coordinating polyhedron in a sentence

1. For typical ionic solids, the cations are smaller than the anions, and each cation is surrounded by ionic radii determines the cation-anion distance, while the cation-anion radius ratio r _ + / r _-( or r _ c / r _ a ) determines the coordination number ( C . N . ) of the cation, as well as the shape of the coordinated polyhedron of anions.
2. It's difficult to find coordinating polyhedron in a sentence.