Crystal structures of fac-tricarbonylchlorido(6,6′-dihydroxy-2,2′-bipyridine)rhenium(I) tetrahydrofuran monosolvate and fac-bromidotricarbonyl(6,6′-dihydroxy-2,2′-bipyridine)manganese(I) tetrahydrofuran monosolvate

The structures of two facially coordinated Group VII metal complexes, fac-[ReCl(6,6′-dihydroxy-2,2′-bipyridine)(CO)3]·C4H8O and fac-[MnBr(6,6′-dihydroxy-2,2′-bipyridine)(CO)3]·C4H8O, are reported. These complexes are relevant to catalysis for CO2 reduction.

In I, the bipyridine rings present a bite angle of 74.09 (8) to Re, similar to that found in III [74.41 (9) ] and IV [74.9 (2) ]. The bipyridine-Mn bite angle in II,78.35 (4) , is similar to that in V [79.0 (5) ]. The bipyridine ligands are not strictly planar. The dihedral angles between the pyridine rings are 11.68 (9) in I and 9.49 (5) in II. Additionally, the bipyridine ligands are not oriented strictly perpendicularly to the coordination planes of the metal ions. The dihedral angles between the mean plane through the -diimine ligands and the CO equatorial -M-CO equatorial planes are 23.51 (7) and 18.93 (3) for the Re and Mn complexes, respectively. Neither IÁTHF nor IIÁTHF exhibit intramolecular hydrogen bonding.

Supramolecular features
Hydrogen bonds for both structures are listed in Tables 1 and  2 The molecular structure of IÁTHF, with 50% probability displacement ellipsoids for non-H atoms. The O-HÁ Á ÁO hydrogen bond is shown by a dashed line. For the THF molecule, only one disordered component is shown.

Figure 2
The molecular structure of IIÁTHF, with 50% probability displacement ellipsoids for non-H atoms. The O-HÁ Á ÁO hydrogen bond is shown by a dashed line. group (O16-H16) and the chloride ligand from the neighboring complex. The other hydroxy group (O26-H26) is hydrogen-bonded to the O atom of the THF molecule. The nearest pyridine rings between neighboring complexes have centroid-centroid distances of 3.9448 (16) Å , longer than the maximum distance typically given forinteractions (Janiak, 2000). In IIÁTHF, a chain of complexes is formed along the b axis through an O-HÁBr hydrogen bond involving the O10-H1group and the bromide ligand of the adjacent molecule, whereas the other hydroxy group (O20-H2) is hydrogen-bonded to O1S of the solvent THF molecule. There are weakstacking interactions between pairs of  Symmetry code: (i) Àx þ 1; y þ 1 2 ; Àz þ 1 2 .

Figure 3
Crystal packing diagram of IÁTHF viewed along the b axis, showing hydrogen bonding (dashed lines) in the structure.

Figure 4
Crystal packing diagram of IIÁTHF viewed along the a axis, showing hydrogen bonding (dashed lines) in the structure. complexes from neighboring chains. The centroid-centroid distance between pairs of pyridine rings is 3.7019 (9) Å and the angle between the ring normal and the vector between the ring centroids is 9.3 , within the parameters typically given for suchinteractions (Janiak, 2000). Packing diagrams are shown in Figs. 3, 4 and 5.

Synthesis and crystallization
Methanol was degassed by sparging with N 2 . THF and diethyl ether were dried over molecular sieves and degassed using the freeze-pump-thaw method. MnBr(CO) 5 and ReCl(CO) 5 were purchased commercially and used as received. The ligand 6,6 0dihydroxy-2,2 0 -bipyridine was synthesized according to the synthetic procedure of Umemoto et al. (1998). IÁTHF: 6,6 0 -dihydroxy-2,2 0 -bipyridine (249 mg, 1.32 mmol) and ReCl(CO) 5 (477 mg, 1.32 mmol) were heated at 333 K in 50 mL methanol under nitrogen for five h. The flask was covered with aluminum foil to keep out light. The reaction was then allowed to cool to room temperature and the solvent was removed under vacuum to give a yellow precipitate. Slow cooling of a hot THF solution of the complex in a glove box under a nitrogen atmosphere gave yellow plate-shaped crystals suitable for single crystal X-ray diffraction. Due to limited solubility of the complex in THF, this method could not be used for a bulk recrystallization of the complex.

IIÁTHF:
6,6 0 -dihydroxy-2,2 0 -bipyridine (100 mg, 0.532 mmol) and MnBr(CO) 5 (146 mg, 0.532 mmol) were heated at 333 K in 24 mL methanol under nitrogen for five h. The flask was covered with aluminum foil to keep out light. The reaction was then allowed to cool to room temperature and the solvent was removed under vacuum to give an orange precipitate. The complex was recrystallized in bulk by layering pentane on a THF solution of the complex in a glove box under a nitrogen atmosphere at room temperature, giving the pure product in near quantitative yield. Slow diffusion of diethyl ether into a THF solution of the complex in a glove box under a nitrogen atmosphere gave yellow rod-shaped crystals suitable for single crystal X-ray diffraction.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. For both complexes, the coordinates of H atoms forming hydrogen bonds (the hydroxy group hydrogens) were refined freely with U iso (H) = 1.5 U eq (O). Cbound H atoms were placed in calculated positions and refined with riding coordinates, with U iso (H) = 1.2 U eq (C). In IÁTHF, disorder occurs for one carbon and six hydrogens of the THF solvent with occupancies of 0.748 (11) and 0.252 (11). Rigid bond (DELU) and similar ADP (SIMU) restraints were used for atoms O1S, C1S, C2S, C3T, C3S and C4S.  For both compounds, data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009). 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.

(Re_complex) fac-Tricarbonylchlorido(6,6′-dihydroxy-2,2′-bipyridine)rhenium(I) tetrahydrofuran monosolvate
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )  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.