Triaqua(1,4,7-triazacyclononane-κ3 N 1,N 4,N 7)nickel(II) bromide nitrate

In the title half-sandwich compound, [Ni(C6H15N3)(H2O)3]Br(NO3), the central NiII ion, lying on a threefold rotation axis, is six-coordinated by three amine N atoms from the face-capping triaza macrocycle and three water O atoms in a slightly distorted octahedral geometry. In the crystal, O—H⋯O hydrogen bonding and weak O—H⋯Br interactions associate the NiII cations and the counter-ions into a three-dimensional supramolecular network.

In the title half-sandwich compound, [Ni(C 6 H 15 N 3 )(H 2 O) 3 ]-Br(NO 3 ), the central Ni II ion, lying on a threefold rotation axis, is six-coordinated by three amine N atoms from the facecapping triaza macrocycle and three water O atoms in a slightly distorted octahedral geometry. In the crystal, O-HÁ Á ÁO hydrogen bonding and weak O-HÁ Á ÁBr interactions associate the Ni II cations and the counter-ions into a threedimensional supramolecular network.
In the selected crystal, the title compound (I) crystallizes in a chiral space group P2 1 3 and Flack parameter of 0.01 (3) indicates that a spontaneous resolution has been achieved during crystallization. As depicted in Fig. 1, the Ni II center in the complex cation lies on a three-fold rotation axis and three amine N atoms from facially coordinated TACN and three water molecules complete the slightly distorted octahedral arrangement. Upon coordination, three five-membered Ni-N-C-C-N chelating rings subtended at metal center adopt (λλλ) conformation, which is the source of the chirality of  (Table 1) into three-dimensional supramolecular network (Fig. 2).
To a solution of 0.074 g (0.02 mmol) of TACN . 3HBr in water (10 ml), 0.1 M NaOH was added to adjust the pH to 6.
Then aqueous solution (5 ml) of 0.058 g (0.02 mmol) of Ni(NO 3 ) 2 . 6H 2 0 was added and the resulting mixture was stirred under reflux for 6 h. After cooling, the mixture was filtered, and the filtrate was allowed to standing at ambient temperature.
Plate-like green single crystals suitable for X-ray crystallographic analysis were collected by slow evaporation of the filtrate within two months.

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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )