catena-Poly[[(pyrimidine-2-carboxylic acid)iron(II)]-μ-oxalato]

In the title complex, [Fe(C2O4)(C5H4N2O4)]n, the FeII ion is coordinated by two oxalate anions and a pyrimidine-2-carboxylic acid ligand in a slightly distorted octahedral geometry. Each oxalate anion chelates to two FeII ions, forming chains along the a axis. The chains are further connected by O—H⋯O and C—H⋯O hydrogen bonds, stabilizing the structure. An intramolecular O—H⋯N interaction results in a five-membered ring.

In the title complex, [Fe(C 2 O 4 )(C 5 H 4 N 2 O 4 )] n , the Fe II ion is coordinated by two oxalate anions and a pyrimidine-2carboxylic acid ligand in a slightly distorted octahedral geometry. Each oxalate anion chelates to two Fe II ions, forming chains along the a axis. The chains are further connected by O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds, stabilizing the structure. An intramolecular O-HÁ Á ÁN interaction results in a five-membered ring.

Related literature
For related structures, see: Zhang et al. (2008).
structure of a new iron complex with pyrimidine-2-carboxylic acid and oxalate as co-ligands.
In the title complex, the Fe II ions are coordinated by one HL ligand and two oxalate anions in a slightly distorted octahedral geometry (Fig. 1). Each oxalate anion chelates to two Fe II ions resulting a chain along the a-axis. There is an intramolecular interaction O6-H6···N2 resulting in a five membererd ring. The O-H···O and C-H···O type hydrogen bonds between the oxalate and HL ligands impart stability to the structure (Fig. 2).

Experimental
A mixture of Fe(III) chloride (2 mmol), oxalate acid (2 mmol)and pyrimidine-2-carbonitrile (1 mmol), in 10 ml dimethyl formamate (DMF) solvent was sealed in a Teflon-lined stainless-steel Parr bomb was heated at 413 K for 48 h. Red crystals of the title complex were collected after the bomb was allowed to cool to room temperature; yield 20%.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 Rfactors(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.