Crystal structure, conformational diversity and solution NMR spectroscopy of four tris(indenyl)lanthanoid(III) tetrahydrofuran adducts:: [Ln(C9H7)3•THF] (Ln = La, Pr, Nd, Sm)
Crystal structure, conformational diversity and solution NMR spectroscopy of four tris(indenyl)lanthanoid(III) tetrahydrofuran adducts:: [Ln(C9H7)3•THF] (Ln = La, Pr, Nd, Sm)
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DOI：
10.1016/s0022-328x(97)00565-2
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发表时间：
1997-12-18
影响因子：
2.3
通讯作者：
Fischer, RD
中科院分区：
文献类型：
--
作者：
Guan, JW;Shen, Q;Fischer, RD
本文报道了四个同系三茚基镧系元素加合物[Ln（C_9H_7）（3）THF]（THF =四氢呋喃）（Ln = La（1），Pr（2），Nd（3）和Sm（4））的高产率合成，并对六个单晶1a，1b，2，3a，3b和4（1和3至少是二晶型的）进行了详细的X射线研究。C9 H7配体的C-5-片段几乎是pentahapto-bonded，并且两个或三个C9 H7单元采用桨轮状取向。晶体1a、2和3a含有两个不同构象的分子，一个分子显示一个相对于THF配体呈transoid取向的C9 H7苯并基团。一个类似的构象，虽然有一个cisoid苯并基团，实现在1b。三个特征性的结构基序，I（1a，2，3a），II（1b）和III（3b，4），出现从目前的结果，似乎是与早期的研究结果一致。基序III是最显着的，鉴于其六边形，手性空间群P6（3），由于“三角无序”的THF单元。溶液H-1 NMR光谱表明三个快速平衡的几乎相等的C9 H7配体，1的La-139 NMR光谱和2的MCD光谱再次允许eta（5）-配位。长期悬而未决的建议，主要是eta（1）协调C9 H7配体溶解分子4似乎不再合理。(C)1997年Elsevier Science S.A.
Four homologous tris(indenyl)lanthanoid(III) adducts, [Ln(C9H7)(3)THF] (THF = tetrahydrofuran), with Ln = La (1), Pr (2), Nd (3) and Sm (4) were prepared in excellent yields, and six single crystals, 1a, 1b, 2, 3a, 3b and 4 (1 and 3 being at least dimorphic) have been subjected to detailed X-ray studies. The C-5-fragments of the C9H7 ligands are almost pentahapto-bonded, and either two or three C9H7 units adopt paddle-wheel-like orientations. The crystals 1a, 2 and 3a contain two molecules of different conformation, one molecule displaying one C9H7 benzo group in a transoid orientation relative to the THF ligand. A similar conformation, albeit with one cisoid benzo group, is realized in 1b. Three characteristic structural motifs, I(1a, 2, 3a), II (1b) and III (3b, 4), emerge from the present results, and appear to be consistent with earlier findings. Motif III is most remarkable in view of its hexagonal, chiral space group P6(3), owing to 'trigonally disordered' THF units. Solution H-1 NMR spectroscopy indicates three rapidly equilibrating virtually equivalent C9H7 ligands, the La-139 NMR spectrum of 1 and the MCD spectrum of 2 admitting again eta(5)-coordination. The long-pending suggestion of predominantly eta(1)-coordinated C9H7 ligands in dissolved molecules of 4 seems to be no longer justified. (C) 1997 Elsevier Science S.A.