A new salt - [Ni II(DMSO) 5(TTFPy)] 2[α -SiW 12O 40] (1) - based on polyoxometalates was prepared by coordinating a cationic electron donor of pyridyltetrathiafulvalene (TTFPy) with Ni II. Although the TTFPy molecule did not form a salt with the anionic α-[SiW VI 12O 40] 4- because of the weak charge-transfer (CT) interaction, the coordination of Ni with the pyridyl moiety permitted salt formation driven by electrostatic interaction, giving a single crystal of 1. Crystallographic analysis, UV-vis and IR spectroscopy and electrochemical characterization revealed that the fully oxidized α-[SiW VI 12O 40] 4- was crystallized with the neutral TTFPy moiety from the acetonitrile solution because of the low electron-withdrawing ability of α-[SiW VI 12O 40] 4-, forming a brown-orange crystal. The crystal colour quickly turned to black by immersing in methanol, due to CT from TTF moiety to α-[SiW VI 12O 40] 4-, which was caused by the solvent effect. Increase in the solvent acceptor number from 18.9 for acetonitrile to 41.3 for methanol resulted in the enhancement of the electron withdrawing ability of α-[SiW VI 12O 40] 4- by 0.317 V in methanol.
ASJC Scopus subject areas
- Inorganic Chemistry