Bis(fulvalene)dimetal Complexes Revisited: Synthesis and Properties of [M2(2,2′,4,4′-(Me3C)4C10H4)2] (M = Mg, Fe, Mn)

The bis­(fulvalene)­dimetal compounds [M2(fulv′)2] (fulv′ = 2,2′,4,4′-(Me3C)4C10H4)2, M = Fe, Mn) have been isolated from the reaction of [Mg2(fulv′)2] and M­(OTf)2, and they have been fully characterized. In the solid state these species have approximate D2 symmetry with the two metallocene units being twisted relative to each other. While [Mg2(fulv′)2] and [Fe2(fulv′)2] are diamagnetic, the magnetic susceptibility data for the manganese derivative can be successfully modeled by two high-spin (S = 5/2) Mn­(II) atoms that are weakly antiferromagnetically coupled (J ≈ 11 cm–1). Density functional theory (DFT) computations were performed to elucidate the bonding in these dimetal compounds.

双(富瓦烯)二金属化合物[M₂(fulv′)₂]（其中fulv′代表2,2′,4,4′-四(叔丁基)富瓦烯，即2,2′,4,4′-(Me₃C)₄C₁₀H₄，M为Fe或Mn）可通过[Mg₂(fulv′)₂]与M(OTf)₂的反应分离得到，且已被完全表征。在固态下，这类化合物具有近似的D₂点群对称性，两个茂金属单元彼此相互扭转。尽管[Mg₂(fulv′)₂]与[Fe₂(fulv′)₂]均为反磁性物质，但锰衍生物的磁化率数据可通过两个高自旋（S=5/2）的Mn(II)原子成功拟合，二者间存在弱反铁磁耦合作用（J≈11 cm⁻¹）。本研究通过密度泛函理论（Density Functional Theory, DFT）计算阐明了这类二金属化合物的成键本质。