fac-[N,N′-Bis(3-chloro-2-fluorobenzylidene)ethylenediamine]bromidotricarbonylrhenium(I)

In the title compound, [ReBr(C16H12Cl2F2N2)(CO)3], the Re atom is in a slightly distorted octahedral coordination environment with the three carbonyl ligands having a fac configuration. The diimine ligand is equatorial and is bonded to the Re centre in an N,N′-bidentate chelating fashion, with a bite angle of 77.7 (2)°. The dihedral angle between the two benzene rings is 88.7 (6)°. In the crystal structure, there are F⋯O [2.856 (9) Å], Cl⋯C [3.150 (8) Å] and O⋯C [2.984 (10) Å] contacts which are shorter than the sum of the van der Waals radii for these atoms. In addition, symmetry-related molecules are linked via intermolecular C—H⋯O, C—H⋯Br and the F⋯O interactions into one-dimensional chains extending along the a axis. The crystal structure is further stabilized by intermolecular π–π interactions [centroid–centroid distance = 3.571 (5) Å].

In the title compound, [ReBr(C 16 H 12 Cl 2 F 2 N 2 )(CO) 3 ], the Re atom is in a slightly distorted octahedral coordination environment with the three carbonyl ligands having a fac configuration. The diimine ligand is equatorial and is bonded to the Re centre in an N,N 0 -bidentate chelating fashion, with a bite angle of 77.7 (2) . The dihedral angle between the two benzene rings is 88.7 (6) . In the crystal structure, there are FÁ Á ÁO [2.856 (9) Å ], ClÁ Á ÁC [3.150 (8) Å ] and OÁ Á ÁC [2.984 (10) Å ] contacts which are shorter than the sum of the van der Waals radii for these atoms. In addition, symmetry-related molecules are linked via intermolecular C-HÁ Á ÁO, C-HÁ Á ÁBr and the FÁ Á ÁO interactions into onedimensional chains extending along the a axis. The crystal structure is further stabilized by intermolecularinteractions [centroid-centroid distance = 3.571 (5) Å ].

S1. Comment
Rhenium tricarbonyl diimine complexes have been the subject of much attention, mainly because of their photophysical and photochemical properties (Lee 1987;Farrell & Vlcek 2000;Balzani et al. 1996) and their use in the photoreducetion and electroreduction of CO 2 to CO (Collin & Sauvage 1989), a process of interest in the conversion and storage of solar energy. We report here the results of an X-ray structure determination of the title complex, (I).
In the title compound (I, Fig. 1), the Re atom is in a slightly distorted octahedral coordination environment. The bond lengths (Allen et al., 1987) and angles are within the normal ranges and are comparable to related structures (Kia et al., 2007). The three carbonyl ligands bonded to the Re atom are arranged in a fac configuration. The cis-equatorial bite angle [N1-Re1-N2] is 77.7 (2)°. The deviation of the Re atom from the mean plane defined by N1/N2/C2/C3 is 0.04 (4) Å.

S2. Experimental
The synthetic method has been described earlier (Kia et al., 2007), except that N,N′-bis(3-chloro-2-fluoro-benzylidene) ethylenediamine ligand and [Re(CO) 5 Br] were used as starting materials. Single crystals suitable for X-ray diffraction were obtained by evaporation of an dichloromethane/toluene (4/1 ratio) solution at room temperature.

Special details
Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment. 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.