Synthesis and property of BrCCH- and BrCCBr-coordinated tetrairon clusters

Treatment of the acetylene-coordinated tetrairon cluster, [(η5-C5H4Me)4Fe4(HCCH)2]+, with N-bromosuccinimide (NBS) led to stepwise bromination of two acetylene ligands to form [(η5-C5H4Me)4Fe4(HCCBr)(HCCH)]+, [(η5-C5H4Me)4Fe4(HCCBr)2]+, [(η5-C5H4Me)4Fe4(BrCCBr)(HCCBr)]+, and [(η5-C5H4Me)4Fe4(BrCCBr)2]+. The bromoacetylene part shows a novel reactivity toward nucleophiles such as water, ZnR2 (R = Me, Et), H-CCMgBr, LiSpTol, pyridine, and bipyridyl to give the corresponding adducts.