Expanded Mercaptocalixarenes: A New Kind of Macrocyclic Ligands for Stabilization of Polynuclear Thiolate Clusters. Issue 21 (14th March 2022)

• Record Type: Journal Article
• Authors: Schleife, Frederik; Bonnot, Clément; Chambron, Jean‐Claude; Börner, Martin; Kersting, Berthold
• Is Part Of: Chemistry. Volume 28:Issue 21(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-14
• Subjects: coordination chemistry -- expanded mercaptocalix[4]arenes -- synthesis -- X-ray crystallography; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202104255
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The syntheses and properties of expanded 4‐ tert ‐butyl‐mercaptocalix[4]arenes, in which the methylene linkers are replaced by −CH2 NRCH2 − or −CH2 NRCH2 − and −CH2 NRCH2 CH2 CH2 NRCH2 − units, are described. The new macrocycles were obtained in a step‐wise manner, utilizing fully protected, i. e. S ‐alkylated, derivatives of the oxidation‐sensitive thiophenols in the cyclisation steps. Reductive cleavage of the macrobicyclic or macrotricyclic intermediates (6, 7, 11 ) afforded the free thiophenols (H4 8, H4 9, and H4 12 ) in preparative yields as their hydrochloride salts. The protected proligands can exist in two conformations, resembling the "cone" and "1, 3‐alternate" conformations found for the parent calix[4]arenes. The free macrocycles do not show conformational isomerism, but are readily oxidized forming intramolecular disulfide linkages. Preliminary complexation experiments show that these expanded mercaptocalixarenes can serve as supporting ligands for tetranuclear thiolato clusters. Abstract : The synthesis of expanded mercaptocalix[4]arenes, in which four 4‐tert‐butyl‐thiophenolato units are joined by −CH2 NRCH2 − and −CH2 NR(CH2 )3 NRCH2 − linkers, has been achieved. The new macrocycles do not show the conformational isomerism typical of the parent mercaptocalix[4]arenes. The potential of these macrocycles to form mixed‐ligand complexes with first row‐transition metal ions is demonstrated.