New 1,1′- or 1,2- or 1,3-bis(diphenylphosphino)ferrocenes

The syntheses of ferrocenyl phosphines with bulky substituents are reported using the reaction between FeCl2 and the suitably substituted cyclopentadienyl salts, LiC5H3-1,3-(PPh2)2, LiC5H3-1-PPh2-3-tBu, LiC5H2-1,2-(PPh2)2-4-tBu. This strategy leads to bi-, tri- and tetraphosphines, which cannot be obtained by the other access paths used to prepare substituted ferrocenes. [C5H3-1,3-(PPh2)2](C5H5)Fe, [C5H3-1-PPh2-3-tBu]2Fe racemic and meso and [C5H2-1,2-(PPh2)2-4-tBu](C5H5)Fe have been characterized by single-crystal X-ray diffraction studies.