Tricarbonylchlorido(6′,7′-dihydro-5′H-spiro[cyclohexane-1,6′-dipyrido[3,2-d:2′,3′-f][1,3]diazepine]-κ2 N 1,N 11)rhenium(I)

In the title compound, [ReCl(C16H18N4)(CO)3], the ReI ion is coordinated in a distorted octahedral geometry by one Cl atom, two N atoms of the bidentate ligand and three carbonyl groups. The cyclohexane group is orientated in a transoid fashion with respect to the chloride ligand. In the crystal, N—H⋯Cl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (100).

In the title compound, [ReCl(C 16 H 18 N 4 )(CO) 3 ], the Re I ion is coordinated in a distorted octahedral geometry by one Cl atom, two N atoms of the bidentate ligand and three carbonyl groups. The cyclohexane group is orientated in a transoid fashion with respect to the chloride ligand. In the crystal, N-HÁ Á ÁCl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (100).

Comment
The title complex was prepared as part of a larger study into conjugation of [Re(3,3′-diamino-2,2′-bipyridine)(CO) 3 Cl] with oxo-steroids to form luminescent derivatives (Bullock et al. 2012). These steroids contain a cyclohexyl ring (ring A) with a ketone group in the 3-position; therefore, cyclohexanone was used as a model compound to examine the potential reactivity of such steroids with the rhenium complex.
Single-crystal X-ray analysis of the title complex gave the structure shown in Fig. 1. The rhenium centre adopts a distorted octahedral geometry which is coordinated by two nitrogen atoms from a 3,3′-diamino-2,2′-bipyridyl ligand and two carbonyl ligands in the equatorial sites and by a carbonyl ligand and a chloride ion in the axial sites. The cyclohexyl ring adopts a chair conformation and is orientated in a trans-oid fashion relative to the chloride ion on the rhenium centre.
In the crystal, N-H···Cl hydrogen bonds (Table 1 & Fig. 2) link complex molecules to form a two-dimensional network parallel (100).
A similar compound has been prepared using cyclopentanone instead of cyclohexanone. The title compound compound is essentially isostructural with that compound (Clegg et al. 2013).

Experimental
To a solution of [Re(3,3′-diamino-2,2′-bipyridine)(CO) 3 Cl] in dichloromethane was added cyclohexanone (10 µL, ca. 2 eq.) and a few grains of camphorsulfonic acid. The solution was stirred at room temperature for 2 h. The resulting precipitate was filtered in vacuo, washed with dichloromethane and dried, giving the product as a yellow solid. Crystals suitable for X-ray analysis were prepared by slow evaporation of an acetonitrile solution of the complex.

Refinement
All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on sp 2 and sp 3 C atoms were placed in calculated positions and refined with riding constraints and isotropic displacement parameters 1.2 × their parent carbon atoms. H atoms bonded to N atoms were refined independently with a bond length constraint of 0.91 (2)Å and U iso (H) = 1.2U eq (N).  The molecular structure of the title compound with displacement ellipsoids shown at the 50% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > 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.