The dichloro Group 15 complexes [{Cpx(CO)2Fe}BiCl2] (Cpx = Cp, 5-C5H3tBu2{Cp}) 1a, b and [{Cp(CO)2Fe}SbCl2] 3 are prepared. The crystal structure determination of 1b and 3 shows a polymeric chlorine bridged structure for the bismuth complex 1b whereas for the antimony compound 3 a molecular structure with weak intermolecular chlorine bridges is found. The reaction of 1a or 3 with magnesium leads to the threefold transition-metal substituted complexes [(µ3-E){Fe(CO)2Cpx}3] ( 5: E = Bi, Cpx = Cp; 7: E = Sb, Cpx = Cp), whereas the analogous reaction of 1b results in the disubstituted bismuth chloro complex [{Cp(CO)2Fe}2BiCl] 6. Finally, the reaction of an equimolar mixture of 1a and 3 with magnesium yields the novel antimony-bridged compound [(µ3-Sb){Fe2(µ-CO)(CO)2Cp2}{Fe(CO)2Cp}] 8.