Tunable polymerization of silver complexes with organosulfur ligand: counterions effect, solvent- and temperature-dependence in the formation of silver(I)-thiolate(and/or thione) complexes

Abstract

The reaction of pyridine-2-thiol with AgBF 4 and AgClO 4 in MeCN gave rise to polymeric compounds [{Ag(HPyS) 2} 2(BF 4) 2] n ( 1) and [{Ag(HPyS) 2} 2(ClO 4) 2] n ( 2) (HPyS=pyridine-2-thione), respectively, while the similar reaction of pyridine-2-thiol with AgNO 3 resulted in a polymeric compound [{Ag 4(HPyS) 6}(NO 3) 4] n ( 3). X-ray single-crystal diffraction analyses showed that the cations of both 1 and 2 possess a single-metal-atom chain structure but that of 3 is a double-metal-atom chain structure. The difference between 1 (or 2) and 3 showed counterion effect in polymerization of silver-thione compounds. In the presence of water, the treatment of pyridine-2-thiol with AgBF 4 in DMF at 0 °C generated a polymeric compound [Ag(SPy)] n ( 4) (Spy=pyridine-2-thiolate) with graphite-like layered array of silver ions. Compound 4 can convert into its isomer [Ag 6(SPy) 6] n ( 5) through soaking in DMF for 1 month. However, the similar reaction of pyridine-2-thiol with AgBF 4 in MeCN–H 2O (v:v=40:1) at room temperature gave another layered polymeric compound [{Ag 5(Spy) 4(HPyS)}BF 4] n ( 6). The preparation of 4, 5, and 6 showed that temperature and solvent exert influence on formation of silver-thiolate polymers. The reaction of AgNO 3 with K 2i-mnt (i-mnt=2,2-dicyanoethene-1,1,-dithiolate) and pyridine-2-thiol gave a polymer [Ag 4(μ 4-i-mnt) 2(μ-HPyS) 2(μ-HPyS) 4/2] n ( 7) with one-dimensional (1-D) chain structure consisting of Ag 4 square planar cluster units linked by 1H-pyridine-2-thione ligand. The treatment of AgNO 3 with NaS 2CNEt 2 and pyridine-2-thiol in DMF resulted in another polymeric compound [Ag 4(μ 3-S 2CNEt 2) 2(μ 2-SPy) 4/2] n ( 8). The preparation and characterization of these polymeric compounds demonstrated that polymerization of silver(I)-thione and silver(I)-thiolate complexes is tunable through controlling reaction conditions. Semiconducting property studies of 1– 8 demonstrated that the electrical conductivity of 4 is 2.04×10 −5 S cm −1 at 25 °C and increases as temperature rises, and those of 1– 3 and 5– 8 are in the range of 1×10 −12–1×10 −15 S cm −1 at room temperature and independent on the temperature, indicating that 1 is a semiconductor and the others are insulators.