Trinuclear rare earth pyridyl-β-diketonate complexes: developing new methods towards finding lost toroidal spin states†

IF 3.3 3区化学 Q2 CHEMISTRY, INORGANIC & NUCLEAR

Dalton Transactions Pub Date : 2025-06-13 DOI:10.1039/D5DT01067E

Patrick Mangundu, Kate E. Tanner, Andrew Bloomfield, Peter J. Barnard, Keith F. White, Curtis C. Ho, Nageshwar R. Yepuri, Richard A. Mole and Rebecca O. Fuller

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Abstract

A series of rare earth (RE) ‘triangles’ have been synthesised to investigate the low energy excitations of toroic molecules using inelastic neutron scattering (INS) experiments. β-Diketonate, 1-(2-pyridinyl)-1,3-butandione (o-pbdH) has been employed to synthesise [{Ho₃(O)₂(o-pbd)₃Cl(H₂O)₅}₂]·8Cl·3H₂O·0.5EtOH (1) and [{Dy₃(O)₂(o-pbd)₃Cl(H₂O)₅}₂]·6Cl·2EtOH·2hexane (2). With further examples, [Ho₃(OH)₂(o-pbd)₃Cl(H₂O)₃(EtOH)₂]·3Cl (3), [{Ho₃(OH)₂(o-pbd)₃Cl(H₂O)₅}₂]·6Cl·2H₂O (4) and [Dy₃(O)(OH)(o-pbd)₃(NO₃)₄(H₂O)₂]·2NO₃·H₂O (5) aimed towards the generation of variation in coordinated ancillary ligands that are capable of reducing symmetry and inhibiting toroic behaviour. A sterically bulky 3-(1-naphthyl)-1-(2-pyridyl)-propane-1,3-dione (o-nppdH) ligand impeded the formation of the RE₃ motif with [Dy₂(O)₂(o-nppd)₅(H₂O)]·6Cl (6) isolated. The RE₃ complexes are structurally similar to known trinuclear based single molecular toroics (SMTs), including RE-β-diketonate analogues prone to mixing between electronic states. Consistent with these, a non-magnetic SMT ground state was not observable in the new complexes utilising conventional magnetometry. Spectroscopic confirmation of toroic properties with INS was attempted for the first time on 1 and the structurally similar SMT [Ho₃(OH)₂(o-dppd-d₁₀)₃Cl(H₂O)₅]. The observed intensity of a broad Lorentzian at 0.69(1) meV for [Ho₃(OH)₂(o-dppd)₃Cl(H₂O)₅] and 0.44(1) meV for 1, is remarkably close to the calculated energy gap ∼5 cm⁻¹ (or 0.62 meV) and potentially provides a new probe that can validate complexes with a poorly separated toroidic ground state.

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三核稀土吡啶基-β-二酮酸配合物：开发寻找丢失环向自旋态的新方法

本文合成了一系列稀土“三角形”，利用非弹性中子散射（INS）实验研究了环面分子的低能激发。用β-二酮酸1-（2-吡啶基）-1,3-丁二酮（O - pbdh）合成了[{Ho3(O)2(O -pbd)3Cl(H2O)5}2]·8Cl·3H2O·0.5EtOH(1)和[{Dy3(O)2(O -pbd)3Cl(H2O)5}2]·6Cl·2EtOH·2己烷(2)]。进一步的例子是，[Ho3(OH)2(O -pbd)3Cl(H2O)3(EtOH)2]·3Cl (3), [{Ho3(OH)2(O -pbd)3Cl(H2O)5}2]·6Cl·2H2O(4)和[Dy3(O)(OH)(O -pbd)3(NO3)4(H2O)2]·2NO3·H2O(5)]旨在产生能够降低对称性和抑制环回行为的配体变异。大体积的3-（1-萘基）-1-（2-吡啶基）-丙烷-1,3-二酮（O - nppdh）配体阻碍了[Dy2(O)2(O -nppd)5(H2O)]·6Cl (6)] RE3基序的形成。RE3配合物在结构上类似于已知的基于三核的单分子环形物（smt），包括易于在电子态之间混合的RE-β-二酮酸类似物。与这些一致，一个非磁性SMT基态没有观察到新的配合物利用传统的磁强计。首次尝试用INS对1和结构相似的SMT [Ho3(OH)2(o-dppd-d10)3Cl(H2O)5]的环面性质进行光谱确认。[Ho3(OH)2(o-dppd)3Cl(H2O)5]和[Ho3(OH)2(o-dppd)3Cl(H2O)5]的宽洛伦兹强度分别为0.69(1)meV和0.44(1)meV，与计算出的能隙~5 cm-1（或0.62 meV）非常接近，并有可能提供一种新的探针，用于验证环向基态分离差的配合物。

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来源期刊

Dalton Transactions 化学-无机化学与核化学

CiteScore

6.60

自引率

7.50%

发文量

1832

审稿时长

1.5 months

期刊介绍： Dalton Transactions is a journal for all areas of inorganic chemistry, which encompasses the organometallic, bioinorganic and materials chemistry of the elements, with applications including synthesis, catalysis, energy conversion/storage, electrical devices and medicine. Dalton Transactions welcomes high-quality, original submissions in all of these areas and more, where the advancement of knowledge in inorganic chemistry is significant.