trans-Bis{1-[2-(2,6-diisopropylanilino)phenyl]-3-isopropylimidazolin-2-ylidenyl-κC 2}diiodidopalladium(II) benzene disolvate

In the title complex, [PdI2(C24H31N3)2]·2C6H6, the Pd2+ ion is located on an inversion centre in a slightly distorted square-planar geometry. The angle between the I2C2 square plane and the mean plane of the N-heterocyclic carbene ring is 79.8 (2)°, with I—Pd—C—N torsion angles of −81.1 (6) and −78.2 (5)°. The Pd—carbene and Pd—I distances are 2.016 (6) and 2.5971 (10) Å, respectively.

Previously, we have reported tridentate amido-bis(NHC) (CNC) complexes of palladium and platinum, a bidentate amido-NHC (C,N-dipp) complex of palladium and a complex [trans-(C 24 H 31 N 3 )PdI 2 (py)], in which the amine-NHC ligand binds to Pd only through the carbene (Cross et al., 2011). In the synthesis of [trans-(C 24 H 31 N 3 )PdI 2 (py)], we isolated a single-crystal of the title complex.
The solid state structure of the title complex is shown in Fig. 1. Two NHC and two iodide ligands are coordinated to the square planar Pd, which is located at an inversion centre. The Pd-carbene distance of 2.016 (6) Å is ca 0.05 Å longer than in the corresponding complex [trans-(C 24

S2. Experimental
The title complex was an unexpected by-product in the synthesis of [trans-(C 24  Crystals of the title complex were grown by slow evaporation from benzene.

S3. Refinement
Hydrogen atoms were included in calculated positions at distances C-H = 0.95 to 1.00 Å and N-H = 0.88 Å in riding mode on the bonded atoms with U iso (H) set to 1.5 U eq (C) for methyl H atoms and 1.2 U eq (C/N) for all other H atoms. The final difference map was essentially featureless with some residual electron density in the close proximity of iodine atom.  The molecular structure of the title complex, with 50% probablity ellipsoids. Two molecules of benzene and H atoms except N-H have been omitted for clarity. Symmetry operation i = -x + 2, -y, -z.

trans-Bis{1-[2-(2,6-diisopropylanilino)phenyl]-3-isopropylimidazolin-2-ylidenyl-κC 2 }diiodidopalladium(II
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.