Chlorido(η 4-cycloocta-1,5-diene)(N,N′-diethylthiourea-κS)rhodium(I)

In the title rhodium(I) complex, [RhCl(C8H12)(C5H12N2S)], N,N′-diethylthiourea acts as a monodenate S-donor ligand. The rhodium(I) coordination sphere is completed by the Cl atom and the COD [= 1,5-cyclooctadiene] ligand interacting through the π-electrons of the double bonds. If the midpoints of these two bonds are taken into account, the Rh atom exhibits a distorted square-planar coordination. The syn conformation of the N,N′-diethylthiourea ligand with respect to the Cl atom is stabilized by an intramolecular N—H⋯Cl hydrogen bond. A weak intermolecular N—H⋯Cl interaction links molecules along the a axis.

In the title rhodium(I) complex, [RhCl(C 8 H 12 )(C 5 H 12 N 2 S)], N,N 0 -diethylthiourea acts as a monodenate S-donor ligand. The rhodium(I) coordination sphere is completed by the Cl atom and the COD [= 1,5-cyclooctadiene] ligand interacting through the -electrons of the double bonds. If the midpoints of these two bonds are taken into account, the Rh atom exhibits a distorted square-planar coordination. The syn conformation of the N,N 0 -diethylthiourea ligand with respect to the Cl atom is stabilized by an intramolecular N-HÁ Á ÁCl hydrogen bond. A weak intermolecular N-HÁ Á ÁCl interaction links molecules along the a axis.

Comment
Thiourea and thiourea-based ligands form complexes with a number of transition metals (Wilkinson, 1987;Gibson et al., 1994;Robinson et al., 2000) and their application as ligands for metal catalyst in styrene hydroformylation has been recently shown (Breuzard et al., 2000).
In order to investigate the coordination chemistry of symmetrically substituted thiourea derivatives as ligands for metal complexes applicable in asymmetric catalysis, the reaction between chloro(η 4 -1,5-cyclooctadiene)rhodium(I) dimer and N,N'-diethylthiourea has been performed in dichloromethane. The obtained crystals were identified as the title compound by single-crystal X-ray diffraction. Figure 1 shows that in the compound (I) structure the N,N'-diethylthiourea acts as a monodenate S-donor ligand. Therefore the rhodium(I) coordination sphere is completed by a chlorine atom and COD [= 1,5-cyclooctadiene] ligand interacting with the metal center through the π-electrons of the double bonds. If the midpoints of these two bonds are taken into account the rhodium atom displays a distorted square planar coordination, as evidenced by the angles at Rh (1) In the thiourea moiety the distance S(1)-C(1) [1.732 (2) Å] is slightly longer than that found in the crystallographic structure of the N,N'-diethythiourea [1.707 (3) Å] (Ramnathan et al., 1995). This lengthening of the S-C bond is consistent with the decreasing double bond character due to the coordination at the metal center.  (Cauzzi et al., 1995(Cauzzi et al., , 1997. The syn conformation of the substituent on the sulfur with respect to the chlorine atom is stabilized by the intramolecular N(1)-H(1)···Cl(1) hydrogen bonding interaction.
The crystal packing arrangement is stabilized by van der Walls forces and the very weak intermolecular N(2)-H(2)···Cl(1) A hydrogen interaction along the a axis ( Fig. 2) between the thioamide N(2) and the Cl(1) A of the neighbor complex molecule generated by applying the crystallographic (x + 1, y, z) symmetry operation.

Experimental
The compound was prepared by reacting [Rh(COD)(µ-Cl)] 2 (0.050 g, 0.10 mmol) with the N,N'-diethylthiourea ligand (0.0264 g, 0.2 mmol) in CH 2 Cl 2 solution at room temperature for 30 min. After evaporation of the solvent in vacuo, the residue was dissolved in dichloromethane. Recrystallization from CH 2 Cl 2 /hexane gave orange crystals of the complex.

Refinement
Several H atoms were located in a difference Fourier map and placed in idealized positions using the riding-model technique  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.  (2)