Abstract
The synthesis, structures and magnetic properties of an η5-silole complex and an η5-stannole complex of erbium are reported. The sandwich complex anions [(η5-CpSi)Er(η8-COT)]- and [(η5-CpSn)Er(η8-COT)]-, where CpSi is [SiC4-2,5-(SiMe3)2-3,4-Ph2]2- (1Si), CpSn is [SnC4-2,5-(SiMe3)2-3,4-Me2]2- (1Sn) and COT = cyclo-octatetraenyl, were obtained as their [K(2.2.2-cryptand)]+ salts and found to be isostructural, with remarkably similar bond lengths and angles, differing only in the lengths of the Er-E interactions (E = Si, Sn). The parallels in the molecular structures of 1Si and 1Sn are reflected in their dynamic magnetic properties, which show single-molecule magnet behaviour in zero applied field, with effective energy barriers of 115 ± 7 and 125 ± 3 cm-1, respectively, along with comparable magnetic relaxation times. Analysis of the two complexes using ab initio calculations reveals differences at a quantitative level, but overall similar electronic structures, with the thermally activated relaxation likely to proceed via the first-excited Kramers doublet. Comparing 1Si and 1Sn with the previously reported germanium analogue 1Ge reveals that swapping one heavier group 14 element for another in complexes of the type [(η5-CpE)Er(η8-COT)]- has a minimal impact on the SMM behaviour.
Published Version
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