rac-Carbonyl{1-[(diphenylphosphino)methyl]ethanethiolato}(triphenylphosphine)rhodium(I)

The title compound, [Rh(C15H16PS)(C18H15P)(CO)], was synthesized from the reaction of the ligand rac-[Ph2PCH2CH(CH3)SH] with trans-[Rh(F)(CO)(PPh3)2] in a 1:1 molar ratio in toluene. The Rh atom is four-coordinated in a distorted square-planar geometry with the P—S ligand [Ph2PCH2CH(CH3)S] acting as a chelate and the PPh3 and disordered CO [site occupation factors of 0.61 (5) and 0.39 (5)] ligands completing the coordination.


S1. Comment
In recent years, attention has increasingly been paid to the coordination chemistry of polydentate ligands incorporating both thiolate and tertiary phosphine donor ligands, as their combination is likely to confer unusual structures and reactivities on their metal complexes , Morales-Morales, et al., 2002. In the specific case of compounds with platinum group metals these may be suitable species for catalytic screening. Addiconally, the presence of these ligands in their transition metal complexes may render interesting behaviors in solution as these ligands can be capable of full or partial deligation (hemilability), (Dilworth & Weatley, 2000, Braunstein & Naud, 2001 being able to provide important extra coordination sites for incoming substrates during a catalytic process ( [Dilworth & Weatley, 2000, Braunstein & Naud, 2001. Moreover, chiral or potentially bidentate ligands have been used extensively to perform asymmetric transformations [Au-Yeung, et al. 2004, & Xie et al., 2008, however the most commonly employed are bidentated phosphines and the use of sulfur containing ligands has been avoided owing to the well known propensity of platinum group metals to sulfur poisoning. Thus, owing to our continuous interest in the synthesis of transition metal complexes bearing P-S hybrid ligands [Morales-Morales, et al., 2002, Gómez-Benítez, et al., 2007, Fierro-Arias, et al. 2008 we would like to report the crystal structure of the rhodium(I) complex [Rh(Ph 2 PCH 2 CH(CH 3 )S)(PPh 3 )(CO)] (I).
The rhodium atom is four-coordinated in a distorted square planar geometry with the P-S ligand [Ph 2 PCH 2 CH(CH 3 )S] acting as a chelate and the PPh 3 and CO ligands completing the coordination sphere ( Fig. 1). Similar geometry has been found in a previously reported rhodium complex (Lee et al., 2002). The phenyl ring on the P atoms are essentially planar, these phenyl rings are rotated around the P-C bond, forming the dihedral angles with the coordination plane P1-C34-P2-S1 (Table 1).

Figure 1
Molecular structure of (I) with the atom-labeling scheme. Displacement ellipsoids are drawn at the 30% probability level.
Disordered atom and hydrogen atoms were omitted for clarity.

Crystal data
[Rh(C 15 H 16 PS)(C 18 H 15 P)(CO)] M r = 652.50 Orthorhombic, Pbca Hall symbol: -P 2ac 2ab a = 10.3142 (7)   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.

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