Oxidative Addition of Hydrosilanes, Hydrogermane, and Hydrostannane to Cyclopentadienylcobalt(I) Bearing a Pendant Phosphane Ligand: Cyclopentadienylhydridocobalt(III) Chelate Complexes with Silyl, Germyl, and Stannyl Ligands

Oxidative addition of hydrosilanes, a hydrogermane, and a hydrostannane to the ((cyclopentadienylalkyl)phosphane)cobalt(I) chelate 1 results in the formation of cyclopentadienylhydridocobalt(III) complexes having a tethered phosphorus ligand and silyl ( rac - 4 − rac - 8 ), germyl ( rac - 10 ), and stannyl substituents ( rac - 11 ). The pseudo-four-coordinate complexes are chiral. The X-ray structures of 5 and 7 have been determined. Variable-temperature NMR spectra indicate racemization in solution due to reversible dissociation of the phosphorus ligand. The barrier of this process has been estimated to be in the range of 13−16 kcal/mol.