Synthesis and characterization of enanti­opure planar–chiral phospho­rus-linked diferrocenes

In the course of an ongoing synthetic project on cyclic diferrocenylphosphines, we obtained a group of planar–chiral diferrocenyl com­pounds useful as precursors for subsequent cyclization. Here we report the crystal structures of two sym­metric com­pounds [(Fc(A))(2)(Ph)P], one of which contains four stereogenic centres (two C chiral and two planar chiral centres), i.e. 1,1′-(phenyl­phos­phane­di­yl)bis­{(2S (p))-2-[(1R)-1-(acet­yloxy)eth­yl]ferrocene}, [Fe(2)(C(5)H(5))(2)(C(24)H(25)O(4)P)], and the other phosphine sulfide is a purely planar–chiral com­pound (two planar chiral centres), i.e. bis[(2S (p))--2-ethenylferrocen-1-yl]phenylphosphane sulfide, [Fe(2)(C(5)H(5))(2)(C(20)H(17)PS)]. Owing to the stereocentres present, reactions performed on [(Fc(A))(2)(Ph)P]-type com­pounds strongly favour one ferrocene unit over the other due to diastereoselectivity. Furthermore, we present four related structures where the ferrocene units are not identical [(Fc(A))(Fc(B))(Ph)P]. These are {(2S (p))-2-[(1R)-1-(acet­yloxy)eth­yl]ferrocen-1-yl}[(2S (p))-2-ethenylferrocen-1-yl]phenyl-(S)-phosphine sulfide, [Fe(2)(C(5)H(5))(2)(C(22)H(21)O(2)PS)], [(2S (p))-2-ethenylferrocen-1-yl]{(2S (p))-2-[(1R)-1-hy­droxy­eth­yl]ferrocen-1-yl}phenyl-(S)-phosphine sulfide, [Fe(2)(C(5)H(5))(2)(C(20)H(19)OPS)], {(2S (p))-2-[(1R)-1-(acet­yloxy)eth­yl]ferro­cen-1-yl}{(2S (p))-2-[(1R)-1-hy­droxy­eth­yl]ferrocen-1-yl}phenyl-(R)-phos­phine sulfide, [Fe(2)(C(5)H(5))(2)(C(22)H(23)O(3)PS)], and {(2S (p))-2-[(1R)-1-benzyl­amino)­eth­yl]ferrocen-1-yl}[(2S (p))-2-ethenylferrocen-1-yl]phenyl-(S)-phosphine sulfide, [Fe(2)(C(5)H(5))(2)(C(27)H(26)NPS)]. All of the structures are accessible in one step from known precursors.