Molecular and Electronic Structures of Iron(II)/(III) Complexes Containing N,S-Coordinated, Closed-Shell o-Aminothiophenolato(1−) and o-Iminothiophenolato(2−) Ligands

Abstract

The coordination chemistry of the ligands o-aminothiophenol, H(abt), 4,6-di-tert-butyl-2-aminothiophenol, H[L(AP)], and 1,2-ethanediamine-N,N'-bis(2-benzenethiol), H(4)('N(2)S(2')), with FeCl(2) under strictly anaerobic and increasingly aerobic conditions has been systematically investigated. Using strictly anaerobic conditions, the neutral, air-sensitive, yellow complexes (mu-S,S)[Fe(II)(abt)(2)](2) (1), (mu-S,S)[Fe(II)(L(AP))(2)](2).8CH(3)OH (2), and (mu-S,S)[Fe(II)('H(2)N(2)S(2'))](2).CH(3)CN (3) containing high spin ferrous ions have been isolated where (abt)(1-), (L(AP))(1-), and ('H(2)N(2)S(2'))(2-) represent the respective N,S-coordinated, aromatic o-aminothiophenolate derivative of these ligands. When the described reaction was carried out in the presence of trace amounts of O(2) and [PPh(4)]Br, light-green crystals of [PPh(4)][Fe(II)(abt)(2)(itbs)].[PPh(4)]Br (4) were isolated. The anion [Fe(II)(abt)(2)(itbs)](-) contains a high spin ferrous ion, two N,S-coordinated o-aminophenolate(1-) ligands, and an S-bound, monoanionic o-iminothionebenzosemiquinonate(1-) pi radical, (itbs)(-). Complex 4 possesses an S(t) = 3/2 ground state. In the absence of [PPh(4)]Br and presence of a base NEt(3) and a little O(2), the ferric dimer (mu-NH,NH)[Fe(III)(L(AP))(L(IP))](2) (5a) and its isomer (mu-S,S)[Fe(III)(L(AP))(L(IP))](2) (5b) formed. (L(IP))(2-) represents the aromatic o-iminothiophenolate(2-) dianion of H[L(AP)]. The structures of compounds 2, 4, and 5a have been determined by X-ray crystallography at 100(2) K. Zero-field Mössbauer spectroscopy of 1, 2, 3, and 4 unambiguously shows the presence of high spin ferrous ions: The isomer shift at 80 K is in the narrow range 0.85-0.92 mm s(-1), and a large quadrupole splitting, |DeltaE(Q)|, in the range 3.24-4.10 mm s(-1), is observed. In contrast, 5a and 5b comprise both intermediate spin ferric ions (S(Fe) = 3/2) which couple antiferromagnetically in the dinuclear molecules yielding an S(t) = 0 ground state.

Structures, Spectroscopic Properties, and Dioxygen Reactivity of 5- and 6-Coordinate Nonheme Iron(II) Complexes: A Combined Enzyme/Model Study of Thiol Dioxygenases

“…A search of the Cambridge Structural Database (CSD) 37 reveals that there are only three other iron complexes 38–40 with longer terminal Fe–S bond distances, excluding those with partial thione character, and one of these systems is an Fe(abt) complex containing an oxidized ligand radical. 39 The Fe–OTf bond length in 2 is 0.07 Å longer than that seen in 1 , which seems opposite to what is expected given the electron-deficient thiolate donor in 2 . This observation may be explained by the fact that the triflate ligand in both 1 and 2 forms a hydrogen bond with the nearby coordinated NH 2 moiety.…”

Fuel mediated solution combustion synthesis of ZnO supported gold clusters and nanoparticles and their catalytic activity and in vitro cytotoxicity

“…It must be said that we could not get a UV-Vis spectrum of the 4-aminophenolate anion in the literature though there is a reference by Ghosh et al 49 to the formation of complexes of Fe(II), Ni(II), Zn(II) and Cu(II) with this 4-aminophenolate anion. One of the most significant observations from the study of gold nanoparticles/clusters with or without attachment to other molecules is its relevance and importance to biology.…”

Reactivity pathways for nitric oxide and nitrosonium with iron complexes in biologically relevant sulfur coordination spheres

“…In the present article, we describe the reactivity of a variety of [Fe II (SR) 4 ] 2À species with NO (g) and nitrosonium (NO + ) ion in order to establish the general reactivity pattern of these reactive nitrogen species with iron-sulfur complexes. For comparison, we also explored the NO-based reactivity of an Fe II complex containing the N,S-coordinated ortho-aminothiophenolate ligand [44]. Because of the known NO-delivery properties of the DNICs, we also investigated the mononitrosyl complex 1 as an NO-transfer agent where the receptor was the model heme system, [Fe(TPP)Cl] (TPP = tetraphenylporphyrin).…”