Bis[2-(2-pyridylmethyleneamino)benzenesulfonato-κ3 N,N′,O]cobalt(II) dihydrate

The title complex, [Co(C12H9N2O3S)2]·2H2O, has site symmetry 2 with the CoII cation located on a twofold rotation axis. Two tridentate 2-(2-pyridylmethyleneamino)benzenesulfonate (paba) ligands chelate to the CoII cation in a distorted octahedral geometry. The pyridine and benzene rings in the paba ligand are oriented at a dihedral angle of 42.86 (13)°. Intermolecular O—H⋯O and C—H⋯O hydrogen bonding is present in the crystal structure.

The title complex, [Co(C 12 H 9 N 2 O 3 S) 2 ]Á2H 2 O, has site symmetry 2 with the Co II cation located on a twofold rotation axis. Two tridentate 2-(2-pyridylmethyleneamino)benzenesulfonate (paba) ligands chelate to the Co II cation in a distorted octahedral geometry. The pyridine and benzene rings in the paba ligand are oriented at a dihedral angle of 42.86 (13) . Intermolecular O-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonding is present in the crystal structure.

S1. Comment
The design of supermolecular coordination complexes in which both coordination bonds and hydrogen bonds take part in the self-assembly chemistry have recently generated increasing interest. Our group have focused on the exploration of the coordination chemistry of the sulfonate ligands (Jiang et al.., 2006). We report here the structure of the title complex ( Fig.   1).
The Co II complex is isostructural with [Zn(Paba) 2 ].2H 2 O and [Cd(Paba) 2 ].2H 2 O whose structure has been described in detail (Cai et al.., 2008;Ou-Yang et al.., 2008). The Co(II) atom lies on the twofold rotation axis and is coordinated by pyridine N, imine N and sulfonate O atoms from two pabaligands with a distorted octahedral geometry (Table 1). This structure is similar to complexes with N,N′,O-tridentate donor ligands (Casella et al.., 1986). The O-H···O and C-H···O hydrogen bonding (Table 2) is present in the crystal structure.

S3. Refinement
H atoms bonded to C atoms were positioned geometrically with the C-H distance of 0.93 A, and treated as riding atoms, with U iso (H) = 1.2U eq (C). Water H atoms were placed in a difference Fourier map and refined as riding in as-found relative positions with U iso (H) = 1.5U eq (O).  The molecular structure of the complex, showing the atom-numbering scheme. Symmetry code: -x + 2, y, -z + 1/2.

Bis[2-(2-pyridylmethyleneamino)benzenesulfonato-κ 3 N,N′,O]cobalt(II) dihydrate
Crystal data [Co(C 12   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.