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.

The structure of the title quinoline carboxamide derivative, C26H25N3O, is described. The quinoline moiety is not planar as a result of a slight puckering of the pyridine ring. The secondary amine has a slightly pyramidal geometry, certainly not planar. Both intra- and inter­molecular hydrogen bonds are present. Hirshfeld surface analysis and lattice energies were used to investigate the inter­molecular inter­actions.

The title hydrazine carbodi­thio­ate, C13H18N2OS2, is constructed about a central and almost planar C2N2S2 chromophore (r.m.s. deviation = 0.0263 Å); the terminal meth­oxy­benzene group is close to coplanar with this plane [dihedral angle = 3.92 (11)°]. The n-butyl group has an extended all-trans conformation [torsion angles S—Cm—Cm—Cm = −173.2 (3)° and Cm—Cm—Cm—Cme = 180.0 (4)°; m = methyl­ene and me = meth­yl]. The most prominent feature of the mol­ecular packing is the formation of centrosymmetric eight-membered {⋯HNCS}2 synthons, as a result of thio­amide-N—H⋯S(thio­amide) hydrogen bonds; these are linked via meth­oxy-C–H⋯π(meth­oxy­benzene) inter­actions to form a linear supra­molecular chain propagating along the a-axis direction. An analysis of the calculated Hirshfeld surfaces and two-dimensional fingerprint plots point to the significance of H⋯H (58.4%), S⋯H/H⋯S (17.1%), C⋯H/H⋯C (8.2%) and O⋯H/H⋯O (4.9%) contacts in the packing. The energies of the most significant inter­actions, i.e. the N—H⋯S and C—H⋯π inter­actions have their most significant contributions from electrostatic and dispersive components, respectively. The energies of two other identified close contacts at close to van der Waals distances, i.e. a thione–sulfur and meth­oxy­benzene–hydrogen contact (occurring within the chains along the a axis) and between methyl­ene-H atoms (occurring between chains to consolidate the three-dimensional architecture), are largely dispersive in nature.

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 unit cell of the title compound, [Zn(C17H18N3O4)2]·CH4O·C2H6O, contains two complex mol­ecules related by an inversion centre, plus one methanol and one ethanol solvent molecule per complex molecule. In each complex, two deprotonated pyridine aroylhydrazone ligands {3,4,5-trimeth­oxy-N'-[1-(pyridin-2-yl)ethyl­idene]benzohydrazide} coordinate to the ZnII ion through the N atoms of the pyridine group and the ketamine, and, additionally, through the O atom of the enolate group. In the crystal, dimers are formed by π–π inter­actions between the planar ligand moieties, which are further connected by C⋯O and C⋯C inter­actions. The inter­molecular inter­actions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing that the most important contributions for the crystal packing are from H⋯H (44.8%), H⋯C/C⋯H (22.2%), H⋯O/O⋯H (18.7%) and C⋯C (3.9%) inter­actions.

The crystal structure of the title compound, [Ni(C13H11N2O2)(H2O)4]Br3·2H2O, contains an octa­hedral NiII atom coordinated to the enol form of 1,3-di­pyridyl­propane-1,3-dione (dppo) and four water mol­ecules. Both pyridyl rings on the ligand are protonated, forming pyridinium rings and creating an overall ligand charge of +1. The protonated nitro­gen-containing rings are involved in hydrogen-bonding inter­actions with neighoring bromide anions. There are many additional hydrogen-bonding inter­actions involving coordinated water mol­ecules on the NiII atom, bromide anions and hydration water mol­ecules.

In the title compound, [Zn(C50H36N6O5)], the ZnII cation is chelated by four pyrrole N atoms of the porphyrinate anion and coordinated by a symmetry-generated keto O atom of the diazo­ester group in a distorted square-pyramidal geometry. The mean Zn—N(pyrrole) bond length is 2.058 Å and the Zn—O(diazo­ester) bond length is 2.179 (4) Å. The zinc cation is displaced by 0.2202 (13) Å from the N4C20 mean plane of the porphyrinate anion toward the O atom; the involvement of this atom leads to a [100] polymeric chain in the crystal.

The pyran­opyran amide (2S,4aR,8aR)-6-oxo-2,4a,6,8a-tetra­hydro­pyrano[3,2-b]pyran-2-carboxamide, C9H9NO4, 3, was prepared by a chemoselective hydration of the corresponding nitrile, 2, using a heterogeneous catalytic method based on copper(II) supported on mol­ecular sieves, in the presence of acetaldoxime. Compound 3 belongs to a new class of pyran­opyrans that possess anti­bacterial and phytotoxic activity. Crystallographic analysis of 3 shows a bent structure for the cis-fused bicyclic pyran­opyran, similar to nitrile 2. Evidence of an intra­molecular hydrogen bond involving the amide group and ring oxygen was not observed; however, two separate inter­molecular hydrogen-bonding inter­actions were observed between the amide hydrogen atoms and adjacent carbonyl oxygen atoms along the b- and a-axis directions. The latter inter­action may also be supported by an inter­molecular C—H⋯O hydrogen bond. The lattice is filled out by close-packed layers of this hydrogen-bonded network along the c-axis direction, related from one to the next by a 21 screw axis.

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 crystal structure of title salt, C14H36N44+·2ClO4−·2Cl−, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at all four amine N atoms. The asymmetric unit contains one half-cation (completed by crystallographic inversion symmetry), one perchlorate anion and one chloride anion. A distortion of the perchlorate anion is due to its involvement in hydrogen-bonding inter­actions with the cations. The crystal structure is consolidated by inter­molecular hydrogen bonds involving the 1,4,8,11-tetra­methyl-1,4,8,11-tetra­azonia­cyclo­tetra­decane N—H and C—H groups as donor groups, and the O atoms of the perchlorate and chloride anion as acceptor groups, giving rise to a three-dimensional network.

The crystal structures of 5-bromo-1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H29BrOSi, (I), 1,3-di-tert-butyl-2-[(tri­methyl­sil­yl)­oxy]benzene, C17H30OSi, (II), and N-(2,6-diiso­propyl­phen­yl)-1,1,1-trimethyl-N-(tri­methyl­sil­yl)silanamine, C18H35NSi2, (III), are reported. Compound (I) crystallizes in space group P21/c with Z' = 1, (II) in Pnma with Z' = 0.5 and (III) in Cmcm with Z' = 0.25. Consequently, the mol­ecules of (II) are constrained by m and those of (III) by m2m site symmetries. Despite this, both (I) and (II) are distorted towards mild boat conformations, as is typical of 2,6-di-tert-butyl-substituted phenyl compounds, reflecting the high local steric pressure of the flanking alkyl groups. Compound (III) by contrast is planar and symmetric, and this lack of distortion is compatible with the lower steric pressure of the flanking 2,6-diisopropyl substituents.

The title compound represents the thallium(I) salt of a substituted 1,2,5-oxa­diazole, [Tl(C3H3N4O3)]n, with amino- and hydroxamate groups in the 4- and 3- positions of the oxa­diazole ring, respectively. In the crystal, the deprotonated hydroxamate group represents an inter­mediate between the keto/enol tautomers and forms a five-membered chelate ring with the thallium(I) cation. The coordination sphere of the cation is augmented to a distorted disphenoid by two monodentately binding O atoms from two adjacent anions, leading to the formation of zigzag chains extending parallel to the b axis. The cohesion within the chains is supported by π–π stacking [centroid–centroid distance = 3.746 (3) Å] and inter­molecular N—H⋯N hydrogen bonds.

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.

The asymmetric unit of the title compound, C23H28O4, comprises two half-mol­ecules, with the other half of each mol­ecule being completed by the application of twofold rotation symmetry. The two completed mol­ecules both have a V-shaped appearance but differ in their conformations. In the crystal, each independent mol­ecule forms chains extending parallel to the b axis with its symmetry-related counterparts through C—H⋯π(ring) inter­actions. Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (65.4%), H⋯C/C⋯H (21.8%) and H⋯O/O⋯H (12.3%) inter­actions. Optimized structures using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structures in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the title mol­ecule, C12H13N3O2S, the benzo­thia­zine moiety is slightly non-planar, with the imidazolidine portion twisted only a few degrees out of the mean plane of the former. In the crystal, a layer structure parallel to the bc plane is formed by a combination of O—HHydethy⋯NThz hydrogen bonds and weak C—HImdz⋯OImdz and C—HBnz⋯OImdz (Hydethy = hy­droxy­ethyl, Thz = thia­zole, Imdz = imidazolidine and Bnz = benzene) inter­actions, together with C—HImdz⋯π(ring) and head-to-tail slipped π-stacking [centroid-to-centroid distances = 3.6507 (7) and 3.6866 (7) Å] inter­actions between thia­zole rings. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (47.0%), H⋯O/O⋯H (16.9%), H⋯C/C⋯H (8.0%) and H⋯S/S⋯H (7.6%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—H⋯N and C—H⋯O hydrogen-bond energies are 68.5 (for O—HHydethy⋯NThz), 60.1 (for C—HBnz⋯OImdz) and 41.8 kJ mol−1 (for C—HImdz⋯OImdz). Density functional theory (DFT) optimized structures at the B3LYP/6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state.

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.

The crystal structure of the polymeric title compound, catena-poly[[[di­aqua­lithium]-μ-γ-cyclo­dextrin(1−)-[aqua­lithium]-μ-γ-cyclo­dextrin(1−)] pentadecahydrate], {[Li2(C48H79O40)2(H2O)3]·15H2O}n, consists of deprotonated γ-cyclo­dextrin (CD) mol­ecules assembled by lithium ions into metal–organic ribbons that are cross-linked by multiple O—H⋯O hydrogen bonds into sheets extending parallel to (0overline11). Within a ribbon, one Li+ ion is coordinated by one deprotonated hydroxyl group of the first γ-CD torus and by one hydroxyl group of the second γ-CD torus as well as by two water mol­ecules. The other Li+ ion is coordinated by one deprotonated hydroxyl and by one hydroxyl group of the second γ-CD torus, by one hydroxyl group of the first γ-CD torus as well as by one water mol­ecule. The coordination spheres of both Li+ cations are distorted tetra­hedral. The packing of the structure constitute channels along the a axis. Parts of the hy­droxy­methyl groups in cyclo­dextrin molecules as well as water mol­ecules show two-component disorder. Electron density associated with additional disordered solvent mol­ecules inside the cavities was removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] routine in PLATON. These solvent mol­ecules are not considered in the given chemical formula and other crystal data. Five out of the sixteen hy­droxy­methyl groups and one water mol­ecule are disordered over two sets of sites.

A coordination polymer formulated as [Sr(H2BTEC)(H2O)]n (H4BTEC = benzene-1,2,4,5-tetra­carb­oxy­lic acid, C10H6O8), was synthesized hydro­thermally and characterized by single-crystal and powder X-ray diffraction, scanning electron microscopy and thermal analysis. Its crystal structure is made up of a zigzag inorganic chain formed by edge-sharing of [SrO8] polyhedra running along [001]. Adjacent chains are connected to each other via the carboxyl­ate groups of the ligand, resulting in a double-layered network extending parallel to (100). O—H⋯O hydrogen bonds of medium-to-weak strength between the layers consolidate the three-dimensional structure. One of the carb­oxy­lic OH functions was found to be disordered over two sets of sites with half-occupancy.

The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered di­hydro­isoxazole ring to which a p-chloro­phenyl group and a cyclo­hex-2-enone ring are attached in the 3 and 5 positions. The cyclo­hex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C—H⋯O, C—H⋯N and C—H⋯π inter­actions, which generate a three-dimensional network.

The title compound, C22H22O2S2, 1, represents an example of an ortho-vanillin-based functionalized di­thio­ether, which could be useful as a potential chelating ligand or bridging ligand for coordination chemistry. This di­thio­acetal 1 crystallizes in the ortho­rhom­bic space group Pbca. The phenyl rings of the benzyl groups and that of the vanillin unit form dihedral angles of 35.38 (6) and 79.77 (6)°, respectively. The crystal structure, recorded at 100 K, displays both weak intra­molecular O—H⋯O and inter­molecular O—H⋯S hydrogen bonding.

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 polymorphs of the title compound, C19H16N2O3, were obtained from ethano­lic (polymorph I) and methano­lic solutions (polymorph II), respectively. Both polymorphs crystallize in the monoclinic system with four formula units per cell and a complete mol­ecule in the asymmetric unit. The main difference between the mol­ecules of (I) and (II) is the reversed position of the hy­droxy group of the carb­oxy­lic function. All other conformational features are found to be similar in the two mol­ecules. The different orientation of the OH group results in different hydrogen-bonding schemes in the crystal structures of (I) and (II). Whereas in (I) inter­molecular O—H⋯O hydrogen bonds with the pyridazinone carbonyl O atom as acceptor generate chains with a C(7) motif extending parallel to the b-axis direction, in the crystal of (II) pairs of inversion-related O—H⋯O hydrogen bonds with an R22(8) ring motif between two carb­oxy­lic functions are found. The inter­molecular inter­actions in both crystal structures were analysed using Hirshfeld surface analysis and two-dimensional fingerprint plots.

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.

In the title compound, C18H18ClN3O2S, the dihedral angle between the fused pyrazole and pyridine rings is 3.81 (9)°. The benzene ring forms dihedral angles of 35.08 (10) and 36.26 (9)° with the pyrazole and pyridine rings, respectively. In the crystal, weak C—H⋯O hydrogen bonds connect mol­ecules along [100].

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.

The asymmetric unit of the title compound, C10H11NO4, which was synthesized via nitration reaction of eugenol (4-allyl-2-meth­oxy­phenol) with a mixture of nitric acid and sulfuric acid, consists of three independent mol­ecules of similar geometry. Each mol­ecule displays an intra­molecular hydrogen bond involving the hydroxide and the nitro group forming an S(6) motif. The crystal cohesion is ensured by inter­molecular C—H⋯O hydrogen bonds in addition to π–π stacking inter­actions between the aromatic rings [centroid–centroid distances = 3.6583 (17)–4.0624 (16) Å]. The Hirshfeld surface analysis and the two-dimensional fingerprint plots show that H⋯H (39.6%), O⋯H/H⋯O (37.7%), C⋯H/H⋯C (12.5%) and C⋯C (4%) are the most important contributors towards the crystal packing.

In the title compound, C13H15N3O5S, the two rings face each other in a `V' form at the S atom, with one N—H⋯O=S and one C—H⋯O=S contact from the pyrazolyl substituents to the sulfonyl group. Two classical hydrogen bonds from the amine group, one of the form N—H⋯O=S and one N—H⋯O=Coxo, link the mol­ecules to form layers parallel to the bc plane.

Crystal structures are reported for N-(4-meth­oxy­phen­yl)piperazine (MeOPP), (I), and for its 3,5-di­nitro­benzoate, 2,4,6-tri­nitro­phenolate (picrate) and 4-amino­benzoate salts, (II)–(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-meth­oxy­phenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the mol­ecules are linked into simple C(10) chains by N—H⋯O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6−, (II), C11H17N2O+·C6H2N3O7−, (III), and C11H17N2O+·C7H6NO2−·H2O, (IV), the effectively planar 4-meth­oxy­phenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N—H⋯O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N—H⋯O and C—H⋯π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N—H⋯O, O—H⋯O and C—H⋯π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

The crystal structures of praseodymium silicide (5/4), Pr5Si4, and neodymium silicide (5/4), Nd5Si4, were redetermined using high-quality single-crystal X-ray diffraction data. The previous structure reports of Pr5Si4 were only based on powder X-ray diffraction data [Smith et al. (1967). Acta Cryst. 22 940–943; Yang et al. (2002b). J. Alloys Compd. 339, 189–194; Yang et al., (2003). J. Alloys Compd. 263, 146–153]. On the other hand, the structure of Nd5Si4 has been determined from powder data [neutron; Cadogan et al., (2002). J. Phys. Condens. Matter, 14, 7191–7200] and X-ray [Smith et al. (1967). Acta Cryst. 22 940–943; Yang et al. (2002b). J. Alloys Compd. 339, 189–194; Yang et al., (2003). J. Alloys Compd. 263, 146–153] and single-crystal data with isotropic atomic displacement parameters [Roger et al., (2006). J. Alloys Compd. 415, 73–84]. In addition, the anisotropic atomic displacement parameters for all atomic sites have been determined for the first time. These compounds are confirmed to have the tetra­gonal Zr5Si4-type structure (space group: P41212), as reported previously (Smith et al., 1967). The structure is built up by distorted body-centered cubes consisting of Pr(Nd) atoms, which are linked to each other by edge-sharing to form a three-dimensional framework. This framework delimits zigzag channels in which the silicon dimers are situated.

The title compound, bis­(4-hy­droxy-N-isopropyl-N-methyl­tryptammonium) (4-HO-MiPT) fumarate (systematic name: bis­{[2-(4-hy­droxy-1H-indol-3-yl)eth­yl](meth­yl)propan-2-yl­aza­nium} but-2-enedioate), 2C14H21N2O+·C4H2O42−, has a singly protonated tryptammonium cation and one half of a fumarate dianion in the asymmetric unit. The tryptammonium and fumarate ions are held together in one-dimensional chains by N—H⋯O and O—H⋯O hydrogen bonds. These chains are a combination of R42(20) rings, and C22(15) and C44(30) parallel chains along (110). They are further consolidated by N—H⋯π inter­actions. There are two two-component types of disorder impacting the tryptammonium fragment with a 0.753 (7):0.247 (7) occupancy ratio and one of the fumarate oxygen atoms with a 0.73 (8):0.27 (8) ratio.

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.

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 crystal structure of title compound, (C14H36N4)[CrO3Cl]2Cl2, has been determined by synchrotron radiation X-ray crystallography at 220 K. The macrocyclic cation lies across a crystallographic inversion center and hence the asymmetric unit contains one half of the organic cation, one chloro­chromate anion and one chloride anion. Both the Cl− anion and chloro­chromate Cl atom are involved in hydrogen bonding. In the crystal, hydrogen bonds involving the 1,4,8,11-tetra­methyl-1,4,8,11-tetra­azonia­cyclo­tetra­decane (TMC) N—H groups and C—H groups as donor groups and three O atoms of the chloro­chromate and the chloride anion as acceptor groups link the components, giving rise to a three-dimensional network.

The title compound, a major animal feed supplement, abbreviated as HMTBA and alternatively called dl-me­thio­nine hy­droxy analogue, C5H10O3S, (I), was isolated in pure anhydrous monomeric form. The melting point is 302.5 K and the compound crystallizes in the monoclinic space group P21/c, with two conformationally non-equivalent mol­ecules [(IA) and (IB)] in the asymmetric unit. The crystal structure is formed by alternating polar and non-polar layers running along the bc plane and features an extensive hydrogen-bonding network within the polar layers. The Hirshfeld surface analysis revealed a significant contribution of non-polar H⋯H and H⋯S inter­actions to the packing forces for both mol­ecules.

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.

Two salts were prepared by methyl­ation of the respective imidazoline-2-thione at the sulfur atom, using Meerwein's salt (tri­methyl­oxonium tetra­fluorido­borate) in CH2Cl2. 1,3-Dimeth­oxy-2-(methyl­sulfan­yl)imidazolium tetra­fluorido­borate (1), C6H11N2O2S+·BF4−, displays a syn conformation of its two meth­oxy groups relative to each other whereas the two benz­yloxy groups present in 1,3-dibenz­yloxy-2-(methyl­sulfan­yl)imidazolium tetra­fluorido­borate (2), C18H19N2O2S+·BF4−, adopt an anti conformation. In the mol­ecules of 1 and 2, the methyl­sulfanyl group is rotated out of the plane of the respective heterocyclic ring. In both crystal structures, inter­molecular inter­actions are dominated by C—H⋯F—B contacts, leading to three-dimensional networks. The tetra­fluorido­borate counter-ion of 2 is disordered over three orientations (occupancy ratio 0.42:0.34:0.24), which are related by rotation about one of the B—F bonds.

The asymmetric unit of the title compound, C5H7N2O+·C4H4NO4S−, contains one cation and one anion. The 6-methyl-2,2,4-trioxo-2H,4H-1,2,3-oxa­thia­zin-3-ide anion adopts an envelope conformation with the S atom as the flap. In the crystal, the anions and cations are held together by N—H⋯O, N—H⋯N, O—H⋯O and C—H⋯O hydrogen bonds, thus forming a three-dimensional structure. The Hirshfeld surface analysis and fingerprint plots reveal that the crystal packing is dominated by O⋯H/H⋯O (43.1%) and H⋯H (24.2%) contacts.

The title compound, C24H18FNO3, crystallizes in the monoclinic centrosymmetric space group P21/n and its mol­ecular conformation is stabilized via C—H⋯O intra­molecular inter­actions. The supra­molecular network mainly comprises C—H⋯O, C—H⋯F and C—H⋯π inter­actions, which contribute towards the formation of the crystal structure. The different inter­molecular inter­actions have been further analysed via Hirshfeld surface analysis and fingerprint plots.

The title compound, C17H12O4, was synthesized from the dye alizarin. The dihedral angle between the mean plane of the anthra­quinone ring system (r.m.s. deviation = 0.039 Å) and the dioxepine ring is 16.29 (8)°. In the crystal, the mol­ecules are linked by C—H⋯O hydrogen bonds, forming sheets lying parallel to the ab plane. The sheets are connected through π–π and C=O⋯π inter­actions to generate a three-dimensional supra­molecular network. Hirshfeld surface analysis was used to investigate inter­molecular inter­actions in the solid-state: the most important contributions are from H⋯H (43.0%), H⋯O/O⋯H (27%), H⋯C/C⋯H (13.8%) and C⋯C (12.4%) contacts.

In the fused ring system of the title compound, C32H37NO4, the central di­hydro­pyridine ring adopts a flattened boat conformation, the mean and maximum deviations of the di­hydro­pyridine ring being 0.1429 (2) and 0.2621 (2) Å, respectively. The two cyclo­hexenone rings adopt envelope conformations with the tetra­substituted C atoms as flap atoms. The benzene and phenyl rings form dihedral angles of 85.81 (2) and 88.90 (2)°, respectively, with the mean plane of the di­hydro­pyridine ring. In the crystal, mol­ecules are linked via an O—H⋯O hydrogen bond, forming a helical chain along the b-axis direction. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (65.2%), O⋯H/H⋯O (18.8%) and C⋯H/H⋯C (13.9%) contacts. Quantum chemical calculations for the frontier mol­ecular orbitals were undertake to determine the chemical reactivity of the title compound.

The title compound, C19H16ClNO3S, consists of chloro­phenyl methyl­idene and di­hydro­benzo­thia­zine units linked to an acetate moiety, where the thia­zine ring adopts a screw-boat conformation. In the crystal, two sets of weak C—HPh⋯ODbt (Ph = phenyl and Dbt = di­hydro­benzo­thia­zine) hydrogen bonds form layers of mol­ecules parallel to the bc plane. The layers stack along the a-axis direction with inter­calation of the ester chains. The crystal studied was a two component twin with a refined BASF of 0.34961 (5). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (37.5%), H⋯C/C⋯H (24.6%) and H⋯O/O⋯H (16.7%) inter­actions. Hydrogen-bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, C—HPh⋯ODbt hydrogen bond energies are 38.3 and 30.3 kJ mol−1. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap. Moreover, the anti­bacterial activity of the title compound has been evaluated against gram-positive and gram-negative bacteria.

The title centrosymmetric NiII complex, [Ni(NCS)2(C15H22N2O2)2], crystallizes with one half mol­ecule in the asymmetric unit of the monoclinic unit cell. The complex adopts an octa­hedral coordination geometry with two mutually trans benzyl-2-(heptan-4-yl­idene)hydrazine-1-carboxyl­ate ligands in the equatorial plane with the axial positions occupied by N-bound thio­cyanato ligands. The overall conformation of the mol­ecule is also affected by two, inversion-related, intra­molecular C—H⋯O hydrogen bonds. The crystal structure features N—H⋯S, C—H⋯S and C—H⋯N hydrogen bonds together with C—H⋯π contacts that stack the complexes along the b-axis direction. The packing was further explored by Hirshfeld surface analysis. The thermal properties of the complex were also investigated by simultaneous TGA–DTA analyses.

The title compound, C18H16N2O2, consists of perimidine and meth­oxy­phenol units, where the tricyclic perimidine unit contains a naphthalene ring system and a non-planar C4N2 ring adopting an envelope conformation with the NCN group hinged by 47.44 (7)° with respect to the best plane of the other five atoms. In the crystal, O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl (Phnl = phenol and Prmdn = perimidine) hydrogen bonds link the mol­ecules into infinite chains along the b-axis direction. Weak C—H⋯π inter­actions may further stabilize the crystal structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.0%), H⋯C/C⋯H (35.8%) and H⋯O/O⋯H (12.0%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the O—HPhnl⋯NPrmdn and N—HPrmdn⋯OPhnl hydrogen-bond energies are 58.4 and 38.0 kJ mol−1, respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined mol­ecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

Terbium oxychloride, TbOCl, was synthesized via the simple heat-treatment of TbCl3·6H2O and its structure was determined by refinement against X-ray powder diffraction data. TbOCl crystallizes with the matlockite (PbFCl) structure in the tetra­gonal space group P4/nmm and is composed of alternating (001) layers of (TbO)n and n Cl−. The unit-cell parameters, unit-cell volume, and density were compared to the literature data of other isostructural rare-earth oxychlorides in the same space group and showed good agreement when compared to the calculated trendlines.

The asymmetric unit of the title compound, C22H31NO3, comprises of one mol­ecule. The mol­ecule is not planar, with the carboxyl­ate ester group inclined by 33.47 (4)° to the heterocyclic ring. Individual mol­ecules are linked by aromaticC—H⋯Ocarbon­yl hydrogen bonds into chains running parallel to [001]. Slipped π–π stacking inter­actions between quinoline moieties link these chains into layers extending parallel to (100). Hirshfeld surface analysis, two-dimensional fingerprint plots and mol­ecular electrostatic potential surfaces were used to qu­antify the inter­molecular inter­actions present in the crystal, indicating that the most important contributions for the crystal packing are from H⋯H (72%), O⋯H/H⋯O (14.5%) and C⋯H/H⋯C (5.6%) inter­actions.

Reaction of 2-(4,4-dimethyl-2-oxazolin-2-yl)aniline (H2-L1) with one equivalent of Na[N(SiMe3)2] in toluene afforded pale-yellow crystals of tetra­meric poly[bis­[μ3-2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido][μ2-2-(4,4-dimethyl-2-oxa­zolin-2-yl)aniline]tetra­sodium(I)], [Na4(C11H13N2O)4]n or [Na4(H-L1)4]n (2), in excellent yield. Subsequent reaction of [Na4(H-L1)4]n (2) with 1.33 equivalents of anhydrous YbCl3 in a 50:50 mixture of toluene–THF afforded yellow crystals of tris­[2-(4,4-dimethyl-2-oxazolin-2-yl)anilinido]ytterbium(III), [Yb(C11H13N2O)3] or Yb(H-L1)3 (3) in moderate yield. Direct reaction of three equivalents of 2-(4',4'-dimethyl-2'-oxazolin­yl)aniline (H2-L1) with Yb[N(SiMe3)2]3 in toluene resulted in elimination of hexa­methyl­disilazane, HN(SiMe3)2, and produced Yb(H-L1)3 (3) in excellent yield. The structure of 2 consists of tetra­meric Na4(H-L1)4 subunits in which each Na+ cation is bound to two H-L1 bridging bidentate ligands and these subunits are connected into a polymeric chain by two of the four oxazoline O atoms bridging to Na+ cations in the adjacent tetra­mer. This results in two 4-coordinate and two 5-coordinate Na+ cations within each tetra­meric unit. The structure of 3 consists of a distorted octa­hedron where the bite angle of ligand L1 ranges between 74.72 (11) and 77.79 (11) degrees. The oxazoline (and anilide) N atoms occupy meridional sites such that for one ligand an anilide nitro­gen is trans to an oxazoline nitro­gen while for the other two oxazoline N atoms are trans to each other. This results in a significantly longer Yb—N(oxazoline) distance [2.468 (3) Å] for the bond trans to the anilide compared to those for the oxazoline N atoms trans to one another [2.376 (3), 2.390 (3) Å].

The structures are described of two bis-chelated metal complexes of nickel(II) and copper(II) with S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazate Schiff bases in a cis configuration, namely, bis­[S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazato-κ2N3,S]nickel(II), [Ni(C15H21N2S2)2], and bis­[S-n-hexyl 3-(1-phenyl­ethyl­idene)di­thio­carbazato-κ2N3,S]copper(II), [Cu(C15H21N2S2)2]. In both complexes, the metals have distorted square-planar geometries. A search in the Cambridge Structural Database [Groom et al. (2016). Acta Cryst. B72, 171–179] for bis-chelated nickel(II) and copper(II) complexes with similar Schiff bases retrieved 55 and 36 hits for the two metals, respectively. An analysis of the geometrical parameters of complexes showing cis and trans configurations is reported and the values compared with those for the complexes described in this work.