trans-Aqua(4,7-diazadecane-1,10-diamine-κ4 N)fluoridochromium(III) bis(perchlorate) monohydrate

In the title compound, [CrF(C8H20N4)(H2O)](ClO4)2·H2O, the Cr atom is in a slightly distorted octahedral environment, coordinated by four N atoms of the 4,7-diazadecane-1,10-diamine ligand, one water molecule and an F atom trans to water. The five-membered chelate ring is in a gauche form, while the two six-membered chelate rings are in chair conformations. The crystal structure is stabilized by several hydrogen bonds.

In the title compound, [CrF(C 8 H 20 N 4 )(H 2 O)](ClO 4 ) 2 ÁH 2 O, the Cr atom is in a slightly distorted octahedral environment, coordinated by four N atoms of the 4,7-diazadecane-1,10diamine ligand, one water molecule and an F atom trans to water. The five-membered chelate ring is in a gauche form, while the two six-membered chelate rings are in chair conformations. The crystal structure is stabilized by several hydrogen bonds.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CF2211).

S1. Comment
Acyclic flexible 4,7-diazadecane-1,10-diamine (3,2,3-tet) and its related tetradentate ligands provide a rich field of geometric and conformational isomers in octahedral transition metal complexes (Choi et al., 2008). The electronic absorption and infrared spectra often can be used diagnostically to identify the geometric isomers of chromium(III) complexes complexes (Poon & Pun, 1980;Choi & Hoggard, 1992). However, it should be noted that the assignments based on spectroscopic investigations are not always conclusive (Stearns & Armstrong, 1992). [Cr(3,2, can adopt a diverse stereochemistry and configuration, but no structures have been reported. Thus we here report the crystal structure of the title complex ( Fig. 1) in order to confirm the geometric configuration.
There are one fluorine atom and one water molecule coordinated to the chromium atom in a trans arrangement with an F-Cr-O1w bond angle of 179.5 (2)°. The rest of the coordination sites are occupied by four nitrogen atoms from 3,2,3tet ligand in the equatorial plane. The mean Cr-N bond length of 2.079 (4) Å is normal, agreeing with literature values (Choi et al., 1995;Choi et al., 2004). The Cr-N1 and Cr-N2 bond lengths of 2.068 (5) and 2.070 (4) Å of secondary amines are slightly shorter than Cr-N3 and Cr-N4 distances of 2.082 (5) and 2.095 (4) Å of primary amines. The Cr- The uncoordinated ClO 4anions and one water molecule remain outside the coordination sphere. There is an extensive hydrogen bonding network (Table 2) between the oxygens of the ClO 4anions, fluorine atom, water molecule, C-H and the N-H groups of the 3,2,3-tet ligand as shown in Figure 2. These hydrogen-bonded networks help to stabilize the crystal structure.

S2. Experimental
As starting material, trans-[Cr(3,2,3-tet)F 2 ]ClO 4 was prepared according to the literature (Glerup et al., 1970). The complex trans-[Cr(3,2,3-tet)F 2 ]ClO 4 was dissolved in 0.2 M HClO 4 . The solution was heated at 333 K for 50 min and then a saturated solution of sodium perchlorate was added. Dark red crystals suitable for an X-ray structural determination were deposited over several days as the solution evaporated.

S3. Refinement
All H atoms were positioned geometrically and refined using a riding model, with C-H = 0.95 Å for aromatic H atoms and 0.98 Å for methyl H atoms, respectively, and with U iso (H) = 1.2U eq (C) for aromatic and U iso (H) = 1.5U eq (C) for methyl H atoms. H atoms of O1w were located in a difference Fourier map and refined with constraints. Reasonable positions of H atoms for O2w could not obtained from a difference Fourier map.    where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.07 e Å −3 Δρ min = −0.60 e Å −3 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 > 2sigma(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Cr 0.77207 (8)