[(1R,4S)-(+)-3-Benzoyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-olato-κ2 O 2,O 3](η4-norbornadiene)rhodium(I)

In the title complex molecule, [Rh(C17H19O2)(C7H8)], the rhodium(I) metal centre is coordinated by the O atoms of a benzoylcamphorate anion and the C=C bonds of the norbornadiene molecule into a slightly distorted square-planar coordination geometry. The six-membered chelate ring is essentially planar (r.m.s. deviation = 0.0378 Å) and forms a dihedral angle of 31.67 (11)° with the phenyl ring.

In the title complex molecule, [Rh(C 17 H 19 O 2 )(C 7 H 8 )], the rhodium(I) metal centre is coordinated by the O atoms of a benzoylcamphorate anion and the C C bonds of the norbornadiene molecule into a slightly distorted squareplanar coordination geometry. The six-membered chelate ring is essentially planar (r.m.s. deviation = 0.0378 Å ) and forms a dihedral angle of 31.67 (11) with the phenyl ring.
Financial support from the Universitá degli Studi di Parma is gratefully acknowledged.

Comment
Rhodium complexes are widely used in organic chemistry due to their ability to mediate numerous transformations of organic molecules, often in catalytic mode. In particular, rhodium complexes of chiral ligands have shown to perform highly enantioselective transformations (Noyori, 1994;Breuzard et al., 2000;Bernard et al., 2001). Camphor-derived 1,3-diketonato ligands are a potentially attractive class of ligands in organometallic development, because these compounds are readily synthesized and easily varied (Togni, 1990;Togni et al., 1993). Moreover, some of their transition metal complexes can be used as therapeutic drugs (Guo & Sadler, 1999). As a contribution to our research programs aimed at the preparation of transition metal complexes (Spannenberg et al., 2002;Ait Ali, El Firdoussi et al., 2000;Ait Ali et al., 2001, 2006El Firdoussi et al., 2007) and their application in catalytic asymmetric reactions (Naili et al., 2000;Ait Ali, Allaoud et al., 2000;Fdil et al., 2002), we report here the synthesis and crystal structure of the title compound.
In the mononuclear title complex molecule ( Fig. 1), the rhodium(I) metal atom assumes a slightly tetrahedrally distorted square-planar coordination geometry provided by the O atoms of the chelating benzoylcamphorato anion and the centroids of the C═C double bonds of the norbornadiene molecule (maximum displacement 0.078 (5) Å for the centroid of the C18═C19 bonds). The RhO 2 C 3 six-membered chelate ring is essentially planar (r.m.s. deviation = 0.0378 Å) and forms a dihedral angle

Experimental
A solution of [Rh(norbornadiene)Cl] 2 (0.18 mmol, 100 mg) in THF (10 ml) was added to a suspension of (1R)-(+)-3-benzoylcamphor (0.32 mmol, 83.4 mg) and Na 2 CO 3 (0.94 mmol, 100 mg) in THF (10 ml). The mixture was stirred for 3 h at room temperature, then it was evaporated to dryness under reduced pressure. The residue was extracted with CH 2 Cl 2 (3 × 10 ml), and the recovered filtrate was evaporated to dryness to give an orange solid (yield 86%). Crystals suitable for X-ray analysis were obtained by slow evaporation of a diethyl ether solution.
supplementary materials sup-2 Refinement All H atoms were placed at calculated positions and refined using the riding model approximation, with C-H = 0.93-0.97 Å, and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms. The absolute configuration was assigned on the basis of the known absolute configuration of the starting material and confirmed by anomalous scattering effects. Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 40% probability level.

Special details
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 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.