Valence Delocalization in Prussian Blue Fe[FeII(CN)6]3 · XD2O,by Polarized Neutron Diffraction

Polarized neutron diffraction has been used to investigate the spin delocalization from the high-spin Fe(III) sites to the low-spin Fe(II) in deuteriated Prussian Blue, Fe₄[Fe(CN)₆]₃ · xD₂O. Measurements of the 111, 200, and 400 reflections were made on a powdered sample at 3 K and 4.8 T using a neutron wavelength of 1.074 Å. The expectation value of S at the Fe(II) site is - 0.008 ± 0.028 corresponding to an upper limit of about 5% of an electron for the spin delocalization.