trans-Diaquabis(l-phenylalaninato-κ2 N,O)nickel(II)

In the title compound, [Ni(C9H10NO2)2(H2O)2], the coordination geometry around the NiII ion can be described as distorted octahedral, with two N atoms and two O atoms from phenylalaninate ligands in the basal plane and two aqua O atoms at the axial sites. The crystal packing is stabilized by intermolecular O—H⋯O and N—H⋯O hydrogen bonds.

In the title compound, [Ni(C 9 H 10 NO 2 ) 2 (H 2 O) 2 ], the coordination geometry around the Ni II ion can be described as distorted octahedral, with two N atoms and two O atoms from phenylalaninate ligands in the basal plane and two aqua O atoms at the axial sites. The crystal packing is stabilized by intermolecular O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds.

trans-Diaquabis(L-phenylalaninato-κ 2 N,O)nickel(II)
Massomeh Ghorbanloo, Nahid Shahbakhsh and Duane Choquesillo-Lazarte Comment Amino acids are of special importance among the other chemical substances since they form the basic constituents of living organisms. It is imperative to know the properties of amino acids in order to understand and explain their behavior and the synthesis of peptides, proteins and enzymes in living organisms. Also they are widely applied in food, cosmetic, pharmaceutical and chemical industry. It is known that the reactions of peptides, proteins and enzymes with metal ions are of biochemical importance but they are yet to be thoroughly understood (Thanavelan et al., 2011). The explanation of these phenomena in the biological systems can be possible only by the determination of structure of amino acids.
Because of the importance the characterization of amino acid derivatives, here, we report the synthesis and crystal structure of Trans-diaqua-bis[(L-phenylalanine)-κ 2 N,O]nickel(II). In the title compound, [Ni(OH 2 ) 2 (C 18 H 20 N 2 O 4 ) 2 ], the coordination geometry around the nickel(II) can be described as a distored octahedral which is shown in Fig. 1

Experimental
All reagents were commercially available and used as received. For preparing the title compound a methanol (10 ml) solution of L-phenylalanine (2 mmol) and NaOH (2mmol) were added to a methanol solution (10 ml) of Ni(NO 3 ) 2 .6H 2 O (1 mmol), and the mixture was refluxed for 6 h. Refinement H atoms were located in difference Fourier maps and included in the refinement as constrained idealized atoms riding on the parent atom, with C-H = 0.95 Å (aromatic groups), 1.00 Å (CH-N groups), 0.99 Å (CH 2 -Ph groups) or 0.92 Å (-NH 2 groups) and with U iso (H) = 1.2U eq (C,N). The H atoms of the aqua ligands were refined as semi-free with a distance restraint, and with U iso (H) = 1.2U eq (O).

Figure 1
The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level) for non-H atoms.  The packing diagram of the title compound which O-H···O hydrogen bonds shown as blue dashed lines.

Crystal data
[Ni(C 9 H 10 NO 2 ) 2 (H 2 O) 2 ] M r = 423.10 Monoclinic, P2 1 Hall symbol: P 2yb a = 4.8272 (5) Å b = 32.617 (4) Å c = 6.0585 (7)  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 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.