Diammine{N-[2-(hydroxyimino)propionyl]-N′-[2-(oxidoimino)propionyl]propane-1,3-diaminido-κ4 N,N′,N′′,N′′′}iron(III)

In the title compound, [Fe(C9H13N4O4)(NH3)2], the FeIII atom, lying on a mirror plane, is coordinated by four N atoms of a triply deprotonated tetradentate N-[2-(hydroxyimino)propionyl]-N′-[2-(oxidoimino)propionyl]propane-1,3-diaminide ligand in the equatorial plane and two N atoms of two ammonia molecules at the axial positions in a distorted octahedral geometry. A short intramolecular O—H⋯O hydrogen bond between the cis-disposed oxime O atoms stabilizes the pseudo-macrocyclic configuration of the ligand. In the crystal, molecules are linked by N—H⋯O hydrogen bonds into a three-dimensional network. The ligand has a mirror-plane symmetry. One of the methylene groups of the propane bridge is disordered over two sets of sites with equal occupancy factors.

In the title compound, [Fe(C 9 H 13 N 4 O 4 )(NH 3 ) 2 ], the Fe III atom, lying on a mirror plane, is coordinated by four N atoms of a triply deprotonated tetradentate N-[2-(hydroxyimino)propionyl]-N 0 -[2-(oxidoimino)propionyl]propane-1,3-diaminide ligand in the equatorial plane and two N atoms of two ammonia molecules at the axial positions in a distorted octahedral geometry. A short intramolecular O-HÁ Á ÁO hydrogen bond between the cis-disposed oxime O atoms stabilizes the pseudo-macrocyclic configuration of the ligand. In the crystal, molecules are linked by N-HÁ Á ÁO hydrogen bonds into a three-dimensional network. The ligand has a mirror-plane symmetry. One of the methylene groups of the propane bridge is disordered over two sets of sites with equal occupancy factors.
Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97. Polydentate oxime ligands containing both oxime and other donor functions (e.g. carboxylic, amide, hydroxamic) draw considerable attention during past two decades due to their potential for the bridging mode of coordination and mediation of strong magnetic exchange interactions between metal ions (Moroz et al., 2008(Moroz et al., , 2010Skopenko et al., 1990) and for the preparation of metal complexes with efficient stabilization of unusually high oxidation states of 3d-metal ions (Fritsky et al., 1998(Fritsky et al., , 2006Kanderal et al., 2005). The open-chain tetradentate oxime-and-amide ligands were the subjects of several studies carried out in our group, and a series of mono-and polynuclear complexes of copper(III), nickel(II) and cobalt(III) have been reported within past 15 years (Duda et al., 1997;Fritsky et al., 2004Fritsky et al., , 2006Kanderal et al., 2005;Kufelnicki et al., 2010). As a part of our research study of open-chain tetradentate oxime-and-amide ligands, we present the structure of the title compound containing iron(III) as a central atom.
In the title compound, Fe III ion, lying on a mirror plane, is coordinated by four N atoms of a triply deprotonated tetradentate ligand, N,N′-bis(2-hydroxyiminopropionyl)propane-1,3-diamine, in the equatorial plane and by two N atoms of two ammonia molecules at the axial postions in a distorted octahedral geometry (Fig. 1). The tetradentate ligand coordinates the Fe III atom in a planar fashion, forming three condensed 5-, 6-and 5-membered chelate rings. All angles around the Fe III atom deviate insignificantly from 90°. There are no alternating deviations for N(oxime) and N(amide) atoms from the N1, N2, N3 and N4 plane. The values of Fe-N(amide) and Fe-N(oxime) bond lengths in the equatorial plane are in the range of 1.909 (2)-1.917 (2) Å. The distance between the Fe III atom and the two axial N atom is 1.993 (3) Å. Bond lengths of N-C and C═O of the amide groups are 1.323 (3)-1.327 (3) and 1.252 (3)-1.255 (3) Å, respectively, and are typical for the deprotonated amide groups (Dvorkin et al., 1990a, b;Lampeka et al., 1989;Onindo et al., 1995).
The bond lengths N-O and C═N of the oxime groups are 1.349 (3)-1.364 (3) and 1.291 (3)-1.292 (3) Å, respectively, that is typical for the amide derivatives of 2-hydroxypropanoic acid (Duda et al., 1997;Mokhir et al., 2002;Onindo et al., 1995;Sliva et al., 1997a, b). In the crystal, the complex molecules are linked by intermolecular N-H···O hydrogen bonds formed between the coordinated ammonia molecules and O atoms of the ligand into a three-dimensional network ( Fig. 2). An intramolecular O-H···O hydrogen bond is also present. One of the methylene groups of the propane bridge is disordered in a 0.5:0.5 ratio.

Experimental
Fe(ClO 4 ).6H 2 O (0.363 g, 1 mmol) was dissolved in 5 ml of DMSO and added to a solution of N,N′-bis(2-hydroxyiminopropionyl)propane-1,3-diamine (0.246 g, 1 mmol) in 10 ml of DMSO. The resulting deep orange mixture was stirred for 15 min at room temperature, filtered off and set aside for crystallization at ambient conditions in an ammonia atmosphere.
Red insoluble crystals of the title compound suitable for X-ray analysis were obtained in 24 h (yield: 0.227 g, 68%).

Refinement
C5 atom and all C-bound H atoms were disordered over two sets of sites across the mirror plane, with equal occupancies.
These H atoms were positioned geometrically and refined as riding atoms, with C-H = 0.99 (CH 2 ) and 0.98 (CH 3 ) Å and U iso (H) = 1.2(1.5 for methyl)U eq (C). H atoms of OH and NH 3 groups were located from a difference Fourier map and constrained to ride on their parent atoms, with U iso (H) = 1.5U eq (parent atom).

Figure 1
The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. C5 atom and all C-bound H atoms are disordered over two sets of sites across the mirror plane with equal occupancies.

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.