A refinement of the structure of deuterium peroxide

The structure of deuterated hydrogen peroxide, D2O2, at −15 °C was refined by least-squares methods from three dimensional neutron diffraction data. The data were fitted to two models, one with conventional anisotropic temperature factors and the other with the molecule treated as a rigid body except for torsional oscillations of the O–D groups about the O–O bond. The weighted agreement indices were 0.030 over 106 observed reflections for the conventional model and 0.032 over 102 reflections for the rigid body model. The structure is tetragonal, space group P41212 or P43212, with a=4.035 Å, c=7.97 Å, Z=4. Position parameters for the two models are essentially the same. The O–O distance in the molecule, 1.455(2) Å, is identical to that found in H2O2, but the O–D bond is about 0.015 Å shorter than the O–H bond, 0.993 Å as compared with 1.008 Å when corrected for thermal motion by the riding model. The O–O distance corrected for thermal motion in the rigid body model is 1.49 Å, in fair agreement with the value 1.48 Å found in the vapor phase.