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

In the title compound, [ReCl(C15H16N4)(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 cyclopentane group is orientated in a transoid fashion with respect to the chloride ligand. The dihedral angle between the pryridine rings is 10.91 (12)°. In the crystal, N—H⋯Cl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (001).

In the title compound, [ReCl(C 15 H 16 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 cyclopentane group is orientated in a transoid fashion with respect to the chloride ligand. The dihedral angle between the pryridine rings is 10.91 (12) . In the crystal, N-HÁ Á ÁCl hydrogen bonds link complex molecules, forming a two-dimensional network parallel to (001).

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 cyclopentyl ring (ring D) with a ketone group in the 17-position; therefore, cyclopentanone was used as a model compound to examine the potential reactivity of such steroids with the rhenium complex. The photophysical properties of Re-polypyridyl complexes have been studied (Coleman et al., 2008) as well as the reaction of [Re(3,3′-diamino-2,2′-bipyridine)(CO) 3 Cl] with ketones (Clayton et al., 2008).
Single-crystal X-ray analysis of the product gave the structure shown in Fig. 1. The rhenium centre adopts a distorted octahedral coordination geometry and is coordinated by two nitrogen atoms from 3,3′-diamino-2,2′-bipyridyl and two carbonyl ligands in the equatorial positions (Re-N distances 2.158 (2) -2.169 (2) Å, Re-C distances 1.924 (3) -1.925 (3) Å). Carbonyl and chloride ligands occupy the axial positions (Re-C distance 1.891 (3) Å, Re-Cl distance 2.5046 (6) Å). The cyclopentyl ring is orientated in a trans-oid fashion with respect to the chloride ligand on the rhenium centre. In the crystal, N-H···O hydrogen bonds (see , Table 1) link complex molecules to form a two-dimensional network parallel (001).
A similar compound has been prepared using cyclohexanone instead of cyclopentanone. This compound is essentially isostructural with the compound reported here (Clegg et al. 2013).

Experimental
To a solution of [Re(3,3′-diamino-2,2′-bipyridine)(CO) 3 Cl] in dichloromethane was added cyclopentanone (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, affording the product as a yellow solid. Slow evaporation of an acetonitrile solution of the complex gave yellow crystals suitable for X-ray analysis.

Refinement
All non-hydrogen atoms were refined anisotropically. Hydrogen atoms on sp 2 and sp 3 carbons were placed in calculated positions (C-H = 0.95 -0.99Å) and refined with riding constraints and with isotropic displacement parameters 1.2 x their parent carbon atoms. H atoms on the nitrogen atoms were treated similarly with N-H = 0.88Å.

Figure 1
The molecular structure of the title compound with displacement ellipsoids shown for non-H atoms at the 50% probability level.   (3)