Structure, Stereochemistry and Dynamics of Tetranuclear Polyhydride Clusters Containing Chiral Heterobidentate Phosphanes

A novel chiral phosphane ( S )‐2‐(4‐isopropyl‐2‐oxazoline‐2‐yl)phenyl‐di‐ N ‐pyrrolylphosphane ( S‐ PyrPOx) based on asymmetric oxazoline ring has been prepared and characterised. Reaction of this ligand and its phenyl‐substituted analogue ( S‐ PhPOx) with H 4 Ru 4 (CO) 12 and H 3 RhOs 3 (CO) 12 gave substituted derivatives H 4 Ru 4 (CO) 10 (1,1‐PhPOx) ( 2 ), H 4 Ru 4 (CO) 10 (1,1‐PyrPOx) ( 3 ), and H 3 RhOs 3 (CO) 10 (1,1‐PyrPOx) ( 4 ), which were structurally characterised by X‐ray crystallography in solid state and by a variety of multinuclear NMR spectroscopic measurements in solution. In all studied clusters the coordinated ligands form five‐membered chelate rings through phosphorus and nitrogen atoms of oxazoline moiety to afford a novel chiral center associated with the substituted metal atom. The substitution reactions demonstrate extremely high stereoselectivity, which results in formation of only one diastereomer in all three cases to give S , S isomer in 2 and S , R isomer in 3 and 4 .