The dianions {[p-(CO)3MC5H4C(O)]2C6H4}2 reacted with Ph2SnBr2 in a 1:2 or 1:1 ratio to give tetranuclear heterodimetalliccomplexes p-[(Ph2BrSn)(CO)3MC5H4C(O)]2C6H4 (M/Mo (1) or W (2), respectively), and with CH2(SnPhBr2)2 to yieldtetranuclear heterodimetallic metallamacrocycles {p-[(CO)3MC5H4C(O)]2C6H4}{(Ph2 nBrnSn)2CH2} (n/1, M/Mo (5) and W (6); n/0, M/Mo (7) and W (8), respectively). Only one bromide on the tin atom was replaced by the metallic anions owing to theelectron-withdrawing groups on the cyclopentadienyl rings greatly decreasing the nucleophilicity of the metallic anions. Treatmentof complexes 1 and 2 with Na2S/9H2O yielded the novel metallamacrocyclic complexes {p-[(CO)3MC5H4C(O)]2C6H4}{(Ph2Sn)2S}(M/Mo (3) and W (4), respectively). All compounds have been characterized by elemental analyses, IR and 1H-NMR spectra. Thecrystal structures of complexes 3 and 7 determined by X-ray crystallography indicate a novel 14-membered rganometallicmetallamacrocyclic ring system in which two Mo/Sn units are linked by the bridging cyclopentadienyl ligand and the sulfur orcarbon atom. In addition, the carbonyl group p-system is coplanar with the adjacent cyclopentadienyl ring system, but markedlydeviates from the bridging phenyl plane.