Solvent-effect on the interconversion among one-, two- and four-electron reduction waves for the 18-molybdodiphosphate complex, [(P2O7)Mo18O54](4-)

For the [(P2O7)Mo18O54](4-) complex, the presence of small cations such as H+, Li+ and Na+ caused one-electron waves to be converted into four- and tw o-electron waves in a complex manner. With the addition of a trace amount o f H+, a four-electron reduction wave was obtained in solvents of weaker bas icity like acetone, acetonitrile and propylene carbonate (PC); the relative permittivity did not affect the appearance of the four-electron wave. On t he other hand, two-electron waves were obtained in solvents of stronger bas icity like N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), and N- methylpyrrolidinone (NMP). With the addition of Li+ or Na+, the one-electro n waves were converted into two-electron waves only in acetone, indicating that the conversion can occur in solvents of both weak basicity and low rel ative permittivity. (C) 2000 Elsevier Science B.V. All rights reserved.