Under the condition of ultra diluted concentration w;[Pb(OAc)-2l or w[Pb(OAc)-4] < 0.2% , the local structure of lead complex dissolved in ionic liquids has been studied by Pb Z/m-edge EXAFS. Pb~4+ in bulk Pb (OAc)-4 shows 8 nearest oxygen neighbors at (0.200 ± 0.003) nm while Pb~2+ in bulk Pb(OAc)-2 shows 6 nearest oxygen neighbors at (0. 225 ± 0. 003) nm. However, both Pb~4+ and Pb~2+ dissolved in ionic liquids have very low coordination numbers, normally less than 4, indicating a low coordination property for the ionic liquids. On the other hand, the interatomic distance between Pb center and the nearest oxygen seems not comparable with each other. For example, the Pb-0 distance observed for Pb~2+ in [bmim] PF-6 is only (0. 186 ± 0. 005) nm with a very low coordination number of 2.4, while the Fourier transform clearly indicates a second coordination shell for Pb ~+ in [bmim]PF6. The Pb-0 distance observed for Pb~2+ in [bmimJPFs, which is only (0. 211 ±0.005) nm, is also significantly shorter than that (0.225 nm) in bulk Pb(OAc)2- The Pb ions dissolved in [bmim]BF-4, which are 0.223nm for Pb~ + and 0.210 nm for Pb~ + respectively, exhibit that the Pb- 0 distances are of no more difference with those in bulk samples.

Key words: LEAD COMPLEX, COORDINATION NUMBER, SOLUTE, ionic liquids