in tetrahydrofuran byproducts: MgCl2; dropwise addn. of CpMgCl in THF to (Ph2P(CH2)2PPh2)FeCl2 in THF under Ar at 20°C; 24 h at 20°C;; evapn. under vac.; extn. with toluene at 50°C several times; filtration; crystn. from the filtrate on cooling at -20°C for 10 d; elem. anal.;;

in tetrahydrofuran byproducts: MgCl2; dropwise addn. of CpMgCl in THF to (Ph2P(CH2)4PPh2)FeCl2 in THF under Ar at -40°C;; evapn. at 20°C under vac.; extn. with toluene at 40°C; filtered; concn. of the filtrate;, dissolving in toluene; addn. of pentane; filtered; crystn. from filtrate at -20°C after several d; elem.anal.;;