Figure 2 Six ferrocenylphosphonic acid molecules are connected by intermolecular O-H...O hydrogen bonds (dashed lines), forming a distorted octahedral cage. [Symmetry codes: (i) 1/3+y, 2/3-x+y, -1/3-z; (ii) 1/3+x-y, -1/3+x, -1/3-z; (iii) 3/4-x, 2/3-y, -1/3-z; (iv) 1-y, x-y, z; (v) 1-x+y, 1-x, z.]  [article HTML]