Diacetonitriletetrakis{μ2-3-anilinocarbonyl-1-[(5-chloro-2-oxidophenyl)diazenyl]-2-naphtholato}tetraaquadiiron(III)disodium(I) dihydrate

The title compound, [Fe2Na2(C23H14ClN3O3)4(C2H3N)2(H2O)4]·2H2O, is a hydrated Fe–azo complex dimer that is used as a charge-control agent in electrophotography. The molecule is a centrosymmetric dimer with two octahedral FeIII units linked by two bridging five-coordinate NaI cations. Each FeIII atom is chelated by the N and two O atoms from two 3-anilinocarbonyl-1-[(5-chloro-2-oxidophenyl)diazenyl]-2-naphtholate ligands. The Na+ cation is coordinated by a carbonyl O atom from the two ligands of each octahedral FeIII unit, two water molecules and the N atom of an acetonitrile molecule. Two solvent water molecules complete the structure. In the crystal structure, the dimeric molecules are bridged by a pair of discrete intermolecular O—H⋯O hydrogen bonds, one of which involves a sodium-bound water molecule and a hydrate water, and the other a 5-chlorophenolate O atom and a water molecule to form an extended chain along b.


Related literature
For general background to charge-control agents, see Tanaka (1995); and for the preparation of the title compound, see Yasumatsu et al. (2006). For related structures, see: ; Mizuguchi et al. (2007a,b); .
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SJ2453). The dimer comprises two octahedral Fe III units linked by two bridging five-coordinate Na I cations. Each Fe III atom is chelated by the N and two O atoms from two 3-anilinocarbonyl-1-[(5-chloro-2-oxidophenyl)diazenyl]-2-naphtholate ligands with the naphtholate and chloro-2-oxidophenyl O atoms mutually cis. In each octahedral Fe III unit, there are two intramolecular N3-H3N···O1 and N6-H6N···O3 hydrogen bonds that effect the conformation of the molecule ( Table   2). The five-coordinate Na cation binds to N7 of the acetonitrile molecule, the O7 and O8 atoms of the two coordinated water molecules, and to the O6 and O5 i carbonyl O atoms from of each octahedral Fe III unit [symmetry code (i): 1 -x, -y, 1 -z]). There are also two hydrated water molecules O9 and O9 ii [symmetry code (ii): x, y -1,z].
In the crystal structure the dimeric molecules are bridged by a pair of discrete intermolecular O-H···O hydrogen bonds as shown in Fig. 3. One of these involves a sodium bound water molecule and a hydrate water, and the other a 5chlorphenolate O atom and a hydrate water to form an extended chain along b. The atoms involved are: O8-(H)···O9 and O9-(H)···O4 ii [symmetry code: (ii) x, -1 + y, z] with the H atoms in parenthesis not located. The H atoms on the O7, O8 and O9 atoms of the water molecules could not be found in difference density maps. However the bond distances O8 -O9, 2.730 (7) and O9-O4 ii , 2.710 (6) Å [symmetry code: (ii) x, -1 + y, z] strongly suggest the presence of classical hydrogen bonds.

S2. Experimental
Compound I was prepared according to the previously reported method (Yasumatsu et al., 2006). Single crystals of (I) were recrystallized from an acetonitrile solution as blocks over a 48 h period.

S3. Refinement
All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H = 0.93 except for C-H in methyl groups (0.96) and N-H = 0.86 A, and U iso (H) = 1.2 U eq (parent atom). Six H atoms on supporting information sup-2 Acta Cryst. (2008). E64, m240-m241 the three water molecules (O7, O8 and O9) were not located in difference electron density maps. R-merge for the reflection data was 12.5%. This indicates poor crystal quality resulting in a rather high value of the R factor.

Diacetonitriletetrakis{µ 2 -3-anilinocarbonyl-1-[(5-chloro-2-oxidophenyl)diazenyl]-2-naphtholato}tetraaquadiiron(III)disodium(I) dihydrate
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.17 e Å −3 Δρ min = −1.00 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq