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Trimethylsilyl versus Bis(trimethylsilyl) Substitution in Tris(cyclopentadienyl) Complexes of La, Ce, and Pr: Comparison of Structure, Magnetic Properties, and Reactivity
Organometallics ( IF 2.5 ) Pub Date : 2018-03-07 00:00:00 , DOI: 10.1021/acs.organomet.7b00881
Chad T. Palumbo 1 , Lucy E. Darago 2 , Cory J. Windorff 1 , Joseph W. Ziller 1 , William J. Evans 1
Affiliation  

To evaluate the effect of cyclopentadienyl ligand substitution in complexes of new +2 ions of the lanthanides, comparisons in reactivity and spectroscopic and magnetic properties have been made between [K(crypt)][Cp′3Ln], 1-Ln (Cp′ = C5H4SiMe3; crypt = 2.2.2-cryptand; Ln = La, Ce, Pr, and Nd), and [K(crypt)][Cp′′3Ln], 2-Ln [Cp′′ = C5H3(SiMe3)2]. The 2-Ln complexes (Ce, Pr, and Nd) were synthesized by reduction of Cp′′3Ln with potassium graphite in the presence of crypt and crystallographically characterized. The structures and UV–visible spectra of 2-Ln are similar to those of 1-Ln, as expected, but greater thermal stability for 2-Ln, expected from comparisons of 2-U and 1-U, was not observed. The magnetic susceptibilities of 2-Ce and 2-Pr were investigated because those of 1-Ce and 1-Pr did not match simple coupling models for 4fn5d1 electron configurations. The magnetic data of the 2-Ln complexes are similar to those of 1-Ln, which suggests that Ce2+ and Pr2+ complexes with 4fn5d1 electron configurations may have more complex electronic structures compared to nontraditional divalent complexes of the later lanthanides. Reactivity studies of isolated samples of 1-Ln and 2-Ln with 1,2-dimethoxyethane (DME) were conducted to determine if methoxide products, found in previous in situ studies of the synthesis of 2-Ln by Lappert and co-workers, would form. Methoxide products were not observed, which shows that the chemistry of the isolated complexes differs from that of the in situ reduction reactions.

中文翻译:

La,Ce和Pr的三(环戊二烯基)配合物中的三甲基甲硅烷基与双(三甲基甲硅烷基)取代:结构,磁性和反应性的比较

为了评估环戊二烯基配取代在新+2离子的镧系元素的配合物的效果,在反应性和光谱和磁特性的比较已被[K(隐窝)] [CP'之间进行3 LN],1-LN(CP' = C 5 H ^ 4森达3 ;隐窝= 2.2.2-穴醚; Ln为镧,铈,镨,和Nd)和[K(隐窝)] [CP'' 3 LN],2-LN [CP'' = C 5 H 3(SiMe 32 ]。的2-LN络合物(铈,镨,和Nd)通过还原CP''的合成3Ln在存在隐窝的情况下具有石墨化钾和晶体学特征。的结构和紫外-可见光谱2-LN类似于的1-LN,如所预期,但对于更高的热稳定性2-LN,从比较预期2-U1-U ,也未观察到。研究了2-Ce2-Pr的磁化率,因为1-Ce1-Pr的磁化率与4f n 5d 1电子构型的简单耦合模型不匹配。2-Ln络合物的磁数据类似于1-Ln的磁数据,这表明与后期镧系元素的非传统二价配合物相比,具有4f n 5d 1电子构型的Ce 2+和Pr 2+配合物可能具有更复杂的电子结构。进行了分离的1-Ln2-Ln样品与1,2-二甲氧基乙烷(DME)的反应性研究,以确定在先前由Lappert和同事进行的2-Ln合成原位研究中发现的甲醇盐产物是否存在,会形成。没有观察到甲醇氧化物产物,这表明分离的配合物的化学性质与原位还原反应的化学性质不同。
更新日期:2018-03-08
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