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.