Ligandstruktur und Komplexierung, XXX. Lipophile und konformativ gehinderte Cryptanden

Abstract

Die Synthese der lipophile Strukturelemente (0-, m-, p-Phenylen-, Biphenyl-und Pyridin-Kerne) enthaltenden neuen Cryptandsysteme 1-17 und 27-32 wird mitgeteilt. In der Reihe 15-17 ist das Diaza[2.2]kronenethersystem jeweils durch zwei starre p-Phenylen-, 4,4'-Biphenyl-und 2-Nitro-m-phenylen-Bausteine als ,,Spacer"-Gruppen in fixiertem Abstand auseinandergehalten, so daO Modellsubstanzen fur kanalbildende Ionentransport-Systeme entstehen. Von einigen der neuen Neutralliganden mit variierter HohlraumgroDe und Donoratomzahl wurden kristalline Alkalimetallion-Komplexe dargestellt. Die Komplexkonstanten von 27 -32 werden im Hinblick auf eine rr-Donorbeteiligung von Arenringen an der Koordination der Alkalimetall-Kationen verglichen. Durch temperaturabhangige "C-NMR-Spektren wird die gehinderte Rotation von p-Phenylen-Einheiten quantitativ untersucht.Ligand Structure and Complexation, XXX" Lipophilic and Conformationally Hindered CryptandsThe synthesis of the new cryptand systems 1 -17 and 27-32 with lipophilic structural elements (like 0-, m-, p-phenylene, biphenyl, and pyridine nuclei) is reported. The diaza[2.2]crown ether system of the series 15-17 is held apart at a fixed distance by two p-phenylene, 4,4'-biphenyl, and 2-nitro-m-phenylene systems thus providing model compounds for channel building ion transport systems. A few of the neutral ligands displaying varying cavity size and numbers of donor atoms give crystalline alkali metal ion complexes. The alkali and alkaline-earth complex constants of the diazacrown ether systems 27-32 are compared to elucidate the extent of donor participation ofarene rings in the coordination. By means of temperature-dependent I3C NMR spectroscopy, the conformationally hindered rotation of the p-phenylene units is quantitatively studied. Lipophile und sterisch modifizierte Cryptanden als Ionencarrier-ModellsystemeSeit der ersten Mitteilung iiber Cryptate2) wurde eine Reihe neuer Cryptanden verschiedener Strukturen beschrieben '). Uns interessiert der Einbau heteroaromatischer Kerne in Cryptandsysteme und die damit einhergehende konformative Fixierung4).In dieser Arbeit berichten wir iiber Synthese, Stereochemie, Kation-Komplexierung ufid spektroskopische Studien von neuen Cryptandsystemen, in denen einzelne aliphatische bzw. Oligoethylenglycolether-Ketten verschiedener Lange durch aromatische Struktureinheiten ersetzt sind (1 -7).

NMR Investigations of Restricted Rotations and Metallotropic Shifts in Rhenium(I) Tricarbonyl Halide Complexes of Pyridyl Carboxamide and Thioamide Ligands

“…An MO study [21] of acetamide and thioacetamide ascribes even greater imied previously, albeit rather less accurately in one case, and the present ∆G values of 75.3 and 74.9 kJ mol Ϫ1 are in portance to the N lone pair and the preference of the N atom for pyramidalization. moderately good agreement with the previous values of 74.9 [12] and 73.4 [16] kJ mol Ϫ1 . The full set of activation energy data for the various motional processes occurring in the [ReX(CO) 3 L] (X ϭ Cl, Br) These results imply that there is negligible electronic influence between the two amide groups in these systems.…”

Catenated Cyclodextrins

“…MeCN from P,O, and pyridine from CaH,) according to procedures described in the literature [56]. 1.1 I-Diamino-3.6.9-trioxaundecane 1291. biphenyl-4.4'-dicarbonyl dichloride [31] and 4,4'-bis(bromomethyl)biphenyl [57] were prepared according to published literature. Thin layer chromatography (TLC) was carried out on aluminium sheets precoated with silica gel 60F (Merck 5554) or glass plates precoated with reverse-phase silica gel RP-8 F (Merck 15684).…”

ChemInform Abstract: A New Generation of 6,6′‐Disubstituted 2,2′‐Bipyridines: Towards Novel Oligo(bipyridine) Building Blocks for Potential Applications in Materials Science and Supramolecular Chemistry.

“…Reaction of mesylate 3 with a 10-fold excess of lithium 4-tert-butyloxybutoxide [24] afforded (93%) 6-(4ЈЈ-tert-butyloxytetramethylenoxymethyl)-6Ј-(hydroxymethyl)-2,2Ј-bipyridine (8) [25] (Scheme 3), which represents a very soluble, monoprotected bisfunctionalized bipyridine. Using LiI instead of LiBr resulted (90%) in the corresponding iodo-terminated product (11). Using LiI instead of LiBr resulted (90%) in the corresponding iodo-terminated product (11).…”