56577-99-2Relevant academic research and scientific papers
Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes
Moilanen, Jani O.,Mansikkam?ki, Akseli,Lahtinen, Manu,Guo, Fu-Sheng,Kalenius, Elina,Layfield, Richard A.,Chibotaru, Liviu F.
, p. 13582 - 13589 (2017)
The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of single-molecule behaviour in 2 arises from the rotation of the principal magnetic axis as compared to the pseudo-C5 axis of the pentagonal bipyramidal environment as suggested by ab initio calculations. The cyclic voltammetry and chemical reduction experiments demonstrated that complexes 1 and 2 can be reduced to radical species containing [BQ3-]. This study establishes efficient synthetic strategy to make bridged redox-active multinuclear lanthanide complexes with a pentagonal bipyramidal coordination environment that are potential precursors for single-molecule magnets.
Intermolecular Migration of Silyl Groups in (Trimethylsiloxy)enones
Reetz, Manfred T.,Neumeier, Guenther
, p. 1234 - 1243 (2007/10/02)
Crossover experiments prove that the silyl groups in quadratic acid bis(trimethylsilyl ester) (1) undergo rapid intermolecular migrations.This causes the two 13C-NMR signals of the fourmembered ring, which appear at 35 deg C as singlets, to coalesce at 83 deg C and to reappear as a single signal above 170 deg C.The activation energy amounts to 16.9 kcal/mol.Other bis(silylated) ketoenols 2,3,4, and 5 show no dynamic effects; nevertheless, they rearrange intermolecularly.
