Weak hydrogen and halogen bonding in 4‐[(2,2‐difluoroethoxy)methyl]pyridinium iodide and 4‐[(3‐chloro‐2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium iodide

To enable a comparison between a C—H…X hydrogen bond and a halogen bond, the structures of two fluorous‐substituted pyridinium iodide salts have been determined. 4‐[(2,2‐Difluoroethoxy)methyl]pyridinium iodide, C₈H₁₀F₂NO⁺·I⁻, (1), has a –CH₂OCH₂CF₂H substituent at the para position of the pyridinium ring and 4‐[(3‐chloro‐2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium iodide, C₉H₉ClF₄NO⁺·I⁻, (2), has a –CH₂OCH₂CF₂CF₂Cl substituent at the para position of the pyridinium ring. In salt (1), the iodide anion is involved in one N—H…I and three C—H…I hydrogen bonds, which, together with C—H…F hydrogen bonds, link the cations and anions into a three‐dimensional network. For salt (2), the iodide anion is involved in one N—H…I hydrogen bond, two C—H…I hydrogen bonds and one C—Cl…I halogen bond; additional C—H…F and C—F…F interactions link the cations and anions into a three‐dimensional arrangement.     

Weak hydrogen bonding and fluorous interactions in the chloride and bromide salts of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium

Neutralization of 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridine with hydrohalo acids HX (X = Cl and Br) yielded the pyridinium salts 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium chloride, C₉H₁₀F₄NO⁺·Cl⁻, (1), and 4‐[(2,2,3,3‐tetrafluoropropoxy)methyl]pyridinium bromide, C₉H₁₀F₄NO⁺·Br⁻, (2), both carrying a fluorous side chain at the para position of the pyridinium ring. Single‐crystal X‐ray diffraction techniques revealed that (1) and (2) are isomorphous. The halide anions accept four hydrogen bonds from N—H, ortho‐C—H and CF₂—H groups. Two cations and two anions form a centrosymmetric dimeric building block, utilizing complimentary N—H…X …H—Csp ³ connections. These dimers are further crosslinked, utilizing another complimentary Csp ²—H…X …H—Csp ² connection. The pyridinium rings are π‐stacked, forming columns running parallel to the a axis that make angles of ca 44–45° with the normal to the pyridinium plane. There are also supramolecular C—H…F—C interactions, namely bifurcated C—H…F and bifurcated C—F…H interactions; additionally, one type II C—F…F—C halogen bond has been observed.     

New fluorous ponytailed 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium halide salts

It is possible that fluorous compounds could be utilized as directing forces in crystal engineering for applications in materials chemistry or catalysis. Although numerous fluorous compounds have been used for various applications, their structures in the solid state remains a lively matter for debate. The reaction of 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridine with HX (X = I or Cl) yielded new fluorous ponytailed pyridinium halide salts, namely 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium iodide, C₈H₉F₃NO⁺·I⁻, (1), and 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium chloride, C₈H₉F₃NO⁺·Cl⁻, (2), which were characterized by IR spectroscopy, multinuclei (¹H, ¹³C and ¹⁹F) NMR spectroscopy and single‐crystal X‐ray diffraction. Structure analysis showed that there are two types of hydrogen bonds, namely N—H…X and C—H…X. The iodide anion in salt (1) is hydrogen bonded to three 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations in the crystal packing, while the chloride ion in salt (2) is involved in six hydrogen bonds to five 4‐[(2,2,2‐trifluoroethoxy)methyl]pyridinium cations, which is attributed to the smaller size and reduced polarizability of the chloride ion compared to the iodide ion. In the IR spectra, the pyridinium N—H stretching band for salt (1) exhibited a blue shift compared with that of salt (2).     

Synthesis and single crystal X‐ray determination of the Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene

The reaction of acetylferrocene [Fe(η‐C₅H₅)(η‐C₅H₄COCH₃)] (1) with (2‐isopropyl‐5‐methylphenoxy) acetic acid hydrazide [CH₃C₆H₃CH(CH₃)₂OCH₂CONHNH₂] (2) in refluxing ethanol gives the stable light‐orange–brown Schiff base 1‐[(2‐isopropyl‐5‐methylphenoxy)hydrazono] ethyl ferrocene, [CH₃C₆H₃CH(CH₃)₂OCH₂CONHN?C(CH₃)Fe(η‐C₅H₅)(η‐C₅H₄)] (3). Complex 3 has been characterized by elemental analysis, IR, ¹H NMR and single crystal X‐ray diffraction study. It crystallizes in the monoclinic space group P2₁/n, with a = 9.6965(15), b = 7.4991(12), c = 29.698(7) Å, β = 99.010(13) °, V = 2132.8(7) ų, D_calc = 1.346 Mg m^?3; absorption coefficient, 0.729 mm^?1. The crystal structure clearly shows the characteristic [N? H···O] hydrogen bonding between the two adjacent molecules of 3. This acts as a bidentale ligand, which, on treatment with [Ru(CO)₂Cl₂] _n, gives a stable bimetallic yellow–orange complex (4). Copyright © 2002 John Wiley & Sons, Ltd.     

Hydrogen bonding and fluorous weak interactions in the non‐isomorphous {4,4′‐bis[(2,2,3,3‐tetrafluoropropoxy)methyl]‐2,2′‐bipyridine‐κ2N,N′}dibromidopalladium and ‐platinum complexes

The polyfluorinated title compounds, [MBr₂(C₁₈H₁₆F₈N₂O₂)] or [4,4′‐(HCF₂CF₂CH₂OCH₂)₂‐2,2′‐bpy]MBr₂, ( 1 ) (M = Pd and bpy is bipyridine) and ( 2 ) (M = Pt), have –CH_(α)2OCH_(β)2CF₂CF₂H side chains with methylene H‐atom donors at the α and β sites, and methine H‐atom donors at the terminal sites, in addition to aromatic H‐atom donors. In contrast to the original expectation of isomorphous structures, ( 1 ) crystallizes in the space group C2/c and ( 2 ) in P2₁/n, with similar unit‐cell volumes and Z = 4. The asymmetric unit of ( 1 ) is one half of the molecule, which resides on a crystallographic twofold axis. Both ( 1 ) and ( 2 ) display stacking of the molecules, indicating a planar (bpy)MBr₂ skeleton in each case. The structure of ( 1 ) exhibits columns with C—H_(β)…Br hydrogen bonds between consecutive layers which conforms to a static (β,β) linkage between layers. In the molecular plane, ( 1 ) shows double C—H_(α)…Br hydrogen bonds self‐repeating along the b axis, the planar molecules being connected into infinite belts. Compound ( 2 ) has no crystallographic symmetry and forms π‐dimer pairs as supermolecules, which then stack parallel to the a axis. The π‐dimer‐pair supermolecules exhibit (Pt—)Br…Br(—Pt) contacts [3.6937 (7) Å] to neighbouring π‐dimer pairs crosslinking the columns. The structure of ( 2 ) reveals many C—H…F(—C) interactions between F atoms and aromatic C—H groups, in addition to those between F atoms and methylene C—H groups.     

Poly[[diaquabis[μ2‐2‐(4‐pyridinio)propane‐1,3‐dionato‐κ2O:O′]cobalt(II)] dinitrate]

The title compound, {[Co(C₈H₇NO₂)₂(H₂O)₂](NO₃)₂}_n, is the first d‐metal ion complex involving bidentate bridging of a β‐dialdehyde group. The Co²⁺ ion is situated on an inversion centre and adopts an octahedral coordination with four equatorial aldehyde O atoms [Co—O = 2.0910 (14) and 2.1083 (14) Å] and two axial aqua ligands [Co—O = 2.0631 (13) Å]. The title compound has a two‐dimensional square‐grid framework structure supported by propane‐1,3‐dionate O:O′‐bridges between the metal ions. The organic ligand itself possesses a zwitterionic structure, involving conjugated anionic propane‐1,3‐dionate and cationic pyridinium fragments. Hydrogen bonding between coordinated water molecules, the pyridinium NH group and the nitrate anions [O...O = 2.749 (2) and 2.766 (3) Å, and N...O = 2.864 (3) Å] is essential for the crystal packing.     

Side‐chain conformations in the isomorphous polyfluorinated {4,4′‐bis[(2,2‐difluoroethoxy)methyl]‐2,2′‐bipyridine‐κ2N,N′}dichloridopalladium and ‐platinum complexes

The polyfluorinated title compounds, [M Cl₂(C₁₆H₁₆F₄N₂O₂)] or [4,4′‐(HCF₂CH₂OCH₂)₂‐2,2′‐bpy]M Cl₂ [M = Pd, ( 1 ), and M = Pt, ( 2 )], have –C(H_α)₂OC(H_β)₂CF₂H side chains with H‐atom donors at the α and β sites. The structures of ( 1 ) and ( 2 ) are isomorphous, with the nearly planar (bpy)M Cl₂ molecules stacked in columns. Within one column, π‐dimer pairs alternate between a π‐dimer pair reinforced with C—H…Cl hydrogen bonds (α,α) and a π‐dimer pair reinforced with C—H_β…F(—C) interactions (abbreviated as C—H_β…F—C,C—H_β…F—C). The compounds [4,4′‐(CF₃CH₂OCH₂)₂‐2,2′‐bpy]M Cl₂ [M = Pd, ( 3 ), and M = Pt, ( 4 )] have been reported to be isomorphous [Lu et al. (2012). J. Fluorine Chem. 137 , 54–56], yet with disorder in the fluorous regions. The molecules of ( 3 ) [or ( 4 )] also form similar stacks, but with alternating π‐dimer pairs between the (α,β; α,β) and (β,β) forms. Through (C—)H…Cl hydrogen‐bond interactions, one molecule of ( 1 ) [or ( 2 )] is expanded into an aggregate of two inversion‐related π‐dimer pairs, one pair in the (α,α) form and the other pair in the (C—H_β…F—C,C—H_β…F—C) form, with the plane normals making an interplanar angle of 58.24 (3)°. Due to the demands of maintaining a high coordination number around the metal‐bound Cl atoms in molecule ( 1 ) [or ( 2 )], the ponytails of molecule ( 1 ) [or ( 2 )] bend outward; in contrast, the ponytails of molecule ( 3 ) [or ( 4 )] bend inward.     

Isomorphism in 1‐(2‐halidobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium halide hemihydrates (halide = Cl,Br)

The crystal structures of two (E)‐stilbazolium salts, namely 1‐(2‐chlorobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium chloride hemihydrate, C₂₀H₁₇ClNO⁺·Cl⁻·0.5H₂O, (I), and 1‐(2‐bromobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium bromide hemihydrate, C₂₀H₁₇BrNO⁺·Br⁻·0.5H₂O, (II), are isomorphous; the isostructurality index is 99.3%. In both salts, the azastyryl fragments are almost planar, while the rings of the benzyl groups are almost perpendicular to the azastyryl planes. The building blocks of the structures are twofold symmetric hydrogen‐bonded systems of two cations, two halide anions and one water molecule, which lies on a twofold axis. In the crystal structure, these blocks are connected by means of weaker interactions, viz. van der Waals, weak hydrogen bonding and stacking. This study illustrates the robustness of certain supramolecular motifs created by a spectrum of intermolecular interactions in generating these isomorphous crystal structures.     

(M)‐ and (P)‐8‐[(1S,2R)‐2‐hydroxy‐1‐methyl‐2‐phenylethyl]‐8‐methyl‐8,9‐dihydro‐7H‐dinaphth[2,1‐c:1′,2′‐e]azepinium bromide solvates

The title compounds are diastereoisomers with antipodean axial chirality. The M isomer crystallizes as a (1/3) acetone solvate, C₃₂H₃₀NO⁺·Br^?·3C₃H₆O, while the P isomer crystallizes as a (1/1) di­chloro­methane solvate, C₃₂H₃₀NO⁺·Br^?·CH₂Cl₂. In each structure, O—H?Br hydrogen bonds link the cations and anions to give ion pairs. The seven‐membered azepinium ring adopts the usual twisted‐boat conformation and its ring strain causes a slight curvature of the plane of each naphthyl ring.     

The cocrystal rac‐1‐[(N,4‐dimethylbenzenesulfonamido)methyl]‐2‐(diphenylphosphoryl)ferrocene–rac‐1‐[(N,4‐dimethylbenzenesulfonamido)methyl]‐2‐(diphenylphosphanyl)ferrocene (0.45/0.55)

As part of our interest in the synthesis and catalytic applications of chiral (diphenylphosphanyl)ferrocene ligands, we designed a number of P,N‐containing ligands for use in asymmetric transfer hydrogenation (ATH). During the synthetic procedure to obtain rac‐1‐[(N,4‐dimethylbenzenesulfonamido)methyl]‐2‐(diphenylphosphanyl)ferrocene, the title compound, [Fe(C₅H₅)(C₂₆H₂₅NO₂PS)]_0.55·[Fe(C₅H₅)(C₂₆H₂₅NO₃PS)]_0.45, was obtained as a by‐product. It is composed of a ferrocene group disubstituted by a partially oxidized diphenylphosphanyl group, as confirmed by ³¹P NMR analysis, and an (N,4‐dimethylbenzenesulfonamido)methyl substituent. Owing to the partially oxidized diphenylphosphanyl group, it is best to view the crystal as being composed of a mixture of non‐oxidized and oxidized phosphane, so it can be regarded as a cocrystal. It is also a racemate. To the best of our knowledge, the P=O distance [1.344 (4) Å] is the shortest observed for related (diphenylphosphoryl)ferrocene compounds. The packing is stabilized by weak C—H...O interactions, forming R₂²(10) hydrogen‐bonding motifs, which build up a chain along the c axis.     

trans‐Bis[3‐(2‐fluorophenyl)‐1‐(4‐nitrophenyl)triazenido‐κN3]bis(pyridine‐κN)palladium(II)

In the title complex, [Pd(C₁₂H₈FN₄O₂)₂(C₅H₅N)₂] or trans‐[Pd(FC₆H₄N=N—NC₆H₄NO₂)(C₅H₅N)₂], the Pd atom lies on a centre of inversion in space group P. The coordination geometry about the Pd²⁺ ion is square planar, with two deprotonated 3‐(2‐fluoro­phenyl)‐1‐(4‐nitro­phenyl)­triazenide ions, FC₆H₄N=N—NC₆H₄NO₂^?, acting as monodentate ligands (two‐electron donors), while two neutral pyridine mol­ecules complete the metal coordination sphere. The whole triazenide ligand is not planar, with the largest interplanar angle being 16.8 (5)° between the phenyl ring of the 2‐­fluorophenyl group and the plane defined by the N=N—N moiety. The Pd—N(triazenide) and Pd—N(pyridine) distances are 2.021 (3) and 2.039 (3) Å, respectively.     

Ferrocene compounds. XXXIV. 1′‐(tert‐Butoxycarbonylamino)ferrocene‐1‐carboxylic acid

Heteroannularly substituted ferrocene derivatives can act as model systems for various hydrogen‐bonded assemblies of biomol­ecules formed, for instance, by means of O—H⋯O and N—H⋯O hydrogen bonding. The crystal structure analysis of 1′‐(tert‐butoxy­carbonyl­amino)­ferrocene‐1‐carbox­ylic acid, [Fe(C₁₀H₁₄NO₂)(C₆H₅O₂)] or (C₅H₄COOH)Fe(C₅­H₄NHCOOC(CH₃)₃, reveals two independent mol­ecules within the asymmetric unit, and these are joined into discrete dimers by two types of intermolecular hydrogen bonds, viz. O—H⋯O and N—H⋯O. The –COOH and –NHCOOR groups are archetypes for dimer formation via two eight‐membered rings. The O—H⋯O hydrogen bonds [2.656 (3) and 2.663 (3) Å] form a cyclic carboxylic acid dimer motif. Another eight‐membered ring is formed by N—H⋯O hydrogen bonds [2.827 (3) and 2.854 (3) Å] between the N—H group and an O atom of another carbamoyl moiety. The dimers are assembled in a herring‐bone fashion in the bc plane.     

ZnII and CuII complexes generated from 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione

A new 1,3,4‐oxadiazole‐containing bispyridyl ligand, namely 5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione (L), has been used to create the novel complexes tetranitratobis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}zinc(II), [Zn₂(NO₃)₄(C₁₄H₁₂N₄OS)₂], (I), and catena‐poly[[[dinitratocopper(II)]‐bis{μ‐5‐(pyridin‐4‐yl)‐3‐[2‐(pyridin‐4‐yl)ethyl]‐1,3,4‐oxadiazole‐2(3H)‐thione}] nitrate acetonitrile sesquisolvate dichloromethane sesquisolvate], {[Cu(NO₃)(C₁₄H₁₂N₄OS)₂]NO₃·1.5CH₃CN·1.5CH₂Cl₂}_n, (II). Compound (I) presents a distorted rectangular centrosymmetric Zn₂L₂ ring (dimensions 9.56 × 7.06 Å), where each Zn^II centre lies in a {ZnN₂O₄} coordination environment. These binuclear zinc metallocycles are linked into a two‐dimensional network through nonclassical C—H...O hydrogen bonds. The resulting sheets lie parallel to the ac plane. Compound (II), which crystallizes as a nonmerohedral twin, is a coordination polymer with double chains of Cu^II centres linked by bridging L ligands, propagating parallel to the crystallographic a axis. The Cu^II centres adopt a distorted square‐pyramidal CuN₄O coordination environment with apical O atoms. The chains in (II) are interlinked via two kinds of π–π stacking interactions along [01]. In addition, the structure of (II) contains channels parallel to the crystallographic a direction. The guest components in these channels consist of dichloromethane and acetonitrile solvent molecules and uncoordinated nitrate anions.     

2,3,5,6‐Tetra­kis(phenoxy­methyl)­pyrazine and 2,3,5,6‐tetrakis(phenyl­sulfanyl­methyl)pyrazine

The title compounds, C₃₂H₂₈N₂O₄, (I), and C₃₂H₂₈N₂S₄, (II), respectively, are tetra­substituted pyrazines and both possess C_i symmetry. They differ only in the hetero atom (X) of the –­CH₂XPh side‐arm substituents: X = O in (I) and S in (II). Compound (I) has an overall S‐shape with a pair of adjacent –­CH₂OPh side arms alternately above and below the plane of the central pyrazine ring. The phenyl rings are inclined to one another by 12.63 (18)° and there is one intra­molecular C—H⋯O hydrogen bond involving adjacent –CH₂OPh side arms. In compound (II), adjacent –CH₂SPh side arms point in opposite directions with respect to the pyrazine ring plane, with the phenyl rings inclined at 60.45 (8)°. Both structures have weak C—H⋯π inter­molecular inter­actions.     

Di‐μ‐aqua‐bis­[(N‐salicyl­idene‐β‐alaninato‐κ3O,N,O′)copper(II)] urea disolvate

Crystals of the title compound, [Cu₂(C₁₀H₉NO₃)₂(H₂O)₂]·2CH₄N₂O, consist of two (N‐salicyl­idene‐β‐alaninato‐κ³O,N,O′)copper(II) coordination units bridged by two water moieties to form a dimer residing on a crystallographic inversion center, along with two uncoordinated urea mol­ecules. The Cu^II atom has square‐pyramidal coordination, with three donor atoms of the tridentate Schiff base and an O atom of the bridging aqua ligand in the basal plane. The axial position is occupied by the second bridging water ligand at a distance of 2.5941 (18) Å. Hydro­gen bonds between mol­ecules of urea and the neighboring dimer units lead to the formation of a two‐dimensional grid of mol­ecules parallel to [101]. The superposition of the normals of the pyramidal base planes in the direction [100] indicates possible π–π interactions between the neighboring units.     

(E)‐2‐[2‐(1‐Naphthyl)­vinyl]‐3‐tosyl‐2,3‐di­hydro‐1,3‐benzo­thia­zole

The title compound, C₂₆H₂₁NO₂S₂, which consists of a benzo­thia­zole skeleton with α‐naphthyl­vinyl and tosyl groups at positions 2 and 3, respectively, was prepared by palladium–copper‐catalyzed heteroannulation. The E configuration of the mol­ecule about the vinyl C=C bond is established by the benzothiazole–naphthyl C—C—C—C torsion angle of 177.5 (4)°. The five‐membered heterocyclic ring adopts an envelope conformation with the Csp³ atom 0.380 (6) Å from the C₂NS plane. The two S—C [1.751 (4) and 1.838 (4) Å] and two N—C [1.426 (5) and 1.482 (5) Å] bond lengths in the thia­zole ring differ significantly.     

cis‐Dichlorido(3,6,9‐trithiabicyclo[9.3.1]pentadecane‐κ2S3,S6)palladium(II) acetonitrile 0.8‐solvate

In the title complex, [PdCl₂(C₁₂H₂₂S₃)]·0.8CH₃CN, a potentially tridentate thioether ligand coordinates in a cis‐bidentate manner to yield a square‐planar environment for the Pd^II cation [mean deviation of the Pd from the Cl₂S₂ plane = 0.0406 (7) Å]. Each square‐planar entity packs in an inverse face‐to‐face manner, giving pairs with plane‐to‐plane separations of 3.6225 (12) Å off‐set by 1.1263 (19) Å, with a Pd...Pd separation of 3.8551 (8) Å. A partial acetonitrile solvent molecule is present. The occupancy of this molecule was allowed to refine, and converged to 0.794 (10). The synthesis of the previously unreported 3,6,9‐trithiabicyclo[9.3.1]pentadecane ligand is also outlined.     

Three‐dimensional hydrogen‐bonded structures in the 1:1 proton‐transfer compounds of l‐tartaric acid with the associative‐group monosubstituted pyridines 3‐aminopyridine, 3‐carboxypyridine (nicotinic acid) and 2‐carboxypyridine (picolinic acid)

The 1:1 proton‐transfer compounds of l ‐tartaric acid with 3‐aminopyridine [3‐aminopyridinium hydrogen (2R,3R)‐tartrate dihydrate, C₅H₇N₂⁺·C₄H₅O₆⁻·2H₂O, (I)], pyridine‐3‐carboxylic acid (nicotinic acid) [anhydrous 3‐carboxypyridinium hydrogen (2R,3R)‐tartrate, C₆H₆NO₂⁺·C₄H₅O₆⁻, (II)] and pyridine‐2‐carboxylic acid [2‐carboxypyridinium hydrogen (2R,3R)‐tartrate monohydrate, C₆H₆NO₂⁺·C₄H₅O₆⁻·H₂O, (III)] have been determined. In (I) and (II), there is a direct pyridinium–carboxyl N⁺—H...O hydrogen‐bonding interaction, four‐centred in (II), giving conjoint cyclic R₁²(5) associations. In contrast, the N—H...O association in (III) is with a water O‐atom acceptor, which provides links to separate tartrate anions through O_hydroxy acceptors. All three compounds have the head‐to‐tail C(7) hydrogen‐bonded chain substructures commonly associated with 1:1 proton‐transfer hydrogen tartrate salts. These chains are extended into two‐dimensional sheets which, in hydrates (I) and (III) additionally involve the solvent water molecules. Three‐dimensional hydrogen‐bonded structures are generated via crosslinking through the associative functional groups of the substituted pyridinium cations. In the sheet struture of (I), both water molecules act as donors and acceptors in interactions with separate carboxyl and hydroxy O‐atom acceptors of the primary tartrate chains, closing conjoint cyclic R₄⁴(8), R₃⁴(11) and R₃³(12) associations. Also, in (II) and (III) there are strong cation carboxyl–carboxyl O—H...O hydrogen bonds [O...O = 2.5387 (17) Å in (II) and 2.441 (3) Å in (III)], which in (II) form part of a cyclic R₂²(6) inter‐sheet association. This series of heteroaromatic Lewis base–hydrogen l ‐tartrate salts provides further examples of molecular assembly facilitated by the presence of the classical two‐dimensional hydrogen‐bonded hydrogen tartrate or hydrogen tartrate–water sheet substructures which are expanded into three‐dimensional frameworks via peripheral cation bifunctional substituent‐group crosslinking interactions.     

catena‐Poly­[[tri‐n‐butyl­tin]‐μ‐N‐(1‐naphthyl)­maleamato]

The crystal structure of catena‐poly­[[tri‐n‐butyl­tin]‐μ‐3‐(1‐naph­thyl­amino­carbonyl)­acrylato‐κ²O¹:O³], [Sn(C₄H₉)₃(C₁₄H₁₀NO₃)]_n, is composed of polymeric chains wherein the metal center exhibits a distorted trigonal‐bipyramidal geometry, with three n‐butyl groups defining the trigonal plane [mean Sn—C 2.133 (7) Å] and the axial positions being occupied by the carboxyl­ate O atoms of two different N‐(1‐naphthyl)­maleamate ligands with inequivalent Sn—O distances [2.167 (4) and 2.457 (4) Å]. The N‐(1‐naphthyl)­maleamate fragment forms an essentially planar seven‐membered ring involving an intramolecular N—H?O hydrogen bond.     

Bis(pyridine‐2,6‐dimethanol‐N,O,O′)cobalt(II) and ‐copper(II) disacchar­inate dihydrate: three‐dimensional structures with extensive hydrogen bonds and aromatic π–π‐stacking interactions

Bis­(pyridine‐2,6‐di­methanol‐N,O,O′)­cobalt(II) disaccharinate dihydrate, [Co(C₇H₉NO₂)₂](C₇H₄NO₃S)₂·2H₂O, (I), and bis­(pyridine‐2,6‐di­methanol‐N,O,O′)copper(II) disaccharinate dihydrate, [Cu(C₇H₉NO₂)₂](C₇H₄NO₃S)₂·2H₂O, (II), collectively [M(dmpy)₂](sac)₂·2H₂O (where M is Co^II or Cu^II, sac is the saccharinate anion and dmpy is pyridine‐2,6‐di­methanol), are isostructural. The [M(dmpy)₂]²⁺ cations exhibit distorted octahedral geometry in which the two neutral dmpy species act as tripodal N,O,O′‐tridentate ligands. The crystal packing is determined by hydrogen bonding, as well as by weak pyridine–saccharinate π–π‐stacking interactions.