title: The cobalt(II) salt of the azo dye Orange G.
abstract: Crystallizing the cobalt(II) salt of the azo dye Orange G from water was found to give the solvent-separated ion-pair species hexa-aqua-cobalt(II) 7-oxo-8-(2-phenyl-hydrazin-1-ylidene)-7,8-dihydro-naphthalene-1,3-disulfonate tetra-hydrate, [Co(H(2)O)(6)](C(16)H(10)N(2)O(7)S(2))·4H(2)O. The asymmetric unit of the cobalt(II) salt contains three independent octa-hedral [Co(OH(2))(6)](2+) cations, three azo anions, all with similar configurations, and 12 uncoordinated water mol-ecules. The structure is closely related to that of one of the known magnesium analogues. Both structures have Z' = 3, feature nearly planar azo anions [maximum displacement of azo-N atoms from the plane of the phenyl ring = 0.058 (7) Å] in their hydrazone tautomeric form, form layer structures with hydro-philic and hydro-phobic layers alternating along the b-axis direction, and are stabilized by an extensive network of hydrogen bonds..
authors.forename: Alan R
authors.initials: AR
authors.lastname: Kennedy
authors.forename: Scott C
authors.initials: SC
authors.lastname: McKellar
authors.forename: Maurice O
authors.initials: MO
authors.lastname: Okoth