Bis(triphenylsulfonium) tetrachloridozinc(II), (C18H15S)2[ZnCl4] (I), bis(triphenylsulfonium) tetrachloridocadmium(II), (C18H15S)2[CdCl4] (II), and bis(triphenylsulfonium) tetrachloridomercury(II) methanol monosolvate, (C18H15S)2[HgCl4]·CH3OH (III), each crystallize in the monoclinic space group P21/n. In all three structures, there are two crystallographically independent triphenylsulfonium (TPS) cations per asymmetric unit, each adopting a distorted trigonal–pyramidal geometry about the S atom (S—C bond lengths in the 1.77–1.80 Å range and C—S—C angles of 100–107°). The [MCl4]2– anions (M = Zn2+, Cd2+, Hg2+) are tetrahedral; their M—Cl bond lengths systematically increase from Zn2+ to Hg2+, consistent with the larger ionic radius of the heavier metal. Hirshfeld surface analyses show that H...H and H...C contacts dominate the TPS cation environments, whereas H...Cl and S...M interactions anchor each [MCl4]2– anion to two surrounding TPS cations. Weak C—H...Cl hydrogen bonds, as well as inversion-centered π–π stacking, generate layers in (I) and (II) and dimeric [(TPS)2–HgCl4]2 assemblies in (III).

The reaction of one equivalent of zinc(II) halide salts with two equivalents of isoquinoline N-oxide (iQNO; C9H7NO) in methanol yields compounds of the general formula [ZnX2(iQNO)2], with X = Cl− (I), Br− (II) and I− (III). However, starting with zinc(II) perchlorate or nitrate leads to the formation of complex ions with the compositions [Zn(iQNO)6](X)2 for X = ClO4− (IV), and [Zn(iQNO)(H2O)5](iQNO)2X2 for X = NO3− (V). Complexes (I), (II) and (III), namely dichloridobis(isoquinoline N-oxide-κO)zinc(II) [ZnCl2(C9H7NO)2], dibromidobis(isoquinoline N-oxide-κO)zinc(II) [ZnBr2(C9H7NO)2], and diiodidobis(isoquinoline N-oxide-κO)zinc(II) [ZnI2(C9H7NO)2], each exhibit a distorted tetrahedral coordination geometry around the zinc(II) ion coordinated by two iQNO ligands bound through the oxygen atom and two halide ions. The zinc ion lies on a crystallographic twofold axis in the bromo complex. The X—Zn—X bond angles are approximately 15–17° larger than the O—Zn—O bond angles resulting in the observed tetrahedral distortion. In complex (IV), hexakis(isoquinoline N-oxide-κO)zinc(II) bis(perchlorate), [Zn(C9H7NO)6](ClO4)2, the zinc(II) ion occupies a special position with 3 site symmetry and is octahedrally coordinated by six iQNO ligands, albeit with slight distortions evidenced by a spread of cis bond angles from 85.82 (4) to 94.18 (4)°. The chlorine atom of the perchlorate anion lies on a crystallographic threefold axis. Finally, complex (V) crystallizes with a pseudo-octahedral geometry; pentaaqua(isoquinoline N-oxide-κO)zinc(II) dinitrate–isoquinoline N-oxide (1/2), [Zn(C9H7NO)(H2O)5](NO3)2·2(C9H7NO). The nitrate ions and non-coordinated iQNO molecules engage in π-stacking and hydrogen-bonding interactions with the coordinated water molecules. The iQNO—Zn—O equatorial bond angles range from 88.98 (9) to 94.90 (9)°, with the largest deviation from a perfect octahedral angle attributed to the influence of a weak C—H...O (from water) interaction (2.287 Å) involving the bound iQNO ligand.

The reactions of tri-phenyl-sulfonium chloride ([TPS][Cl]) with various acids in methanol yield the corresponding salts tri-phenyl-sulfonium triiodide, C18H15S+·I3 - or [TPS][I3] (I), tri-phenyl-sulfonium perchlorate, C18H15S+·ClO4 - or [TPS][ClO4] (II), and tri-phenyl-sulfonium hexa-fluoro-phosphate, C18H15S+·PF6 - or [TPS][PF6] (III), as crystalline products. These crystals were structurally characterized by single-crystal X-ray diffraction. In all three compounds, the sulfur atom in the tri-phenyl-sulfonium cation adopts a distorted trigonal-pyramidal geometry. [TPS][I3] (I) and [TPS][PF6] (III) both crystallize in the space group P21/n, while [TPS][ClO4] (II) crystallizes in P21. The S-C bond lengths are comparable across the three salts, and the S-C-S bond angles are consistently between 102 and 106°. Hirshfeld surface analyses reveal that each structure is dominated by hydrogen-based inter-molecular contacts, supplemented by anion-specific inter-actions such as I⋯H in (I), O⋯H in (II), and F⋯H in (III). These contacts organize the ions into mono-periodic ribbon- or chain-like arrangements. No significant π-π stacking is observed.

The syntheses and structures of the dimethyl sulfoxide (DMSO) solvate of 3,6-bis(indol-3-yl)-1,4-dimethylpiperazine-2,5-dione, C11H10N2O (I), and of the dimethyl sulfoxide and tetrahydrofuran (THF) solvates of 1,4-dimethyl-3,6-bis(2-methylindol-3-yl)piperazine-2,5-dione, C12H12N2O, (II) and (III), respectively, are reported. The asymmetric units of (I) and (II) each contain two crystallographically independent half-molecules that are completed by inversion symmetry, whereas (III) contains one independent half-molecule. In all three structures, the piperazine-2,5-dione core is essentially planar and the overall molecular non-planarity arises from rotations of the indole substituents: ranging between 58 and 63° in (I), approximately 72° for both independent molecules in (II) and approximately 62° in (III). In the crystal of (I), molecules are linked by two N—H...O hydrogen bonds to form C(18) chains; (II) features a single N—H...O contact giving C(8) chains; and (III) exhibits N—H...O interactions that generate C(7) chains assembling into sheets lying parallel to (100). No significant π–π stacking is present in any of these structures. All three structures contain regions of disordered solvent (DMSO or THF) that were treated with a solvent mask during refinement.

Bis(triphenylsulfonium) tetrachloridomanganate(II), (C18H15S)2[MnCl4] (I), triphenylsulfonium tetrachloridoferrate(III), (C18H15S)[FeCl4] (II), and bis(triphenylsulfonium) tetrachloridocobaltate(II), (C18H15S)2[CoCl4] (III), crystallize in the monoclinic space groups P21/n [(I) and (III)] and P21/c [(II)]. Compounds (I) and (III) each contain two crystallographically independent triphenylsulfonium (TPS+) cations in the asymmetric unit, whereas (II) has one. In all three compounds, the sulfonium centers adopt distorted trigonal–pyramidal geometries, with S—C bond lengths falling roughly in the 1.78–1.79 Å range and C—S—C angles observed at about 101 to 106°. The [MCl4]n− anions (M = Mn2+, Fe3+, Co2+; n = 2,1,2) adopt slightly distorted tetrahedral geometries, with M—Cl bond lengths in the 2.19–2.38 Å range and Cl—M—Cl angles of approximately 104–113°. Hirshfeld surface analyses shows that H...H and H...C contacts dominate the TPS+ cation environments, whereas H...Cl and short M—S interactions link each [MCl4]n− anion to the surrounding cations. In (I) and (III), inversion-centered π–π stacking further consolidates the crystal packing, while in (II) no π–π interactions are observed.

In the title solvates, the indole ring rotations (58–72°) relative to the plane of the central ring govern non-planarity. In the extended structures, N—H⋯O links form chains or sheets and disordered solvents were masked.

A series of cocrystals of halogen bond donors 1,4-diiodotetrafluorobenzene (p-F4DIB) and tetraiodoethylene (TIE) with five aromatic heterocyclic diazine mono-N-oxides based on pyrazine, tetramethylpyrazine, quinoxaline, phenazine, and pyrimidine as halogen bonding acceptors were studied. Structural analysis of the mono-N-oxides allows comparison of the competitive occurrence of N···I vs O···I interactions and the relative strength and directionality of these two types of interactions. Of the aromatic heterocyclic diazine mono-N-oxide organoiodine cocrystals examined, six exhibited 1:1 stoichiometry, forming chains that utilized both N···I and O···I interactions. Two cocrystals presented 1:1 stoichiometry with exclusive O···I interactions. Two cocrystals displayed a 2:1 stoichiometry-one characterized solely by O···I interactions and the other solely by N···I interactions. We have also compared these interactions to those present in the corresponding diazines, some of which we report here and some which have been previously reported. In addition, a computational analysis using density functional theory (M062X/def2-SVPD) was performed on these two systems and has been compared to the experimental results. The calculated complex formation energies were, on average, 4.7 kJ/mol lower for the I···O halogen bonding interaction as compared to the corresponding N···I interaction. The average I···O interaction distances were calculated to be 0.15 Å shorter than the corresponding I···N interactions.

The reaction of one equivalent of zinc(II) halide with two equivalents of quinoline N -oxide (QNO) in methanol yields compounds as Zn X 2 (QNO) 2 , where X = Cl ( I ), Br ( II ) and I ( III ), namely, dichloridobis(quinoline N -oxide-κ O )zinc(II), [ZnCl 2 (C 9 H 7 NO) 2 ], dibromidobis(quinoline N -oxide-κ O )zinc(II), [ZnBr 2 (C 9 H 7 NO) 2 ], and diiodidobis(quinoline N -oxide-κ O )zinc(II) [ZnI 2 (C 9 H 7 NO) 2 ]. In all three complexes, Zn cations are coordinated by two QNO ligands bound through the oxygen atoms and two halide atoms, with X —Zn— X bond angles ca 20° wider than the O—Zn—O, giving rise to a distorted tetrahedral geometry. Crystals of ( II ) and ( III ) are isostructural and both show pairwise π-stacking of QNO ligands and weak C—H... X hydrogen bonds, while ( I ) packs differently, with a shorter C—H...Cl bond and without π-stacking.

A series of ionic compounds based on the dicationic vitamin B1 structure have been synthesized and characterized. A set of perfluoroalkyl-based anions, each with a distinct structure, were paired with the cations and the solid-state structures of the salts were analyzed via single-crystal X-ray diffraction. Phase transitions and thermal stability of the compounds were examined via dynamic scanning calorimetry and thermogravimetric analysis. It was found that the salt of the cyclical anion, 1,3-disulfonylhexafluoropropyleneimide [NCyF]−, exhibited higher thermal stability while displaying comparable phase transition temperatures as compared to the linear anionic congeners. The cations within the [NCyF]− compound were found to interact as paired dimers, a form which is not observed in the other ionic species. Hirshfeld surface analyses supplemented with computational studies of the compounds is used to rationalize and evaluate the distinct properties of the compounds arising from changes in anion geometry.

Our work in the area of synthesis of tris indole compounds as a potential chelator led to the synthesis and crystallization of ethyl 1H-indole-2-carboxyl-ate, C11H11NO2, an indole that was synthesized by the thionyl chloride reaction of 1H-indole-2-carb-oxy-lic acid, followed by dissolution in ethanol. The mol-ecular packing exhibits a herringbone pattern with the zigzag running along the b-axis direction; the compound crystallizes as a hydrogen-bonded dimer resulting from O⋯H-N hydrogen bonds, between the indole N-H group and the keto oxygen atom, which build centrosymmetric R 2 2(10) ring motifs in the crystal.

Our work in the area of synthesis of metal–organic frameworks (MOFs) based on organic N-oxides led to the crystallization of pyridine-4-carboxamidoxime N-oxide. Herein we report the first crystal structure of the title compound, C6H7N3O2 [systematic name: (Z)-4-(N′-hydroxycarbamimidoyl)pyridine N-oxide]. The hydroxycarbamimidoyl group is essentially coplanar with the aromatic ring, r.m.s.d. = 0.112 Å. The compound crystallizes in hydrogen-bonding layers built from the formation of strong O—H...O hydrogen bonds between the oxime oxygen atom and the oxygen atom of the N-oxide, and the formation of N—H...O hydrogen bonds between one amine nitrogen atom and the N-oxide oxygen atom. These combined build R34(24) ring motifs in the crystal. The crystal structure has no π–π interactions.

The reaction of 3-hydroxyflavone with copper(II) bromide in various alcohols (ethanol, isopropanol, and methanol) yielded a mixture of their respective 3-hydroxy-2,3-dialkoxy-2-phenylchroman-4-ones (hemiacetals) and 3,3-dihydroxy-2-alkoxy-2-phenylchroman-4-ones (hydrates). Herein, we report the synthesis, reactivity and characterization of three hemiacetals (1, 3, and 5) and three hydrates (2, 4, and 6) as well as the single crystal Xray structures of 1-4 & 6. While the hemiacetals were shown to be kinetically accessible, the hydrates were thermodynamically preferred. The single X-ray structures of compounds 1-4 & 6 reveals the alkoxy groups occupying the axial position of the coumarin ring, which is surmised to be the source of the instability of the hemiacetals. As a result of the axial strain, the hemiacetals (1, 3, and 5) readily convert in to their respective hydrates (2, 4, and 6) when heated in non-alcoholic solvents. The qualitative rate of these conversion was largely a function of the size of the alkoxy group (i-Pr > Et > Me). We propose a mechanism for the conversion of hemiacetals to hydrates that involves a chromane-3,4-dione intermediate, which was evidenced by trapping it as a diimine, quinoxaline heterocycle.

Four manganese(II) bromide coordination complexes have been prepared with four pyridine N-oxides, viz. pyridine N-oxide (PNO), 2-methylpyridine N-oxide (2MePNO), 3-methylpyridine N-oxide (3MePNO), and 4-methylpyridine N-oxide (4MePNO). The compounds are bis(μ-pyridine N-oxide)bis[aquadibromido(pyridine N-oxide)manganese(II)], [Mn2Br4(C5H5NO)4(H2O)2] (I), bis(μ-2-methylpyridine N-oxide)bis[diaquadibromidomanganese(II)]–2-methylpyridine N-oxide (1/2), [Mn2Br4(C6H7NO)2(H2O)4]·2C6H7NO (II), bis(μ-3-methylpyridine N-oxide)bis[aquadibromido(3-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(H2O)2] (III), and bis(μ-4-methylpyridine N-oxide)bis[dibromidomethanol(4-methylpyridine N-oxide)manganese(II)], [Mn2Br4(C6H7NO)4(CH3OH)2] (IV). All the compounds have one unique MnII atom and form a dimeric complex that contains two MnII atoms related by a crystallographic inversion center. Pseudo-octahedral six-coordinate manganese(II) centers are found in all four compounds. All four compounds form dimers of Mn atoms bridged by the oxygen atom of the PNO ligand. Compounds I, II and III exhibit a bound water of solvation, whereas compound IV contains a bound methanol molecule of solvation. Compounds I, III and IV exhibit the same arrangement of molecules around each manganese atom, ligated by two bromide ions, oxygen atoms of two PNO ligands and one solvent molecule, whereas in compound II each manganese atom is ligated by two bromide ions, one O atom of a PNO ligand and two water molecules with a second PNO molecule interacting with the complex via hydrogen bonding through the bound water molecules. All of the compounds form extended hydrogen-bonding networks, and compounds I, II, and IV exhibit offset π-stacking between PNO ligands of neighboring dimers.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Reaction of tetrakis(acetonitrile)copper(I) perchlorate ([Cu(NCCH3)(4)][ClO4]), tris-1-ethyl-4-methylimidazolylphosphine (T1Et4MeIP) (1) and 3-hydroxyflavone (flavH) under ambient conditions produces an in-situ generated flavonol bound copper(II) complex, which converts to a stable green complex that formulates to [Cu(T1Et4MeIP)(flav)][ClO4] (2). The crystal structure of 2 was determined by X-ray diffraction and crystallizes in a triclinic system (P (1) over bar) with unit cell dimensions of a = 14.537(15) angstrom, b = 15.794(14) angstrom, c = 17.044(17) angstrom, alpha = 65.58(3)degrees, beta = 86.80(5)degrees, gamma = 73.34(4)degrees, V = 3376(6) angstrom(3) and Z = 2. While the five-coordinate copper(II) complex is stable under ambient conditions in the solid state, it undergoes oxidative scission of the flavonol pyrone ring under photolytic (300 nm) and/or thermal (120 degrees C) conditions in the presence of molecular oxygen. The degradative process produces the corresponding methylated products: methylbenzoate, methyl salicylate and N,N-dimethylbenzamide. In addition, the previously undisclosed single crystal X-ray structure of tris-1-ethyl-4-methylimidazolylphosphine (1), T1Et4MeIP, is also reported. (C) 2019 Elsevier B.V. All rights reserved.

Manganese(II) acetate coordination polymers have been prepared with three derivatives of pyridine N -oxide. The compounds are catena -poly[manganese(II)-μ 3 -acetato-di-μ 2 -acetato-[aquamanganese(II)]-μ 2 -acetato-μ-(pyridine N -oxide)-manganese(II)-μ 3 -acetato-μ 2 -acetato-μ-(pyridine N -oxide)-[aquamanganese(II)]-di-μ 2 -acetato], [Mn 4 (CH 3 COO) 8 (C 5 H 5 NO) 2 (H 2 O) 2 ] n , ( I ), catena -poly[[manganese(II)]-μ 3 -acetato-μ 2 -acetato-μ-(2-methylpyridine N -oxide)-[aquamanganese(II)]-di-μ 2 -acetato-manganese(II)-di-μ 2 -acetato-μ 3 -acetato-[aquamanganese(II)]-μ 2 -acetato-μ-(2-methylpyridine N -oxide)], [Mn 4 (CH 3 COO) 8 (C 6 H 7 NO) 2 (H 2 O) 2 ] n , ( II ), and catena -poly[[manganese(II)-di-μ 2 -acetato-μ-(4-methylpyridine N -oxide)] monohydrate], {[Mn(CH 3 COO) 2 (C 6 H 7 NO)]·H 2 O} n , ( III ). Compounds ( I ) and ( II ) both have three unique Mn atoms; in both compounds two of them sit on a crystallographic inversion center while the third is on a general position. In compound ( III ), the single unique Mn atom sits on a general position. Pseudo-octahedral six-coordinate manganese(II) centers are found in all compounds. All of the compounds form chains of Mn atoms bridged by acetate ions and the oxygen atom of the N- oxide in pyridine N- oxide (PNO), 2-methylpyridine N- oxide (2MePNO), or 4-methylpyridine N -oxide (4MePNO). Compound (I) and ( II ) both exhibit a bound water of solvation. In ( I ), the water hydrogen bonds to a nearby acetate whereas in ( II ) the water molecule forms bridging hydrogen bonds between two neighboring acetates. In compound (III) a water molecule of solvation is found in the lattice, not bound to the metal ion but hydrogen bonding to a bridging acetate.

The reaction of bis(pyrazol-1-yl)acetic acid (L) with copper(II) bromide provides two new complexes: [Cu(L-H)Br(µ-Br)]2 (1) and [Cu(L)2]⋅4H2O (2). Complex 1 is prepared by the stoichiometric reaction of L-H with copper(II) bromide in tetrahydrofuran. Dissolution of 1 in methanol causes its conversion into the bis-ligated complex (2), a highly hygroscopic material. Complex 2 can also be synthesized directly by the stoichiometric reaction of L-H with CuBr2 in methanol. Complex 1 is dimeric, interlinked by two bridging bromide ligands, and possesses terminal bromide ligands on each copper atom. The two pyrazolyl ligands in 1 coordinate with the nitrogen atoms to complete the coordination sphere of copper, resulting in a highly distorted geometry that lies between a trigonal bipyramidal or square pyramidal geometry with wide bond angles between the trans-oriented pyrazolyl nitrogen atoms and bromide ligands. Complex 2 assumes a pseudo-trigonal prismatic geometry with the deprotonated carboxylic acid that interacts weakly with copper.