In the title 1:1 cocrystal, C7H4ClNO4·C6H6N2O, nicotinamide (NIC) and 2-chloro-5-nitro­benzoic acid (CNBA) cocrystallize with one mol­ecule each of NIC and CNBA in the asymmetric unit. In this structure, CNBA and NIC form hydrogen bonds through O—H⋯N, N—H⋯O and C—H⋯O inter­actions along with N—H⋯O dimer hydrogen bonds of NIC. Further additional weak π–π inter­actions stabilize the mol­ecular assembly of this cocrystal.

The structures of two isomeric com­pounds of 5-nitro­quinoline with chloro- and nitro-substituted benzoic acid, namely, 2-chloro-4-nitro­benzoic acid–5-nitro­quinoline (1/1), (I), and 5-chloro-2-nitro­benzoic acid–5-nitro­quinoline (1/1), (II), both C7H4ClNO4·C9H6N2O2, have been determined at 190 K. In each com­pound, the acid and base mol­ecules are held together by an O—H⋯N hydrogen bond. In the crystal of (I), the hydrogen-bonded acid–base units are linked by a C—H⋯O hydrogen bond, forming a tape structure along [1overline{2}0]. The tapes are stacked into a layer parallel to the ab plane via N—O⋯π inter­actions between the nitro group of the base mol­ecule and the quinoline ring system. The layers are further linked by other C—H⋯O hydrogen bonds, forming a three-dimensional network. In the crystal of (II), the hydrogen-bonded acid–base units are linked into a wide ribbon structure running along [1overline{1}0] via C—H⋯O hydrogen bonds. The ribbons are further linked via another C—H⋯O hydrogen bond, forming a layer parallel to (110). Weak π–π inter­actions [centroid–centroid distances of 3.7080 (10) and 3.7543 (9) Å] are observed between the quinoline ring systems of adjacent layers. Hirshfeld surfaces for the 5-nitro­quinoline mol­ecules of the two com­pounds mapped over shape index and dnorm were generated to visualize the weak inter­molecular inter­actions.

In the crystal structures of the title com­pounds, namely μ-aqua-κ2O:O-di-μ-di­phenyl­acetato-κ4O:O'-bis­[(di­phenyl­acetato-κO)bis­(pyridine-κN)nickel(II)], [Ni2(C14H11O2)4(C5H5N)4(H2O)] (1) and μ-aqua-κ2O:O-di-μ-di­phenyl­acetato-κ4O:O'-bis­[(2,2'-bi­pyridine-κ2N,N')(di­phenyl­acetato-κO)nickel(II)]–aceto­nitrile–di­phenyl­acetic acid (1/2.5/1), [Ni2(C14H11O2)4(C10H8N2)2(H2O)]·2.5CH3CN·C14H12O2 (2), the com­plex units are stabilized by a variety of intra- and inter­molecular hydrogen bonds, as well as C—H⋯π and π–π contacts between the aromatic systems of the pyridine, dipyridyl and di­phenyl­acetate ligands. Despite the fact that the di­phenyl­acetate ligand is sterically bulky, this does not inter­fere with the formation of the described aqua-bridged dimeric core, even with a 2,2'-bi­pyridine ligand, which has a strong chelating effect.

A zinc metal–organic framework, namely poly[bis­(N,N-di­ethyl­formamide)(μ4-naphthalene-2,6-di­carboxyl­ato)(μ2-naphthalene-2,6-di­carboxyl­ato)dizinc(II)], [Zn(C12H6O4)(C15H11NO)]n, built from windmill-type secondary building units and forming zigzag shaped two-dimensional stacked layers, has been solvothermally synthesized from naphthalene-2,6-di­carb­oxy­lic acid and zinc(II) acetate as the metal source in N,N-di­ethyl­formamide containing small amounts of formic acid.

2-(4-Nitro­phen­yl)-2-oxoethyl picolinate, C14H10N2O5, was synthesized under mild conditions. The chemical and mol­ecular structures were confirmed by single-crystal X-ray diffraction analysis. The mol­ecules are linked by inversion into centrosymmetric dimers via weak inter­molecular C—H⋯O inter­actions, forming R22(10) ring motifs, and further strengthened by weak π–π inter­actions. Hirshfeld surface analyses, the dnorm surfaces, electrostatic potential and two-dimensional fingerprint (FP) plots were used to verify the contributions of the different inter­molecular inter­actions within the supra­molecular structure. The shape-index surface shows that two sides of the mol­ecules are involved with the same contacts in neighbouring mol­ecules and curvedness plots show flat surface patches that are characteristic of planar stacking.

In the title com­plex, [Cu(C18H12F6N2O4)]·0.5C6H6O2, the CuII ion has a square-planar coordination geometry, being ligated by two N and two O atoms of the tetra­dentate open-chain Schiff base ligand 6,6'-{(1E,1'E)-[ethane-1,2-diylbis(aza­nylyl­idene)]bis­(methanylyl­idene)}bis­[2-(tri­fluoro­meth­oxy)phenol]. The crystal packing is stabilized by intra­molecular O—H⋯O and inter­molecular C—H⋯F, C—H⋯O and C—H⋯π hydrogen bonds. In addition, weak π–π inter­actions form a three-dimensional structure. Hirshfeld surface analysis and two-dimensional fingerprint plots were performed and created to analyze the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from F⋯H/H⋯F (25.7%), H⋯H (23.5%) and C⋯H/H⋯C (12.6%) inter­actions.

In the asymmetric unit of the title coordination compound, {[Cu(CN)(C4H3OC2H5N2)][Cu(CN)]}n, there are two Cu atoms with different coordination environments. One CuI ion is coordinated in a triangular coordination geometry by the N atom of the 2-eth­oxy­pyrazine mol­ecule and by two bridging cyanide ligands, equally disordered over two sites exchanging C and N atoms, thus forming polymeric chains parallel to the c axis. The other Cu atom is connected to two bridging cyanide groups disordered over two sites with an occupancy of 0.5 for each C and N atom, and forming an almost linear polymeric chain parallel to the b axis. In the crystal, the two types of chain, which are orthogonal to each other, are connected by cuprophilic Cu⋯Cu inter­actions [2.7958 (13) Å], forming two-dimensional metal–organic coordination layers parallel to the bc plane. The coordination framework is further stabilized by weak long-range (electrostatic type) C—H⋯π inter­actions between cyano groups and 2-eth­oxy­pyrazine rings.

The title compound, [IrZnI2(C10H15)(C3H9P)2]·0.5C6H6 or [Cp*(PMe3)2Ir]-[ZnI2] (Cp* = cyclo-C5Me5) was obtained and characterized as its benzene solvate [Cp*(PMe3)2Ir]-[ZnI2]·0.5C6H6. The bimetallic complex in this structure contains the Lewis-acidic fragment ZnI2 bonded to the Lewis-basic fragment Cp*(PMe3)2Ir, with an Ir—Zn bond distance of 2.452 (1) Å. The compound was obtained by reacting [Cp*(PMe3)IrI2] with 2-Ad2Zn (2-Ad = 2-adamant­yl), resulting in the reduction of the IrIII complex and formation of the IrI–ZnII adduct. The crystal studied was a twin by non-merohedry with a refined BASF parameter of 0.223 (1).

A reaction of copper(II) carbonate and potassium 4-sulfo­benzoic acid in water acidified with hydro­chloric acid yielded two crystalline products. Tetra­aqua­bis­(4-carb­oxy­benzene­sulfonato)­copper(II) dihydrate, [Cu(O3SC6H4CO2H)2(H2O)4]·2H2O, (I), crystallizes in the triclinic space group Poverline{1} with the Cu2+ ions located on centers of inversion. Each copper ion is coordinated to four water mol­ecules in a square plane with two sulfonate O atoms in the apical positions of a Jahn–Teller-distorted octa­hedron. The carboxyl­ate group is protonated and not involved in coordination to the metal ions. The complexes pack so as to create a layered structure with alternating inorganic and organic domains. The packing is reinforced by several O—H⋯O hydrogen bonds involving coordinated and non-coordinated water mol­ecules, the carb­oxy­lic acid group and the sulfonate group. Hexa­aqua­copper(II) 4-carb­oxy­benzene­sulfonate, [Cu(H2O)6](O3SC6H4CO2H)2, (II), also crystallizes in the triclinic space group Poverline{1} with Jahn–Teller-distorted octa­hedral copper(II) aqua complexes on the centers of inversion. As in (I), the carboxyl­ate group on the anion is protonated and the structure consists of alternating layers of inorganic cations and organic anions linked by O—H⋯O hydrogen bonds. A reaction of silver nitrate and potassium 4-sulfo­benzoic acid in water also resulted in two distinct products that have been structurally characterized. An anhydrous silver potassium 4-carb­oxy­benzene­sulfonate salt, [Ag0.69K0.31](O3SC6H4CO2H), (III), crystallizes in the monoclinic space group C2/c. There are two independent metal sites, one fully occupied by silver ions and the other showing a 62% K+/38% Ag+ (fixed) ratio, refined in two slightly different positions. The coordination environments of the metal ions are composed primarily of sulfonate O atoms, with some participation by the non-protonated carboxyl­ate O atoms in the disordered site. As in the copper compounds, the cations and anions cleanly segregate into alternating layers. A hydrated mixed silver potassium 4-carb­oxy­benzene­sulfonate salt dihydrate, [Ag0.20K0.80](O3SC6H4CO2H)·2H2O, (IV), crystallizes in the monoclinic space group P21/c with the Ag+ and K+ ions sharing one unique metal site coordinated by two water mol­ecules and six sulfonate O atoms. The packing in (IV) follows the dominant motif of alternating inorganic and organic layers. The protonated carboxyl­ate groups do not inter­act with the cations directly, but do participate in hydrogen bonds with the coordinated water mol­ecules. (IV) is isostructural with pure potassium 4-sulfo­benzoic acid dihydrate.

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di­carboxyl­ate and DMF = di­methyl­formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal–organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter­actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol­ecule, which shows positional disorder. Parallel planes are connected mainly through weak C—H⋯O, H⋯H and H⋯C inter­actions between DMF mol­ecules, as shown by Hirshfeld surface analysis.

The reaction of t-Bu2Si(OH)2 with two equivalents of Cp2Zr(CH3)2 produces the title t-Bu2SiO2-siloxide bridged dimer, [Zr2(CH3)2(C5H5)4(C8H18O2Si)] or [Cp2Zr(CH3)]2[μ-t-Bu2SiO2] (1), where one methyl group is retained per zirconium atom. The same product is obtained at room temperature even when equimolar ratios of the silanediol and Cp2Zr(CH3)2 are used. Attempts to thermally eliminate methane and produce a bridging methyl­ene complex resulted in decomposition. The crystal structure of 1 displays typical Zr—CH3 and Zr—O distances but the Si—O distance [1.628 (2) Å] and O—Si—O angle [110.86 (15)°] are among the largest observed in this family of compounds suggesting steric crowding between the t-Bu substituents of the silicon atom and the cyclo­penta­dienyl groups. The silicon atom lies on a crystallographic twofold axis and both Cp rings are disordered over two orientations of equal occupancy.

The title compound, [Fe(C44H24N8Cl4)(CN)2][K2(C18H36N2O6)2]·2C4H8O was synthesized and characterized by single-crystal X-ray diffraction as well as FTIR and UV–vis spectroscopy. The central FeII ion is coordinated by four pyrrole N atoms of the porphyrin core and two C atoms of the cyano groups in a slightly distorted octa­hedral coordination environment. The complex mol­ecule crystallizes with two tetra­hydro­furan solvent mol­ecules, one of which was refined as disordered over two sets of sites with refined occupancies of 0.619 (5) and 0.381 (5). It has a distorted porphyrin core with mean absolute core-atom displacements Ca, Cb, Cm and Cav of 0.32 (3), 0.22 (3), 0.56 (2) and 0.37 (14) Å, respectively. The axial Fe—Ccyano bond lengths are 1.991 (2) and 1.988 (2) Å. The average Fe—Np (Np is a porphyrin N atom) bond length is 1.964 (10) Å. One of the O atoms and several C atoms of the 222 moiety [222 = 4,7,13,16,21,24-hexa­oxa-1,10-di­aza­bicyclo­[8.8.8]hexa­cosa­ne] were refined as disordered over two sets of sites with occupancy ratios of 0.739 (6):0.261 (6) and 0.832 (4):0.168 (4). Additional solvent mol­ecules were found to be highly disordered and their contribution to the scattering was removed using the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18], which indicated a solvent cavity of volume 372 Å3 containing approximately 83 electrons. These solvent mol­ecules are not considered in the given chemical formula and other crystal data.

In the title compound, (2,2'-bi­pyridine-κ2N,N')bis­(2-meth­oxy­ethyl xanthato-κS)zinc(II), [Zn(C4H7O2S2)2(C10H8N2)], the ZnII ion is coordinated to two N atoms of the 2,2'-bi­pyridine ligand and two S atoms from two 2-meth­oxy­ethyl xanthate ligands. The ZnII ion lies on a crystallographic twofold rotation axis and has distorted tetra­hedral coordination geometry. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming supramolecular chains propagating along the a-axis direction. Weak intra­molecular C—H⋯S hydrogen bonds are also observed. The inter­molecular contacts in the crystal were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are H⋯H (36.3%), followed by S⋯H/H⋯S (24.7%), C⋯H/H⋯C (15.1%), O⋯H/H⋯O (14.4%), N⋯H/H⋯N (4.1%) and C⋯C (2.9%).

The solid-state structures of two cobalt–pyridine–sulfate compounds, namely catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ2O:O'], [Co(SO4)(C5H5N)4]n, (1), and catena-poly[[tetra­kis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O:O',O''-[bis­(pyridine-κN)cobalt(II)]-μ-sulfato-κ3O,O':O'']n, [Co2(SO4)2(C5H5N)6]n, (2), are reported. Compound (1) displays a polymeric structure, with infinite chains of CoII cations adopting octa­hedral N4O2 coordination environments that involve four pyridine ligands and two bridging sulfate ions. Compound (2) is also polymeric with infinite chains of CoII cations. The first Co center has an octa­hedral N4O2 coordination environment that involves four pyridine ligands and two bridging sulfate ligands. The second Co center has an octa­hedral N2O4 coordination environment that involves two pyridine ligands and two bridging sulfate ions that chelate the Co atom. The structure of (2) was refined as a two-component inversion twin.

In the title hydrated hybrid compound C14H14N2OS2·H2O, the planar imidazo[1,2-a]pyridine ring system is linked to the 1,3-di­thiol­ane moiety by an enone bridge. The atoms of the C—C bond in the 1,3-di­thiol­ane ring are disordered over two positions with occupancies of 0.579 (14) and 0.421 (14) and both disordered rings adopt a half-chair conformation. The oxygen atom of the enone bridge is involved in a weak intra­molecular C—H⋯O hydrogen bond, which generates an S(6) graph-set motif. In the crystal, the hybrid mol­ecules are associated in R22(14) dimeric units by weak C—H⋯O inter­actions. O—H⋯O hydrogen bonds link the water mol­ecules, forming infinite self-assembled chains along the b-axis direction to which the dimers are connected via O—H⋯N hydrogen bonding. Analysis of inter­molecular contacts using Hirshfeld surface analysis and contact enrichment ratio descriptors indicate that hydrogen bonds induced by water mol­ecules are the main driving force in the crystal packing formation.

In the title mol­ecule, C13H16N4O3, the mean planes of the phenyl and triazole rings are nearly perpendicular to one another as a result of the intra­molecular C—H⋯O and C—H⋯π(ring) inter­actions. In the crystal, layers parallel to (101) are generated by O—H⋯N, N—H⋯O and N—H⋯N hydrogen bonds. The layers are connected by inversion-related pairs of C—H⋯O hydrogen bonds. The experimental mol­ecular structure is close to the gas-phase geometry-optimized structure calculated by DFT methods. Hirshfeld surface analysis indicates that the most important inter­action involving hydrogen in the title compound is the H⋯H contact. The contribution of the H⋯O, H⋯N, and H⋯H contacts are 13.6, 16.1, and 54.6%, respectively.

The mol­ecular structure of the title bis-pyridyl substituted di­amide hydrate, C14H14N4O2·H2O, features a central C2N2O2 residue (r.m.s. deviation = 0.0205 Å) linked at each end to 3-pyridyl rings through methyl­ene groups. The pyridyl rings lie to the same side of the plane, i.e. have a syn-periplanar relationship, and form dihedral angles of 59.71 (6) and 68.42 (6)° with the central plane. An almost orthogonal relationship between the pyridyl rings is indicated by the dihedral angle between them [87.86 (5)°]. Owing to an anti disposition between the carbonyl-O atoms in the core, two intra­molecular amide-N—H⋯O(carbon­yl) hydrogen bonds are formed, each closing an S(5) loop. Supra­molecular tapes are formed in the crystal via amide-N—H⋯O(carbon­yl) hydrogen bonds and ten-membered {⋯HNC2O}2 synthons. Two symmetry-related tapes are linked by a helical chain of hydrogen-bonded water mol­ecules via water-O—H⋯N(pyrid­yl) hydrogen bonds. The resulting aggregate is parallel to the b-axis direction. Links between these, via methyl­ene-C—H⋯O(water) and methyl­ene-C—H⋯π(pyrid­yl) inter­actions, give rise to a layer parallel to (10overline{1}); the layers stack without directional inter­actions between them. The analysis of the Hirshfeld surfaces point to the importance of the specified hydrogen-bonding inter­actions, and to the significant influence of the water mol­ecule of crystallization upon the mol­ecular packing. The analysis also indicates the contribution of methyl­ene-C—H⋯O(carbon­yl) and pyridyl-C—H⋯C(carbon­yl) contacts to the stability of the inter-layer region. The calculated inter­action energies are consistent with importance of significant electrostatic attractions in the crystal.

The polymeric title compound, [Cu2(C2H3N)2(C3H6S2)2](PF6)2, represents an example of a one-dimensional coordination polymer resulting from the reaction of [Cu(MeCN)4][PF6] with 1,3-di­thiol­ane. The cationic one-dimensional ribbon consists of two copper(I) centers each ligated by one aceto­nitrile mol­ecule and inter­connected through two bridging 1,3-di­thiol­ane ligands. One S-donor site of each ligand is κ1-bound to Cu, whereas the second S atom acts as a four-electron donor, bridging two Cu atoms in a κ4-bonding mode. The positive charge of each copper cation is compensated for by a hexa­fluorido­phosphate counter-ion. In the crystal, the polymer chains are linked by a series of C—H⋯F hydrogen bonds, forming a supra­molecular framework. The crystal studied was refined as a two-component twin.

The complexes bis­(acetyl­acetonato-κ2O,O')(N,N,N',N'-tetra­methyl­ethylenedi­amine-κ2N,N')manganese(II), [Mn(C5H7O2)2(C6H16N2)], bis­(acetyl­acetonato-κ2O,O')(N,N,N',N'-tetra­methyl­ethylenedi­amine-κ2N,N')iron(II), [Fe(C5H7O2)2(C6H16N2)], and bis­(acetyl­acetonato-κ2O,O')(N,N,N',N'-tetra­methyl­ethylenedi­amine-κ2N,N')zinc(II), [Zn(C5H7O2)2(C6H16N2)], were synthesized from the reaction of the corresponding metal acetyl­acetonates [M(acac)2(H2O)2] with N,N,N',N'-tetra­methyl­ethylenedi­amine (TMEDA) in toluene. Each of the complexes displays a central metal atom which is nearly octa­hedrally surrounded by two chelating acac and one chelating TMEDA ligand, resulting in an N2O4 coordination set. Despite the chemical similarity of the complex units, the packing patterns for compounds 1–3 are different and thus the crystal structures are not isotypic.

The complete mol­ecule of the binuclear title complex, bis­[μ-1H-1,2,4-triazole-5(4H)-thione-κ2S:S]bis­{(thio­cyanato-κS)[1H-1,2,4-triazole-5(4H)-thione-κS]silver(I)}, [Ag2(SCN)2(C2H3N3S)4], is generated by crystallographic inversion symmetry. The independent triazole-3-thione ligands employ the exocyclic-S atoms exclusively in coordination. One acts as a terminal S-ligand and the other in a bidentate (μ2) bridging mode to provide a link between two AgI centres. Each AgI atom is also coordinated by a terminal S-bound thio­cyanate ligand, resulting in a distorted AgS4 tetra­hedral coordination geometry. An intra­molecular N—H⋯S(thio­cyanate) hydrogen bond is noted. In the crystal, amine-N—H⋯S(thione), N—H⋯N(triazol­yl) and N—H⋯N(thio­cyanate) hydrogen bonds give rise to a three-dimensional architecture. The packing is consolidated by triazolyl-C—H⋯S(thio­cyanate), triazolyl-C—H⋯N(thiocyanate) and S⋯S [3.2463 (9) Å] inter­actions as well as face-to-face π–π stacking between the independent triazolyl rings [inter-centroid separation = 3.4444 (15) Å]. An analysis of the calculated Hirshfeld surfaces shows the three major contributors are due to N⋯H/H⋯N, S⋯H/H⋯S and C⋯H/H⋯C contacts, at 35.8, 19.4 and 12.7%, respectively; H⋯H contacts contribute only 7.6% to the overall surface.

The title homoleptic Schiff base complexes, [M(C14H9Cl2N2O)2], for M = CoII, (I), and CuII, (II), present distinct coordination geometries despite the Schiff base dianion coordinating via the phenolato-O and imine-N atoms in each case. For (I), the coordination geometry is based on a trigonal bipyramid whereas for (II), a square-planar geometry is found (Cu site symmetry overline{1}). In the crystal of (I), discernible supra­molecular layers in the ac plane are sustained by chloro­benzene-C—H⋯O(coordinated), chloro­benzene-C—H⋯π(fused-benzene ring) as well as π(fused-benzene, chloro­benzene)–π(chloro­benzene) inter­actions [inter-centroid separations = 3.6460 (17) and 3.6580 (16) Å, respectively]. The layers inter-digitate along the b-axis direction and are linked by di­chloro­benzene-C—H⋯π(fused-benzene ring) and π–π inter­actions between fused-benzene rings and between chloro­benzene rings [inter-centroid separations = 3.6916 (16) and 3.7968 (19) Å, respectively] . Flat, supra­molecular layers are also found in the crystal of (II), being stabilized by π–π inter­actions formed between fused-benzene rings and between chloro­benzene rings [inter-centroid separations = 3.8889 (15) and 3.8889 (15) Å, respectively]; these stack parallel to [10overline{1}] without directional inter­actions between them. The analysis of the respective calculated Hirshfeld surfaces indicate diminished roles for H⋯H contacts [26.2% (I) and 30.5% (II)] owing to significant contributions by Cl⋯H/H⋯Cl contacts [25.8% (I) and 24.9% (II)]. Minor contributions by Cl⋯Cl [2.2%] and Cu⋯Cl [1.9%] contacts are indicated in the crystals of (I) and (II), respectively. The inter­action energies largely arise from dispersion terms; the aforementioned Cu⋯Cl contact in (II) gives rise to the most stabilizing inter­action in the crystal of (II).

In the title compound, di­aqua­bis­(ethyl­enedi­amine-κ2N,N')copper(II) bis­(2-nitro­benzoate), [Cu(C2H8N2)2(H2O)2](C7H4NO4)2, two di­aqua­bis­(ethyl­enedi­amine)­copper(II) cations and four nitro­benzoate anions are present in the asymmetric unit. All four anions are `whole-mol­ecule' disordered over two sets of sites. The major components have refined occupancies of 0.572 (13), 0.591 (9), 0.601 (9) and 0.794 (10). The CuII ions exhibit slightly distorted octa­hedral geometries. In the crystal, cations and anions are connected to each other via N—H⋯O and O—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (200). The inter­molecular contacts in the crystal were further analysed using Hirshfeld surface analysis, which indicates that the most significant contacts are O⋯H/H⋯O (42.9%), followed by H⋯H (35.7%), C⋯H/H⋯C (14.2%), C⋯C (2.9%), C⋯O/O⋯C (2.2%), N⋯H/H⋯N (0.9%) and N⋯O/O⋯N (0.3%).

The crystal and mol­ecular structures of the title 1:2 co-crystal, C14H14N4O2·2C7H6O2, are described. The oxalamide mol­ecule has a (+)-anti­periplanar conformation with the 4-pyridyl residues lying to either side of the central, almost planar C2N2O2 chromophore (r.m.s. deviation = 0.0555 Å). The benzoic acid mol­ecules have equivalent, close to planar conformations [C6/CO2 dihedral angle = 6.33 (14) and 3.43 (10)°]. The formation of hy­droxy-O—H⋯N(pyrid­yl) hydrogen bonds between the benzoic acid mol­ecules and the pyridyl residues of the di­amide leads to a three-mol­ecule aggregate. Centrosymmetrically related aggregates assemble into a six-mol­ecule aggregate via amide-N—H⋯O(amide) hydrogen bonds through a 10-membered {⋯HNC2O}2 synthon. These are linked into a supra­molecular tape via amide-N—H⋯O(carbon­yl) hydrogen bonds and 22-membered {⋯HOCO⋯NC4NH}2 synthons. The contacts between tapes to consolidate the three-dimensional architecture are of the type methyl­ene-C—H⋯O(amide) and pyridyl-C—H⋯O(carbon­yl). These inter­actions are largely electrostatic in nature. Additional non-covalent contacts are identified from an analysis of the calculated Hirshfeld surfaces.

The equimolar reaction between a racemic mixture of (R)- and (S)-camphorquinone with thio­semicarbazide yielded the title compound, C11H17N3OS [common name: (R)- and (S)-camphor thio­semicarbazone], which maintains the chirality of the methyl­ated chiral carbon atoms and crystallizes in the centrosymmetric space group C2/c. There are two mol­ecules in general positions in the asymmetric unit, one of them being the (1R)-camphor thio­semicarbazone isomer and the second the (1S)- isomer. In the crystal, the mol­ecular units are linked by C—H⋯S, N—H⋯O and N—H⋯S inter­actions, building a tape-like structure parallel to the (overline{1}01) plane, generating R21(7) and R22(8) graph-set motifs for the H⋯S inter­actions. The Hirshfeld surface analysis indicates that the major contributions for crystal cohesion are from H⋯H (55.00%), H⋯S (22.00%), H⋯N (8.90%) and H⋯O (8.40%) inter­actions.

The reaction of N-phenyl-1-(pyridin-2-yl)methanimine with copper chloride dihydrate produced the title neutral complex, [CuCl2(C12H10N2)(H2O)]·H2O. The CuII ion is five-coordinated in a distorted square-pyramidal geometry, in which the two N atoms of the bidentate Schiff base, as well as one chloro and a water mol­ecule, form the irregular base of the pyramidal structure. Meanwhile, the apical chloride ligand inter­acts through a strong hydrogen bond with a water mol­ecule of crystallization. In the crystal, mol­ecules are arranged in pairs, forming a stacking of symmetrical cyclic dimers that inter­act in turn through strong hydrogen bonds between the chloride ligands and both the coordinated and the crystallization water mol­ecules. The mol­ecular and electronic structures of the complex were also studied in detail using EPR (continuous and pulsed), FT–IR and Raman spectroscopy, as well as magnetization measurements. Likewise, Hirshfeld surface analysis was used to investigate the inter­molecular inter­actions in the crystal packing.

In the title compound, C12H15N3O5S, a tris­ubstituted thio­urea derivative, the central CN2S chromophore is almost planar (r.m.s. deviation = 0.018 Å) and the pendant hy­droxy­ethyl groups lie to either side of this plane. While to a first approximation the thione-S and carbonyl-O atoms lie to the same side of the mol­ecule, the S—C—N—C torsion angle of −47.8 (2)° indicates a considerable twist. As one of the hy­droxy­ethyl groups is orientated towards the thio­amide residue, an intra­molecular N—H⋯O hydrogen bond is formed which leads to an S(7) loop. A further twist in the mol­ecule is indicated by the dihedral angle of 65.87 (7)° between the planes through the CN2S chromophore and the 4-nitro­benzene ring. There is a close match between the experimental and gas-phase, geometry-optimized (DFT) mol­ecular structures. In the crystal, O—H⋯O and O—H⋯S hydrogen bonds give rise to supra­molecular layers propagating in the ab plane. The connections between layers to consolidate the three-dimensional architecture are of the type C—H⋯O, C—H⋯S and nitro-O⋯π. The nature of the supra­molecular association has been further analysed by a study of the calculated Hirshfeld surfaces, non-covalent inter­action plots and computational chemistry, all of which point to the significant influence and energy of stabilization provided by the conventional hydrogen bonds.

Crystals of the new compound, AgSr4Cu4.5(PO4)6, were grown successfully by the hydro­thermal process. The asymmetric unit of the crystal structure of the title compound contains 40 independent atoms (4 Sr, 4.5 Cu, 1 Ag, 6 P and 24 O), which are all in general positions except for one Cu atom, which is located on an inversion centre. The Cu atoms are arranged in CuOn (n = 4 or 5) polyhedra, linked through common oxygen corners to build a rigid three-dimensional motif. The connection of these copper units is assured by PO4 tetra­hedra. This arrangement allows the construction of layers extending parallel to the (100) plane and hosts suitable cavities in which Ag+ and Sr2+ cations are located. The crystal-structure cohesion is ensured by ionic bonds between the silver and strontium cations and the oxygen anions belonging to two adjacent sheets. Charge-distribution analysis and bond-valence-sum calculations were used to validate the structural model.

The crystal and mol­ecular structures of the title organotin di­thio­carbamate compounds, [Sn(C6H5)3(C7H10NS2)] (I) and [Sn(C6H5)2(C7H10NS2)2] (II), present very distinct tin atom coordination geometries. In (I), the di­thio­carbamate ligand is asymmetrically coordinating with the resulting C3S2 donor set defining a coordination geometry inter­mediate between square-pyramidal and trigonal–bipyramidal. In (II), two independent mol­ecules comprise the asymmetric unit, which differ in the conformations of the allyl substituents and in the relative orientations of the tin-bound phenyl rings. The di­thio­carbamate ligands in (II) coordinate in an asymmetric mode but the Sn—S bonds are more symmetric than observed in (I). The resulting C2S4 donor set approximates an octa­hedral coordination geometry with a cis-disposition of the ipso-carbon atoms and with the more tightly bound sulfur atoms approximately trans. The only directional inter­molecular contacts in the crystals of (I) and (II) are of the type phenyl-C—H⋯π(phen­yl) and vinyl­idene-C—H⋯π(phen­yl), respectively, with each leading to a supra­molecular chain propagating along the a-axis direction. The calculated Hirshfeld surfaces emphasize the importance of H⋯H contacts in the crystal of (I), i.e. contributing 62.2% to the overall surface. The only other two significant contacts also involve hydrogen, i.e. C⋯H/H⋯C (28.4%) and S⋯H/H⋯S (8.6%). Similar observations pertain to the individual mol­ecules of (II), which are clearly distinguishable in their surface contacts, with H⋯H being clearly dominant (59.9 and 64.9%, respectively) along with C⋯H/H⋯C (24.3 and 20.1%) and S⋯H/H⋯S (14.4 and 13.6%) contacts. The calculations of energies of inter­action suggest dispersive forces make a significant contribution to the stabilization of the crystals. The exception is for the C—H⋯π contacts in (II) where, in addition to the dispersive contribution, significant contributions are made by the electrostatic forces.

The title compound, C8H7NO5, is planar with an r.m.s. deviation for all non-hydrogen atoms of 0.018 Å. An intra­molecular O—H⋯O hydrogen bond involving the adjacent hy­droxy and nitro groups forms an S(6) ring motif. In the crystal, mol­ecules are linked by O—H⋯O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked by C—H⋯O hydrogen bonds, forming layers parallel to the bc plane. The layers are linked by a further C—H⋯O hydrogen bond, forming slabs, which are linked by C=O⋯π inter­actions, forming a three-dimensional supra­molecular structure. Hirshfeld surface analysis was used to investigate inter­molecular inter­actions in the solid state. The mol­ecule was also characterized spectroscopically and its thermal stability investigated by differential scanning calorimetry and by thermogravimetric analysis.

A copper(II) dimer with the deprotonated anion of 2-bromo­nicotinic acid (2-BrnicH), namely, tetrakis(μ-2-bromonicotinato-κ2O:O')bis[aquacopper(­II)](Cu—Cu), [Cu2(H2O)2(C6H3BrNO2)4] or [Cu2(H2O)2(2-Brnic)4], (1), was prepared by the reaction of copper(II) chloride dihydrate and 2-bromo­nicotinic acid in water. The copper(II) ion in 1 has a distorted square-pyramidal coordination environment, achieved by four carboxyl­ate O atoms in the basal plane and the water mol­ecule in the apical position. The pair of symmetry-related copper(II) ions are connected into a centrosymmetric paddle-wheel dinuclear cluster [Cu⋯Cu = 2.6470 (11) Å] via four O,O'-bridging 2-bromo­nicotinate ligands in the syn-syn coordination mode. In the extended structure of 1, the cluster mol­ecules are assembled into an infinite two-dimensional hydrogen-bonded network lying parallel to the (001) plane via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of various hydrogen-bond ring motifs: dimeric R22(8) and R22(16) loops and a tetra­meric R44(16) loop. The Hirshfeld surface analysis was also performed in order to better illustrate the nature and abundance of the inter­molecular contacts in the structure of 1.

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises two half mol­ecules of oxalamide (4LH2), as each is disposed about a centre of inversion, and two mol­ecules of 4-chloro­benzoic acid (CBA), each in general positions. Each 4LH2 mol­ecule has a (+)anti­periplanar conformation with the pyridin-4-yl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angles between the respective central core and the pyridyl rings being 68.65 (3) and 86.25 (3)°, respectively, representing the major difference between the independent 4LH2 mol­ecules. The anti conformation of the carbonyl groups enables the formation of intra­molecular amide-N—H⋯O(amide) hydrogen bonds, each completing an S(5) loop. The two independent CBA mol­ecules are similar and exhibit C6/CO2 dihedral angles of 8.06 (10) and 17.24 (8)°, indicating twisted conformations. In the crystal, two independent, three-mol­ecule aggregates are formed via carb­oxy­lic acid-O—H⋯N(pyrid­yl) hydrogen bonding. These are connected into a supra­molecular tape propagating parallel to [100] through amide-N—H⋯O(amide) hydrogen bonding between the independent aggregates and ten-membered {⋯HNC2O}2 synthons. The tapes assemble into a three-dimensional architecture through pyridyl- and methyl­ene-C—H⋯O(carbon­yl) and CBA-C—H⋯O(amide) inter­actions. As revealed by a more detailed analysis of the mol­ecular packing by calculating the Hirshfeld surfaces and computational chemistry, are the presence of attractive and dispersive Cl⋯C=O inter­actions which provide inter­action energies approximately one-quarter of those provided by the amide-N—H⋯O(amide) hydrogen bonding sustaining the supra­molecular tape.

The title compound, di­aqua­[tris­(2-amino­eth­yl)amine]­nickel(II) hexa­aqua­nickel(II) bis­(sulfate), [Ni(C6H18N4)(H2O)2][Ni(H2O)6](SO4)2 or [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2, consists of two octa­hedral nickel complexes within the same unit cell. These metal complexes are formed from the reaction of [Ni(H2O)6](SO4) and the ligand tris­(2-amino­eth­yl)amine (tren). The crystals of the title compound are purple, different from those of the starting complex [Ni(H2O)6](SO4), which are turquoise. The reaction was performed both in a 1:1 and 1:2 metal–ligand molar ratio, always yielding the co-precipitation of the two types of crystals. The asymmetric unit of the title compound, which crystallizes in the space group Pnma, consists of two half NiII complexes and a sulfate counter-anion. The mononuclear cationic complex [Ni(tren)(H2O)2]2+ comprises an Ni ion, the tren ligand and two water mol­ecules, while the mononuclear complex [Ni(H2O)6]2+ consists of another Ni ion surrounded by six coordinated water mol­ecules. The [Ni(tren)(H2O)2] and [Ni(H2O)6] subunits are connected to the SO42− counter-anions through hydrogen bonding, thus consolidating the crystal structure.

The whole mol­ecule of the cadmium(II) complex, di­iodido­{N,N',N'',N'''-[pyrazine-2,3,5,6-tetra­yltetra­kis­(methyl­ene)]tetra­kis­(N-methyl­aniline)-κ3N2,N1,N6}cadmium(II), [CdI2(C36H40N6)], (I), of the ligand N,N',N'',N'''-[pyrazine-2,3,5,6-tetra­yltetra­kis­(methyl­ene)]tetra­kis­(N-methyl­aniline) (L), is generated by a twofold rotation symmetry; the twofold axis bis­ects the cadmium atom and the nitro­gen atoms of the pyrazine ring. The ligand coordinates in a mono-tridentate manner and the cadmium atom has a fivefold CdN3I2 coordination environment with a distorted shape. In the zinc(II) complex, dichlorido{N,N',N'',N'''-[pyrazine-2,3,5,6-tetra­yltetra­kis­(methyl­ene)]tetra­kis­(N-methyl­aniline)-κ3N2,N1,N6}zinc(II) di­chloro­methane 0.6-solvate, [ZnCl2(C36H40N6)]·0.6CH2Cl2, (II), ligand L also coordinates in a mono-tridentate manner and the zinc atom has a fivefold ZnN3Cl2 coordination environment with a distorted shape. It crystallized as a partial di­chloro­methane solvate. In the crystal of I, the complex mol­ecules are linked by weak C—H⋯I contacts, forming ribbons propagating along [100]. In the crystal of II, the complex mol­ecules are linked by a series of C—H⋯π inter­actions, forming layers lying parallel to the (1overline{1}1) plane. In the crystals of both compounds there are metal–halide⋯π(pyrazine) contacts present. The Hirshfeld analyses confirm the importance of the C—H⋯halide contacts in the crystal packing of both compounds.

Chalcones of type 4-XC6H4C(O)CH=CHC6H4(OCH2CCH)-4, where X = Cl, Br or MeO, have been converted to the corresponding 4,5-di­hydro­pyrazole-1-carbo­thio­amides using a cyclo­condensation reaction with thio­semicarbazide. The chalcones 1-(4-chloro­phen­yl)-3-[4-(prop-2-yn­yloxy)phen­yl]prop-2-en-1-one, C18H13ClO2, (I), and 1-(4-bromo­phen­yl)-3-[4-(prop-2-yn­yloxy)phen­yl]prop-2-en-1-one, C18H13BrO2, (II), are isomorphous, and their mol­ecules are linked into sheets by two independent C—H⋯π(arene) inter­actions, both involving the same aryl ring with one C—H donor approaching each face. In each of the products (RS)-3-(4-chloro­phen­yl)-5-[4-(prop-2-yn­yloxy)phen­yl]-4,5-di­hydro­pyrazole-1-carbo­thio­amide, C19H16ClN3OS, (IV), (RS)-3-(4-bromo­phen­yl)-5-[4-(prop-2-yn­yloxy)phen­yl]-4,5-di­hydro­pyrazole-1-carbo­thio­amide, C19H16BrN3OS, (V), and (RS)-3-(4-meth­oxy­phen­yl)-5-[4-(prop-2-yn­yloxy)phen­yl]-4,5-di­hydro­pyrazole-1-carbo­thio­amide, C20H19N3O2S, (VI), the reduced pyrazole ring adopts an envelope conformation with the C atom bearing the 4-prop-2-yn­yloxy)phenyl substituent, which occupies the axial site, displaced from the plane of the four ring atoms. Compounds (IV) and (V) are isomorphous and their mol­ecules are linked into chains of edge-fused rings by a combination of N—H⋯S and C—H⋯S hydrogen bonds. The mol­ecules of (VI) are linked into sheets by a combination of N—H⋯S, N—H⋯N and C—H⋯π(arene) hydrogen bonds. Comparisons are made with the structures of some related compounds.

Three huntite-type aluminoborates of stoichiometry REAl3(BO3)4 (RE = Tb, Dy and Ho), namely, terbium/dysprosium/holmium trialuminium tetrakis(borate), were synthesized by slow cooling within a K2Mo3O10 flux with spontaneous crystallization. The crystal structures were determined using single-crystal X-ray diffraction (SC-XRD) data. The synthesized borates are isostructural to the huntite [CaMg3(CO3)4] structure and crystallized within the trigonal R32 space group. The structural parameters were compared to literature data of other huntite REAl3(BO3)4 crystals within the R32 space group. All three borates fit well into the trends calculated from the literature data. The unit-cell parameters and volumes increase linearly with larger RE cations whereas the densities decrease. All of the crystals studied were refined as inversion twins.

The crystal structures of tris­[9,9-dihexyl-2-(5-meth­oxy­pyridin-2-yl-κN)-9H-fluoren-3-yl-κC3]iridium pentane monosolvate, [Ir(C31H38NO)3]·C5H12, (I), di-μ2-chlorido-bis­{bis­[2-(5-fluoro­pyridin-2-yl)-9,9-dihexyl-9H-fluoren-3-yl]iridium} pentane 0.3-solvate, [Ir2(C30H35FN)4Cl2]·0.3C5H12, (II), di-μ2-cyanato-bis­{bis­[9,9-dihexyl-2-(5-meth­oxy­pyridin-2-yl)-9H-fluoren-1-yl]iridium} pentane monosolvate, [Ir2(C31H38NO)4(NCO)2(NCO)2]·C5H12, (III), and {μ-N,N'-bis­[3,5-bis­(tri­fluoro­meth­yl)phen­yl]oxamidato}bis(bis{2-[4-(2,4,6-trimethylphenyl)pyridin-2-yl]phenyl-κ2C1,N'}iridium)–chloro­benzene–pentane (1/2.3/0.4), [Ir2(C20H19N)4(C18H6F12N2O2)]·2.3C6H5Cl·0.4C5H12, (IV), synthesized in the quest for organic light-emitting devices, were determined. The bis-μ2-chloro and bis-μ2-cyanato complexes have ΔΔ and ΛΛ configurations of the distorted octa­hedral Ir centres in racemic crystals, whereas the oxamido complex has a centrosymmetric (meso) structure with the ΔΛ configuration. The bridging oxamido moiety has a nearly planar anti geometry. All structures show substantial disorder of both host mol­ecules and solvents of crystallization.

The title pyrazine dicarboxamide ligand, N2,N3-bis­(quinolin-8-yl)pyrazine-2,3-dicarboxamide (H2L1), C24H16N6O2, has a twisted conformation with the outer quinoline groups being inclined to the central pyrazine ring by 9.00 (6) and 78.67 (5)°, and by 79.94 (4)° to each other. In the crystal, molecules are linked by C—H⋯O hydrogen bonds, forming layers parallel to the (10overline{1}) plane, which are in turn linked by offset π–π inter­actions [inter­centroid distances 3.4779 (9) and 3.6526 (8) Å], forming a supra­molecular three-dimensional structure. Reaction of the ligand H2L1 with Cu(ClO4)2 in aceto­nitrile leads to the formation of the binuclear complex, [μ-(3-{hy­droxy[(quinolin-8-yl)imino]­meth­yl}pyrazin-2-yl)[(quinolin-8-yl)imino]­methano­lato]bis­[diaceto­nitrile­copper(II)] tris­(per­chlor­ate) aceto­nitrile disolvate, [Cu2(C24H15N6O2)(CH3CN)4](ClO4)3·2CH3CN or [Cu2(HL1−)(CH3CN)4](ClO4)3·2CH3CN (I). In the cation of complex I, the ligand coordinates to the copper(II) atoms in a bis-tridentate fashion. A resonance-assisted O—H⋯O hydrogen bond is present in the ligand; the position of this H atom was located in a difference-Fourier map. Both copper(II) atoms are fivefold coordinate, being ligated by three N atoms of the ligand and by the N atoms of two aceto­nitrile mol­ecules. The first copper atom has a perfect square-pyramidal geometry while the second copper atom has a distorted shape. In the crystal, the cation and perchlorate anions are linked by a number of C—H⋯O hydrogen bonds, forming a supra­molecular three-dimensional structure.

In the title compound, [Cu(C16H8Br3N2O)2]·C2H6OS, the CuII atom is tetra­coordinated in a square-planar coordination, being surrounded by two N atoms and two O atoms from two N,O-bidentate (E)-1-[(2,4,6-tri­bromo­phen­yl)diazen­yl]naphthalen-2-olate ligands. The two N atoms and two O atoms around the metal center are trans to each other, with an O—Cu—O bond angle of 177.90 (16)° and a N—Cu—N bond angle of 177.8 (2)°. The average distances between the CuII atom and the coordinated O and N atoms are 1.892 (4) and 1.976 (4) Å, respectively. In the crystal, complexes are linked by C—H⋯O hydrogen bonds and by π–π inter­actions involving adjacent naphthalene ring systems [centroid–centroid distance = 3.679 (4) Å]. The disordered DMSO mol­ecules inter­act weakly with the complex mol­ecules, being positioned in the voids left by the packing arrangement of the square-planar complexes. The DMSO solvent mol­ecule is disordered over two positions with occupancies of 0.70 and 0.30.

A new conjugated carbazole chalcone compound, (E)-3-[4-(9,9a-di­hydro-8aH-carbazol-9-yl)phen­yl]-1-(4-nitro­phen­yl)prop-2-en-1-one (CPNC), C27H18N2O3, was synthesized using a Claisen–Schmidt condensation reaction. CPNC crystallizes in the monoclinic non-centrosymmetric space group Cc and adopts an s-cis conformation with respect to the ethyl­enic double bonds (C=O and C=C). The crystal packing features C—H⋯O and C—H⋯π inter­actions whose percentage contribution was qu­anti­fied by Hirshfeld surface analysis. Quantum chemistry calculations including geometrical optimization and mol­ecular electrostatic potential (MEP) were analysed by density functional theory (DFT) with a B3LYP/6–311 G++(d,p) basis set.

The new heterometallic complex, aqua-1κO-bis­(μ2-2-imino­methyl-6-meth­oxy­phenolato-1κ2O1,O6:2κ2O1,N)bis­(thio­cyanato-1κN)calcium(II)copper(II), [CaCu(C8H8NO2)2(NCS)2(H2O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thio­cyanate in methanol under ambient conditions. The Schiff base ligand (C8H9NO2) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH4SCN. The title compound consists of a discrete binuclear mol­ecule with a {Cu(μ-O)2Ca} core, in which the Cu⋯Ca distance is 3.4275 (6) Å. The coordination geometries of the four-coordinate copper atom in the [CuN2O2] chromophore and the seven-coordinate calcium atom in the [CaO5N2] chromophore can be described as distorted square planar and penta­gonal bipyramidal, respectively. In the crystal, O—H⋯S hydrogen bonds between the coordinating water mol­ecules and thio­cyanate groups form a supra­molecular chain with a zigzag-shaped calcium skeleton.

Two new co-crystals, tetra­iodo­ethyl­ene–phenanthridine (1/2), 0.5C2I4·C13H9N (1) and tetra­iodo­ethyl­ene–benzo[f]quinoline (1/2), 0.5C2I4·C13H9N (2), were obtained from tetra­iodo­ethyl­ene and aza­phenanthrenes, and characterized by IR and fluorescence spectroscopy, elemental analysis and X-ray crystallography. In the crystal structures, C—I⋯π and C—I⋯N halogen bonds link the independent mol­ecules into one-dimensional chains and two-dimensional networks with subloops. In addition, the planar aza­phenanthrenes lend themselves to π–π stacking and C—H⋯π inter­actions, leading to a diversity of supra­molecular three-dimensional structural motifs being formed by these inter­actions. Luminescence studies show that co-crystals 1 and 2 exhibit distinctly different luminescence properties in the solid state at room temperature.

In the crystal of the title Schiff base compound, C13H9ClN2O2, [CNBA; systematic name: (E)-N-(4-chloro­phen­yl)-1-(4-nitro­phen­yl)methanimine], the CNBA mol­ecule shows whole-mol­ecule disorder (occupancy ratio 0.65:0.35), with the disorder components related by a twofold rotation about the shorter axis of the mol­ecule. The aromatic rings are inclined to each other by 39.3 (5)° in the major component and by 35.7 (9)° in the minor component. In the crystal, C—H⋯O hydrogen bonds predominate in linking the major components, while weak C—H⋯Cl inter­actions predominate in linking the minor components. The result is the formation of corrugated layers lying parallel to the ac plane. The crystal packing was analysed using Hirshfeld surface analysis and compared with related structures.

The asymmetric units of the title compounds, namely, catena-poly[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4N1,N4,N8,N11)nickel(II)]-μ-1,3-bis­(3-carboxyl­ato­prop­yl)tetra­methyl­disiloxane-κ2O:O'], [Ni(C10H24O5Si2)(C12H24N4)]n (I), and catena-poly[[[(1,4,8,11-tetra­aza­cyclo­tetra­decane-κ4N1,N4,N8,N11)nickel(II)]-μ-4-({[(3-carb­oxy­prop­yl)di­methyl­sil­yl]­oxy}di­methyl­sil­yl)butano­ato-κ2O:O'] per­chlorate], {[Ni(C10H25O5Si2)(C12H24N4)]ClO4}n (II), consist of one (in I) or two crystallographically non-equivalent (in II) centrosymmetric macrocyclic cations and one centrosymmetric dianion (in I) or two centrosymmetric monoanions (in II). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and the mutually trans O atoms of the carboxyl­ate in a slightly tetra­gonally distorted trans-NiN4O2 octa­hedral coordination geometry. The crystals of both types of compounds are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] and [110] directions in I and II, respectively. In I, each polymeric chain is linked to four neighbouring ones by hydrogen bonding between the NH groups of the macrocycle and the carboxyl­ate O atoms, thus forming a three-dimensional supra­molecular network. In II, each polymeric chain contacts with only two neighbours, forming hydrogen bonds between the partially protonated carb­oxy­lic groups of the bridging ligand. As a result, a lamellar structure is formed with the layers oriented parallel to the (1overline{1}1) plane.

The title crystal structure is assembled from the superposition of two mol­ecular structures, (E)-1-(5-chloro­thio­phen-2-yl)-3-(3-methyl­thio­phen-2-yl)prop-2-en-1-one, C12H9ClOS2 (93%), and (Z)-1-(5-chloro­thio­phen-2-yl)-3-(3-methyl­thio­phen-2-yl)prop-1-en-1-ol, C12H11ClOS2 (7%), 0.93C12H9ClOS2·0.07C12H11ClOS2. Both were obtained from the reaction of 3-methyl­thio­phene-2-carbaldehyde and 1-(5-chloro­thio­phen-2-yl)ethanone. In the extended structure of the major chalcone component, mol­ecules are linked by a combination of C—H⋯O/S, Cl⋯Cl, Cl⋯π and π–π inter­actions, leading to a compact three-dimensional supra­molecular assembly.

In the title hydrated complex, [Co(C15H10ClN3)2]Cl2·4H2O, the complete dication is generated by overline{4} symmetry. The CoN6 moiety shows distortion from regular octa­hedral geometry with the trans bond angles of two N—Co—N units being 160.62 (9)°. In the crystal, O—H⋯Cl and C—H⋯O inter­actions link the components into (001) sheets. The title compound exhibits blue-light emission, as indicated by photoluminescence data, and a HOMO–LUMO energy separation of 2.23 eV was obtained from its diffuse reflectance spectrum.

The redetermined structure [for the previous study, see: Godfrey & Waters (1975). Cryst. Struct. Commun. 4, 5–8] of ammonium μ-oxido-μ-[1,5,6-tri­hydroxy­hexane-2,3,4-tris­(olato)]bis­[dioxidomolybdenum(V)] monohydrate, NH4[Mo2(C6H11O6)O5]·H2O, was obtained from an attempt to prepare a glutamic acid complex from the [Co2Mo10H4O38]6− anion. Subsequent study indicated the complex arose from a substantial impurity of mannitol in the glutamic acid sample used. All hydrogen atoms have been located in the present study and the packing displays N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds. A Hirshfeld surface analysis was also performed.

In the title compound, C9H10ClNOS, the amide functional group –C(=O)NH– adopts a trans conformation with the four atoms nearly coplanar. This conformation promotes the formation of a C(4) hydrogen-bonded chain propagating along the [010] direction. The central part of the mol­ecule, including the six-membered ring, the S and N atoms, is fairly planar (r.m.s. deviation of 0.014). The terminal methyl group and the C(=O)CH2 group are slightly deviating out-of-plane while the terminal Cl atom is almost in-plane. Hirshfeld surface analysis of the title compound suggests that the most significant contacts in the crystal are H⋯H, H⋯Cl/Cl⋯H, H⋯C/C⋯H, H⋯O/O⋯H and H⋯S/S⋯H. π–π inter­actions between inversion-related mol­ecules also contribute to the crystal packing. DFT calculations have been performed to optimize the structure of the title compound using the CAM-B3LYP functional and the 6–311 G(d,p) basis set. The theoretical absorption spectrum of the title compound was calculated using the TD–DFT method. The analysis of frontier orbitals revealed that the π–π* electronic transition was the major contributor to the absorption peak in the electronic spectrum.

A one-dimensional nickel(II) coordination polymer with the mixed ligands 6-fluoro­nicotinate (6-Fnic) and 4,4'-bi­pyridine (4,4'-bpy), namely, catena-poly[[di­aqua­bis­(6-fluoro­pyridine-3-carboxyl­ato-κO)nickel(II)]-μ-4,4'-bi­pyri­dine-κ2N:N'] trihydrate], {[Ni(6-Fnic)2(4,4'-bpy)(H2O)2]·3H2O}n, (1), was prepared by the reaction of nickel(II) sulfate hepta­hydrate, 6-fluoro­nicotinic acid (C6H4FNO2) and 4,4'-bi­pyridine (C10H8N2) in a mixture of water and ethanol. The nickel(II) ion in 1 is octa­hedrally coordinated by the O atoms of two water mol­ecules, two O atoms from O-monodentate 6-fluoro­nicotinate ligands and two N atoms from bridging 4,4'-bi­pyridine ligands, forming a trans isomer. The bridging 4,4'-bi­pyridine ligands connect symmetry-related nickel(II) ions into infinite one-dimensional polymeric chains running in the [1overline{1}0] direction. In the extended structure of 1, the polymeric chains and lattice water mol­ecules are connected into a three-dimensional hydrogen-bonded network via strong O—H⋯O and O—H⋯N hydrogen bonds, leading to the formation of distinct hydrogen-bond ring motifs: octa­meric R88(24) and hexa­meric R86(16) loops.

The syntheses and crystal structures of three mol­ecular salts of protonated 3,4-di­amino­benzoic acid, viz. 2-amino-5-carb­oxy­anilinium chloride, C7H9N2O2+·Cl−, (I), 2-amino-5-carb­oxy­anilinium bromide, C7H9N2O2+·Br−, (II), and 2-amino-5-carb­oxy­anilinium nitrate monohydrate, C7H9N2O2+·NO3−·H2O, (III), are described. The cation is protonated at the meta-N atom (with respect to the carb­oxy group) in each case. In the crystal of (I), carb­oxy­lic acid inversion dimers linked by pairwise O—H⋯O hydrogen bonds are seen and each N—H group forms a hydrogen bond to a chloride ion to result in (100) undulating layers of chloride ions bridged by the inversion dimers into a three-dimensional network. The extended structure of (II) features O—H⋯Br, N—H⋯Br and N—H⋯O hydrogen bonds: the last of these generates C(7) chains of cations. Overall, the packing in (II) features undulating (100) sheets of bromide ions alternating with the organic cations. Inter­molecular inter­actions in the crystal of (III) include O—H⋯O, O—H⋯(O,O), N—H⋯O, N—H⋯N and O—H⋯N links. The cations are linked into (001) sheets, and the nitrate ions and water mol­ecules form undulating chains. Taken together, alternating (001) slabs of organic cations plus anions/water mol­ecules result. Hirshfeld surfaces and fingerprint plots were generated to give further insight into the inter­molecular inter­actions in these structures. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio.

The two new pyrazine­ophanes, 5,7-di­hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b:6',7'-e]pyrazine, C12H16N2S4, L2, both crystallize with half a mol­ecule in the asymmetric unit; the whole mol­ecules are generated by inversion symmetry. The mol­ecule of L1, which is planar (r.m.s. deviation = 0.008 Å), consists of two sulfur atoms linked by a rigid tetra-2,3,5,6-methyl­ene­pyrazine unit, forming planar five-membered rings. The mol­ecule of L2 is step-shaped and consists of two S–CH2–CH2–S chains linked by the central rigid tetra-2,3,5,6-methyl­ene­pyrazine unit, forming eight-membered rings that have twist-boat-chair con­fig­urations. In the crystals of both compounds, there are no significant inter­molecular inter­actions present. The reaction of L1 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[(μ-5,7-di­hydro-1H,3H-dithieno[3,4-b;3',4'-e]pyrazine-κ2S:S')(μ-nitrato-κ2O:O')silver(I)], [Ag(NO3)(C8H8N2S2)]n, (I), with the nitrato anion bridging two equivalent silver atoms. The central pyrazine ring is situated about an inversion center and the silver atom lies on a twofold rotation axis that bis­ects the nitrato anion. The silver atom has a fourfold AgO2S2 coordination sphere with a distorted shape. The reaction of L2 with silver nitrate also leads to the formation of a two-dimensional coordination polymer, poly[[μ33,4,8,10,11,13-hexa­hydro-1H,6H-bis­([1,4]di­thio­cino)[6,7-b;6',7'-e]pyrazine-κ3S:S':S''](nitrato-κO)silver(I)], [Ag(NO3)(C12H16N2S4)]n, (II), with the nitrate anion coordinating in a monodentate manner to the silver atom. The silver atom has a fourfold AgOS3 coordination sphere with a distorted shape. In the crystals of both complexes, the networks are linked by C—H⋯O hydrogen bonds, forming supra­molecular frameworks. There are additional C—H⋯S contacts present in the supra­molecular framework of II.