Sulfur‐linked Phenolates as Ligands for the Syntheses of Low‐Nuclearity Iron(III) Complexes

Abstract

Exploiting thiacalix[4]arene and sulfur-bridged bisphenolates as ligands for bioinorganic studies involving iron(III) requires the prior development of synthetic routes (varying substituents and reaction conditions) to construct complexes with low nuclearities and accessible coordination sites, which was in the focus of this investigation. Treating p-tert-butylthiacalix[4]arene (H 4 TC) and 1,4-dimethylp-tert-butylthiacalix[4]arene (Me 2 H 2 TC) with Fe[N(SiMe 3 ) 2 ] 3 yielded in the formation of the iron(III) complexes [(Me 3 SiTC) 2 Fe 2 ] (1) and [(Me 2 TC) 3 Fe 2 ] (3), respectively. While 1 is a sandwich compound, in 3

Elucidating the role of the o-methoxy group in the lower rim appended salicylideneamine substituents of calix[4]arene ligands on the molecular and electronic structures of dinuclear Fe(iii)-based diamond-core complexes

“…Apart from the homometallic species, heterometallic [Ln III 2 -Fe III 2 ] 52 (Ln = Dy, Gd, or Tb) and [M 4 -Fe III 4 ] 53 (M = Na, or K) clusters, which exhibit a sandwich-like motif, can also be generated, and their magnetic or catalytic properties have been documented. Thiacalix [4]arene (2) and sulfonylcalix [4]arene (3) have also demonstrated particular ability to bind Fe(III) cations, forming di-, 54 tri-55 and tetranuclear 56,57 clusters.…”

“…Apart from the homometallic species, heterometallic [Ln III 2 –Fe III 2 ] 52 (Ln = Dy, Gd, or Tb) and [M 4 –Fe III 4 ] 53 (M = Na, or K) clusters, which exhibit a sandwich-like motif, can also be generated, and their magnetic or catalytic properties have been documented. Thiacalix[4]arene ( 2 ) and sulfonylcalix[4]arene ( 3 ) have also demonstrated particular ability to bind Fe( iii ) cations, forming di-, 54 tri- 55 and tetranuclear 56,57 clusters. Moreover, an unprecedented round-cake-like [Fe III 24 ] cluster capped by six molecules of thiacalix[4]arene 2 has been recently reported, evidencing antiferromagnetic exchange between the metal centres.…”

Direct Proof for a Lower Reactivity of Monomeric vs. Dimeric Oxidovanadium Complexes in Alcohol Oxidation

“…For several years we have been interested in the elucidation of the reaction mechanisms of these catalysts, by mimicking their postulated active sites on a molecular level,2–10 that is, we used molecular model compounds capable of simulating either the structural and the spectroscopic properties or the reactivity of corresponding vanadium oxide surface species. In order to simulate the oxidic environments that oxidovanadium moieties experience on the surfaces of oxidic support materials we have successfully employed three different types of ligands: The deprotonated forms of incompletely condensed silsesquioxanes,2–4 calixarenes,5–8 and thiacalixarenes, and very recently, of thiobisphenols,9,10 which represent a section of a thiacalixarene 10,20. As part of these studies, the results of a detailed mechanistic work on the thiobisphenolate based oxidovanadium model system I (Scheme ) with respect to the ODH of alcohols were reported.…”