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Ammonium oxathioamidate (1) was synthesised by the reaction between O-ethyl-thioxamate (oxalic acid-1-amide-2-O-ethyl ester) and ammonium hydrogen carbonate in water solution. Compound 1 was fully characterised by both microanalytical (elemental analysis, melting point determination) and spectroscopic means (FT-IR and NMR spectroscopy). Crystals suitable for single-crystal X-ray diffraction were isolated by slow evaporation of an ethanol solution of the compound. The analysis of the crystal packing reveals the prominent role exerted by intermolecular hydrogen bonding (HB) and chalcogen bonding (ChB) interactions.

4,4′-(Disulfanediyl)dipyridinium chloride triiodide, C10H10N2S22+·Cl−·I3−, (1) was synthesized by reaction of 4,4′-dipyridyldisulfide with ICl in a 1:1 molar ratio in dichloromethane solution. The structural characterization of 1 by SC-XRD analysis was supported by elemental analysis, FT–IR, and FT–Raman spectroscopic measurements.

The reaction between cadmium nitrate tetrahydrate and N,N′-bis(pyridin-3-ylmethyl)oxalamide (L) in a 1:3 molar ratio in a water/acetonitrile (1:6 v/v) mixture afforded single crystals of compound 1 suitable for X-ray diffraction analysis. Compound 1 consists of the coordination polymer (CP) [[Cd(L)2(OH2)2](NO3)2·4H2O]∞, in which CdII ions are bridged by neutral L antiperiplanar N-ligands in a wavy ribbon fashion developed along the c-axis. Two trans-disposed water molecules complete the pseudo-octahedral coordination geometry of the metal ion. The crystal packing of 1 revealed the interplay between π–π stacking interactions and an intricate hydrogen-bonded network involving oxalamides, nitrates, and water molecules. The donor properties of L and the intermolecular interactions in compound 1 are interpreted based on hybrid-DFT calculations.

The reactivity of 3,5-di-(pyridin-4-yl)-1,2,4-thiadiazole (L1) with 1,4-diiodotetrafluorobenzene (1,4-DITFB) was explored and the halogen-bonded 1:1 co-crystal (1) was successfully isolated and structurally characterized.

N,N′-Dipropyloxamide (1) was synthesised by the reaction between diethyloxalate and n-propylamine in ethanol. Compound 1 was fully characterised by both microanalytical (elemental analysis, melting point determination) and spectroscopic means (FT-IR and NMR spectroscopy). Crystals suitable for single crystal X-ray diffraction were isolated by the slow evaporation of a methyl alcohol solution of the compound. The resulting crystal structure shows the prominent role exerted by intermolecular hydrogen bonds in the crystal packing.

2,7-Bis(pyridin-4-ylethynyl)-9H-carbazole (1) was synthesized by reacting 4-ethynylpyridine hydrochloride with 2,7-dibromo-9H-carbazole. The full characterization of compound 1 is presented, and the crystal structure of its monohydrate was determined by single-crystal XRD analysis.

2-(5,6-diphenyl-1,2,4-triazin-3-yl)pyridinium dichloroiodate (I) (1) was synthesized by reacting 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine with ICl in dichloromethane solution. The structural characterization of 1 by SC-XRD analysis was accompanied by elemental analysis, FT-IR, and FT-Raman spectroscopy measurements.

The 2-(2,7-bis(pyridin-3-ylethynyl)fluoren-9-ylidene)malononitrile (1) was synthesized by reaction of 2,7-bis(pyridin-3-ylethynyl)fluoren-9-one with malononitrile in DMSO solution. The structural characterization of 1 by SC-XRD analysis was accompanied by elemental analysis, FT-IR, NMR, and MS measurements.

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.

Ammonium N-(pyridin-2-ylmethyl)oxamate (AmPicOxam), synthesized from O-methyl-N-(pyridin-2-ylmethyl)oxamate, was spectroscopically and structurally characterized and assayed as a novel precursor for the protection and consolidation of carbonate stone substrates. An in-depth characterization of treated and untreated biomicritic limestone and white Carrara marble samples was carried out by means of SEM microscopy, X-ray powder diffraction, helium pycnometry, determination of water transport properties, and pull-off tests. The improved solubility (1.00 M, 16.5% w/w) of the title compound with respect to ammonium oxalate (0.4 M, 5% w/w) results in the formation of a thicker protective coating of calcium oxalate (CaOx) dihydrate (weddellite) on marble and biomicrite samples after the treatment with 5% and 12% w/w water solutions, producing a reduction in the stone porosity and increased cohesion. Theoretical calculations were carried out at the DFT level to investigate both the electronic structure of the N-(pyridin-2-ylmethyl)oxamate anion and the hydrolysis reaction leading from AmPicOxam to CaOx.

The experimental structural features of chalcogen bonding (ChB) interactions in over 34,000 linear fragments R–Ch⋯A (Ch = S, Se, Te; R = C, N, O, S, Se, Te; A = N, O, S, Se, Te, F, Cl, Br, I) were analyzed. The bond distances dR–Ch and the interaction distances dCh⋯A were investigated, and the functions δR–Ch and δCh⋯A were introduced to compare the structural data of R–Ch⋯A fragments involving different Ch atoms. The functions δR−Ch and δCh⋯A were calculated by normalizing the differences between the relevant bond dR–Ch and ChB interaction dCh⋯A distances with respect to the sum of the relevant covalent (rcovR + rcovCh) and the van der Waals (vdW) radii (rvdWCh + rvdWA), respectively. A systematic comparison is presented, highlighting the role of the chalcogen involved, the role of the R atoms covalently bonded to the Ch, and the role of the A species playing the role of chalcogen bond acceptor. Based on the results obtained, an innovative approach is proposed for the evaluation and categorization of the ChB strength based on structural data.

The reaction of the complex [Au(phen)Br2](PF6) (phen = 1,10-phenanthroline) with molecular dibromine afforded {[Au(phen)Br2](Br3)}∞ (1). Single crystal diffraction analysis showed that the [Au(phen)Br2]+ complex cations were bridged by asymmetric tribromide anions to form infinite zig-zag chains featuring the motif ···Au–Br···Br–Br–Br···Au–Br···Br–Br–Br···. The complex cation played an unprecedented halogen bonding (XB) donor role engaging type-I and type-II XB noncovalent interactions of comparable strength with symmetry related [Br3]− anions. A network of hydrogen bonds connects parallel chains in an infinite 2D network, contributing to the layered supramolecular architecture. DFT calculations allowed clarification of the nature of the XB interactions, showing the interplay between orbital mixing, analyzed at the NBO level, and electrostatic contribution, explored based on the molecular potential energy (MEP) maps of the interacting synthons.

This study investigates the coordination chemistry of the tetradentate pyridine-containing 12-membered macrocycles L1-L3 towards Platinum Group metal ions PdII, PtII, and RhIII. The reactions between the chloride salts of these metal ions and the three ligands in MeCN/H2O or MeOH/H2O (1:1 v/v) are shown, and the isolated solid compounds are characterized, where possible, by mass spectroscopy and 1H- and 13C-NMR spectroscopic measurements. Structural characterization of the 1:1 metal-to-ligand complexes [Pd(L1)Cl]2[Pd2Cl6], [Pt(L1)Cl](BF4), [Rh(L1)Cl2](PF6), and [Rh(L3)Cl2](BF4)·MeCN shows the coordinated macrocyclic ligands adopting a folded conformation, and occupying four coordination sites of a distorted square-based pyramidal and octahedral coordination environment for the PdII/PtII, and RhIII complexes, respectively. The remaining coordination site(s) are occupied by chlorido ligands. The reaction of L3 with PtCl2 in MeCN/H2O gave by serendipity the complex [Pt(L3)(μ-1,3-MeCONH)PtCl(MeCN)](BF4)2·H2O, in which two metal centers are bridged by an amidate ligand at a Pt1-Pt2 distance of 2.5798(3) Å and feature one square-planar and one octahedral coordination environment. Density Functional Theory (DFT) calculations, which utilize the broken symmetry approach (DFT-BS), indicate a singlet d8-d8 PtII-PtII ground-state nature for this compound, rather than the alleged d9-d7 PtI-PtIII mixed-valence character reported for related dinuclear Pt-complexes.

The reactions of 2,4-bis(4-methoxyphenyl)-1,3-dithio-2,4-diphosphetane-2,4-disulfide (Lawesson’s Reagent, LR) with benzylamine (BzNH2) and 4-phenylbutylamine (PhBuNH2) yield benzylammonium P-(4-methoxyphenyl)-N-benzyl-amidodithiophosphonate (BzNH3)(BzNH-adtp) and 4-phenylbutylammonium P-(4-methoxyphenyl)-N-(4-phenylbutyl)-amidodithiophosphonate (PhBuNH3)(PhBuNH-adtp). The relevant nickel complexes [Ni(BzNH-adtp)2] and [Ni(PhBuNH-adtp)2] and the corresponding hydrolysed derivatives (BzNH3)2[Ni(dtp)2] and (PhBuNH3)2[Ni(dtp)2] were prepared and fully characterized. The antimicrobial activity of the aforementioned amidodithiophosphonates against a set of Gram-positive and Gram-negative pathogen bacteria was evaluated, and [Ni(BzNH-adtp)2] and [Ni(PhBuNH-adtp)2] showed antiproliferative activity towards Staphylococcus aureus and Staphylococcus haemolyticus strains. density functional theory (DFT) calculations were performed to shed some light on the activity of reported compounds related to their tendency towards P–N bond cleavage.

Reactions between methyldiphenylphosphane selenide, SePPh2Me, and different group 11 metal starting materials {CuCl, [CuNO3(PPh3)2], AgOTf, [AgOTf(PPh3)] (OTf = OSO2CF3), [AuCl(tht)], [Au(C6F5)(tht)] and [Au(C6F5)3(tht)] (tht = tetrahydrothiophene)} were performed in order to obtain several new species with metal–selenium bonds. The new complexes [CuCl(SePPh2Me)] (1), [AgOTf(SePPh2Me)] (2), [AuCl(SePPh2Me)] (5), [Au(C6F5)(SePPh2Me)] (6) and [Au(C6F5)3(SePPh2Me)] (7) were isolated and structurally characterized in solution by multinuclear NMR spectroscopy (1H, 31P, 77Se and 19F where appropriate). Solid products were isolated also from the reactions between SePPh2Me and [CuNO3(PPh3)2] or [AgOTf(PPh3)], respectively. NMR experiments, including low temperature 1H and 31P NMR, revealed for them a dynamic behaviour in solution, involving the transfer of selenium from PPh2Me to PPh3. In case of the isolated silver(i) containing solid an equilibrium between, respectively, monomeric [AgOTf(PPh3)(SePPh2Me)] (3) and [AgOTf(PPh2Me)(SePPh3)] (4), and dimeric [Ag(PPh3)(μ-SePPh2Me)]2(OTf)2(3a) and [Ag(PPh2Me)(μ-SePPh3)]2(OTf)2(4a) species was observed in solution. In case of the isolated copper(i) containing solid the NMR studies brought no clear evidence for a similar behaviour, but it can not be excluded in a first stage of the reaction. However the transfer of selenium between the two triorganophosphanes takes place also in this case, but the NMR spectra suggest that the final reaction mixture contains the free triorganophospane selenides SePPh2Me and SePPh3as well as the complex species [CuNO3(PPh3)2], [CuNO3(PPh2Me)2] and [CuNO3(PPh3)(PPh2Me)] in equilibrium. Single-crystal X-ray diffraction studies revealed monomeric structures for the gold(i) 6and gold(iii) 7complexes. In case of compound 6weak aurophilic gold(i)gold(i) contacts were also observed in the crystal. DFT calculations were performed in order to understand the solution behaviour of the silver(I) and copper(i) species containing both P(iii) and P(v) ligands, to verify the stability of possible dimeric species and to account for the aurophilic interactions found for 6. In addition, the nature of the electronic transitions involved in the absorption/emission processes observed for 6and 7in the solid state were also investigated by means of TD-DFT calculations. [ABSTRACT FROM AUTHOR]

The I2-adducts of drugs propylthiouracil (PTU) and methimazole (MeImSH) oxidize liquid mercury in dichloromethane to separate in good yield the neutral complexes [HgI2(PTU)2·MeOH] (1), [HgI2(PTU)2·HgI2] (2), and [Hg2I4(MeImSH)2] (3). The single crystal X-ray diffraction analysis of 1–2shows that the Hg(ii) center is coordinated by two sulfur atoms and by two iodine atoms in a tetrahedral geometry. In complex 2almost linear molecules of HgI2result encapsulated in the crystal packing enfolded by the hydrophobic propyl appendages of coordinated units of PTU. X-ray analysis of complex 3shows the presence of dimeric [Hg2I4(MeImSH)2] molecules to form Hg2S2I4cores. The intra- and intermolecular hydrogen bonds concerning PTU and MeImSH have been evaluated. The oxidation of Hg(0) to Hg(ii) requires a two-electron transfer process accomplished by an oxidative addition from the “activated” iodine moiety. The oxidizing and complexing properties of PTU-I2and MeImSH-I2have been interpreted considering the S-donor to I2interaction that leads to a charge separation between the sulfur-bound iodine atom S–I and the terminal I atom. Compounds 1, 2, and 3react with tetraethylammonium iodide to separate the compound (Et4N)2[HgI4] with the release of free PTU and MeImSH, respectively. The reported dissolution technique could be applied to the recovery of mercury from waste electrical and electronic equipment (WEEE) scrap, the nature of complexes 1–3makes it possible the easy separation of the mercury as tetraiodomercurate anion and the recycling of the donors. [ABSTRACT FROM AUTHOR]