Synthesis, study and structural characterization of a new water soluble hexanuclear silver(I) cluster with the 2-mercapto-nicotinic acid with possible antiviral activity

Silver(I) chloride reacts with 2-mercapto-nicotinic acid (H(2)mna, C6H5NO2S) in the presence of an excess of triethylamine in DMSO to form a hexanuclear, water soluble, cluster of formula {[Ag-6(mu(3)-Hmna)(4)(mu(3)-mna)(2)](2-) (.)[(Et3NH)(+)](2)(.)(DMSO)(2)(.)(H2O)} (1). The complex 1 was characterized by elemental analyses, and FT-IR, UV-Vis and H-1 NMR spectroscopy. Crystal structures of complex 1 and the ligand, 2-mecapto-nicotinic acid (2), have been determined by X-ray diffraction. Compound 1, C52H68Ag6-N8O15S8, is monoclinic with a space group P2(1)/c (No. 14) and a = 11.7080(10), b = 16.2920(10), c = 18.3010(10) Angstrom, beta = 91.350(10)degrees, Z = 4. The entire molecule is ionic and consists of a double anionic hexa-nuclear cluster and two protonated triethylamine counter cations while it is solvated by two DMSO and one water molecule. The 2-mercapto-nicotinic acid (2), C6H5NO2S, is orthorhombic (space group Pna2(1) (No. 33), a = 8.3910(10), b = 13.2720(10), c = 5.892 Angstrom, Z = 4). An extended inter-molecular hydrogen bonding via (OH)-H-...-N contacts (O(1)H-...(5)[N(5)] = 1.8998, O(1)N-...(5) = 2.8049 Angstrom) links the molecules forming a supramolecular two-dimensional network. Complex 1, was evaluated for anti-HIV-RT activity. It was found to inhibit the human immunodeficiency viral replication reverse transcriptase (HIV-RT) with calculated inhibiting concentration (IC50) 0.01275 +/- 0.00115 mg ml(-1). (C) 2002 Elsevier Science B.V. All rights reserved.Chemistry, Inorganic & NuclearSCI(E)42ARTICLE361-36534