We report the mechanical properties of a framework structure, [Cu2F(HF)(HF2)(pyz)4][(SbF6)2]n (pyz = pyrazine), in which [Cu(pyz)2]2+ layers are pillared by HF2− anions containing the exceptionally strong F–H⋯F hydrogen bonds. Nanoindentation studies on single-crystals clearly demonstrate that such bonds are extremely robust and mechanically comparable with coordination bonds in this system.
