Identification of an Asymmetric Pauson−Khand Precatalyst

X-ray crystallographic analysis of red crystals formed on mixing octacarbonyldicobalt(0) and BINAP, combined with NMR evidence obtained from a catalytic asymmetric Pauson−Khand reaction, suggests that this complex is a precatalyst to this reaction and leads to a new hypothesis for the role of axially chiral diphosphanes in the catalytic asymmetric Pauson−Khand reaction.