Abstract The PH-functional methylene bridged diphosphines R2P-CH2-PRH and RHP-CH2- PHR have been synthesized using Cl2P-CH2-PCl2 as a starting material. On reaction with Fe2 (CO) 9 oxidative addition and cleavage of the PCP-skeleton occur yielding cluster compounds, eg (CO) 9Fe3 (RR'P-CH2-PR) H (R [dbnd] Me, Pri, But, CH2-Ph, R'[dbnd] R or H) or (CO) 9Fe3 (μ3PR)(μ2PMeR) H.