Chromium trifluoride, structure

The structure can be divided into infinite chains of linked octahedra. Those for Cr(III), joined through opposite corners, with a Cr—F—Cr angle of 160°, have a very similar orientation to that in chromium trifluoride itself. Similarly, those for Cr(II), joined through opposite edges, have the same orientation as in the distorted rutile structure of the difluoride. 

A comparison of the volumes per formula unit for the trifluorides is more complicated than for the difluorides because of the changes in structure type. If these changes are ignored, then some correlation with electronic configuration is possible. For the first transition series the volume decreases from scandium to chromium, increases from chromium to iron, and decreases to cobalt. This is as expected for the characteristic ligand-field stabilization effects (49), comparable with those for the difluorides. In the second series, there is a decrease from... 

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