in pentane byproducts: (CO)4FeP(NMe2)3, (CO)3Fe(P(NMe2)3)2; (Ar); dropwise addn. of freshly prepared Fe(CO)4CS in pentane to a soln. of P(NMe2)3 in pentane at 0°C; sepn. of a black-brown oily product from which violet crystals can be isolated after several days, decantation of soln., evapn. in vac., extn. of residue with toluene, filtn., the filtrate is layered with pentane, sepn. of product, elem. anal.;