(3-Methylbenzonitrile-κN)tetrakis(μ-N-phenylacetamidato)-κ4 N:O;κ4 O:N-dirhodium(II)(Rh—Rh)

In the title compound, [Rh2(C8H8NO)4(C8H7N)], the four acetamidate ligands bridging the dirhodium core are arranged in a 2,2-trans manner. One RhII atom is five-coordinate, in a distorted pyramidal geometry, while the other is six-coordinate, with a disorted octahedral geometry. For the six-coordinate RhII atom, the axial nitrile ligand shows a non-linear Rh–nitrile coordination with an Rh—N—C bond angle of 166.4 (4)° and a nitrile N—C bond length of 1.138 (6) Å. Each unique RhII atom is coordinated by a trans pair of N atoms and a trans pair of O atoms from the four acetamide ligands. The Neq—Rh—Rh—Oeq torsion angles on the acetamide bridge varies between 12.55 (11) and 14.04 (8)°. In the crystal, the 3-methylbenzonitrile ring shows a π–π interaction with an inversion-related equivalent [interplanar spacing = 3.360 (6) Å]. A phenyl ring on one of the acetamide ligands also has a face-to-face π–π interaction with an inversion-related equivalent [interplanar spacing = 3.416 (5) Å].

In the title compound, [Rh 2 (C 8 H 8 NO) 4 (C 8 H 7 N)], the four acetamidate ligands bridging the dirhodium core are arranged in a 2,2-trans manner. One Rh II atom is five-coordinate, in a distorted pyramidal geometry, while the other is six-coordinate, with a disorted octahedral geometry. For the six-coordinate Rh II atom, the axial nitrile ligand shows a non-linear Rhnitrile coordination with an Rh-N-C bond angle of 166.4 (4) and a nitrile N-C bond length of 1.138 (6) Å . Each unique Rh II atom is coordinated by a trans pair of N atoms and a trans pair of O atoms from the four acetamide ligands. The N eq -Rh-Rh-O eq torsion angles on the acetamide bridge varies between 12.55 (11) and 14.04 (8) . In the crystal, the 3-methylbenzonitrile ring shows ainteraction with an inversion-related equivalent [interplanar spacing = 3.360 (6) Å ]. A phenyl ring on one of the acetamide ligands also has a face-to-faceinteraction with an inversion-related equivalent [interplanar spacing = 3.416 (5) Å ].

Related literature
For the synthesis and structures of three related compounds, see Eagle et al. (2000Eagle et al. ( , 2012Eagle et al. ( , 2013.

Figure 1
An ellipsoid plot of title compound showing 30% probability ellipsoids. Hydrogen atoms are drawn as small spheres.  Packing diagram of title compound viewed down the a axis.

(3-Methylbenzonitrile-κN)tetrakis(µ-N-phenylacetamidato)-κ 4 N:O;κ 4 O:N-dirhodium(II)(Rh-Rh)
Special details Geometry. The 3-methyl benzonitrile rings (composed of carbon atoms C22-27) are π-stacked with inversion related symmetry equivalents (symmetry code: 2 -x, 2 -y, 1 -z). The interplanar spacing is 3.360 (6) Å. One of the phenyl rings on the acetamide ligand (composed of carbon atoms C34-C39) has face to face π-π interaction with its symmetry equivalent (symmetry code:2 -x, 1 -y, -z). The interplanar spacing is 3.416 (5) Å. 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 was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).

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