RESUMEN
The title thia-pyrazino-phanes, 2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane, C16H24N2S6, (I), and 2,5,8,11,14,17-hexa-thia-[9.9](2,5,3,6)-pyrazino-phane, C16H24N2S6, (II), are regioisomers; m-bis L1 and p-bis L1, respectively. Both compounds have a central tetra-2,3,5,6-methyl-ene-pyrazine unit with two -S-CH2-CH2-S-CH2-CH2-S- chains, linking the methyl-ene C atoms at positions 2 and 6 and 3 and 5 on the pyrazine ring of I, but linking the methyl-ene C atoms at positions 2 and 5 and 3 and 6 on the pyrazine ring of II. Both compounds crystallize with half a mol-ecule in the asymmetric unit. The whole mol-ecule of I is generated by inversion symmetry, with the pyrazine ring being located about a center of symmetry. The whole mol-ecule of II is generated by twofold rotation symmetry, with the pyrazine N atoms being located on the twofold rotation axis. In compound I, there are pairs of intra-molecular C-Hâ¯S contacts present, but none in compound II. In the crystal of I, there are no significant inter-molecular inter-actions present, while in the crystal of II, mol-ecules are linked by pairs of C-Hâ¯S hydrogen bonds, forming corrugated layers lying parallel the ac plane. The Hirshfeld surfaces and the energy frameworks of the two regioisomers indicate little difference in the inter-atomic contacts, which are dominated by dispersion forces.
RESUMEN
The reaction of the hexa-thia-pyrazino-phane ligand, 2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane (L1), with copper(II) dibromide led to the formation of a binuclear complex, [µ2-2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane]bis-[bromi-docopper(II)] dibromide, [Cu2Br2(C16H24N2S6)]Br2, (I). The complex possesses inversion symmetry with the pyrazine ring being situated about a center of symmetry. The ligand coordinates to the copper(II) atom in a bis-tetra-dentate manner and the copper atom has a fivefold NS3Br coordination environment with a distorted shape. The reaction of ligand L1 with copper(I) iodide also gave a binuclear complex, which is bridged by a Cu2I2 unit to form a two-dimensional coordination polymer, poly[[µ2-2,5,8,11,14,17-hexa-thia-[9.9](2,6,3,5)-pyrazino-phane]tetra-µ-iodido-tetra-copper(I)], [Cu4I4(C16H24N2S6)] n , (II). The binuclear unit possesses inversion symmetry with the pyrazine ring being located about a center of symmetry. The Cu2I2 unit is also located about an inversion center. The two independent copper(I) atoms are both fourfold coordinate. That coordinating to the ligand L1 in a bis-tridentate manner has an NS2I coordination environment and an irregular shape, while the second copper(I) atom, where L1 coordinates in a bis-monodentate manner, has an SI3 coordination environment with an almost perfect tetra-hedral geometry. In the crystal of I, the cations and Br- anions are linked by a number of C-Hâ¯S and C-Hâ¯Br hydrogen bonds, forming a supra-molecular network. In the crystal of II, the two-dimensional coordination polymers lie parallel to the ab plane and there are no significant inter-layer contacts present.
RESUMEN
The two new pyrazine-ophanes, 5,7-di-hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b:6',7'-e]pyrazine, C12H16N2S4, L2, both crystallize with half a mol-ecule in the asymmetric unit; the whole mol-ecules are generated by inversion symmetry. The mol-ecule of L1, which is planar (r.m.s. deviation = 0.008â Å), consists of two sulfur atoms linked by a rigid tetra-2,3,5,6-methyl-ene-pyrazine unit, forming planar five-membered rings. The mol-ecule of L2 is step-shaped and consists of two S-CH2-CH2-S chains linked by the central rigid tetra-2,3,5,6-methyl-ene-pyrazine unit, forming eight-membered rings that have twist-boat-chair con-fig-urations. In the crystals of both compounds, there are no significant inter-molecular inter-actions present. The reaction of L1 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[(µ-5,7-di-hydro-1H,3H-dithieno[3,4-b;3',4'-e]pyrazine-κ2 S:S')(µ-nitrato-κ2 O: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 bis-ects 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-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b;6',7'-e]pyrazine-κ3 S: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-Hâ¯O hydrogen bonds, forming supra-molecular frameworks. There are additional C-Hâ¯S contacts present in the supra-molecular framework of II.
RESUMEN
The reaction of ligand 3,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b:6',7'-e]pyrazine (L) with CuI led to the formation of a two-dimensional coordination polymer, incorporating a [Cu2I2] motif. These units are linked via the four S atoms of the ligand to form the title two-dimensional coordination poly-mer, poly[[µ4-3,4,8,10,11,13-hexa-hydro-1H,6H-bis-([1,4]di-thio-cino)[6,7-b:6',7'-e]pyrazine]di-µ-iodido-dicopper(I)], [Cu2I2(C12H16N2S4)] n , (I). The asymmetric unit is composed of a ligand mol-ecule, two copper(I) atoms and two I- ions. Both copper(I) atoms are fourfold S2I2 coordinate with almost regular trigonal-pyramidal environments. In the crystal, the layers, lying parallel to (102), are linked by C-Hâ¯I hydrogen bonds, forming a supra-molecular framework.
RESUMEN
The reaction of ligand 5,7-di-hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine (L) with CuI lead to the formation of a three-dimensional coordination polymer, incorporating the well known [Cu x I x ] n staircase motif (x = 4). These polymer [Cu4I4] n chains are linked via the N and S atoms of the ligand to form the three-dimensional coordination polymer poly[(µ4-5,7-di-hydro-1H,3H-dithieno[3,4-b:3',4'-e]pyrazine-κ4 N:N':S:S')tetra-µ3-iodido-tetra-copper], [Cu4I4(C8H8N2S2)] n (I). The asymmetric unit is composed of half a ligand mol-ecule, with the pyrazine ring located about a center of symmetry, and two independent copper(I) atoms and two independent I- ions forming the staircase motif via centers of inversion symmetry. The framework is consolidated by C-Hâ¯I hydrogen bonds.
RESUMEN
The reaction of the ligand 2,3,5,6-tetra-kis-[(methyl-sulfanyl)-meth-yl]pyrazine (L1) with silver(I) nitrate led to {[Ag(C12H20N2S4)](NO3)} n , (I), catena-poly[[silver(I)-µ-2,3,5,6-tetra-kis-[(methyl-sulfan-yl)meth-yl]pyrazine] nitrate], a compound with a metal-organic chain structure. The asymmetric unit is composed of two half ligands, located about inversion centres, with one ligand coordinating to the silver atoms in a bis-tridentate manner and the other in a bis-bidentate manner. The charge on the metal atom is compensated for by a free nitrate anion. Hence, the silver atom has a fivefold S3N2 coordination sphere. The reaction of the ligand 2,3,5,6-tetra-kis-[(phenyl-sulfanyl)-meth-yl]pyrazine (L2) with silver(I) nitrate, led to [Ag2(NO3)2(C32H28N2S4)] n , (II), poly[di-µ-nitrato-bis-{µ-2,3,5,6-tetra-kis-[(phenyl-sulfan-yl)meth-yl]pyrazine}disilver], a compound with a metal-organic network structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. The nitrate anion coordinates to the silver atom in a bidentate/monodentate manner, bridging the silver atoms, which therefore have a sixfold S2NO3 coordination sphere. The reaction of the ligand 2,3,5,6-tetra-kis-[(pyridin-2-yl-sulfanyl)-meth-yl]pyrazine (L3) with silver(I) nitrate led to [Ag3(NO3)3(C28H24N6S4)] n , (III), poly[trinitrato{µ6-2,3,5,6-tetra-kis[(pyri-din-2-ylsulfan-yl)meth-yl]pyrazine}-trisilver(I)], a compound with a metal-organic framework structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. One pyridine N atom bridges the monomeric units, so forming a chain structure. Two nitrate O atoms also coordinate to this silver atom, hence it has a sixfold S2N2O2 coordination sphere. The chains are linked via a second silver atom, located on a twofold rotation axis, coordinated by the second pyridine N atom. A second nitrate anion, also lying about the twofold rotation axis, coordinates to this silver atom via an Ag-O bond, hence this second silver atom has a threefold N2O coordination sphere. In the crystal of (I), the nitrate anion plays an essential role in forming C-Hâ¯O hydrogen bonds that link the metal-organic chains to form a three-dimensional supra-molecular structure. In the crystal of (II), the metal-organic networks (lying parallel to the bc plane) stack up the a-axis direction but there are no significant inter-molecular inter-actions present between the layers. In the crystal of (III), there are a number of C-Hâ¯O hydrogen bonds present within the metal-organic framework. The role of the nitrate anion in the formation of the coordination polymers is also examined.
RESUMEN
The title compound, C12H20N2S4, synthesized by the reaction of 2,3,5,6-tetra-kis-(bromo-meth-yl)pyrazine with sodium methane-thiol-ate, crystallizes with a half -mol-ecule in the asymmetric unit. The whole mol-ecule is generated by inversion symmetry; the inversion centre being located in the centre of the pyrazine ring. The mol-ecule has an S-shaped conformation with two (methyl-sulfan-yl)methyl substituent arms directed above the plane of the pyrazine ring and two below. The C(H3)-S-C(H2)-C(aromatic) torsion angles are 70.47â (18) and -67.65â (17)°, respectively. In the crystal, mol-ecules are linked via weak C-Hâ¯S hydrogen bonds, forming chains along [001] and enclosing R 2 (2)(12) ring motifs. The chains are linked by further weak C-Hâ¯S hydrogen bonds, forming sheets lying parallel to (101).
RESUMEN
The title compound, C8H8Br4N2, crystallizes in the enanti-omorphic-defining space group P41212 and has a refined Flack x parameter of 0.04â (4). In the asymmetric unit, there are two half-mol-ecules; the whole mol-ecules (A and B) are generated by twofold rotation symmetry. In mol-ecule A, the twofold axis is normal to the pyrazine ring passing through the centre of the ring, while in mol-ecule B, the twofold rotation axis lies in the plane of the pyrazine ring bis-ecting the C-C aromatic bonds. The two mol-ecules are pseudo-mirror images of one another, and the best fit of the two mol-ecules was obtained for inverted mol-ecule B on mol-ecule A, with an r.m.s. deviation of 0.1048â Å and a maximum deviation of any two equivalent atoms of 0.2246â Å. In the crystal, the A mol-ecules are linked by weak C-Hâ¯Br hydrogen bonds and Brâ¯Br inter-actions [3.524â (3)â Å], forming a three-dimensional framework. The B mol-ecules are also linked by weak C-Hâ¯Br hydrogen bonds and Brâ¯Br inter-actions [3.548â (3)â Å], forming a three-dimensional network that inter-penetrates the network of A mol-ecules.
RESUMEN
The title compounds, C(32)H(28)N(2)O(4), (I), and C(32)H(28)N(2)S(4), (II), respectively, are tetrasubstituted pyrazines and both possess C(i) symmetry. They differ only in the hetero atom (X) of the -CH(2)XPh side-arm substituents: X = O in (I) and S in (II). Compound (I) has an overall S-shape with a pair of adjacent -CH(2)OPh side arms alternately above and below the plane of the central pyrazine ring. The phenyl rings are inclined to one another by 12.63 (18) degrees and there is one intramolecular C-H...O hydrogen bond involving adjacent -CH(2)OPh side arms. In compound (II), adjacent -CH(2)SPh side arms point in opposite directions with respect to the pyrazine ring plane, with the phenyl rings inclined at 60.45 (8) degrees. Both structures have weak C-H...pi intermolecular interactions.
RESUMEN
A short, efficient synthesis of the lignan (+)-lyoniresinol dimethyl ether is described. The synthesis is achieved by asymmetric photocyclization of an achiral dibenzylidenesuccinate to a chiral aryldihydronaphthalene. (-)-Ephedrine is used as a chiral auxiliary to bias the atropisomeric equilibrium in the dibenzylidenesuccinate prior to the photochemical reaction. The synthesis of the title compound was accomplished in five steps, and the final product was recrystallized to constant melting point and rotation.