RESUMEN

In the title compound, [Zn(C4H8NOS2)2(C12H10N4)], the ZnII atom exists within a NS4 donor set defined by two chelating di-thio-carbamate ligands and a pyridyl-N atom derived from a terminally bound 4-pyridine-aldazine ligand. The distorted coordination geometry tends towards square-pyramidal with the pyridyl-N atom occupying the apical position. In the crystal, hydroxyl-O-H⋯O(hydrox-yl) and hydroxyl-O-H⋯N(pyrid-yl) hydrogen-bonding give rise to a supra-molecular double-chain along [1-10]; methyl-C-H⋯π(chelate ring) inter-actions help to consolidate the chain. The chains are connected into a three-dimensional architecture via pyridyl-C-H⋯O(hydrox-yl) inter-actions. In addition to the contacts mentioned above, the Hirshfeld surface analysis points to the significance of relatively weak π-π inter-actions between pyridyl rings [inter-centroid distance = 3.901 (3) Å].

RESUMEN

The complete mol-ecule of the title compound, [Cd(C(6)H(12)NOS(2))(2)(C(12)H(10)N(4))(2)], is generated by crystallographic inversion symmetry. The distorted octa-hedral trans-N(2)S(4) donor set for the Cd(2+) ion is defined by two symmetrically S,S'-chelating dithio-carbamate anions and two pyridine N atoms derived from two monodentate 4-pyridine-aldazine (or 4-{[(pyridin-4-yl-methyl-idene)hydrazinyl-idene}meth-yl]pyridine) mol-ecules [dihedral angle between the aromatic rings = 17.33 (8)°]. In the crystal, mol-ecules are connected into a supra-molecular chain via O-H⋯N hydrogen bonds involving the 4-pyridine-aldazine N atoms not involved in coordination to cadmium. Weak C-H⋯O and C-H⋯N links consolidate the packing.

RESUMEN

In the title hydrate, C(18)H(20)BrO(4)P·H(2)O, a staggered conformation is found when the organic mol-ecule is viewed down the central P-C bond, with the oxo and hydroxyl groups being diagonally opposite; each of the central P and C atoms has an S-configuration. The crystal structure features supra-molecular double chains along the b axis mediated by O(hydrox-yl)-H⋯O(oxo), O(water)-H⋯O(oxo), and O(water)-H⋯O(water) hydrogen bonds.

RESUMEN

The asymmetric unit of the title salt, 2C(4)H(12)NO(+)·C(14)H(8)O(4)S(2) (2-), contains an eth-yl(2-hydr-oxy)aminium cation and half a 2,2'-disulfanediyldibenzoate anion, with the latter disposed about a twofold axis. The cation is a straight chain with the exception of the terminal hydr-oxy group [the N-C-C-O torsion angle is 66.5 (2)°]. A twisted conformation is found for the anion [the C-S-S-C torsion angle is 91.51 (9)° and the dihedral angle between the rings is 81.01 (4)°]. A supra-molecular chain with base vector [101] and a tubular topology is formed in the crystal structure mediated by charge-assisted O-H⋯O(-) and N(+)-H⋯O(-) hydrogen bonding.

RESUMEN

In the title hydrated salt, C(4)H(15)N(3) (2+)·C(14)H(8)O(4)S(2) (-)·2H(2)O, the dication (with both terminal -NH(2) groups protonated) adopts a U-shaped conformation, the N(amine)-C-C-N(aza-nium) torsion angles being 57.9 (6) and 60.3 (6)°. The dianion is twisted: the central C-S-S-C torsion angle is 81.3 (2)° and the dihedral angle between the benzene rings is 85.4 (3)°. In the crystal, a chain in the a-axis direction mediated by water-carboxyl-ate O-H⋯O hydrogen bonds through a sequence of alternating 12-membered {⋯OCO⋯HOH}(2) and eight-membered {⋯O⋯HOH}(2) synthons occurs, which involves only one of the carboxyl-ate residues. The second carboxyl-ate residue participates in N-H⋯O hydrogen bonding, generating a three-dimensional network, along with aza-nium-water N-H⋯O hydrogen bonds.

RESUMEN

With the exception of the terminal hydr-oxy group [N-C-C-O = 53.8 (5)°], the cation of the title salt hydrate, C(5)H(14)NO(+)·C(14)H(9)O(4)S(2) (-.)H(2)O, is a straight chain. A twisted conformation is found for the anion [C-S-S-C = -87.44 (16)°]. In the crystal, the anions self-assemble into a helical supra-molecular chain via charge-assisted O-H⋯O(c) hydrogen bonds. These chains are connected into a three-dimensional network via N-H⋯O(c), N-H⋯O(w), O(h)-H⋯O(cb), and O(w)-H⋯O(c) hydrogen-bonding inter-actions (c = carboxyl-ate, w = water, h = hydr-oxy and cb = carbon-yl).

RESUMEN

In the title compound, C(10)H(22)NO(6)P, a staggered conformation is found when the mol-ecule is viewed down the central P-C bond, with the oxo and hydr-oxy groups gauche to each other. The crystal structure features supra-molecular chains of helical topology propagating along the b axis, mediated by O-H⋯O hydrogen bonds.

RESUMEN

In the title compound, C(14)H(21)FNO(6)P, a staggered conformation about the central P-C bond occurs, with the oxo and hydroxyl groups occupying diagonally opposite positions. The crystal structure features supra-molecular chains mediated by O-H⋯O hydrogen bonds, which propagate in the a-axis direction. A C-H⋯O inter-action consolidates the chains. Disorder was resolved for one of the isopropyl groups with a 0.60 (2):0.40 (2) occupancy ratio for the two components.

RESUMEN

Two palladium(II) complexes, [Pd(phen)(N identical withCCH(3))(2)][O(3)SCF(3)](2) (1) and [Pd(phen)(mu-OH)](2)[O(3)SCF(3)](2).2H(2)O (2) (where phen= 1,10-phenanthroline), have been crystallized following the reaction of Pd(phen)Cl(2) with silver triflate, Ag(O(3)SCF(3)), in acetonitrile and water, respectively. The structures of both complexes are based on a Pd(phen)(2+) metal core, with two acetonitrile molecules binding in a monodentate fashion in complex 1 and two hydroxo bridges holding together two cores to form a dimer in complex 2. Additionally, both complexes present a hydrogen bonded 3-D network involving the triflate anions in 1, and water and triflate anions in 2. Both complexes have been characterized by infrared and (1)H NMR spectroscopy and their crystal structures determined by X-ray crystallography.

RESUMEN

Enantioenriched 2,3,4-trisubstituted thiochromanes have been synthesized by using a cupreine-catalyzed tandem Michael addition-Henry reaction between 2-mercaptobenzaldehydes and ß-nitrostyrenes. Good diastereoselectivities and enantioselectivities were obtained for the title compounds, which may be further improved through a single recrystallization (up to 98% de and> 99% ee).

RESUMEN

A nearly linear coordination geometry for Au is found in the title compound, [Au(C(9)H(9)N(2)O(3)S)(C(21)H(21)P)]. The thio-carbamate ligand is orientated so that the aryl group is in close proximity to the Au atom, consistent with an Au⋯π contact [Au⋯Cg = 3.351 (5) Å; Cg is the centroid of the aromatic ring].

RESUMEN

New homonuclear dimeric Pd(ii) complexes have been synthesized by the reaction of Pd(en)(2+) or Pd(bipy)(2+) (where en = ethylenediamine and bipy = 2,2'-bipyridine) units with acetamide or by the Pd(ii) mediated hydrolysis of CH(3)CN. In these dimers the two metal centers are bridged by either two amidates or by the combination of one hydroxo group and one amidate ligand. The crystal structures of complexes {[Pd(bipy)](2)(micro-1,3-CH(3)CONH)(2)}(NO(3))(2).H(2)O.1/2(CH(3))(2)CO.1/2CH(3)CN () and {[Pd(bipy)](2)(micro-1,3-CH(3)CONH)(2)}(OTf)(2) () showed intrametallic Pd-Pd distances of 2.8480(8) A () and 2.8384(7) A (), respectively, in accordance with the accepted values for a strong Pd-Pd interaction. The presence of pi[dot dot dot]pi interactions between the bipyridine ligands on the di-micro-amidate complexes of Pd(bipy)(2+) shortens the distance between the two Pd centers and allows the formation of the metal-metal interaction. By contrast, the crystal structure of complex {[Pd(en)](2)(micro-1,3-CH(3)CONH)(2)}(OTf)(2).H(2)O (), (where OTf = triflate) where there is no pi[dot dot dot]pi interaction between the ligands on the metal centers, is also reported, and no Pd-Pd interaction is observed. Additionally, one of the complexes, {[Pd(en)](2)(micro-OH)(micro-CH(3)CONH)}(NO(3))(2) (), presents an interesting hydrogen bonded 3-D network formed by nitrate ions and water molecules. All complexes have been characterized by infrared and (1)H NMR spectroscopy.

Asunto(s)

RESUMEN

The crystal structures of R3PAu[SC6H4C(=O)NH2-2], R = Et (1), Ph (2), and Cy (3) show linear coordination geometries for gold defined by sulfur and phosphorus atoms. Supramolecular aggregation via {...H-N-C=O}2 synthons lead to dimeric aggregates in each case. In (1) and (2), the aggregates are spherical, but steric effects exerted by cyclohexyl rings in (3) dictate a rodlike form; no Au...Au interactions were noted in the crystal structures. Solvent dependence in their NMR spectra is correlated with intra- and intermolecular hydrogen bonding. The compounds uniformly decompose under controlled conditions to give gold. The complexes excited by UV light produce strong blue-green luminescence. The configuration interaction singles (CIS) post-Hartree-Fock (HF) calculations for the compounds indicate that it is the charge transfer from the sulfur and pi-orbitals of SC6H4C(=O)NH2-2 to gold that produce the emission from gold. The assignment of the observed luminescence is presented in terms of the relaxed excited states of gold, in which the vibronic interactions for three p-orbitals of gold are taken into account.

RESUMEN

This report describes an investigation into the coordination chemistry of trivalent lanthanides in solution and the solid state with acyclic and preorganized bicyclic malonamide ligands. Two experimental investigations were performed: solution binding affinities were determined through single-phase spectrophotometric titrations and the extent of conformational change upon binding was investigated with single-crystal X-ray crystallography. Both experimental methods compare the bicyclic malonamide (BMA), which is designed to be preorganized for binding trivalent lanthanides, to an analogous acyclic malonamide. Results from the spectrophotometric titrations indicate that BMA exhibits a 10-100x increase in binding affinity to Ln(III) over acyclic malonamide. In addition, BMA forms compounds with high ligand-metal ratios, even when competing with water and nitrate ligands for binding sites. The crystal structures exhibit no significant differences in the nature of the binding between Ln(III) and the BMA or acyclic malonamide. These results support the conclusion that rational ligand design can lead to compounds that enhance the binding affinities within a ligand class.

Asunto(s)

RESUMEN

There are now more than 1200 papers a year describing research results using the 'neoteric' solvents, known as ionic liquids (ILs). If ILs are such highly studied solvents, why has there been so comparatively little research in their use in crystallization? Here we explore this question and discuss possible strategies for utilization of the mundane and the unique aspects of ILs for novel crystallization strategies including crystallization of high and low melting solids using thermal shifts; "solvothermal" techniques; slow diffusion; electrocrystallization; and use of a co-solvent. The results presented here and those appearing in the literature indicate both the complex nature of these solvents and their promise in delivering unique solvation, metal ion coordination numbers, coordination polymer motifs, and metal-anion interactions, to name but a few. These complex, but fascinating, results and the promise of much more intimate control over crystallization processes will drive a growing interest in using ILs as crystallization solvents.

RESUMEN

Three tripodal hexamine chelators based on cis,cis-1,3,5-triaminocyclohexane (tach) have been synthesized and their aqueous coordination chemistry with Ni(II), Cu(II) and Zn(II) is reported. The chelators have a 2-aminoethyl pendant arm attached to each nitrogen of tach, specifically 'tachen'(N,N',N''-tris(2-aminoethyl)cyclohexane-cis,cis-1,3,5-triamine), and two with S,S,S-chiral pendant arms, 'tachpn'(N,N',N''-tris(2-aminopropyl)cyclohexane-cis,cis-1,3,5-triamine) and 'tachbn'(N,N',N''-tris(2-amino-3-phenylpropyl)cyclohexane-cis,cis-1,3,5-triamine. These chelators complex Ni(II), Cu(II) and Zn(II) in aqueous or aqueous/methanolic medium. The crystalline products [M(II)L](X)2 are isolated, where M = Ni(II), Cu(II) or Zn(II), L = tachen, tachpn or tachbn, and X = ClO4-. Crystallographic study of selected tachpn and tachbn complexes shows the chelate arms are constrained in a Lambda(deltadeltadelta) configuration about M(II), which is attributed to their chirality. Solution UV-vis spectroscopy of the Ni(II) and Cu(II) complexes indicates six-coordination and little effect of the pendant arm substitution on ligand-field strength. The single exception is [Cu(tachbn)]2+, whose spectrum is consistent with five-coordination in solution. The cytotoxicities of tachen, tachpn and tachbn toward cultured cancer cells is in the order tachen < tachpn < tachbn < tachpyr, where tachpyr is the aminopyridyl chelator N,N',N''-tris(2-pyridylmethyl)cyclohexane-cis,cis-1,3,5-triamine. The cytotoxicity difference is attributed to an order of increasing lipophilicity, tachen < tachpn < tachbn.

Asunto(s)

RESUMEN

[reaction: see text] Benzo[c]selenophene has been generated via facile bromination-dehydrobromination as well as oxidation of the 1,3-dihydrobenzo[c]selenophene. Benzo[c]selenophene thus generated has been lithiated in situ and treated with ClCOOEt to give the first functionalized derivative subject to X-ray crystallographic analysis.

RESUMEN

Hydrophilic ionic liquids can be salted-out and concentrated from aqueous solution upon addition of kosmotropic salts forming aqueous biphasic systems as illustrated by the phase behavior of mixtures of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and K3PO4.

RESUMEN

The palladium-catalyzed copolymerization of styrene and CO in an ionic liquid solvent, 1-hexylpyridinium bis(trifluoromethanesulfonyl)imide, gave improved yields and increased molecular weights compared to polymerizations run in methanol.

Asunto(s)