Pair-distribution function analysis of the structural valence transition in Cp*2Yb(4,4'-Me2-bipy)

The Cp*2Yb(L) class of compounds, where Cp*=pentamethylcyclopentadienyl = C5Me5 and L is either a 1,4-diazabutadiene or bipy = 2,2'-bipyridine related ligand, have provided excellent analogies to the Kondo state on the nanoscale. Cp*2Yb(4,4'-Me2-bipy) furthers this analogy by demonstrating a valence transition as the sample is cooled below 200 K. Here, pair-distribution function (PDF) analysis of x-ray powder diffraction data demonstrate that the Cp*2Yb(4,4'-Me2-bipy) molecule is virtually unchanged through the valence transition. However, the molecule's stacking arrangement is altered through the valence transition.