Ws. Hwang et al., SILVER(I) COMPLEXES OF SCHIFF-BASES DERIVED FROM THIOPHENE-2,5-DICARBOXALDEHYDE AND FURAN-2,5-DICARBOXALDEHYDE, Journal of the Chinese Chemical Society, 45(2), 1998, pp. 269-275
The reactions of Schiff bases, derived by the condensation of thiophen
e-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde with 2-thienylmethyl
amine or 2-furanmethylamine, with silver nitrate have been studied in
refluxing anhydrous methanol under nitrogen atmosphere. Complexes thus
formed have been isolated and characterized by elemental analysis, el
ectrical conductance, cyclic voltammetry, and H-1 NMR, C-13 NMR, IR, U
V-Vis, and mass spectroscopic studies. The experimental results reveal
that the complexes are primarily ionic in nature, consisting of (L)(3
)Ag-2 dication and Ag(NO3)(3) negatively charged dianions. The molecul
ar structure of one of the complexes, [((C4H3O)CH2N=CH(C4H2S)CH=NCH2(C
4H3O))(3)Ag-2] [Ag(NO3)(3)] has been studied in the solid state. The c
omplex is crystallized in the triclinic space group P (1) over bar wit
h a = 12.889(7) Angstrom, b = 14.884(5) Angstrom, c = 15.084(6) Angstr
om, alpha = 92.18(4)degrees, beta = 79.78(4)degrees, gamma = 110.92(4)
degrees. The structure is disordered. Each Ag in dication is tri-coord
inated by three azomethine N atoms from three ligands, and each ligand
employs two azomethine N atoms to coordinate to two Ag ions such that
the geometry around the Ag ... Ag axis conforms to a propeller-shape.
The two Ag ions are between the two N-3 planes with Ag ... Ag distanc
e ca. 4.81 Angstrom. There is no bonding between any Ag ion and any th
iophene of the three ligands. However, two Ag ions and three thiophene
S atoms form a trigonal bipyramidal geometry.