Isolation and crystal and mol­ecular structures of [(C(5)H(2)Br(3))(2)Fe], [(C(5)HBr(4))(2)Fe] and [(C(5)Br(5))(C(5)Br(4)HgBr)Fe]

The reaction of [(C(5)H(3)Br(2))(2)Fe] with lithium tetra­methyl­piperidinide (LiTMP) in a 1:10 molar ratio in tetra­hydro­furan yields, after quenching with C(2)H(2)Br(4), a mixture of the polybromo­ferrocenes [C(10)H(10–n )Br( n )Fe] with n = 4–9, from which single crystals of bis­(1,2,3-tri­bromo­cyclo­penta­dien­yl)iron(II), [Fe(C(5)H(2)Br(3))(2)], and bis­(1,2,3,4-tetra­bromo­cyclo­penta­dien­yl)iron(II), [Fe(C(5)HBr(4))(2)Fe], were obtained by a combination of chromatography and fractional crystallization. Treatment of ‘[C(10)(HgOAc)(10)Fe]’ with KBr(3) yields a mixture of polybromo­ferrocenes [C(10)H(10–n )Br( n )Fe] with n = 8–10 and bromo­mercurioferrocenes [C(10)H(9–n )Br( n )(HgBr)Fe] with n = 7–9, from which single crystals of (1-bromo­mercurio-2,3,4,5-tetra­bromo­cyclo­penta­dien­yl)(1,2,3,4,5-penta­bromo­cyclo­penta­dien­yl)iron(II), [FeHgBr(C(5)Br(4))(C(5)Br(5))], were obtained by fractional crystallization. The crystal structures of all the com­pounds show Br⋯Br, Br⋯H and sometimes Br⋯Cp⋯π (Cp is a ring centroid) interactions, as well as π–π inter­actions. The findings are supported by Hirshfeld analyses.