An ordered low-temperature phase of barium nitro­prusside trihydrate studied by neutron diffraction

Crystals of barium penta­cyano­nitro­syl­ferrate trihydrate (barium nitro­prusside trihydrate), Ba[Fe(CN)₅(NO)]·3H₂O, have been studied by neutron diffraction in order to ex­amine the structural behaviour of the compound in the 20-120 K temperature range and to determine the structure at 105 K.