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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Synthesis, structure and solution dynamics of lithium salts of superbulky cyclopentadienyl ligands
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Synthesis, structure and solution dynamics of lithium salts of superbulky cyclopentadienyl ligands

机译：超大体积环戊二烯基配体锂盐的合成，结构和溶液动力学

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The superbulky cyclopentadienes (CpAr_5)H (Ar~# = 3.5-Me_2C_6H_3 (1a); Ar~* = 3.5-~tBu_2C_2H_3(1b)) were prepared by the palladium-catalyzed reaction of metallocenes with aryl bromides. NMR spectroscopy was consistent with C_s symmetric solution structures with free rotation of the substituted aryl rings. The molecular structure of 1a is similar to that previously determined for pentaphenylcyclopentadiene, with a planar Cp ring bisected by an approximate mirror plane. Addition of BuLi to 1a,b yielded the lithium salts (CpAr_5~#)Li(THF)_2 (2a) and (CpAr_5~*)Li (2b) in good yield. ~7Li NMR spectroscopy of 2a,b indicated more than one species in solution. Crystallization of 2a from toluene revealed an infinite one-dimensional chain structure with alternating [(CpAr_5~#)_2Li]~- and [(THF)Li(CpAr_5~*)Li(CpAr_5~#)Li(THF)]~+ units; due to the sterics of the Cp rings, the lithium atom appears to be only loosely held in place with a larger than usual Li-Cp distance. ~7Li NMR spectroscopy suggested an equilibrium between the monomeric species (CpAr_5~#)Li(THF)_x and the metallate [(CpAr_5~#)_2Li][Li(THF)_x] in C_6D_6 which was supported by variable temperature and NOESY ~7Li NMR experiments. Crystallization of 2a from THF/TMEDA yielded the solvent separated ion pair [(CpAr_5~#)_2Li][Li(TMEDA)_2(3a). In this case, ~7Li NMR spectroscopy pointed towards the presence of a single species in solution.
机译：超金属环戊二烯（CpAr_5）H（Ar〜＃= 3.5-Me_2C_6H_3（1a）; Ar〜* = 3.5-tBu_2C_2H_3（1b））是通过钯催化的茂金属与芳基溴化物反应制得的。 NMR光谱与取代芳基环自由旋转的C_s对称溶液结构一致。 1a的分子结构类似于先前对五苯基环戊二烯所确定的分子结构，其平面Cp环被近似镜平面一分为二。将BuLi添加到1a，b中可得到高产率的锂盐（CpAr_5〜＃）Li（THF）_2（2a）和（CpAr_5〜*）Li（2b）。 2a，b的7Li NMR光谱表明溶液中存在不止一种物质。从甲苯中结晶2a揭示了一个无限的一维链结构，其中[[CpAr_5〜＃）_ 2Li]〜和[（THF）Li（CpAr_5〜*）Li（CpAr_5〜＃）Li（THF）]〜+单元交替排列;由于Cp环的空间，锂原子似乎只是松散地固定在适当的位置，其距离比通常的Li-Cp大。 〜7Li NMR光谱表明C_6D_6中的单体种类（CpAr_5〜＃）Li（THF）_x和金属化物[（CpAr_5〜＃）_ 2Li] [Li（THF）_x]之间存在平衡，这是由可变温度和NOESY支持的。 7Li NMR实验。从THF / TMEDA中结晶2a，得到溶剂分离的离子对[（CpAr_5〜＃）_ 2Li] [Li（TMEDA）_2（3a）。在这种情况下，〜7Li NMR光谱表明溶液中存在单个物质。

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