Poly[bis­(acetone-κO)bis­{μ(3)-1-[(5-chloro-2-oxidophenyl)diazenyl]-2-naphtholato-κ(4) O:O,O′:O′}­sodium(I)­chromium(III)]

The title compound, [CrNa(C(16)H(9)ClN(2)O(2))(2)(C(3)H(6)O)(2)](n), is an azo-Cr(III) complex polymer that is used as a charge-control agent in electrophotography. The monomeric unit is composed of octa­hedral Cr(III) and Na(I) units, and is characterized by twofold rotation symmetry. The Cr(III) atom is chelated by two N and four O atoms from two [(5-chloro-2-oxidophen­yl)diazen­yl]-2-naphtholate ligands. The ligand anion exists in the cis form. The Na(I) atom is coordinated by two phen­oxy O atoms from a neighboring Cr(III) unit, two naphth­oxy O atoms from another neighboring Cr(III) unit and two O atoms from acetone mol­ecules. The dinuclear complex forms a one-dimensional polymer running along the c axis.