Three and four coordinate Fe carbodiphosphorane complexes
Carbodiphosphoranes (CDPs) are a family of divalent carbon ligands that are known for their exceptional electron donor properties. Herein, the preparation and reactivity of a family of three and four co-ordinate Fe carbodiphosphorane complexes is described. Hexaphenylcarbodiphosphorane (HCDP)  is shown to react with FeCl2(PPh3)2 to form the three coordinate adduct Fe(HCDP)Cl2 , which is equilibrium with its four coordinate dimer. Reaction of  with two equivalents of benzyl Grignard yields the corresponding dialkyl complex (HCDP)FeBn2 . Combination of  with LiHMDS results in salt metathesis and the formation of the monosilylated derivative Fe(HCDP)Cl(N(SiMe3)2) . Subsequent anion exchange leads to the three coordinate Fe(HCDP)(OTf)(N(SiMe3)2)  which was characterized crystallographically and in solution.