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Lanthanide cryptate monometallic coordination complexes.
Dalton Transactions ( IF 3.5 ) Pub Date : 2020-08-28 , DOI: 10.1039/d0dt02448a
Christian D Buch 1 , Dmitri Mitcov 1 , Stergios Piligkos 1
Affiliation  

We report the synthesis, characterisation and magnetic properties of six novel neutral lanthanide cryptate coordination complexes. Reaction of 2,6-diformyl-4-methylphenol, tris(2-aminoethyl)amine and Ln(OTf)3·9H2O in the ratio 3 : 2 : 1, respectively, and in the presence of base affords the isolation of the six complexes LnL·4H2O (Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6)), with H3L being the cryptand N[(CH2)2N[double bond, length as m-dash]CH–R–CH[double bond, length as m-dash]N–(CH2)2]3N (R = m-C6H2OH-2-Me-5). Powder X-ray diffraction confirms that the six complexes are isostructural. The crystal structure of 6 reveals that the Ln(III) centre is heptacoordinated, in a geometry close to a monocapped distorted octahedron and lies on a pseudo (non-crystallographically imposed) C3 axis. This coordination sphere is similar to the one found in the previously studied Ln(trensal) complexes (H3trensal = 2,2′,2′′-tris(salicylideneimino)triethylamine). The static and dynamic magnetic properties of these complexes were investigated by SQUID magnetometry. Crystal field parameters were determined for all complexes by modelling of the direct current magnetic susceptibility and variable-temperature-variable-field magnetisation data. As for Ln(trensal), only complexes containing the Kramers ions Dy, Er and Yb displayed out-of-phase susceptibility signals in SQUID measurements in an applied magnetic field. Investigation of the dynamic susceptibility of the Yb complex revealed that the magnetic relaxation is governed by a direct process at low temperatures and a Raman process at higher temperatures, similar to Yb(trensal).

中文翻译:

镧系元素的单金属配位配合物。

我们报告了六种新型中性镧系元素配合物的合成,表征和磁性。2,6-二甲酰基-4-甲基苯酚,三(2-氨基乙基)胺和Ln(OTf)3 ·9H 2 O分别以3:2:1的比例在碱的存在下反应可分离出六个复合物LnL·4H 2 O(Ln = Tb(1),Dy(2),Ho(3),Er(4),Tm(5)和Yb(6)),H 3 L是cryptand N [(CH 22 N [双键,长度为m-破折号]CH–R–CH [双键,长度为m-破折号]N–(CH 22 ] 3N(R =m -C 6 H 2 OH-2-Me-​​5)。粉末X射线衍射证实这六个络合物是同构的。6的晶体结构表明Ln(III)中心是七配位的,其几何形状接近单峰形畸变的八面体,并位于(非晶体施加)C 3轴上。该配位域与先前研究的Ln(延性)络合物(H 3trensal = 2,2',2''-三(水杨亚胺基)三乙胺)。通过SQUID磁力分析法研究了这些配合物的静态和动态磁性。通过对直流磁化率和可变温度可变场磁化数据进行建模,确定了所有配合物的晶场参数。至于Ln(趋势),只有包含Kramers离子Dy,Er和Yb的络合物在施加的磁场中的SQUID测量中显示出异相磁化率信号。Yb络合物的动态磁化率研究表明,磁弛豫由低温下的直接过程和高温下的拉曼过程控制,类似于Yb(trensal)。
更新日期:2020-10-12
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