‐Cyclodextrin‐Hohlräume chlorophil? Das Cyclodextrin‐Diphosphan 1, als Ligand ideal geeignet zur trans‐Chelatisierung, liefert die Antwort: Bei der Reaktion von 1 mit einer Reihe von Übergangsmetallchloriden entstehen Komplexe, bei denen wenigstens eine M‐Cl‐Bindung in den Hohlraum gerichtet ist, wobei schwache Wechselwirkungen zwischen dem Cl‐Atom und nach innen orientierten Cyclodextrin‐C‐H5‐Bindungen bestehen. So beträgt im Pd‐Komplex der kleinste H5⋅⋅⋅Cl‐Abstand 2.64(2) Å.

Rigid trans-spanning triptycene-based ligands: How flexible they can be?

“…2). This intriguing lowfield shift may result from either steric (van der Waals) repulsion [16] or week hydrogen bonding [17]. More solid indication, however, might come from the structure elucidation.…”

Chemistry of metalated container molecules

“…In particular, by adjusting the size and form of the pocket it is often possible to stabilize reactive intermediates or to coordinate coligands in unusual coordination modes. Such assemblies also offer the opportunity to study secondary host-guest interactions between the coordinated coligands and the walls of the host [60]. For systematic investigations it is of importance that various coligands can be accommodated in the binding pocket of the container molecules.…”

Trans-chelating diphosphines, the elusive ligands!

“…Remarkably, these diphosphines also demonstrated a marked tendency to form trans-complexes confining the metal in the entry of the cavity and some ligands (especially chlorides) included in it (see Scheme 17) [130]. In this case, the ligand entrapment is supposed to be assisted by weak interactions with the H5 of the cyclodextrine.…”

“…In this case, the ligand entrapment is supposed to be assisted by weak interactions with the H5 of the cyclodextrine. The molecular structure of two examples of this type of complexes has been analyzed by X-ray diffraction (Pt17Cl 2 and Ru17(CO) 2 Cl 2 , Table 6) [130]. In the latter, in which the ligand spans trans-position in an octahedral compound, two chlorides are located inside the cavity!…”