Abstract
Reactions of Mn(ClO~4~)~2~·6H~2~O with FcCO~2~Na [Fc = (η^5^‐C~5~H~4~)Fe(η^5^‐C~5~H~5~)] in methanol solution gave [Mn~3~(FcCO~2~)~6~(CH~3~OH)~4~]~n~ (1), and, in the presence of 4,4′‐bipyridine (4,4′‐bpy), [Mn~3~(FcCO~2~)~6~(H~2~O)~2~(4,4′‐bpy)]~n~ (2). Both complexes have the similar chains with a sequence of –Mn–(μ~2~‐COO)~n~–Mn–(μ~2~‐COO)–Mn–(μ~2~‐COO)–Mn–(μ~2~‐COO)~n~–Mn– (n = 4 and 2 for complex 1 and 2, respectively), which are constructed alternatively from mononuclear [Mn^II^] units and dinuclear [Mn~2~(FcCO~2~)~4~] units by μ~2~‐ferrocenecarboxylato‐O,O′ bridging. The two Mn^II^ ions in the dinuclear [Mn~2~(FcCO~2~)~4~] units of complex 1 are connected by four ferrocenecarboxylato ligands to form a swastika‐like shaped skeleton, which is rare in metallocenecarboxylato complexes. However, the two Mn^II^ ions in the dinuclear [Mn~2~(FcCO~2~)~4~] units of complex 2 are bridged only by two carboxylato ligands, and the other two ferrocenecarboxylato ligands in this unit bind in a chelating mode. The chains in complex 2 are further interconnected by the coordinated 4,4′‐bipyridine molecules to form two‐dimensional coordination sheets. Magnetic susceptibility measurements revealed a weak antiferromagnetic coupling for both complexes. A model Heisenberg chain comprising classical spins coupled through alternating exchange interactions J~1~–J~1~–J~2~ (AF1–AF1–AF2) is proposed to describe the magnetic behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)