Niobium and Tantalum Diphosphanato Complexes: Synthesis, Structure, and NMR Studies of Cp2MH[(PR)2] (R = Ph, Cy, H)

The reactions of Cp2MH3 (M = Nb, Ta) or Cp‘2NbH3 (Cp‘ = Me3SiC5H4) with excess primary phosphines yield the complexes Cp2NbH[(PPh)2] (1), Cp‘2NbH[(PPh)2] (2), and Cp2TaH[(PR)2] (R = Ph, 3; R = Cy, 4). Crystallographic studies of each of these compounds confirmed the transoid disposition of the phosphorus substituents with respect to the MP2 ring. Reaction of Cp2TaH3 with white phosphorus afforded the parent complex Cp2TaH[(PH)2] (5). While …