Crystal structure of {2,6-bis[(dimethylamino)methyl]phenyl-κ3N,C1,N′}(bromido/chlorido)mercury(II)

In the molecular structure of the title compound, {2,6-bis[(dimethylamino)methyl]phenyl-κ3N,C1,N′}[bromido/chlorido(0.30/0.70)]mercury(II)–{2,6-bis[(dimethylamino)methyl]phenyl-κ3N,C1,N′}[bromido/chlorido(0.24/0.76)]mercury(II) (1/1), [HgBr0.30Cl0.70(C12H19N2)]·[HgBr0.24Cl0.76(C12H19N2)], there are two molecules in the asymmetric unit of formulaLHgX{L= 2,6-bis[(dimethylamino)methyl]phenyl andX= Cl/Br}. In each molecule, the halide site is mixed Cl/Br, with occupancies of 0.699 (7):0.301 (7) and 0.763 (7):0.237 (7), respectively. The two molecules are linked into dimers by a combination of Hg...Hg [Hg...Hg = 3.6153 (3) Å] and C—H...Cl and C—H...π interactions.

Cation tautomerism, twinning and disorder in the triclinic and monoclinic forms of 4-amino-5-chloro-2,6-dimethylpyrimidinium 5-chloro-2-hydroxybenzoate and a new disordered refinement of 2-amino-4,6-dimethoxypyrimidin-1-ium thiophene-2-carboxylate

Pyrimidines are important compounds in biology and medicine, and the aminopyrimidine fragment can be identified in three of the four bases in DNA. The targeted drug action of pharmaceuticals containing this functionality is likely to depend heavily on molecular recognition processes involving hydrogen bonding. Crystallization of an equimolar mixture of 4-amino-5-chloro-2,6-dimethylpyrimidine and 5-chloro-2-hydroxybenzoic acid yielded two forms of the 1:1 salt, C₆H₉ClN₃⁺·C₇H₄ClO₃^-, each containing a different tautomeric form of the cation. 6-Amino-5-chloro-2,4-dimethylpyrimidin-1-ium 5-chloro-2-hydroxybenzoate, (I), crystallizes in the space group P-1, with Z' = 2, and all of the component ions are fully ordered. 4-Amino-5-chloro-2,6-dimethylpyrimidin-1-ium 5-chloro-2-hydroxybenzoate, (II), also crystallizes with Z' = 2, but in the space group P2₁/c and as a merohedral twin which closely mimics an orthorhombic unit cell. In (II), one of the cations and one of the anions is disordered, each over two sets of atomic sites having occupancies of 0.836 (2) and 0.164 (2), and 0.834 (2) and 0.166 (2). The bond lengths in the cations of (I) and (II) provide evidence for o-quinonoid and p-quinonoid bond fixation, respectively. A combination of six N-H...O hydrogen bonds links the component ions of (I) into two independent four-ion aggregates, but the ions in (II) are linked by a combination of four N-H...O and two N-H...N hydrogen bonds to form a three-dimensional framework structure. The recently reported structure of 2-amino-4,6-dimethoxypyrimidin-1-ium thiophene-2-carboxylate, C₆H₁₀N₃O₂⁺·C₅H₃O₂S^-, (III), has been rerefined, using the original data set, to show that the anion is disordered over two sets of atomic sites, approximately related by a 180° rotation about the exocyclic C-C bond, and having occupancies of 0.8687 (19) and 0.1313 (19).

Crystal structure of aqua-(perchlorato)bis-[μ-(E)-2-({[2-(pyridin-2-yl)eth-yl]imino}-meth-yl)phenolato-κ4N,N',O:O]dicopper(II) perchlorate

The title compound, [Cu2(ClO4)(C14H13N2O)2(H2O)]ClO4, crystallizes as an unsymmetrical dinuclear cation bridged by the phen-oxy O atoms with one CuII atom coordinated by a water mol-ecule and the other by a perchlorate anion, thus making both CuII atoms five-coordinate, and with a further perchlorate anion present for charge balance. A long inter-action [2.9893 (5) Å] between one of the two CuII atoms and an O atom of the perchlorate counter-ion links the cations and anions into linear chains along the a-axis direction. In addition, the water H atoms link with the perchlorate counter-ion. These inter-actions, along with numerous C-H⋯O inter-actions between the tetra-hedral perchlorate anions, link the ions into a complex three-dimensional array. One of the perchlorate anions is disordered over two conformations with occupancies of 0.586 (4) and 0.414 (4).

(E)-2,4-Dibromo-6-(hydrazinylidenemethyl)phenol

The title compound, C7H6Br2N2O, was obtained from a condensation reaction of 3,5-dibromo-2-hydroxybenzaldehyde and hydrazine hydrate. The molecule is approximately planar, the largest deviation from the mean plane through all of the non-H atoms being 0.053 (1) Å. The molecular conformation is stabilized by an intramolecular O—H...N hydrogen bond, generating anS(6) ring motif. In the crystal, intermolecular N—H...Br and N—H...O hydrogen bonds link the molecules, forming chains parallel to thebaxis. Molecules are further linked by π–π stacking interactions, with centroid–centroid distances of 3.925 (3)–3.926 (3) Å, forming a three-dimensional network.

Chain-Breaking Phenolic 2,3-Dihydrobenzo[b]selenophene Antioxidants: Proximity Effects and Regeneration Studies

Phenolic 2,3-dihydrobenzo[b]selenophene antioxidants bearing an OH-group ortho (9), meta (10, 11) and para (8) to the Se were prepared by seleno-Claisen rearrangement/intramolecular hydroselenation. meta-Isomer (11) was studied by X-ray crystallography. The radical-trapping activity and regenerability of compounds 8-11 were evaluated using a two-phase system in which linoleic acid was undergoing peroxidation in the lipid phase while regeneration of the antioxidant by co-antioxidants (N-acetylcysteine, glutathione, dithiothreitol, ascorbic acid, tris(carboxyethyl)phosphine hydrochloride) was ongoing in the aqueous layer. Compound 9 quenched peroxyl radicals more efficiently than α-tocopherol. It also provided the most long-lasting antioxidant protection. With thiol co-antioxidants it could inhibit peroxidation for more than five-fold longer than the natural product. Regeneration was more efficient when the aqueous phase pH was slightly acidic. Since calculated O-H bond dissociation energies for 8-11 were substantially larger than for α-tocopherol, an antioxidant mechanism involving O-atom transfer from peroxyl to selenium was proposed. The resulting phenolic selenoxide/alkoxyl radical would then exchange a hydrogen atom in a solvent cage before antioxidant regeneration at the aqueous lipid interphase.

(Aceto-nitrile-κN)aqua-[N,N'-bis-(pyridin-2-yl-methyl)ethane-1,2-di-amine-κ4N,N',N'',N''']zinc(II) perchlorate

The structure of the title compound, [Zn(C14H18N4)(C2H3N)(H2O)](ClO4)2, contains a six-coordinate cation consisting of the tetra-dentate bis-picen ligand, coordinated water, and coordinated aceto-nitrile, with the latter two ligands adopting a cis configuration. There are two formula units in the asymmetric unit. Both cations show almost identical structural features with the bis-picen ligand adopting the more common cis-β conformation. One of the four perchlorate anions is disordered over two positions, with occupancies of 0.9090 (15) and 0.0910 (15). There is extensive inter-ionic hydrogen bonding between the perchlorate anions and O-H and N-H groups in the cations, including a bifurcated hydrogen bond between an N-H group and two O atoms of one perchlorate anion. As a result of this extended hydrogen-bond network, the ions are linked into a complex three-dimensional array.

Bis(3,5-dimeth-oxy-2-{[2-(pyridin-2-yl)ethyl-imino-κN]-meth-yl}phenolato-κO)bis-(dimethyl sulfoxide)-manganese(III) perchlorate methanol 0.774-solvate

The title compound, [Mn(C16H17N2O3)2(C2H6OS)2]ClO4·0.774CH3OH, comprises a central octa-hedrally coordinated MnIII cation, with two bidentate Schiff base ligands occupying the equatorial positions and two dimethyl sulfoxide (DMSO) ligands occupying the axial positions. There are two independant cations in the asymmetric unit, with the MnIII atoms of both cations being positioned on crystallographic centers of inversion. The perchlorate anion is disordered over two equivalent conformations, with occupancies of 0.744 (3) and 0.226 (3). In addition, there is a methanol solvent mol-ecule in the crystal lattice that is too close to the minor component of the perchlorate anion to be present simultaneously and thus it was refined to have the same occupancy as the major component of this anion. There is a Jahn-Teller distortion which results in Mn-ODMSO axial bond lengths of 2.2365 (12) and 2.2368 (12) Å in the two cations. In the crystal, inter-molecular π-π stacking between the non-coordinating pyridine rings of each cation is observed. This π-π stacking, along with extensive O-H⋯O hydrogen bonding and C-H⋯O inter-actions, link the components into a complex three-dimensional array.

Tris(μ2-methano-lato)-μ3-oxido-tris-{[(E)-4-chloro-2-({[2-(pyridin-2-yl)eth-yl]imino}-meth-yl)pheno-lato]manganese(III)} perchlorate-di-chloro-methane-diethyl ether (1/1.1/0.9)

In the title compound, [Mn₃(C₁₄H₁₂ClN₂O)₃(CH₃O)₃O]ClO₄·1.1CH₂Cl₂·0.9C₄H₁₀O, the cation consists of a central Mn₃O core with μ₂-methano-late bridging between adjacent Mn^III atoms, thus giving each Mn^III atom a mer-O₃ coordination environment. Six-coordination for each Mn^III atom is provided by the deprotonated Schiff base ligand (E)-4-chloro-2-({[2-(pyridin-2-yl)eth-yl]imino}-meth-yl)phenolate. There are extensive C-H⋯O and C-H⋯Cl inter-actions, which link the cations, anions, and solvent mol-ecules into a three-dimensional array.

Supramolecular interactions in carboxylate and sulfonate salts of 2,6-diamino-4-chloropyrimidinium

Two new salts, namely 2,6-diamino-4-chloropyrimidinium 2-carboxy-3-nitrobenzoate, C₄H₆ClN₄⁺·C₈H₄NO₆^-, (I), and 2,6-diamino-4-chloropyrimidinium p-toluenesulfonate monohydrate, C₄H₆ClN₄⁺·C₇H₇O₃S^-·H₂O, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both crystal structures, the N atom in the 1-position of the pyrimidine ring is protonated. In salt (I), the protonated N atom and the amino group of the pyrimidinium cation interact with the carboxylate group of the anion through N-H...O hydrogen bonds to form a heterosynthon with an R₂²(8) ring motif. In hydrated salt (II), the presence of the water molecule prevents the formation of the familiar R₂²(8) ring motif. Instead, an expanded ring [i.e. R₃²(8)] is formed involving the sulfonate group, the pyrimidinium cation and the water molecule. Both salts form a supramolecular homosynthon [R₂²(8) ring motif] through N-H...N hydrogen bonds. The molecular structures are further stabilized by π-π stacking, and C=O...π, C-H...O and C-H...Cl interactions.

(Benzylthiolato-κS)phenylmercury(II)

The title complex, [Hg(C6H5)(C7H7S)], was synthesized from benzyl 4-methylpiperidine-1-carbodithioate. In the complex, the HgIIcation binds to a C atom of a phenyl ring and the S atom of a benzylthiolate ligand in a linear coordination geometry. The molecule is bent at the methylene C atom and the S atom, resulting in asynconformation with respect to the benzyl and phenyl rings. The dihedral angle between the phenyl and benzyl rings is 64.6 (2)°. The crystal structure is stabilized by intermolecular Hg...S [3.290 (3) Å] contacts and C—H...π interactions, generating a three-dimensional network.

N′-[Bis(methylsulfanyl)methylidene]-2-methoxybenzohydrazide

In the title compound, C11H14N2O2S2, the diethyl dithioate groups are inclined slightly to the benzoyl ring, making a dihedral angle of 14.0 (3)°. A short intramolecular N—H...O contact generates anS(6) ring. In the crystal, C—H...O contacts generate aC(8) chain motif along [010].

Crystal structure of tetra-aqua-bis-(pyrimidin-1-ium-4,6-diolato-κO4)manganese(II)

The MnII ion in the structure of the mononuclear title compound, [Mn(C4H3N2O2)2(H2O)4], is situated on an inversion center and is coordinated by two O atoms from two deprotonated 4,6-di-hydroxy-pyrimidine ligands and by four O atoms from water mol-ecules giving rise to a slightly distorted octa-hedral coordination sphere. The complex includes an intra-molecular hydrogen bond between an aqua ligand and the non-protonated N ring atom. The extended structure is stabilized by inter-molecular hydrogen bonds between aqua ligands, by hydrogen bonds between N and O atoms of the ligands of adjacent mol-ecules, and by hydrogen bonds between aqua ligands and the non-coordinating O atom of an adjacent mol-ecule.

Structure of 2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benzimidazol-3-ium) tetra-chlorido-mercurate(II)

In the title salt, (C34H44N4)[HgCl4], the [C34H44N4]2+ cations and [HgCl4]2- anions are linked by N-H⋯Cl hydrogen bonds. One of the two n-pentyl side chains was refined as disordered over two sets of sites, with occupancies of 0.733 (18) and 0.267 (18). The geometry around the HgII atom in the [HgCl4]2- anion is distorted tetra-hedral, with bond angles ranging from 98.16 (3) to 120.68 (3)°. In the [HgCl4]2- anion, there are two short Hg-Cl bonds [2.4120 (9) and 2.4171 (11) Å], one inter-mediate Hg-Cl bond [2.4716 (12) Å] and one long Hg-Cl bond [2.6579 (13) Å] for the Cl atom involved in a trifurcated hydrogen bond as an acceptor, including two N-H⋯Cl⋯H-N interactions as well as one C-H⋯Cl inter-action. There are several C-H⋯Cl inter-actions, with C⋯Cl distances ranging from 3.492 (3) to 3.796 (3) Å. These link the cations and anions into a zigzag chain along the c-axis direction. In addition, there are Cl⋯Cl halogen bonds, as well as π-π inter-actions, with centroid-to-centroid distances of 3.4765 (18) Å, which link one of the two benzimidazole moieties into dimeric units.

Synthesis and structure of the mercury chloride complex of 2,2'-(2-bromo-5-tert-butyl-1,3-phenyl-ene)bis-(1-methyl-1H-benzimidazole)

In the title mercury complex, catena-poly[[di-chlorido-mercury(II)]-μ-2,2'-(2-bromo-5-tert-butyl-1,3-phenyl-ene)bis-(1-methyl-1H-benzimidazole)-κ2N3:N3'], [HgCl2(C26H25BrN4)] n , the HgII atom is coordinated by two Cl atoms and by two N atoms from two 2,2'-(2-bromo-5-tert-butyl-1,3-phenyl-ene)bis-(1-methyl-1H-benzimidazole) ligands. The metal cation adopts a distorted tetrahedral coordination geometry with with bond angles around mercury of 100.59 (15)° [N-Hg-N] and 126.35 (7)° [Cl-Hg-Cl]. This arrangement gives rise to a zigzag helical 1-D polymer propagating along the b-axis direction.

Structure of the mercury(II) mixed-halide (Br/Cl) complex of 2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benzo[d]imidazole)

The mercury(II) complex of 2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benz-imidazole), namely catena-poly[[dihalogenido-mercury(II)]-μ-2,2'-(5-tert-butyl-1,3-phenyl-ene)bis-(1-pentyl-1H-benzimidazole)-κ2N3:N3'], [HgBr1.52Cl0.48(C34H42N4)], 2, has a polymeric structure bridging via the N atoms from the benzimidazole moieties of the ligand. The compound crystallizes in the ortho-rhom-bic space group Pca21 and is a racemic twin [BASF = 0.402 (9)]. The geometry around the HgII atom is distorted tetra-hedral, with the HgII atom coordinated to two N atoms, one Br atom, and a fourth coordination site is occupied by a mixed halide (Br/Cl). For the two ligands in the asymmetric unit, there is disorder with one of the two tert-butyl groups and benzimidazole moieties showing twofold disorder, with occupancy factors of 0.57 (2):0.43 (2) for the tert-butyl group and 0.73 (3):0.27 (3) for the benzimidazole group. In addition, there is threefold disorder for two of the four n-pentyl groups, with occupancy factors of 0.669 (4):0.177 (4):0.154 (4) and 0.662 (4):0.224 (4):0.154 (4), respectively. The mol-ecules form a one-dimensional helical polymer propagating in the b-axis direction. The helices are held together by intra-strand C-H⋯Br and C-H⋯Cl inter-actions. Each strand is further linked by inter-strand C-H⋯Br and C-H⋯Cl inter-actions. In addition, there are weak C-H⋯N inter-strand inter-actions which further stabilize the structural arrangement.

Luminescent sulfonate coordination polymers: synthesis, structural analysis and selective sensing of nitroaromatic compounds

Enhanced fluorescence intensity of sulfonate coordination polymers on addition of picric acid.

An insight into the communication between β-olefin/phenyl olefin-mediated acceptors and porphyrin π-system: a way to establish porphyrin based chemodosimeters and chemosensors

Porphyrins bearing electron acceptors attached to β-carbon through olefin or phenyl–olefin bridges act as chemodosimeters for CN⁻ as well as chemosensors for F⁻, CN⁻ and OAc⁻ ions depends on acceptor strength and position.

Nitro-, Azo-, and Amino Derivatives of Ebselen: Synthesis, Structure, and Cytoprotective Effects

Novel azo-bis-ebselen compounds 7 were prepared by reduction of 7-nitro-2-aryl-1,2-benzisoselenazol-3(2H)-ones 3 and 6 with sodium benzenetellurolate, NaTeC₆H₅, and by reaction of 2-bromo-3-nitrobenzamides with Na₂Se₂. The X-ray structure of 7b showed that the molecule, due to strong intramolecular secondary Se···N interactions, is completely planar. Azo-compounds 7 upon further reaction with NaTeC₆H₅ were reductively cleaved to provide 2 equiv of the corresponding aromatic amine. The weak Se-N bond was not stable enough to survive the reaction conditions, and diselenides 8 were isolated after workup. Whereas azo-bis-ebselens 7 were poor mimics of the glutathione peroxidase (GPx)-enzymes, nitroebselens 3, 6, and 11b and diselenides 8 were 3-6-fold more active than ebselen. Based on ⁷⁷Se NMR spectroscopy, a catalytic cycle for diselenide 8b, involving aminoebselen 14, was proposed. As assessed by chemiluminescence measurements, the good GPx-mimics could reduce production of reactive oxygen species (ROS) in stimulated human mononuclear cells more efficiently than Trolox. No toxic effects of the compounds were seen in MC3T3-cells at 25 μM.

5-(2-Methylfuran-3-yl)-N-phenyl-1,3,4-oxadiazol-2-amine

In the title compound, C13H11N3O2, the furan ring is disordered over two orientations, with occupancies of 0.902 (2) and 0.098 (2). The dihedral angles between the central oxadiazole ring and the pendant phenyl ring and the furan ring (major disorder component) are 10.12 (11) and 1.76 (15)°, respectively. A short intramolecular C—H...O contact generates anS(6) ring. In the crystal, inversion dimers linked by pairs of N—H...N hydrogen bonds generateR22(8) loops. The dimers are linked by C—H...π and π–π interactions [range of centroid–centroid distances = 3.301 (7)–3.689 (1) Å], generating a three-dimensional network.

Histamine perchlorate

The perchlorate salt of the histamine dication [systematic name: 4-(2-azaniumylethyl)-1H-imidazol-3-ium bis(perchlorate)], C5H11N32+·2ClO4−, crystallizes in the monoclinic space groupP21/cwith two formula units in the asymmetric unit. One of the histamine dications is disordered [occupancies of 0.718 (4) and 0.282 (4)] and two of the four perchlorate anions are disordered [occupancies of 0.735 (6):0.265 (6) and 0.637 (5):0.363 (5)]. There is extensive hydrogen bonding in the structure involving both N—H...O and C—H...O interactions, which link the histamine dications and perchlorate anions into a three-dimensional array.

Crystal structure of 4-amino-5-chloro-2,6-di-methyl-pyrimidinium thio-phene-2,5-di-carboxyl-ate

In the title salt, C6H9ClN3 (+)·C6H3O4S(-), the cations and anions are linked via O-H⋯O and N-H⋯O hydrogen bonds, forming R 6 (6)(37) ring motifs that are inter-connected with each other, producing sheets. Separate parallel inversion-related sheets are linked through N-H⋯N and π-π stacking inter-actions [centroid-centroid distance = 3.5414 (13) Å], forming double layers parallel to (101). Weak C-H⋯O and C-H⋯S hydrogen bonds, as well as C-H⋯π inter-actions, connect the double layers into a three-dimensional network.

Selone-stabilized aryltellurenyl cations

Controlled bromination of a diarylditelluride, R2Te2 (R = 2,6-dimethylphenyl) (6) in dichloromethane led to the formation of a Te(II)-Te(IV) mixed-valent tellurenyl bromide, RBr2TeTeR (7). A further reaction of 7 with 1,3-dibutylbenzimidazolin-2-selone, C15H22N2Se (L) (9), produced the first selone adduct of the 2,6-dimethylphenyltellurenyl cation with the 2,6-dimethylphenyltellurium dibromide anion, [(2,6-Me2C6H3)Te(L)](+)[(2,6-Me2C6H3)TeBr2](-) (10). The red colored cationic adduct 10 is not stable in acetonitrile and disproportionated to give the selone adduct of 2,6-dimethylphenyltellurenyl bromide, [(2,6-Me2C6H3)Te(L)Br] (11b) and bis(2,6-dimethylphenyl)tellurium dibromide, [(2,6-Me2C6H3)2TeBr2], (13). The metathesis reaction of 11b with AgBF4 produced a stable dark red colored selone adduct of the 2,6-dimethylphenyltellurenyl cation with the BF4(-) anion, [(2,6-Me2C6H3)Te(L)](+)BF4(-) (15). The selone adducts of aryltellurenyl halides, i.e. [(2,6-Me2C6H3)Te(L)X] (X = Cl, Br, I) (11a-11c), have been synthesized by a one-pot reaction of 6 with an equimolar mixture of 9 and 1,3-dibutylbenzimidazolin-2-dihaloselones, C15H22N2SeX2 (14a-14c). Triphenylphosphine (PPh3), when treated with [(2,6-Me2C6H3)Te(L)X] (11a-11c), substitutes selone from the adduct to afford the triphenylphosphine adducts of aryltellurenyl halides, [(2,6-Me2C6H3)Te(PPh3)X] (16a-16c).

Crystal structures of 4-methyl-2-oxo-2H-chromene-7,8-diyl di-acetate and 4-methyl-2-oxo-2H-chromene-7,8-diyl bis-(pent-4-ynoate)

The structures of two substituted coumarin derivatives are reported, one with acetate and the other with pent-4-ynoate substituents.

In the structures of the two title coumarin derivatives, C₁₄H₁₂O₆, (1), and C₂₀H₁₆O₆, (2), one with acetate and the other with pent-4-ynoate substituents, both the coumarin rings are almost planar. In (1), both acetate substituents are significantly rotated out of the coumarin plane to minimize steric repulsions. One acetate substituent is disordered over two equivalent conformations, with occupancies of 0.755 (17) and 0.245 (17). In (2), there are two pent-4-ynoate substituents, the C≡C group of one being disordered over two positions with occupancies of 0.55 (2) and 0.45 (2). One of the pent-4-ynoate substituents is in an extended conformation, while the other is in a bent conformation. In this derivative, the planar part of both pent-4-ynoate substituents deviate from the coumarin plane. The packing of (1) is dominated by π–π stacking involving the coumarin rings and weak C—H⋯O contacts link the parallel stacks in the [101] direction. In contrast, in (2) the packing is dominated by R₂²(24) hydrogen bonds, involving the acidic sp H atom and the oxo O atom, which link the mol­ecules into centrosymmetric dimers. The bent conformation of one of the pent-4-ynoate substituents prevents the coumarin rings from engaging in π–π stacking.

4-(3-Chlorophenyl)-1-(3-chloropropyl)piperazin-1-ium chloride redetermined at 100 K

The crystal structure of the title salt, C13H19Cl2N2+·Cl−, has been reported previously [Homrighausen & Krause Bauer (2002).Acta Cryst.E58, o1395–o1396] based on room-temperature data, where it was found to contain a disordered chloropropyl group. We now present the structure at 100 K in which the chloropropyl group is ordered. The piperazine ring adopts a chair conformation with the exocyclic N—C bonds in equatorial orientations. The dihedral angle between the piperazine ring (all atoms) and the benzene ring is 28.47 (5)°. The chloropropyl group has an extended conformation [N—C—C—C = −177.25 (8) ° and C—C—C—Cl = 174.23 (7)°]. In the crystal, charge-assisted N—H...Cl hydrogen bonds link the cation and anion into ion pairs. Numerous weak C—H...Cl interactions link the ion pairs into a three-dimensional network. Short Cl...Cl contacts [3.2419 (4) Å] are also observed.

Poly[μ2-aqua-aqua-[μ3-N-butyl-N-(2-hy-droxy-ethyl)di-thio-carbamato-κ(3) O,O':S]sodium]

In the title compound, [Na(C7H14NOS2)(H2O)2] n , the Na(I) cation is coordinated by five O atoms [Na-O = 2.3142 (11)-2.4677 (10) Å] from three aqua and two N-butyl-N-(2-hy-droxy-eth-yl)di-thio-carbamate (L) ligands and one S atom [Na-S = 3.0074 (6) Å] from a third L ligand in a highly distorted octa-hedral geometry. Two aqua ligands related by an inversion center bridge two Na(I) cations, and each L ligand coordinates three Na(I) cations, leading to a layered arrangement aligned parallel to the bc plane. Inter-molecular O-H⋯S hydrogen bonds are observed in the inner part of each polymeric layer; these are packed along the a axis and held together by weak van der Waals forces.

Transition metal mediated formation of dicationic diselenides stabilised by N-heterocyclic carbenes: designed synthesis

Designed syntheses of dicationic diselenides have been developed by (i) reduction of dihaloselones (routes A and B) and (ii) by oxidation of selone adducts of metal halides (route C).

Crystal structure of {6,6'-dibenzoyl-4,4'-di-tert-butyl-2,2'-[(ethane-1,2-di-yl)di-nitrilo-bis-(phenyl-methanylyl-idene)]diphenolato-κ(4) O (1),N,N',O (1')}nickel(II)

The mononuclear title complex, [Ni(C50H46N2O4)], crystallizes in the triclinic space group P-1, with two mol-ecules in the asymmetric unit (Z' = 2). Each Ni(II) atom has a slightly distorted square-planar geometry [ω = 3.91 (5)° and 2.04 (7)°] defined by the two phenolate O and two imine N atoms of the tetra-dentate Schiff base ligand. The dihedral angles between the central phenolate ring and peripheral phenyl rings are 60.5 (2)/70.0 (2) and 86.4 (2)/56.1 (2)° in mol-ecule A, and 89.43 (19)/18.0 (2) and 63.87 (19)/68.2 (2)° in mol-ecule B. The two central phenolate rings are twisted by angles of 19.37 (19) and 19.36 (18)° in the two mol-ecules. The packing is stabilized through intra- and inter-molecular C-H⋯O and C-H⋯π inter-actions, forming chains parallel to the b axis. The tert-butyl groups in one of the two mol-ecules are positionally disordered with a refined occupancy ratio of 0.707 (13):0.293 (13).

Multicomponent One-pot Reactions Towards the Synthesis of Stereoisomers of Dipicolylamine Complexes

Reported are multi-component one-pot syntheses of chiral complexes [M(L(R) OR')Cl2 ] or [M(L(R) SR')Cl2 ] from the mixture of an N-substituted ethylenediamine, pyridine-2-carboxaldehyde, a primary alcohol or thiol and MCl2 utilizing in-situ formed cyclized Schiff bases where a C-O bond, two stereocenters, and three C-N bonds are formed (M=Zn, Cu, Ni, Cd; R=Et, Ph; R'=Me, Et, nPr, nBu). Tridentate ligands L(R) OR' and L(R) SR' comprise two chiral centers and a hemiaminal ether or hemiaminal thioether moiety on the dipicolylamine skeleton. Syn-[Zn(L(Ph) OMe)Cl2 ] precipitates out readily from the reaction mixture as a major product whereas anti-[Zn(L(Ph) OMe)Cl2 ] stays in solution as minor product. Both syn-[Zn(L(Ph) OMe)Cl2 ] and anti-[Zn(L(Ph) OMe)Cl2 ] were characterized using NMR spectroscopy and mass spectrometry. Solid-state structures revealed that syn-[Zn(L(Ph) OMe)Cl2 ] adopted a square pyramidal geometry while anti-[Zn(L(Ph) OMe)Cl2 ] possesses a trigonal bipyramidal geometry around the Zn centers. The scope of this method was shown to be wide by varying the components of the dynamic coordination assembly, and the structures of the complexes isolated were confirmed by NMR spectroscopy, mass spectrometry, and X-ray crystallography. Syn complexes were isolated as major products with Zn(II) and Cu(II) , and anti complexes were found to be major products with Ni(II) and Cd(II) . Hemiaminals and hemiaminal ethers are known to be unstable and are seldom observed as part of cyclic organic compounds or as coordinated ligands assembled around metals. It is now shown, with the support of experimental results, that linear hemiaminal ethers or thioethers can be assembled without the assistance of Lewis acidic metals in the multi-component assembly, and a possible pathway of the formation of hemiaminal ethers has been proposed.