Abstract:The reaction of 1,1′-bis(2-chloroethoxy)ferrocene with 1,2-ethanedithiolate in absolute ethanol gave mononuclear 1,10-dioxa-4,7-dithia[10]ferrocenophane and binuclear 1,10,21,30-tetraoxa-4,7,24,27-tetrathia[10,10]ferrocenophane, along with a small amount of unexpected 1,13-dioxa-4,7,10-trithia[13]ferrocenophane and 1,16-dioxa-4,7,10,13-tetrathia[16]ferrocenophane. Extraction of aqueous metal picrates (M; alkali, alkaline earth, Ag+, Tl+, Cd2+, Co2+, Cu2+, Ni2+, and Hg2+) with dioxathia[n]ferrocenophanes was ex… Show more
“…While a large number of redox-active macrocycles have been reported in the literature, the vast majority are based on crown ethers, a structural motif containing hard O donor atoms that supports the coordination of alkali- and alkaline-earth-metal cations. With the exclusion of a few notable examples, those that target the binding of heavy-metal ions have received comparatively little attention. 1 Wurster's thiacrown ethers used in this study.…”
Isomeric p- and o-phenylenediamine-containing macrocyclic hosts (Wurster's thiacrown ethers L1 and L2, respectively) were prepared and studied as Hg(II) ionophores. The distinct electrochemical properties of the two hosts allowed for the formation of a coordination compound with the ortho-Wurster's thiacrown ether but not the para isomer. In the latter case, the Hg(II) ion served as an oxidant in an electron-transfer reaction with the host. Solutions of the Hg(II) complex of L2 were studied by 13C NMR spectroscopy and cyclic voltammetry and revealed a strong interaction between the redox-active phenylenediamine subunit and the bound metal cation. An X-ray analysis confirmed the participation of the three macrocyclic S atoms and both phenylenediamine N atoms in the stabilization of the complex.
“…While a large number of redox-active macrocycles have been reported in the literature, the vast majority are based on crown ethers, a structural motif containing hard O donor atoms that supports the coordination of alkali- and alkaline-earth-metal cations. With the exclusion of a few notable examples, those that target the binding of heavy-metal ions have received comparatively little attention. 1 Wurster's thiacrown ethers used in this study.…”
Isomeric p- and o-phenylenediamine-containing macrocyclic hosts (Wurster's thiacrown ethers L1 and L2, respectively) were prepared and studied as Hg(II) ionophores. The distinct electrochemical properties of the two hosts allowed for the formation of a coordination compound with the ortho-Wurster's thiacrown ether but not the para isomer. In the latter case, the Hg(II) ion served as an oxidant in an electron-transfer reaction with the host. Solutions of the Hg(II) complex of L2 were studied by 13C NMR spectroscopy and cyclic voltammetry and revealed a strong interaction between the redox-active phenylenediamine subunit and the bound metal cation. An X-ray analysis confirmed the participation of the three macrocyclic S atoms and both phenylenediamine N atoms in the stabilization of the complex.
“…Many oxa-and aza-ferrocenophanes have been reported to be good selective electrochemical sensors for cations [1][2][3][4][5] or anions [5][6][7][8][9]. A few analogues with soft S-donors show good affinity to soft metal cations [10][11][12][13][14][15].…”
Macrocyclic organomercury compounds have been known for some time, but their ability to bind anionic guests in their cavity was demonstrated relatively recently. This molecular recognition process is somewhat similar to the formation of the crown ether complexes, except that the binding sites of the macrocycle are occupied by metal atoms, able to function as Lewis acids, and therefore to bind halogen and other Lewis base anions. This approach is only in its beginnings and the recent discovery of mercuracarbaboranes as anion binding cyclic receptors gave a new impetus to research in the field.One of the earliest known organomercury macrocycles was the trimer of ovthophenylene mercury, (o-CgH4Hg)3, known from X-ray diffraction studies to have a planar cyclic structure, 1 [I, 21. It has recently been found, with the aid of 199Hg NMR spectroscopy, that this compound forms complexes with halide anions (Cl-, Br-and I-) in dichloromethane solution, but the complexes could not be isolated in solid state [3]. The fluorinated analog (o-CgF4Hg)3, 2, is a much better electron acceptor and forms stable complexes with the same halide anions; these could be 1 2 2.
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