Boyle T J, Pedrotty D M, Alam T M, Vick S C, Rodriguez M A
Sandia National Laboratories, Advanced Materials Laboratory, Albuquerque, New Mexico 87106, USA.
Inorg Chem. 2000 Oct 30;39(22):5133-46. doi: 10.1021/ic000432a.
A series of sterically varied aryl alcohols H-OAr [OAr = OC6H5 (OPh), OC6H4(2-Me) (oMP), OC6H3(2,6-(Me))2 (DMP), OC6H4(2-Pr(i)) (oPP), OC6H3(2,6-(Pr(i)))2 (DIP), OC6H4(2-Bu(t)) (oBP), OC6H3(2,6-(Bu(t)))2 (DBP); Me = CH3, Pr(i) = CHMe2, and Bu(t) = CMe3] were reacted with LiN(SiMe3)2 in a Lewis basic solvent [tetrahydrofuran (THF) or pyridine (py)] to generate the appropriate "Li(OAr)(solv)x". In the presence of THF, the OPh derivative was previously identified as the hexagonal prismatic complex [Li(OPh)(THF)]6; however, the structure isolated from the above route proved to be the tetranuclear species [Li(OPh)(THF)]4 (1). The other "Li(OAr)(THF)x" products isolated were characterized by single-crystal X-ray diffraction as [Li(OAr)(THF)]4 [OAr = oMP (2), DMP (3), oPP (4)], [Li(DIP)(THF)]3 (5), [Li(oBP)(THF)2]2, (6), and [Li(DBP)(THF)]2, (7). The tetranuclear species (1-4) consist of symmetric cubes of alternating tetrahedral Li and pyramidal O atoms, with terminal THF solvent molecules bound to each metal center. The trinuclear species 5 consists of a six-membered ring of alternating trigonal planar Li and bridging O atoms, with one THF solvent molecule bound to each metal center. Compound 6 possesses two Li atoms that adopt tetrahedral geometries involving two bridging oBP and two terminal THF ligands. The structure of 7 was identical to the previously reported [Li(DBP)(THF)]2 species, but different unit cell parameters were observed. Compound 7 varies from 6 in that only one solvent molecule is bound to each Li metal center of 7 because of the steric bulk of the DBP ligand. In contrast to the structurally diverse THF adducts, when py was used as the solvent, the appropriate "Li(OAr)(py)x" complexes were isolated as [Li(OAr)(py)2]2 (OAr = OPh (8), oMP (9), DMP (10), oPP (11), DIP (12), oBP (13)) and [Li(DBP)(py)]2 (14). Compounds 8-13 adopt a dinuclear, edge-shared tetrahedral complex. For 14, because of the steric crowding of the DBP ligand, only one py is coordinated, yielding a dinuclear fused trigonal planar arrangement. Two additional structure types were also characterized for the DIP ligand: [Li(DIP)(H-DIP)(py)]2 (12b) and [Li2(DIP)2(py)3] (12c). Multinuclear (6,7Li and 13C) solid-state MAS NMR spectroscopic studies indicate that the bulk powder possesses several Li environments for "transitional ligands" of the THF complexes; however, the py adducts possess only one Li environment, which is consistent with the solid-state structures. Solution NMR studies indicate that "transitional" compounds of the THF precursors display multiple species in solution whereas the py adducts display only one lithium environment.
一系列空间结构各异的芳醇H-OAr [OAr = OC6H5 (OPh)、OC6H4(2-Me) (oMP)、OC6H3(2,6-(Me))2 (DMP)、OC6H4(2-Pr(i)) (oPP)、OC6H3(2,6-(Pr(i)))2 (DIP)、OC6H4(2-Bu(t)) (oBP)、OC6H3(2,6-(Bu(t)))2 (DBP)；Me = CH3，Pr(i) = CHMe2，Bu(t) = CMe3] 在路易斯碱性溶剂[四氢呋喃(THF)或吡啶(py)]中与LiN(SiMe3)2反应，生成相应的“Li(OAr)(solv)x”。在THF存在下，OPh衍生物先前被鉴定为六方棱柱配合物[Li(OPh)(THF)]6；然而，从上述路线分离得到的结构却是四核物种[Li(OPh)(THF)]4 (1)。分离得到的其他“Li(OAr)(THF)x”产物通过单晶X射线衍射表征为[Li(OAr)(THF)]4 [OAr = oMP (2)、DMP (3)、oPP (4)]、[Li(DIP)(THF)]3 (5)、[Li(oBP)(THF)2]2 (6)和[Li(DBP)(THF)]2 (7)。四核物种(1 - 4)由交替的四面体Li和金字塔形O原子组成的对称立方体构成，每个金属中心都结合有末端THF溶剂分子。三核物种5由交替的三角平面Li和桥连O原子组成的六元环构成，每个金属中心都结合有一个THF溶剂分子。化合物6有两个采用四面体几何构型的Li原子，涉及两个桥连的oBP和两个末端THF配体。7的结构与先前报道的[Li(DBP)(THF)]2物种相同，但观察到不同的晶胞参数。化合物7与6的不同之处在于，由于DBP配体的空间位阻，7的每个Li金属中心仅结合一个溶剂分子。与结构多样的THF加合物不同，当使用py作为溶剂时，相应的“Li(OAr)(py)x”配合物被分离为[Li(OAr)(py)2]2 (OAr = OPh (8)、oMP (9)、DMP (10)、oPP (11)、DIP (12)、oBP (13))和[Li(DBP)(py)]2 (14)。化合物8 - 13采用双核、边缘共享四面体配合物结构。对于14，由于DBP配体的空间拥挤，仅配位一个py，形成双核稠合三角平面排列。还对DIP配体的另外两种结构类型进行了表征：[Li(DIP)(H-DIP)(py)]2 (12b)和[Li2(DIP)2(py)3] (12c)。多核(6,7Li和13C)固态MAS NMR光谱研究表明，对于THF配合物的“过渡配体”，大块粉末具有几种Li环境；然而，py加合物仅具有一种Li环境，这与固态结构一致。溶液NMR研究表明，THF前体的“过渡”化合物在溶液中显示多种物种，而py加合物仅显示一种锂环境。
