Pavel Poplaukhin

Interwoven coordination polymers sustained by tautomeric forms of the bridging ligand

Supramolecular interwoven double chains are found in two isomeric zinc thiolate complexes which differ in terms of the tautomeric forms of the bridging ligands, i.e. 3-NC5H4CH2N(H)C(O)C(O)N(H)CH2C5H4N-3 or 3-NC5H4CH2NC(OH)C(OH)NCH2C5H4N-3. In each case, the bridging ligands are threaded through 28-membered rings mediated by O–H⋯O hydrogen bonding. Hydrogen bonding interactions between the rings and threading molecules, i.e. O–H⋯Ocarbonyl or O–H⋯Nimine, are dependent on the tautomeric form of the threading molecules.

Supramolecular association in (μ2-pyrazine)-tetrakis(N,N-bis(2-hydroxyethyl)dithiocarbamato)dizinc(II) and its di-dioxane solvate

Abstract The crystal and molecular structures of {Zn[S2CN(CH2CH2OH)2]2}2(pyrazine), (1), and its di-dioxane solvate, (2), are described. In each of these, the centrosymmetric, binuclear molecule features a five-coordinated, highly distorted square-pyramidal geometry based on a NS4 donor set. The three-dimensional architectures in 1 and 2 are sustained by extensive networks of distinctive hydroxyl-O–H···O(hydroxyl) hydrogen bonding. The topology of the lattices are very different with that of 2 having a more regular appearance. The dioxane molecules reside in channels defined by the host molecules in 2 but, do not make many significant interactions with the host. The fact that 1 exhibits a significantly greater packing efficiency and a higher density suggests 1 is more stable than 2. The retention of dioxane in crystals of 2 probably reflects its intimate involvement in nucleation and high boiling point, meaning it is retained during crystallisation. Hirshfeld surface analyses were conducted and confirm the importance of the hydroxyl-O–H···O(hydroxyl) hydrogen bonding but, also reveal the presence of other interactions, most notably C–H···π(chelate) interactions.

Supramolecular isomerism in coordination polymers sustained by hydrogen bonding: bis[Zn(S2CN(Me)CH2CH2OH)2](N,N‘-bis(pyridin-3-ylmethyl)thioxalamide)

Abstract Distinct molecular structures and supramolecular association is found in the title crystal structures. When chloroform was diffused into a solution of {Zn[S2CN(Me)CH2CH2OH)]2}2(N,N‘-bis(pyridin-3-ylmethyl)thioxalamide) in acetonitrile, it was found to have co-crystallised (2:1) with S8 (1) as desulphurisation had occurred during crystallisation. By contrast, when dimethylformamide was diffused in an acetonitrile solution of the same compound, a 2:1 dimethylformamide solvate (2) was isolated. The zinc atom coordination geometry is based on a NS4 donor set in each case but, this defines an approximate square pyramidal geometry in (1) and a geometry intermediate between square pyramidal and trigonal bipyramidal in (2). This difference is ascribed to the hydrogen bonding considerations in (2). The hydroxyl groups in (1) self associate leading to a two-dimensional array; the S8 molecules occupy space between successive layers. The aforementioned hydrogen bonding is disrupted in (2) where one hydroxyl group interacts with the solvent dimethylformamide molecule. Accordingly, the supramolecular association between molecules is restricted to a one-dimensional chain.

[μ2-trans-1,2-Bis­(pyridin-4-yl)ethene-κ2N:N′]bis­{[1,2-bis­(pyridin-4-yl)ethene-κN]bis­[N-(2-hydroxy­eth­yl)-N-iso­propyl­dithio­carbamato-κ2S,S′]cadmium} aceto­nitrile tetra­solvate: crystal structure and Hirshfeld surface analysis

A distorted octahedral cis-N2S4 coordination geometry is found in the title solvated bimetallic complex. The packing features supramolecular layers sustained by O—H⋯O, O—H⋯N and N—H⋯O hydrogen bonding.

2-Pyridone: monoclinic polymorph

The asymmetric unit in the title compound, C5H5NO, comprises two independent but virtually identical molecules of 2-pyridone, and represents a monoclinic polymorph of the previously reported orthorhombic (P212121) form [Penfold (1953 ▶). Acta Cryst. 6, 591–600; Ohms et al. (1984 ▶). Z. Kristallogr. 169, 185–200; Yang & Craven (1998 ▶). Acta Cryst. B54, 912–920]. The independent molecules are linked into supramolecular dimers via eight-membered {⋯HNC(O)}2 amide synthons in contrast to the helical supramolecular chains, mediated by {⋯HNC(O)} links, found in the orthorhombic form.

Structural, Hirshfeld surface and theoretical analysis of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide

Abstract The common feature of two conformational polymorphs of N,N′-bis(pyridin-3-ylmethyl)oxalamide is their crystallisation in the monoclinic space group P21/c with Z=4. In low symmetry form 1, the central core is effectively planar and the terminal pyridyl rings adopt a syn-periplanar conformation. In the high symmetry form, 2, there are two independent molecules in the asymmetric unit but each is located about a centre of inversion. The rings again are almost perpendicular to the central plane but, from symmetry are anti-periplanar. Computational chemistry shows that symmetric molecules with syn (two-fold) and anti (centrosymmetric) conformations have nearly identical energies. In the molecular packing of each of 1 and 2, supramolecular tapes based on amide-N–H···O(amide) hydrogen bonding are found. In 1, these are connected into layers by C–H···N(pyridyl) interactions, while in 2, the chains are linked into a three-dimensional architecture by C–H···N(pyridyl) interactions. The importance of hydrogen bonding is emphasised in the analysis of the Hirshfeld surfaces.

2,6-Dinitrobenzoic acid and its 2 : 1 salts formed with isomeric n-({[(pyridin-1-ium-n-ylmethyl)carbamoyl]formamido}methyl) pyridin-1-ium, n = 2, 3 and 4

Abstract The co-crystallisation of two equivalents of 2,6-dinitrobenzoic acid (1) with one equivalent of a member of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanediamides, n = 2, 3 and 4, resulted in the anticipated 2 : 1 salts, 2–4. The central core, i.e. CH2N(H)C(=O)C(=O)N(H)CH2, of the isomeric di-cations are superimposable and chemically equivalent pairs of carbonyl, amide and pyridinium groups have an anti conformation. By contrast, the relative orientations of the terminal pyridinium rings from the central core vary significantly across the series as do the relative disposition of the acidic-H atoms. This feature of the structure influences the nature of N—H…O hydrogen bonding and, therefore, the observed supramolecular aggregation patterns. Thus, in 2, the syn-disposition of the nitrogen-bound hydrogen atoms enables the benzoate residue to interact via the two oxygen atoms with both pyridinium- and amine-H atoms to yield a zero-dimensional aggregate. By contrast, in each of 3 and 4, having further distance between the acidic-H atoms, the benzoate residues still interact (either through one both or both oxygen atoms) with pyridinium- and amine-H atoms but those derived from symmetry related molecules to generate one-dimensional aggregates. The three-dimensional architectures of 1–3 are consolidated, in the main, by C—H…O interactions. The structure of 1 revealed the benzoic acid residue to be perpendicular in contrast to the co-planar conforämations of the nitro groups. In the crystal packing, O–H…O hydrogen bonding lead to a helical supramolecular chain.

Bis[N-(2-hy­droxy­eth­yl)-N-methyl­dithio­carbamato-κS][2,4,6-tris­(pyridin-2-yl)-1,3,5-triazine-κ3N1,N2,N6]zinc dioxane sesquisolvate

The asymmetric unit of the title compound, [Zn(C4H8NOS2)2(C18H12N6)]·1.5C4H8O2, comprises a Zn-containing molecule and one and a half dioxane molecules as one of the solvent molecules is located about a crystallographic inversion centre. The approximately square-pyramidal N3S2 donor set is defined by two monodentate dithiocarbamate ligands and two pyridine and one triazine N atom from the tridentate triazine ligand. Molecules are connected into a supramolecular array via O—H⋯S and O—H⋯N hydrogen bonds. These stack along the b axis and the solvent molecules reside in the channels thus formed.

Conformational preferences for isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithiodiamides, n = 2, 3 and 4: a combined crystallographic and DFT study

Abstract Crystal structure analysis of the isomeric N,N′-bis(pyridin-n-ylmethyl)ethanedithioamides, n = 2 (1), 3 (2) and 4 (3), show a planar conformation for 1 and conformations whereby the pyridyl rings lie orthogonal and to either side of the central residue for each of 2 and 3. The universal adoption of the all ZZ conformation about the central C–N bonds, which have double bond character, is ascribed to the presence of intramolecular N–H…S hydrogen bonds that close S(5) rings. The gas-phase geometry optimised structure for 1 is the same as the experimental structure which features intramolecular amine-N–H…N(pyridyl) hydrogen bonds. The open structures found for 2 and 3 differ from the somewhat flattened optimised structures. Systematic variations in the geometric parameters characterising the central C2N2S2 residue, in particular the double-bond character of the C–N bond and the elongation of the central C–C bond are shown by theory to be due to conjugative nN → π*C=S interactions and nS → σ*C-C hyperconjugation, respectively.

(μ-trans-1,2-Di-4-pyridylethyl-ene-κ2 N: N′)bis-[bis-(N,N-diethyl-dithio-carbamato-κ2 S,S′)zinc(II)] chloro-form solvate

The dinuclear title solvate, [Zn2(C5H10NS2)4(C12H10N2)]·CHCl3, features two five-coordinate Zn atoms; both coordination polyhedra are distorted, but one has an NS4 donor set approximating to a square pyramid (with the N atom in the apical site), while the other is closer to a ZnNS4 trigonal-bipyramidal arrangement (with the N atom in an equatorial site). In both cases, the ZnII atom is chelated by two S,S′-bidentate dithiolate ligands. In the crystal, the chloroform solvent molecules reside in cavities defined by the dinuclear species and are held in place via C—H⋯S contacts.