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

The reaction of pyridine-2-thiol with AgBF4 and AgClO4 in MeCN gave rise to polymeric compounds [{Ag(HPyS)2}2(BF4)2]n (1) and [{Ag(HPyS)2}2(ClO4)2]n (2) (HPyS=pyridine-2-thione), respectively, while the similar reaction of pyridine-2-thiol with AgNO3 resulted in a polymeric compound [{Ag4(HPyS)6}(NO3)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 AgBF4 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 [Ag6(SPy)6]n (5) through soaking in DMF for 1 month. However, the similar reaction of pyridine-2-thiol with AgBF4 in MeCN–H2O (v:v=40:1) at room temperature gave another layered polymeric compound [{Ag5(Spy)4(HPyS)}BF4]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 AgNO3 with K2i-mnt (i-mnt=2,2-dicyanoethene-1,1,-dithiolate) and pyridine-2-thiol gave a polymer [Ag4(μ4-i-mnt)2(μ-HPyS)2(μ-HPyS)4/2]n (7) with one-dimensional (1-D) chain structure consisting of Ag4 square planar cluster units linked by 1H-pyridine-2-thione ligand. The treatment of AgNO3 with NaS2CNEt2 and pyridine-2-thiol in DMF resulted in another polymeric compound [Ag4(μ3-S2CNEt2)2(μ2-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.