Zur Stereochemie spiranartiger Komplexsalze (Beitrag zur Kenntnis des Cottoneffekts)

Abstract

In der letzten Arbeit uber innere Komplexsalze') haben wir zahlreiche Spiransysteme beschrieben, die sich a d die beiden Formeln I und I1 beziehefi lassen; in ihnen ist das Zentralatom vor allem K u p f e r und Nickel.U Es konnte gezeigt werden, da6 diese Verbindungen engste konstitutionelle Beziehungen zu manchen anderen Verbindungsklassen, so z. B. zu den Schwermetallsalzen der o-Oxyazokorper aufweisen.Die Frage nach der Konstitution all dieser Verbindungen kann als erledigt betrachtet werden. In der vorliegenden Arbeit sol1 an Hand zahlreicher Experimente versucht werden, naheren AufschluB iiber ihre Konfiguration zu erhalten. Es handelt sich im wesentlichen um die Frage, ob die beiden Ringsysteme a und b in einer einzigen Ebene liegen, oder ob sie schr5g bzw. senkrecht zueinander stehen. Im ersteren Falle lage eine p l a n e Lagerung vor, im letzteren Falle aber eine mehr oder weniger ausgepragte t e t r a e d r i s c h e Gruppierung, durch welche das Metallatom ein Asymmetriezentrum wiirde. l) J. pr. Chem. 149, 217 (1937).

Metal–salophen-based receptors for anions

“…Schiff bases of iron(III), 20, have been known since 1938. 87,88 The magnetochemical properties of the m-oxo-bridged complexes, [{Fe(salen)} 2 O] (salenH 2 = N,N 0 -bis(salicylidene)ethylenediamine) and [{Fe(saloph)} 2 O] (salophH 2 = bis(salicylidene)-o-phenylenediamine), 21, have proved to be particularly interesting, and their properties and X-ray studies are mentioned in many works. 89,90 Many derivatives have been prepared in which the bridge is constituted by the monoanion of a carboxylic acid X (trichloroacetic, trifluoroacetic, salicylic and picric acid), and characterized as dimers of composition [Fe(salen)X] 2 .…”

Unsymmetrical chiral salen Schiff base ligands

“…Those of type A are relatively easy to construct, appear early in the literature and are quite common [5,7]. One that showed promise in catalytic epoxidation was complex 4, reported by Ito and Katsuki [30].…”

“…Complexes of the salen ligand and its derivatives [1] have been known since 1869 [2,3] and were first studied systematically in the 1930s by Pfeiffer and co-workers [4] including the first chiral non-racemic cases [5]. Those specifically derived from non-racemic trans-1,2-diaminocyclohexane were first studied in the 1960s [6,7] and, over the subsequent decades, they have been studied widely especially in regard to their use in catalytic asymmetric synthesis [7][8][9].…”

Stereoselective Reactions with Chiral Schiff Base Metal Complexes

“…Salen ligands were established as versatile and effective ligands in 1869, [13] with the first systematic studies conducted in the 1930s by Pfeiffer and co-workers. [14] These workers introduced the first non-racemic Salen ligand. Salen metal complexes are indeed considered privileged catalysts as demonstrated by their successful application in many challenging asymmetric reactions.…”