Synthesis, NMR, and X-ray molecular structure of a unique chiral propeller-like cobalt complex I(Co-2(CO)(4))mu,eta(2),eta(2)-(-H2CC equivalent to CCH2-)(-dppm)(2)][BF4](2) and differentiation of its enantiomers by the trisphat anion

The unusual chiral two-bladed propeller cobalt complex [(Co-2(CO)(4))mu,eta (2),eta (2)-(-H2CC=CCH2-)-(-dppm)(2)][BF4](2) (3) has been, prepared and i ts X-ray structure determined. Addition of the trisphat anion to a CD2Cl2 s olution of 3 has led to the NMR nonequivalency of the two enantiomers 3a,b. This is the first example in which a chiral propeller transition metal com plex with C-2-symmetry has been differentiated by the trisphat anion.