The reaction of [{Cpx(CO)2Fe}SbCl2] [1a: Cpx = 5-C5H3tBu2-1,3 (Cp"); 1b: Cpx = 5-C5Me5 (Cp*)] with Na2[Fe(CO)4] or K[Co(CO)4] affords the novel antimony-transition metal cluster compounds [{3-SbFe(CO)2Cp"}3{Fe(CO)3}4] (2), [{Fe3(CO)9}{3-SbFe(CO)2Cp"}2] (3) and [{4-SbFe(CO)2Cp*}2{Co4(CO)10(-CO)}] (4). All products were characterised by X-ray structure analyses and other methods. Cluster 2 reveals a novel Sb3Fe4 core, which does not follow the Wade-Mingos rules. Cluster 3 forms a square-pyramidal nido-cluster. The Sb2Co4 cluster core of 4 derives from a pentagonal bipyramid and consists of apical Sb and equatorial Co atoms with one missing pentagonal core atom.