Dicarbonyl[4-(2,6-dimethylphenylamino)pent-3-en-2-onato-κ2 N,O]rhodium(I)

In the title compound, [Rh(C13H16NO)(CO)2], a square-planar coordination geometry is observed around the RhI atom, formed by the N and O atoms of the bidentate ligand and two C atoms from two carbonyl ligands. The RhI atom is displaced from the plane through these surrounding atoms by 0.0085 (2) Å. The dihedral angle between the benzene ring and the N—C—C—C—O plane is 89.82 (6)°, and the N—Rh—O bite angle for the bidentate ligand is 90.53 (6)°. An intermolecular C—H⋯O interaction is observed between a methyl group of the benzene ring and a carbonyl O atom.

In the title compound, [Rh(C 13 H 16 NO)(CO) 2 ], a squareplanar coordination geometry is observed around the Rh I atom, formed by the N and O atoms of the bidentate ligand and two C atoms from two carbonyl ligands. The Rh I atom is displaced from the plane through these surrounding atoms by 0.0085 (2) Å . The dihedral angle between the benzene ring and the N-C-C-C-O plane is 89.82 (6) , and the N-Rh-O bite angle for the bidentate ligand is 90.53 (6) . An intermolecular C-HÁ Á ÁO interaction is observed between a methyl group of the benzene ring and a carbonyl O atom.
Bond distances involving the Rh I atom in the title complex differ from complexes in literature involving triphenylphosphine as ligand, with especially the Rh1-C14 distance that is significantly longer ( Table 2). The title complex displays similar Rh-N distances to complexes containing a hydrogen atom instead of an aryl moiety, but is more closely related to complexes containing similar aryl moieties when comparing the Rh-O distance. Complexes containing a bulky substituent on the nitrogen atom also display larger N-Rh-O bite angles than complexes containing a hydrogen atom. Due to the trans influence of the nitrogen atom, the Rh1-C13 distance is significantly longer than the Rh1-C14 distance [1.880 (2) and 1.852 (2) Å].
Intermolecular C-H···O interaction is observed between a methyl group on the aryl moiety and oxygen of the bidentate ligand. The dihedral angle between the plane formed by the N, O and C atoms of the pentenone backbone and the aryl ring moiety is 89.82 (6) °. This angle is distorted from the ideal value of 0° for delocalized electron due to the steric interference of the aryl ring, and is exacerbated by the presence of the methyl groups on the ring.

Refinement
H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C-H = 0.95 (aromatic) and 0.98 (methyl) Å and U iso (H) = 1.2(1.5 for methyl)U eq (C).

Figure 1
Molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level.

Crystal data
[Rh(C 13 H 16 NO)(CO) 2 ] M r = 361.2 Orthorhombic, P2 1 2 1 2 1 Hall symbol: P 2ac 2ab a = 7.9191 (7) (2) Special details Experimental. The intensity data was collected on a Bruker X8 APEXII 4 K Kappa CCD diffractometer using an exposure time of 60 s/frame. A total of 1033 frames were collected with a frame width of 0.5° covering up to θ = 28.31° with 99.8% completeness accomplished. Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq