An expedient synthesis of mellitic triimides

Heating of the solid ammonium salts obtained from treatment of mellitic acid with 3 equiv of a primary amine yields trisubstituted mellitic triimides via dehydration and imide ring closure. This surprisingly simple synthetic approach is amenable to incorporation of alkyl, aryl, and amino acid ester substituents, thereby opening broad access to a family of C(3)-symmetric organic electron acceptors.     

Crystal structures of 2-pyrazinecarboxylato silver(I) and ammine 2,3-pyrazinecarboxylato disilver(I)

X-ray analysis has shown that the complexes of silver(I) with the anionic forms of 2-pyrazinecarboxylic and 2,3-pyrazinedicarboxylic acids are three-dimensional network polymers. Ag(C₅H₃O₂N₂) (1) crystallizes in space groupPna2₁ witha=7.028(2),b=11.510(3),c=6.949(2) Å andZ=4. Silver tetrahedral coordination occurs through three ligands: the first one acts as a bidentate chelator (Ag–O=2.539(4), Ag–N=2.334(4)Å), the second one involves one N pyrazine atom (Ag–N=2.196(4)Å) and the third one bonds through one O-carboxylato atom (Ag–O=2.323(4)Å). The dinuclear complex Ag₂(C₆H₂O₄N₂)(NH₃) (2) crystallizes in space groupP2₁/c witha=7.775(2),b=16.455(2),c=7.174(1) Å, -115.21(1)° andZ =4. Each of the two silver atoms shows a trigonal environment. The first silver atom involves two O carboxylic atoms (Ag–O=2.312(4), 2.374(4)Å) and one N pyrazine atom (Ag–N=2.277(3)Å) belonging to three different ligands. The second one involves one O carboxylic atom (Ag–O=2.364(3)Å) and one N pyrazine atom (Ag–N=2.304(4)Å) from the same chelating ligand and one N ammine atom (Ag–N=2.158(5)Å).