Kronenether, Doppeldecker- und Sandwichkomplexe: kationengesteuerter Aufbau von metallatopomeren Coronaten

Abstract

Metallacoronat oder Metallakronenether‐Sandwichkomplex? Wie bei den Kronenethern bestimmt auch beim Metallakronenethersystem [Cu3L3] die Größe des eingeschlossenen Kations (Na+, Ca2+ oder K+), welches Produkt entsteht – ein Kronenether, ein dimerer Kronenether oder ein Sandwichkomplex (siehe unten). H2L = Ketipinsäureester.

Hydrotris(1,2,4-triazolyl)borato Complexes with the Main Group Elements Ca, Sr, and Pb - Unexpectedly Bent ML2 Structures and a Stereochemically Inactive Lone Pair at Lead(II)

“…Metal ligand distances and angles are listed in Table 1. A search of the Cambridge Crystallographic Database revealed that a coordination number of eight or higher is not uncommon for calcium (over 130 entries) [25]. The aqua ligands are part of a hydrogen bonding framework which involves the two water molecules of crystallization and five out of six of the exodentate nitrogen donor atoms.…”

Inter-conversion of 15-MC-5 to 12-MC-4 manganese metallacrowns: structure and bioactivity of metallacrowns hosting carboxylato complexes

“…Inorganic chemists have been fascinated by the field of molecular recognition for over 30 metallamacrocycles has been developed. Metallacrowns 1 are a new class of complexes which could be considered as molecular recognition agents [1].…”

“…[14], [15][16][17] inverse- [18,19], [20][21][22][23], [24], [25], [26], [24], [27] metallacrowns with Mn III , Fe III , Ni II , Cu II and V V O, metal ions, stacking metallacrowns [28][29][30] as well as a variety of dimers and fused metallacrowns [16,20,31,32] have been reported to date. Metallacrowns are typically prepared using hydroxamic acids and/or ketonoximic acids as constructing ligands (Scheme 1), while suitable organic molecules such as picoline-tetrazolylamides [33], diethyl ketipinate [30], 3-hydroxy-2pyridone [34] or 3-thione-1,2-dithione-4,5-dithiolato [35] have also been used. Salicylhydroxamic acid (H 3 shi) acts as a multifunctional ligand providing the nitrogen and oxygen donors to the metallacrown ring metals as shown in Scheme 1.…”

Metal-Directed Formation of Tetra-, Hexa-, Octa-, and Nonanuclear Complexes of Magnesium, Calcium, Manganese, Copper, and Cadmium

“…[1] Over the last few years we have devised and described a versatile procedure for the synthesis of numerous bis-, [2] tris-, [3] tetra-, [4] hexa- [5] and octanuclear [5,6] chelate complexes. The readiness of metalla-crown ethers of copper(ii) and dialkylketipinate dianions to coronate is highlighted in the formation of metalla-coronates [9] and metalla-crown ether sandwich complexes. [8] Based on the cavity size of the metalla-crown ethers and the radii of the ions to be encapsulated, they display cation-binding selectivities similar to those known for the classical crown ethers.…”