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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Heterometallic 20-membered {Fe_(16)Ln_4} (Ln = Sm, Eu, Gd, Tb, Dy, Ho) metallo-ring aggregates
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Heterometallic 20-membered {Fe_(16)Ln_4} (Ln = Sm, Eu, Gd, Tb, Dy, Ho) metallo-ring aggregates

机译：杂金属20元{Fe_（16）Ln_4}（Ln = Sm，Eu，Gd，Tb，Dy，Ho）金属环聚集体

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摘要

The reaction of triethanolamine (teaH_3) with [Fe ~(III)_3O(O_2CCH_3)_6(H _2O)_3]Cl·6H_2O and Ln(NO_3) _3·6H_2O in acetonitrile yields [Fe _(16)Ln_4(tea)_8(teaH)_(12)(μ-O _2CCH_3)_8](NO_3)_4· 16H_2O·xMeCN (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), Ho (6); x = 10 or 11). These 20-membered metallo-ring complexes are the largest such single-stranded oxygen-bridged rings so far reported. The structure is stabilised by two of the acetate ligands, which form anti,anti-bridges across the centre of the ring, pinching the ring and giving it rigidity. The magnetic properties are dominated by the antiferromagnetic couplings between the Fe ~(III) centres. Although the Fe_2 and Fe_6 sub-chains within the ring are fully spin-compensated at low temperatures with S_(subchain) = 0, coupling between the Gd~(III) cations and the Fe~(III) centres at the ends of the sub-chains (in 3) results in a pinning of the lanthanide spins. The ~(57)Fe M?ssbauer spectra of 3 and 5 obtained at low temperatures are consistent with the presence of Fe ~(III) intracluster strong antiferromagnetic coupling. The applied field spectrum for 3 reveals no magnetic hyperfine interaction apart from that of the nucleus with the applied field, while the one for 5 is a superposition of three subspectra which show contributions from each of the peripheral as well as from the central iron sites.
机译：三乙醇胺（teaH_3）与[Fe〜（III）_3O（O_2CCH_3）_6（H _2O）_3] Cl·6H_2O和Ln（NO_3）_3·6H_2O在乙腈中的反应生成[Fe _（16）Ln_4（tea）_8 （teaH）_（12）（μ-O_2CCH_3）_8]（NO_3）_4·16H_2O·xMeCN（Ln = Sm（1），Eu（2），Gd（3），Tb（4），Dy（5） ，Ho（6）; x = 10或11）。这些20元金属环配合物是迄今为止报道的最大的单链氧桥环。该结构由两个乙酸酯配体稳定，它们在环的中心形成反，反桥，夹住环并赋予其刚性。磁性由Fe〜（III）中心之间的反铁磁耦合决定。尽管环中的Fe_2和Fe_6子链在低温下被S_（subchain）= 0完全自旋补偿，但Gd〜（III）阳离子和Fe〜（III）中心之间的偶联位于子末端-链（在3中）导致镧系元素自旋的固定。低温获得的3和5的〜（57）Fe M？ssbauer光谱与Fe〜（III）团簇内强反铁磁耦合的存在是一致的。 3的施加场谱显示除了核与施加的场之外没有磁超精细相互作用，而5的场谱是三个子谱的叠加，显示了每个外围以及中心铁位点的贡献。

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