The molecule c/s-tetracarbonylbis[tris(p-fluorophenyl)- phosphine] molybdenum(0), [Mo(C18HI2F3P)2(CO)4], has twofold crystallographic symmetry; the Mo geometry is irregular octahedral, with principal dimensions Mo- P 2.5644 (4), Mo--C (troans to P) 1.9869 (16), Mo--C (trans to C) 2.0310 (18) A, P--Mo--P 107.33 (1), trans- P--Mo--C 166.76 (5)and trans-C--Mo--C 174.31 (8)°. The P geometry is irregular tetrahedral, with enlarged Mo--P--C [average 115.94 (5)°] and reduced C--P--C [average 102.22 (7)°] angles. 95Mo NMR chemical shift data are in accord with the observed structure.