1,1'-Binaphthyl-substituted diphosphene: synthesis, structures, and chiral optical properties.

1,1'-Binaphthyl-substituted diphosphene 1 possessing a P[double bond, length as m-dash]P double bond and an axially chiral 1,1'-binaphthyl group was synthesized and fully characterized. Diphosphene 1 was prepared as an optically active form and thus is the first example of a chiral diphosphene. The CD spectra of 1 showed apparent circular dichroism in the longer wavelength region, caused by the P[double bond, length as m-dash]P moiety.