Poly[[tetrakis(μ2-pyrazine N,N′-dioxide-κ2O:O′)holmium(III)] tris(perchlorate)]

The title three-dimensional coordination network, {[Ho(C4H4N2O2)(4)](ClO4)(3)}(n), is isostructural to that of other lanthanides. The Ho+3 cation lies on a fourfold roto-inversion axis. It is coordinated in a distorted square anti-prismatic fashion by eight O atoms from bridging pyrazine N, N'-dioxide ligands. There are two unique pyrazine N, N'-dioxide ligands. One ring is located around an inversion center, and there is a a twofold rotation axis at the center of the other ring. There are also two unique perchlorate anions. One is centered on a two-fold rotation axis and the other on a fourfold roto-inversion axis. The perchlorate anions are located in channels that run perpendicular to (001) (110) and interact with the coordination network through C-H center dot center dot center dot O hydrogen bonds.