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Water loss from the gypsum crystal surfaces is a primary degradation pathway

Water loss from the gypsum crystal surfaces is a primary degradation pathway

Company: P & I Management Consultants
Experience: 0 to 50
location: India
Ref: 24341069
Summary: Job Description: 1. Planning of all maintenance of the factory and delegating work to his team to get the activities done on time. 2. Analysing all breakdowns, finding root cause, take corrective and preventive actions and....

The asymmetric unit of the title MOF, [Zn5(C14H5NO10S2)2(OH)2(H2O)10]n comprises three ZnII atoms, one of which is located on a centre of inversion, a tetra-negative carboxyl­ate ligand, one μ3-hydroxide and five water mol­ecules, each of which is coordinated. The ZnII atom, lying on a centre of inversion, is coordinated by trans sulfoxide-O atoms and four water mol­ecules in an octa­hedral geometry. Another ZnII atom is coordinated by two carboxyl­ate-O atoms, one hy­droxy-O, one sulfoxide-O and a water-O atom to define a distorted trigonal–bipyramidal geometry; a close Zn⋯O(carboxyl­ate) inter­action derived from an asymmetrically coordinating ligand (Zn—O = 1.95 and 3.07 Å) suggests a 5 + 1 coordination geometry. The third ZnII atom is coordinated in an octa­hedral fashion by two hy­droxy-O atoms, one carboxyl­ate-O, one sulfoxide-O and two water-O atoms, the latter being mutually cis. In all, the carboxyl­ate ligand binds six ZnII ions leading to a three-dimensional architecture. In the crystal, all acidic donors form hydrogen bonds to oxygen acceptors to contribute to the stability of the three-dimensional architecture.

The title compound, C4H9N5O2+·SO42−·H2O, is the monohydrate of the commercially available compound `C4H7N5O·H2SO4·xH2O'. It is obtained by reprecipitation of C4H7N5O·H2SO4·xH2O from dilute sodium hydroxide solution with dilute sulfuric acid. The crystal structure of anhydrous 2,4,5-tri­amino-1,6-di­hydro­pyrimidin-6-one sulfate is known, although called by the authors 5-amminium-6-amino-isocytosinium sulfate [Bieri et al. (1993). Private communication (refcode HACDEU). CCDC, Cambridge, England]. In the structure, the sulfate group is deprotonated, whereas one of the amino groups is protonated (R2C—NH3+) and one is rearranged to a protonated imine group (R2C=NH2+). This arrangement is very similar to the known crystal structure of the anhydrate. Several tautomeric forms of the investigated mol­ecule are possible, which leads to questionable proton attributions. The measured data allowed the location of all hydrogen atoms from the residual electron density. In the crystal, ions and water mol­ecules are linked into a three-dimensional network by N—H⋯O and O—H⋯O hydrogen bonds.

The asymmetric unit of the title salt, 2C12H28N+·SO42−·3H2O, contains two n-do­decyl­ammonium cations, one sulfate anion and three water mol­ecules. In the crystal, N—H⋯O hydrogen bonds link the cations and anions into layers parallel to (100). These layers are further connected through O—H⋯O hydrogen-bonding inter­actions involving the sulfate ions and the isolated water mol­ecules. The three-dimensional structure can also be considered as the superposition of thin inorganic layers of SO42− anions and thick layers of alkyl­ammonium cations perpendicular to the c axis.

The title compound, [Co(NCS)2(C15H22N2O2)2] or C32H44CoN6O4S2, was prepared from cobalt(II) nitrate, benzyl carbazate and ammonium thio­cyanate in the presence of 4-hepta­none. The compound crystallizes with two centrosymmetric complexes in which the cobalt(II) atoms have a trans-CoO2N4 octa­hedral coordination geometry. In the crystal, N—H⋯S, C—H⋯S and C—H⋯.π contacts stack the complex mol­ecules along the b-axis direction.

The asymmetric unit of the title compound (systematic name: 3,3,8,8-tetra­methyl-1,4,6,9-tetra­oxa-λ4-bora­spiro­[4.4]nonane-2,7-dione tetra­hydrate), C8H12BO6·4H2O, consists of half a bis­(2-methyl­lactato)borate mol­ecule and two water mol­ecules of solvation. In the crystal, O—H⋯O hydrogen bonds link the components into a three-dimensional network.

The complete mol­ecule of the title compound, C32H22F12N4O2, is generated by a crystallographic twofold axis aligned parallel to [010]. The F atoms of one of the CF3 groups are disordered over three orientations in a 0.6: 0.2: 0.2 ratio. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, forming zigzag chains propagating along the a-axis direction. In addition, weak C—H⋯O and C—H⋯F bonds are observed. The contribution of the disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] of PLATON. The solvent contribution is not included in the reported mol­ecular weight and density.

In the title compound, [Pd(C10H24N4)]I2·H2O, the PdII ion is four-coordinated in a slightly distorted square-planar coordination environment defined by four N atoms from a 1,4,8,11-tetra­aza­cyclo­tetra­decane ligand. The cationic complex, two I− anions and the solvent water mol­ecule are linked through inter­molecular hydrogen bonds into a three-dimensional network structure.

In the title complex, [Ni(C7H3NO4)(C15H11N3)]·C3H7NO·H2O, the NiII ion is six-coordinated within an octa­hedral geometry defined by three N atoms of the 2,2':6',2''-terpyridine ligand, and two O atoms and the N atom of the pyridine-2,6-di­carboxyl­ate di-anion. In the crystal, the complex mol­ecules are stacked in columns parallel to the a axis being connected by π–π stacking [closest inter-centroid separation between pyridyl rings = 3.669 (3) Å]. The connections between columns and solvent mol­ecules to sustain a three-dimensional architecture are of the type water-O—H⋯O(carbon­yl) and pyridyl-, methyl-C—H⋯O(carbon­yl).

The title compound, C16H16N2O6, lies about an inversion centre at the mid-point of the N—N bond. The mol­ecule features two intra­molecular O—H⋯N and two C—H⋯O hydrogen bonds, each of which forms an S(6) ring motif. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds into infinite zigzag chains propagating along the c-axis direction. π–π stacking inter­actions between the pyrone rings [centroid–centroid distances = 3.975 (2) Å] stack the mol­ecules along b.

In the title compound, C22H25NO5·H2O, the ten-membered ring displays an approximate chair–chair conformation, whereas the five-membered furan ring has an envelope conformation, with the C atom of the methine group adjacent to the spiro C atom as the flap. The isoxazole ring is almost planar and its plane is slightly inclined to the plane of the attached phenyl ring. The mean plane of the furan ring is nearly perpendicular to that of the isoxazole ring, as indicated by the dihedral angle between them of 89.39 (12)°. In the crystal, the organic mol­ecules are linked into [010] chains by O—H⋯O hydrogen bonds. The water mol­ecule forms O—H⋯O and O—H⋯N hydrogen bonds and a weak C—H⋯O inter­action is also observed. Together, these lead to a three-dimensional network.

The title compound (systematic name: bis­{[2-(4-hy­droxy-1H-indol-3-yl)eth­yl]bis­(propan-2-yl)aza­nium} but-2-enedioate tetra­hydrate), 2C16H25N2O+·C4H2O42−·4H2O, has a singly protonated DPT cation, one half of a fumarate dianion (completed by a crystallographic centre of symmetry) and two water mol­ecules of crystallization in the asymmetric unit. A series of N—H⋯O and O—H⋯O hydrogen bonds form a three-dimensional network in the solid state.

The title compound, C12H11N3O2S, was synthesized by a condensation reaction of 2-acetyl­indan-1,3-dione and thio­semicarbazide in ethanol in the presence of glacial acetic acid. The mol­ecule adopts a thio­ketone form. The dihedral angle between the mean planes of 1H-inden-1,3(2H)-dione and hydrazinecarbo­thio­amide units is 86.32 (7)°. Weak intra­molecular N—H⋯O and C—H⋯O hydrogen bonds are observed. In the crystal, mol­ecules are linked via pairs of weak inter­molecular N—H⋯O hydrogen bonds, forming inversion dimers. The dimers are further linked into a three-dimensional network through N—H⋯S and N—H⋯O hydrogen bonds, and π–π inter­actions [centroid–centroid distances = 3.5619 (10)–3.9712 (9) Å].

The title 1,3,4-oxa­diazole derivative crystallizes as a hemihydrate, C8H6N2O2S·0.5H2O, with the water mol­ecule located on a twofold rotation axis. The 1,3,4-oxa­diazole mol­ecule is essentially planar, the r.m.s. deviation of the non-H atoms being 0.0443 Å. The dihedral angle between the mean planes of the phenyl and oxa­diazole rings is 6.101 (17)°. In the crystal, mol­ecules are linked via O—H⋯S and N—H⋯O hydrogen bonds involving the water mol­ecule, the N—H group and the thione S atom into undulating ribbons. Additional π–π inter­actions generate a two-dimensional supra­molecular framework extending parallel to (001).

The asymmetric unit of the title compound {systematic name: sodium [2-({2-[(1-carboxyl­ato-2-methyl-2-sulfanidylprop­yl)amino]­eth­yl}amino)-3-methyl-3-sulf­an­idyl­butano­ato-κ4S,N,N',S']indate(III) tetra­hydrate}, Na[In(C12H20N2O4S2)]·4H2O, contains four indate(III) complex anions {[In(d-ebp)]−; d-H4ebp = N,N'-ethyelenebis(d-penicillamine)], four sodium(I) cations and sixteen water mol­ecules. The indate(III) anions and sodium cations are alternately connected through coordination bonds between Na+ ions and the carboxyl­ate groups of the complex anions, forming an infinite sixfold right-handed helix along the c-axis direction. In the crystal, the helices are linked by O—H⋯O hydrogen bonds between water mol­ecules bound to Na+ ions and carboxyl­ate groups. The crystal studied was twinned via a twofold axis about [001].

The title compound, (C8H22N2O)2[Mo8O26]·H2O, (cis-H2L)2[β-Mo8O26]·H2O, where L = (bis­[2-N,N-di­methyl­amino)­eth­yl] ether), was synthesized from bis­[2-(di­methyl­amino)­eth­yl] ether and MoO3 under solvothermal conditions and characterized by multinuclear NMR and single-crystal X-ray diffraction techniques. The structure displays two [oxybis(ethane-1,2-di­yl)]bis­(di­methyl­ammonium), or [cis-H2L]2+, cations, a central [β-Mo8O26]4− anionic cluster consisting of eight distorted MoO6 octa­hedra, and two water mol­ecules in their deuterated form. The central anion lies across an inversion center. The [cis-H2L]2+ cations are hydrogen bonded to the central [β-Mo8O26]4− cluster via bridging water mol­ecules. In the crystal, O—H⋯O hydrogen bonds link the components into chains along [010]. Weak C—H⋯O hydrogen bonds link these chains into a three-dimensional network.

In the title compound, [Pd(C7H3NO4)(C10H8N2)]·H2O, the PdII cation is four-coordinated in a distorted square-planar coordination geometry defined by the two N atoms of the 2,2'-bi­pyridine ligand, one O atom and one N atom from the pyridine-2,6-di­carboxyl­ate anion. The complex and solvent water mol­ecule are linked by inter­molecular hydrogen bonds. In the crystal, the complex mol­ecules are stacked in columns along the a axis.

In the title hydrated salt, [Ni(C21H17F2N3)2](NO3)2·2H2O, the central NiII ion is coordinated by six N atoms from two tridentate chelating 2,6-bis­[(E)-(4-fluoro­benzyl­imino)­meth­yl]pyridine ligands. While the central NiII ion is six-coordinate, its environment is distorted from an octa­hedral structure because of the unequal Ni—N distances. The Ni—N bond lengths vary from 1.8642 (14) to 2.2131 (15) Å, while the N—Ni—N angles range from 79.98 (6) to 104.44 (6)°. Three coordinating sites of each chelating agent are almost coplanar with respect to the pyridine ring, and two pyridine moieties are perpendicular to each other. Two non-coordinating nitrate anions within the asymmetric unit balance the charges of the central metal ion, and are linked with two crystal water mol­ecules, forming a water–nitrate cyclic tetra­meric unit [O⋯O = 2.813 (2) to 3.062 (2) Å]. In an isolated mol­ecule, the fluoro­phenyl rings of one ligand are stacked with the central ring of the other ligand via π–π inter­actions, with the closest centroid-to-plane distances being 3.359 (6), 3.408 (5), 3.757 (6) and 3.659 (5) Å.

In the title hydrated Schiff base, C13H12N4O3·H2O, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra­molecular O—H⋯N hydrogen bond closes an S(6) ring. In the crystal, Ow—H⋯O and Ow—H⋯N (w = water) hydrogen bonds link the components into centrosymmetric tetra­mers (two Schiff bases and two water mol­ecules). Longer N—H⋯O hydrogen bonds link the tetra­mers into [010] chains. A weak C—H⋯O hydrogen bond and aromatic π–π stacking between the pyrazine and phenyl rings [centroid–centroid separations = 3.604 (2) and 3.715 (2) Å] are also observed.

In the title complex, [NiCl2(C12H9N3)2]·H2O, a divalent nickel atom is coordinated by two 2-(pyridin-2-yl)-1H-benzimidazole ligands in a slightly distorted octa­hedral environment defined by four N donors of two N,N'-chelating ligands, along with two cis-oriented anionic chloride donors. The title complex crystallized with a water mol­ecule disordered over two positions. In the crystal, a combination of O—H⋯Cl, O—H.·O and N—H⋯Cl hydrogen bonds, together with C—H⋯O, C—H⋯Cl and C—H⋯π inter­actions, links the complex mol­ecules and the water mol­ecules to form a supra­molecular three-dimensional framework. The title complex is isostructural with the cobalt(II) dichloride complex reported previously [Das et al. (2011). Org. Biomol. Chem. 9, 7097–7107].

The title hemihydrate, C12H9N5·0.5H2O, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4H-1,2,4-triazole. The Schiff base mol­ecule adopts an E configuration about the C=N bond and is approximately planar, with a dihedral angle between the quinoline ring system and the 1,2,4-triazole ring of 12.2 (1)°. In the crystal, one water mol­ecule bridges two Schiff base mol­ecules via O—H⋯N hydrogen bonds. The Schiff base mol­ecules are inter­connected by π–π stacking inter­actions [centroid-centroid distances of 3.7486 (7) and 3.9003 (7) Å] into columns along [1overline{1}0].

The title carbonate hydrate, Cs2Mg4(CO3)5·10H2O, was crystallized at room temperature out of aqueous solutions containing caesium bicarbonate and magnesium nitrate. Its monoclinic crystal structure (P21/n) consists of double chains of composition 1∞[Mg(H2O)2/1(CO3)3/3], isolated [Mg(H2O)(CO3)2]2– units, two crystallographically distinct Cs+ ions and a free water mol­ecule. The crystal under investigation was twinned by reticular pseudomerohedry.

The title Schiff base compound, C13H9ClN4O5·0.5CH3CN, crystallizes as an aceto­nitrile hemisolvate; the solvent mol­ecule being located on a twofold rotation axis. The mol­ecule is nearly planar, with a dihedral angle between the two benzene rings of 3.7 (2)°. The configuration about the C=N bond is E, and there is an intra­molecular N—H⋯Onitro hydrogen bond present forming an S(6) ring motif. In the crystal, mol­ecules are linked by O—H⋯O and N—H⋯O hydrogen bonds, forming layers lying parallel to (10overline{1}). The layers are linked by C—H⋯Cl hydrogen bonds, forming a supra­molecular framework. Within the framework there are offset π–π stacking inter­actions [inter­centroid distance = 3.833 (2) Å] present involving inversion-related mol­ecules. The DFT study shows that the HOMO and LUMO are localized in the plane extending from the phenol ring to the 2,4-di­nitro­benzene ring, and the HOMO–LUMO gap is found to be 0.13061 a.u.

The mol­ecule of the title Schiff base compound, C14H13N3O3·H2O, displays a trans configuration with respect to the C=N bond. The dihedral angle between the benzene and pyridine rings is 29.63 (7)°. The crystal structure features inter­molecular N—H⋯O, C—H⋯O, O—H⋯O and O—H⋯N hydrogen-bonding inter­actions, leading to the formation of a supramolecular framework. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (37.0%), O⋯H/H⋯O (23.7%)), C⋯H/H⋯C (17.6%) and N⋯H/H⋯N (11.9%) inter­actions. The title compound has also been characterized by frontier mol­ecular orbital analysis.

The crystal structure of the title mol­ecular complex, [Ag2{VO2F2}2(C13H17N3O2)4]·4H2O, supported by the heterofunctional ligand tr-ad-COOH [1-(1,2,4-triazol-4-yl)-3-carb­oxy­adamantane] is reported. Four 1,2,4-triazole groups of the ligand link two AgI atoms, as well as AgI and VV centres, forming the heterobimetallic coordination cluster {AgI2(VVO2F2)2(tr)4}. VV exists as a vanadium oxofluoride anion and possesses a distorted trigonal–bipyramidal coordination environment [VO2F2N]. A carb­oxy­lic acid functional group of the ligand stays in a neutral form and is involved in hydrogen bonding with solvent water mol­ecules and VO2F2− ions of adjacent mol­ecules. The extended hydrogen-bonding network is responsible for the crystal packing in the structure.

The title compound, [Ni(C10H8N2)3](C9H5N4O)2·2H2O, crystallizes as a racemic mixture in the monoclinic space group C2/c. In the crystal, the 1,1,3,3-tetracyano-2-ethoxypropenide anions and the water molecules are linked by O—H⋯N hydrogen bonds, forming chains running along the [010] direction. The bpy ligands of the cation are linked to the chain via C—H⋯π(cation) inter­actions involving the CH3 group. The inter­molecular inter­actions were investigated by Hirshfeld surface analysis and two-dimensional fingerprint plots.

The title compound, C13H24O9·H2O, a structural model for part of bacterial O-anti­gen polysaccharides from Shigella flexneri and Escherichia coli, crystallizes with four independent disaccharide mol­ecules and four water mol­ecules in the asymmetric unit. The conformation at the glycosidic linkage joining the two rhamnosyl residues is described by the torsion angles φH of 39, 30, 37 and 37°, and ψH of −32, −35, −31 and −32°, which are the major conformation region known to be populated in an aqueous solution. The hexo­pyran­ose rings have the 1C4 chair conformation. In the crystal, the disaccharide and water mol­ecules are associated through O—H⋯O hydrogen bonds, forming a layer parallel to the bc plane. The layers stack along the a axis via hydro­phobic inter­actions between the methyl groups.

A new quinoline-based hydrazone, C16H12ClN3, was synthesized by a condensation reaction of 2-chloro-3-formyl­quinoline with phenyl­hydrazine. The quinoline ring system is essentially planar (r.m.s. deviation = 0.012 Å), and forms a dihedral angle of 8.46 (10)° with the phenyl ring. The mol­ecule adopts an E configuration with respect to the central C=N bond. In the crystal, mol­ecules are linked by a C—H⋯π-phenyl inter­action, forming zigzag chains propagating along the [10overline{3}] direction. The N—H hydrogen atom does not participate in hydrogen bonding but is directed towards the phenyl ring of an adjacent mol­ecule, so linking the chains via weak N—H⋯π inter­actions to form of a three-dimensional structure. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (35.5%), C⋯H/H⋯C (33.7%), Cl⋯H/H⋯Cl (12.3%), N⋯H/H⋯N (9.5%) contacts.

The crystal structure of title salt, C22H46N42+·2NO3−·2H2O, has been determined using synchrotron radiation at 220 K. The structure determination reveals that protonation has occurred at diagonally opposite amine N atoms. The asymmetric unit contains half a centrosymmetric dication, one nitrate anion and one water mol­ecule. The mol­ecular dication, C22H46N42+, together with the nitrate anion and hydrate water mol­ecule are involved in an extensive range of hydrogen bonds. The mol­ecule is stabilized, as is the conformation of the dication, by forming inter­molecular N—H⋯O, O—H⋯O, together with intra­molecular N—H⋯N hydrogen bonds.

Typical electroless copper baths (ECBs), which are used to chemically deposit copper on printed circuit boards, consist of an aqueous alkali hydroxide solution, a copper(II) salt, formaldehyde as reducing agent, an l-(+)-tartrate as complexing agent, and a 2,2'-bi­pyridine derivative as stabilizer. Actual speciation and reactivity are, however, largely unknown. Herein, we report on the synthesis and crystal structure of aqua-1κO-bis­(4,4'-dimeth­oxy-2,2'-bi­pyri­dine)-1κ2N,N';2κ2N,N'-[μ-(2R,3R)-2,3-dioxidosuccinato-1κ2O1,O2:2κ2O3,O4]dicopper(II) octa­hydrate, [Cu2(C12H12N2O2)2(C4H2O6)(H2O)]·8H2O, from an ECB mock-up. The title compound crystallizes in the Sohncke group P21 with one chiral dinuclear complex and eight mol­ecules of hydrate water in the asymmetric unit. The expected retention of the tartrato ligand's absolute configuration was confirmed via determination of the absolute structure. The complex mol­ecules exhibit an ansa-like structure with two planar, nearly parallel bi­pyridine ligands, each bound to a copper atom that is connected to the other by a bridging tartrato `handle'. The complex and water mol­ecules give rise to a layered supra­molecular structure dominated by alternating π stacks and hydrogen bonds. The understanding of structures ex situ is a first step on the way to prolonged stability and improved coating behavior of ECBs.

The asymmetric units of the title compounds, trans-di­aqua­(3-benzyl-1,3,5,8,12-penta­aza­cyclo­tetra­decane-κ4N1,N5,N8,N12)copper(II) isophthalate monohydrate, [Cu(C16H29N5)(H2O)2](C8H4O4)·H2O, (I), and trans-di­aqua­[3-(pyridin-3-ylmeth­yl)-1,3,5,8,12-penta­aza­cyclo­tetra­decane-κ4N1,N5,N8,N12]copper(II) iso­phthalate 0.9-hydrate, [Cu(C15H28N6)(H2O)2](C8H4O4)·0.9H2O, (II) consist of one di­aqua macrocyclic cation, one di­carboxyl­ate anion and uncoordinated water mol­ecule(s). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand and the mutually trans O atoms of the water mol­ecules in a tetra­gonally distorted octa­hedral geometry. The average equatorial Cu—N bond lengths are significantly shorter than the average axial Cu—O bond lengths [2.020 (9) versus 2.495 (12) Å and 2.015 (4) versus 2.507 (7) Å for (I) and (II), respectively]. The coordinated macrocyclic ligand in the cations of both compounds adopts the most energetically favorable trans-III conformation. In the crystals, the complex cations and counter-anions are connected via hydrogen-bonding inter­actions between the N—H groups of the macrocycles and the O—H groups of coordinated water mol­ecules as the proton donors and the O atoms of the carboxyl­ate as the proton acceptors. Additionally, as a result of O—H⋯O hydrogen bonding with the coordinated and water mol­ecules of crystallization, the isophthalate dianions form layers lying parallel to the (overline{1}01) and (100) planes in (I) and (II), respectively.

The synthesis, spectroscopic data, crystal and mol­ecular structures of two N'-(1-phenyl­benzyl­idene)-2-(thio­phen-3-yl)acetohydrazides, namely N'-[1-(4-hy­droxy­phen­yl)benzyl­idene]-2-(thio­phen-3-yl)acetohydrazide, C13H10N2O2S, (3a), and N'-[1-(4-meth­oxy­phen­yl)benzyl­idene]-2-(thio­phen-3-yl)acetohydrazide, C14H14N2O2S, (3b), are described. Both compounds differ in the substituent at the para position of the phenyl ring: –OH for (3a) and –OCH3 for (3b). In (3a), the thio­phene ring is disordered over two orientations with occupancies of 0.762 (3) and 0.238 (3). The configuration about the C=N bond is E. The thio­phene and phenyl rings are inclined by 84.0 (3) and 87.0 (9)° for the major- and minor-occupancy disorder components in (3a), and by 85.89 (12)° in (3b). Although these dihedral angles are similar, the conformation of the linker between the two rings is different [the C—C—C—N torsion angle is −ac for (3a) and −sc for (3b), while the C6—C7—N9—N10 torsion angle is +ap for (3a) and −sp for (3b)]. A common feature in the crystal packing of (3a) and (3b) is the presence of N—H⋯O hydrogen bonds, resulting in the formation of chains of mol­ecules running along the b-axis direction in the case of (3a), or inversion dimers for (3b). The most prominent contributions to the surface contacts are those in which H atoms are involved, as confirmed by an analysis of the Hirshfeld surface.

Two CuII complexes [Cu(C14H13N4O2)Cl]n, I, and [Cu4(C8H10NO2)4Cl4]n, II, have been synthesized. In the structure of the mononuclear complex I, each ligand is coordinated to two metal centers. The basal plane around the CuII cation is formed by one chloride anion, one oxygen atom, one imino and one pyridine nitro­gen atom. The apical position of the distorted square-pyramidal geometry is occupied by a pyridine nitro­gen atom from a neighbouring unit, leading to infinite one-dimensional polymeric chains along the b-axis direction. Each chain is connected to adjacent chains by inter­molecular C—H⋯O and C—H⋯Cl inter­actions, leading to a three-dimensional network structure. The tetra­nuclear complex II lies about a crystallographic inversion centre and has one core in which two CuII metal centers are mutually inter­connected via two enolato oxygen atoms while the other two CuII cations are linked by a chloride anion and an enolato oxygen. An open-cube structure is generated in which the two open-cube units, with seven vertices each, share a side composed of two CuII ions bridged by two enolato oxygen atoms acting in a μ3-mode. The CuII atoms in each of the two CuO3NCl units are connected by one μ2-O and two μ3-O atoms from deprotonated hydroxyl groups and one chloride anion to the three other CuII centres. Each of the penta­coordinated CuII cations has a distorted NO3Cl square-pyramidal environment. The CuII atoms in each of the two CuO2NCl2 units are connected by μ2-O and μ3-O atoms from deprotonated alcohol hy­droxy groups and one chloride anion to two other CuII ions. Each of the penta­coordinated CuII cations has a distorted NO2Cl2 square-pyramidal environment. In the crystal, a series of intra­molecular C—H⋯O and C—H⋯Cl hydrogen bonds are observed in each tetra­nuclear monomeric unit, which is connected to four tetra­nuclear monomeric units by inter­molecular C—H⋯O hydrogen bonds, thus forming a planar two-dimensional structure in the (overline{1}01) plane.