Abstract
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 = 0.008 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-H⋯O hydrogen bonds, forming supra-molecular frameworks. There are additional C-H⋯S contacts present in the supra-molecular framework of II.
Highlights
The two new pyrazineophanes, 5,7-dihydro-1H,3H-dithieno[3,4-b:30,40-e]pyrazine, C8H8N2S2, L1, and 3,4,8,10,11,13-hexahydro-1H,6H-bis([1,4]dithiocino)[6,7-b:60,70-e]pyrazine, C12H16N2S4, L2, both crystallize with half a molecule in the asymmetric unit; the whole molecules are generated by inversion symmetry
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 reaction of L2 with silver nitrate leads to the formation of a two-dimensional coordination polymer, poly[[33,4,8,10,11,13-hexahydro1H,6H-bis([1,4]dithiocino)[6,7-b;60,70-e]pyrazine-3S:S0:S00](nitrato-O)silver(I)], [Ag(NO3)(C12H16N2S4)]n, (II), with the nitrate anion coordinating in a monodentate manner to the silver atom
Summary
Ligands with mixed hard and soft binding characters, such as N and S donor atoms, are known to display diverse coordination properties, either by binding selectively to metal centers or by coordination to a wide range of metal cations giving rise to unusual coordination geometries. Because of this and the rigidity of the entire molecule, the potential chelating ability appears compromised, as stated by Shimizu and colleagues, who prepared a number of AgI polymer networks with the benzene analogue of L1, 5,7-dihydro-1H,3H-benzo[1,2-c:4,5-c0]dithiophene (Shimizu et al, 1998; 1999; Melcer et al, 2001). Pyrazine ring being located about a center of symmetry It consists of two S–CH2–CH2–S chains linked by the central rigid tetra-2,3,5,6-methylenepyrazine unit, forming eightmembered rings. The molecule is step-shaped with six potential sites for coordination
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
