Crystal structure of tricarbonyltris(pyridine-κN)rhenium(I) tetrafluoridoborate

In the title compound, [Re(C6H5N)3(CO)3]BF4, the ReI ion is six-coordinated by three pyridine N atoms and three carbonyl C atoms. In each case, the carbonyl C atom lies trans to a pyridine N atom. In the crystal, the ions are linked via C—H⋯F hydrogen bonds and C—H⋯π interactions, forming a three-dimensional framework. The F atoms of the BF4 anion are disordered over two positions and gave a final refined occupancy ratio of 0.705 (11):0.295 (11).


S1. Comment
Amoroso and coworkers (Amoroso et al., 2008) prepared a novel 3-chloromethylpyridyl bipyridine tricarbonyl rhenium complex and demonstrated the suitability of this complex in Mitochondria. That report represents the first application of a luminescent agent for specific targeting of a biological entity in imaging. Recently, Coogan and co-workers (Coogan et al., 2009) have also directed their research focus towards such complexes, thus preparing more novel rhenium tricarbonyl compounds to prove that heavy metals are not only erroneously termed as poisons, but can also be useful towards preparing drugs of great biological significance to man. Thus the design, syntheses and characterization of rhenium(I) tricarbonyl complexes has being of great interest due to their biological significance. The first report of the tricarbonyl trispyridyl rhenium(I) cation was published by Franklin et al. (2008), viz. tricarbonyl tris-pyridyl rhenium(I) hexafluorophosphate, which is quite similar to the title compound with some slight differences.
The molecular structure of the title complex is illustrated in Fig. 1. The Re I ion is six-coordinated by three pyridine N atoms and three carbonyl C atoms.
In the crystal, the ions are linked via C-H···F hydrogen bonds and C-H···π interactions forming a three-dimensional framework (Table 1).

S2. Experimental
The preparation of the title compound is illustrated in Fig The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
Preparation of the title compound.

Tricarbonyltris(pyridine-κN)rhenium(I) tetrafluoridoborate
Crystal data  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.