Molecular Borromean Rings Based on Dihalogenated Ligands

Abstract

A series of Cp*Rh-and Cp*Ir-based molecular Borromean rings (BRs) have been prepared by dihalogenated ligands. The strength of the interaction among the rings for different BRs is not the same and can be adjusted by changes in the halogen atoms on the precursor. Jin and colleagues took advantage of this dissimilarity in the interactions to realize selective reversible conversion between BRs and a monomeric rectangle by the use of different p-dihalobenzenes. Subsequently, a stepwise separation method for p-dichlorobenzene, p-dibromobenzene, and p-diiodobenzene at ambient temperature was developed.

Highly Selective Synthesis of Iridium(III) Metalla[2]catenanes through Component Pre‐Orientation by π⋅⋅⋅π Stacking

“…[15] This observation inspired us to test the dinuclear complexes [Cp* 2 Ir 2 (m-CA)-(OTf) 2 ] E3(OTf) 2 and [Cp* 2 Ir 2 (m-BA)(OTf) 2 ] E4(OTf) 2 (Scheme 2), featuring halogenated benzoquinone bridges,a s building blocks for metallacycles and metalla[2]catenanes. [15] This observation inspired us to test the dinuclear complexes [Cp* 2 Ir 2 (m-CA)-(OTf) 2 ] E3(OTf) 2 and [Cp* 2 Ir 2 (m-BA)(OTf) 2 ] E4(OTf) 2 (Scheme 2), featuring halogenated benzoquinone bridges,a s building blocks for metallacycles and metalla[2]catenanes.…”

“…As the conventional distance for p-p interactions measures about 3.5 , [14] the distance between the central anthracene groups in am acrocycle of type 1 4+ should be approximately 7.0 to allow for the construction of an interlocked [2]catenane structure.This was achieved by using the dinuclear iridium complex [Cp* 2 Ir 2 -(m-DHBQ)(OTf) 2 ](E2(OTf) 2 ;Scheme 3, center) as abuilding block for ametallarectangle.Whereas the M···M separation in E2 2+ measures approximately 8.0 , [15] the ability of ligand L to curve inwards was expected to satisfy the geometric requirements. As the conventional distance for p-p interactions measures about 3.5 , [14] the distance between the central anthracene groups in am acrocycle of type 1 4+ should be approximately 7.0 to allow for the construction of an interlocked [2]catenane structure.This was achieved by using the dinuclear iridium complex [Cp* 2 Ir 2 -(m-DHBQ)(OTf) 2 ](E2(OTf) 2 ;Scheme 3, center) as abuilding block for ametallarectangle.Whereas the M···M separation in E2 2+ measures approximately 8.0 , [15] the ability of ligand L to curve inwards was expected to satisfy the geometric requirements.…”

“…Thes tructural features of metallarectangle 1 4+ encouraged us to explore the synthesis of molecular interlocked metalla[2]catenanes.W es peculated that the strong p-p stacking interactions developed by the p-electron-rich anthracene groups of ligand L may enable the self-assembly of metalla[2]catenanes by p-p stacking interactions.H owever, in order to insert an additional anthracene-bridged ligand unit into metallacycles of type 1 4+ ,t he distance between the two anthracene units must be expanded. As the conventional distance for p-p interactions measures about 3.5 , [14] the distance between the central anthracene groups in am acrocycle of type 1 4+ should be approximately 7.0 to allow for the construction of an interlocked [2]catenane structure.This was achieved by using the dinuclear iridium complex [Cp* 2 Ir 2 -(m-DHBQ)(OTf) 2 ](E2(OTf) 2 ;Scheme 3, center) as abuilding block for ametallarectangle.Whereas the M···M separation in E2 2+ measures approximately 8.0 , [15] the ability of ligand L to curve inwards was expected to satisfy the geometric requirements.…”

Selektive Synthese von Iridium(III)‐Metalla[2]catenanen durch Präorganisation der Komponenten über π‐π‐Wechselwirkungen

“…). Die Kombination dieser nicht-kovalenten Wechselwirkungen ermçglicht die Bildung und stabilisiert das Metalla[2]catenan 2 8+ .Kürzlich fanden wir, dass Halogenatome eine wichtige Rolle bei der Bildung von Borromäischen Ringen spielen kçnnen [15]. Sämtliche Protonenresonanzen sind, im Unterschied zu den Singulettresonanzen in 1(OTf) 4 ,inzwei Signale aufgespalten.…”

“…Dies wird durch den Einsatz des zweikernigen Komplexes [Cp* 2 Ir 2 (m-DHBQ)](OTf) 2 (E2(OTf) 2 ;S chema 3) als Baustein fürd ie Synthese eines vierkernigen Metalla-Rechtecks erreicht. Obwohl der M-M-Abstand in E2 2+ ungefähr 8.0 beträgt, [15] sollte die Fähigkeit des Liganden L,e ine kokave Konformation anzunehmen, die geometrischen Voraussetzungen erfüllen.…”