fac-Tricarbonyl(pyridine-κN)(1,1,1-trifluoroacetylacetonato-κ2 O,O′)rhenium(I)

In the title compound, [Re(C5H4F3O2)(C5H5N)(CO)3], the ReI atom is six-coordinated owing to bonding by three carbonyl ligands arranged in a fac configuration, two O atoms from the bidentate 1,1,1-trifluoroacetylacetonate ligand and an N atom from a pyridine ligand. In the crystal, the molecules pack in layers, diagonally, in a head-to-tail fashion across the ab plane. These layers are stabilsed by intermolecular C—H⋯O and C—H⋯F hydrogen bonds.

In the title compound, [Re(C 5 H 4 F 3 O 2 )(C 5 H 5 N)(CO) 3 ], the Re I atom is six-coordinated owing to bonding by three carbonyl ligands arranged in a fac configuration, two O atoms from the bidentate 1,1,1-trifluoroacetylacetonate ligand and an N atom from a pyridine ligand. In the crystal, the molecules pack in layers, diagonally, in a head-to-tail fashion across the ab plane. These layers are stabilsed by intermolecular C-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds.

Comment
This work forms part of our ongoing research in structure/reactivity relationships (Roodt et al., 2011) and the applications of rhenium-tricarbonyl complexes in the radiopharmaceutical industry (Brink et al., 2009(Brink et al., , 2011Schutte et al., 2010).
In the title Rhenium(I) compound, [Re(C 5 F 3 H 4 O 2 )(CO) 3 (py)], each rhenium atom is six-coordinated to three carbonyl ligands, two oxygen atoms from the bidentate 1,1,1-trifluoroacetylacetonato ligand and a nitrogen atom from a pyridine ligand to form a slightly distorted octahedron (see Figure 1). This is illustrated by the small deviations from 90 °, with the O1-Re1-N1 being the furthest outlier (82.72 (11)  The molecules pack in layers, diagonally, in a head-to-tail fashion across the ab plane. These layers are stabilsed by intermolecular CH-O and CH-F hydrogen bonds (see Figure 2).

Experimental
[Re(CO) 3 (Br) 3 ] (500 mg; 0.648 mmol) was prepared according to the method of Alberto (Alberto et al., 1996) and was dissolved in 10 ml water (pH 2.2) while stirring for 30 min. To this solution, AgNO 3 (330 mg; 1.945 mmol) was added and stirred for 24 h at room temperature. The precipitate, AgBr, was filtered off after which trifluoroacetylacetone (0.1 g; 0.649 mmol) was added to the filtrate and stirred for another 48 hrs. To the yellow solution, pyridine (0.0512 g; 0.648 mmol) was added and stirred for 10 min. at room temperature. A bright yellow precipitate formed which was filtered off and recrystallized from acetone (3 ml). Yellow needles were obtained (yield = 0.292 g; 89%)

Refinement
The methine and methylene H atoms were placed in geometrically idealized positions at C-H = 0.93 and 0.97 Å, respectively and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C). The highest peak is located 0.79 Å from Re1 and the deepest hole is situated 0.95 Å from Re1.

Special details
Experimental. The intensity data were collected on a Bruker X8 ApexII 4 K Kappa CCD diffractometer using an exposure time of 40 s/frame. A total of 1709 frames were collected with a frame width of 0.5° covering up to θ = 28.39° with 99.9% completeness accomplished.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The 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 > 2σ(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.