Regio- and Stereochemical Aspects of the Substitution Reaction between the Molybdenocene and Tungstenocene Dichlorides (η5-C5H4-R)2MCl2 (R = CMe3, SiMe3; M = Mo, W) and Metallophosphide Anions [(CO)5M‘PPh2]Li (M‘ = Mo, W)

The reaction of metallophosphide anions [(CO)5M‘PPh2]Li (M‘ = Mo, W) with the metallocene dichlorides (η5-Cp‘)2MCl2 (M = Mo, W; Cp‘ = C5H4−CMe3 (noted -CM) or C5H4−SiMe3 (noted -SiM)) leads to complexes (η5-Cp‘ ‘)(η5-Cp‘)MHCl (Cp‘ ‘ = C5H3-1-R-3-PPh2M‘(CO)5), which arise from a nucleophilic substitution on the cyclopentadienyl ligand. The reaction is partially (molybdenocene series) or completely (tungstenocene series) diastereogenic. In solution, a slow transformation of kinetic to thermodynamic products is detected in the molybdenum derivatives, while their tungsten homologues show a total stereostability. On the basis of X-ray structures and of NMR data the relative configurations of the stereoisomers are established.