A unique case of polymorphism in polyiodide networks resulting from the reaction of the drug methimazole and I2

The oxidation of thioamide methimazole (C4H6N2S) with molecular diiodine in water afforded the ionic compound [2(C4H5N2S–SN2C4H6)]I3I5 (1) in 1-triclinic and 1-monoclinic polymorphs. The polymorphic nature of [C4H5N2S–SN2C4H6]2I3I5 has been highlighted by comparing the structure of the 1-triclinic form with that of the 1-monoclinic form reported in the literature. No significant geometric differences are observed for the cations in the two polymorphs. The polymorphism is essentially due to a different arrangement in the polyiodide network of the [I5]− and [I3]− components. The FT-Raman spectrum of 1-triclinic shows the characteristic bands in the range 200–50 cm−1 which are in good agreement with the structural features of the polyiodide network. The molecular electrostatic potential maps of the cation methimazole-disulfide [C4H5N2S–SN2C4H6]+ and the bis-cation methimazole-disulfide {[C4H5N2S–SN2C4H6]+}2 in 1-triclinic have been studied to clearly identify the electrostatic potential energy distributions over the cations, and the electron belt and σ-hole areas responsible for the directionality of the non-covalent interactions in the polyiodides. It is suggested that the cation methimazole-disulfide may be a reaction intermediate in the inhibition of thyroid hormones by methimazole

The Nature of the Chemical Bond in Linear Three-Body Systems: From I3− to Mixed Chalcogen/Halogen and Trichalcogen Moieties

The 3 centre-4 electrons (3c-4e) and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I3− and related electron-rich (22 shell electrons) systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD). Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall) has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I3− anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom

Structural tailoring of the NIR-absorption of bis(1,2-dichalcogenolene) Ni/Pt electrochromophores deriving from 1,3-dimethyl-2-chalcogenoxo-imidazoline-4,5-dichalcogenolates

The Dipartimento di Scienze Chimiche e Geologiche of the Università degli Studi di Cagliari and Banco di Sardegna, Italy are kindly acknowledged for financial support (PRID 2015).The choice of the metal ion M and the terminal Y and donor X chalcogen species (M = Ni, Pt; X, Y = S, Se) in square-planar complexes with 1,3-dimethyl-2-chalcogenoxo-imidazoline-4,5-dichalcogenolates allows fine-tuning both the redox stability and the energy of the peculiarly intense NIR electrochromic absorption, thanks to the subtle contribution of M, X, and Y to the relevant frontier molecular orbitals, investigated at IEF-PCM DFT and TD-DFT level.Publisher PDFPeer reviewe

reactivity of the drug methimazole and its iodine adduct with elemental zinc

The reactivity of zinc complexes with N,S-donor molecules may be of relevance to the study of Zn-metalloproteins and -metalloenzymes. In this context, the zinc complex [Zn(MeImSH)2I2] was synthesised by the reaction of zinc powder with the 1:1 iodine adduct of the drug methimazole [(MeImSH)·I2]. The molecular structure of the complex, elucidated by X-ray diffraction analysis, showed a tetrahedral zinc(II) centre coordinated by two neutral methimazole units (through the sulfur atoms) and two iodides. From the reaction of MeImSH and Zn powder, the complex [Zn(MeImSH)(MeImS)2] (MeImS = deprotonated form of methimazole) was separated and characterised. An analysis of the crystal packing of the neutral complexes [Zn(MeImSH)2X2] (X = I, Br and Cl) and the ionic complex [Zn(MeImSH)3I]I showed that in all of the complexes the sulfur atom, in addition to binding to the metal centre, contributes to the formation of 1-D chains built via C(4)–H⋯S and N–H⋯X interactions in the neutral complexes, and via C(4)–H⋯S and N–CH3⋯S interactions in the ionic complex [Zn(MeImSH)3I]I. The deprotonation/protonation of the coordinated methimazole units can modulate the coordination environment at the Zn core. From the reaction of complex [Zn(MeImSH)3I]I with a strong non-coordinating organic base, we have shown that, as a consequence of the NH deprotonation of methimazole S-coordinated to zinc(II), the ligand coordination mode changes from S-monodentate to N,S-bridging. Correspondingly, in the complex [Zn(MeImSH)(MeImS)2], the MeImS that displays the N,S-bridging mode at zinc can be N-protonated and thereby changes to the S-monodentate coordination

2,7-Bis(pyridin-3-ylethynyl)fluoren-9-one

2,7-bis(pyridin-3-ylethynyl)fluoren-9-one [(3-PyE)2FO] was synthesized in one step by the Sonogashira coupling reaction between 3-ethynylpyridine and 2,7-dibromofluoren-9-one. The title compound was fully characterized, and its crystal structure was determined through single-crystal XRD analysis

Stabilization of caesium ions by simple organic molecules: crystal structures of Cs(OXL) (OXL = oxalurate anion), and CsOH/cyanuric acid co-crystal Cs3(CYH3)4(OH)3 (CYH3 = cyanuric acid)

The reaction in water between CsOH and parabanic acid (PBH2) leads to the formation of the caesium salt of the oxalurate anion Cs(OXL), while the reaction with cyanuric acid (CYH3) leads to the formation of the CsOH co-crystal of cyanuric acid Cs3(CYH3)4(OH)3. The X-ray crystal structures of these compounds show that both the organic moieties OXL and CYH3 form robust homomeric ribbons based on strong and articulated N–HO hydrogen bonds. The stabilization of the Cs+ ions can occur regardless of whether the ribbon of organic units is negatively charged or neutral. In Cs(OXL), each cation displays nine-fold coordination with Cs–O distances in the range of 2.975(3)–3.601(4) Å; in Cs3(CYH3)4(OH)3, two of the Cs+ cations (Cs1 and Cs2) display a nine-fold coordination with Cs–O distances in the range of 3.007(9)–3.823(13) Å and one (Cs3) is ten-fold coordinated with Cs–O distances in the range of 3.161(14)– 3.653(17) Å. The molecular electrostatic potential maps of OXL and di-OXL anions have been reported and discussed

Bis(2-pyridylmethyl)alkyl(thioalkyl)diamines as promising scaffolds for the construction of fluorescent and redox chemosensors for transition and post-transition metal ions

Abstract N , N ′- Bis (2-pyridylmethyl)propylendiamine ( 1 ) and N , N ′- bis (2-pyridylmethyl)-1,5-diamino-3-thiapentane ( 2 ) have been functionalised at the secondary nitrogen atoms with dansylamidoethyl ( L 1 , L 3 ), 2-quinolinylmethyl ( L 2 , L 4 ) and ferrocenylmethyl ( L 6 , L 7 ) pendant arms with the intention to study their potentiality as receptor units in molecular sensors. The optical response of L 1 – L 4 to the presence of the metal ions Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ has been investigated in MeCN/H 2 O (4:1 v/v) solution. The electrochemical response of L 6 and L 7 to the presence of the same metal ions has been investigated in anhydrous MeCN/CH 2 Cl 2 10:1 (v/v) solution. Results are compared and discussed with the aim to clarify the mutual role played by the bis (2-methylpyridyl)alkyl(thioalkyl)diamines and the signalling units attached to them in reaching the selectivity of the responses observed

Coordination polymers and polygons using di-pyridyl-thiadiazole spacers and substituted phosphorodithioato NiII complexes: potential and limitations for inorganic crystal engineering

Coordinatively unsaturated P-substituted dithiophosphonato, dithiophosphato, and dithiophosphito complexes {[Ni?(MeO)2PS2)2] (1), [Ni((EtO)2PS2)2] (2), [Ni(MeOdtp)2] (3), and [Ni((Ph)2PS2)2] (4)} were reacted with the bis-functional ligands 3,5-di-(4-pyridyl)-1,2,4-thiadiazole (L1) and 3,5-di-(3-pyridyl)-1,2,4-thiadiazole (L2) to give the coordination polymers (1–4·L1)?, (3·L2)?, and (4·L2·2C7H8)? and the discrete dimers (1–2·L2)2, all characterised by single crystal X-ray diffraction. A comparison of the structures shows that L1 can be exploited for the predictable assembly of undulating chains independent of the nature of the NiII complex, while L2 allows for the existence of different supramolecular constructs ensuing from different ligand conformations deriving from the rotation of the pyridyl rings

New PtII diimine–dithiolate complexes containing a 1,2-dithiolate-1,2-closo-dicarbadodecarborane: an experimental and theoretical investigation

A new class of solvatochromic diimine–dithiolate complexes [Pt(N^N)(dtoc)] (dtoc2− = 1,2-dithiolate-1,2-closo-dicarbadodecaborane) is reported

Oxamate salts as novel agents for the restoration of marble and limestone substrates : case study of ammonium N-phenyloxamate

The ammonium salt of N-phenyloxamic acid (AmPhOxam) was synthesised, characterised by FT-IR, FT-Raman, UV-Vis, 1H-NMR spectroscopic methods and single crystal X-ray diffraction, and evaluated as a protective and consolidating agent for calcareous stone substrates under mild conditions. Hydro-alcoholic solutions of AmPhOxam were tested for the treatment of naturally weathered white marble and biomicritic limestone. Mercury intrusion porosimetry, FT-NIR spectroscopy measurements and SEM microscopy showed the formation of a superficial protective layer of crystals of the corresponding monohydrated calcium salt, CaPhOxam, on both treated stones.Publisher PDFPeer reviewe