Aquadicrotonato(di-2-pyridylamine)cobalt(II)

The Co atom in the title complex, [Co(CH3CHCHCOO)2(C10H9N3)(H2O)], has a distorted rectangular–pyramidal geometry formed by the chelating dipyridylamine ligand, and two O atoms of monodentate carboxylate groups of two different crotonate anions and a water molecule. The complex forms a three-dimensional supramolecular network via intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen-bonding contacts.

The Co atom in the title complex, [Co(CH 3 CHCHCOO) 2 -(C 10 H 9 N 3 )(H 2 O)], has a distorted rectangular-pyramidal geometry formed by the chelating dipyridylamine ligand, and two O atoms of monodentate carboxylate groups of two different crotonate anions and a water molecule. The complex forms a three-dimensional supramolecular network via intermolecular O-HÁ Á ÁO, N-HÁ Á ÁO and C-HÁ Á ÁO hydrogenbonding contacts.

Comment
Transition metal complexes with polypyridylamine ligands, possessing diverse structures and special optical and electromagnetic properties (Peng et al., 2000), have aroused great interest among researchers. The pyridyldiamine ligand usually exhibits donor as well as acceptor properties and can be used as a popular chelating ligand (Chang et al., 1999;Xu et al., 2004).
As shown in the Scheme and Fig. 1, the Co atom in the title complex has a contorted rectangular pyramidal coordination geometry formed by the chelating dipyridine-2-ylamine (tpdaH2) ligand and two oxygen atoms of monodenate carboxylate groups of two different crotonic acid anions. The tpdaH2 ligand and the crotonic acid ligand consist of the basal plane. The coordinated water molecule hold the vertex location. The O1-Co1-N3 and O3-Co1-N1 angles are α = 156.63 (9)° and β = 175.67 (10)°, respectively. These angles were used to calculate a parameter τ, which is defined as τ = (β -α)/60 (Addison et al., 1984). In the case of a perfectly tetragonal symmetry, this value is equal to zero, and for a perfectly trigonal symmetry it is 1.0. In the presented structure this value is 0.317, indicating that the polyhedron is about 70% rectangular pyramidal. The dihedral angle between the pyridine ring planes is 12.74 (8)°, which is much larger than that of our reported similar organic ligand (6.10 (15)°) (Wu, 2007). The average bond lengths with Co-N is 2.01 Å, and the Co-O bond lengths range from 1.943 (2) to 2.215 (3) Å. The bond lengths with Co-N are shorter than those of a nickel complex with 2,3'-dipyridylamine (Zhang, 2007).
In the title complex the H atoms of two NH groups of tpdaH2 act as donors to form intermolecular classical hydrogen bonds with O2 as acceptor atoms. Synchronously, the coordinated water molecule takes as donor and binds to the uncoordinated oxygen atom O2 of one of the carboxylate groups, and to the intramolecular acceptor atom O4. A weak intermolecular C-H···O contact completes the three-dimensional supramolecular network (Table 1 and Fig. 2).

Experimental
CoSO 4 (0.022 g, 0.011 mmol), L(0.035 g, 0.023 mmol), tpdaH2 (0.028 mg, 0.013 mmol) and NaOH(0.048 mmol,0.12 mmol), were added in a mixed solvent of benzene and methanol, the mixture was heated for six hours under reflux. During the process stirring and influx were required. The resultant was then filtered to give a pure solution which was infiltrated by diethyl ether freely in a closed vessel. Two weeks later some single crystals of the size suitable for X-ray diffraction analysis were obtained.

Refinement
All H atoms (except the water H atoms) were placed in calculated positions [Csp 2 -H and N-H = 0.93 Å and 0.86 Å, respectively, and Csp 3 -H = 0.96 Å] and they were refined using a riding model, with U iso (H) = 1.2U eq (C,N) and 1.5U eq for the CH 3 groups. The methyl H atoms were allowed to rotate (AFIX 137) to optimal positions. The water H atoms were found supplementary materials sup-2 in a difference electron density map, they were refined using distance restraints (O-H = 0.900(0.015) Å), with U iso (H) = 1.5U eq (O). Fig. 1. The molecular structure of the title complex, showing 30% probability displacement ellipsoids and the atomic numbering scheme. H atoms are shown as spheres of arbitrary radii.

Special details
Geometry. All e.s. 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.