Structural diversity in solvated lithium aryloxides.: Syntheses, characterization, and structures of [Li(OAr)(THF)x]n and [Li(OAr)(py)x]2 complexes where OAr=OC6H5, OC6H4(2-Me), OC6H3(2,6-(Me))2, OC6H4(2-Pri), OC6H3(2,6-(Pri))2, OC6H4(2-But), OC6H3(2,6-(But))2
Structural diversity in solvated lithium aryloxides.: Syntheses, characterization, and structures of [Li(OAr)(THF)x]n and [Li(OAr)(py)x]2 complexes where OAr=OC6H5, OC6H4(2-Me), OC6H3(2,6-(Me))2, OC6H4(2-Pri), OC6H3(2,6-(Pri))2, OC6H4(2-But), OC6H3(2,6-(But))2
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DOI：
10.1021/ic000432a
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发表时间：
2000-10-30
影响因子：
4.6
通讯作者：
Rodriguez, MA
中科院分区：
文献类型：
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作者：
Boyle, TJ;Pedrotty, DM;Rodriguez, MA
一系列空间位阻不同的芳基醇H-OAr [OAr = OC_6H_5（OPh），OC_6H_4（2-Me）（oMP），OC_6H_3（2，6-（Me））（2）（NO_3），OC_6H_4（2-Pr-i）（oPP），OC_6H_3（2，6-（Pr-i））（2）（DIP），OC6H4（2-Bu-t）（oBP），OC6H3（2，6-二叔丁基）（2）（DBP）; Me = CH3，Pr1 = CHMe2，和Bu-t = CMe 3]与LiN（SiMe 3）（2）在刘易斯碱性溶剂[四氢呋喃（THF）或吡啶（py）]中反应，生成合适的“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，从上述路线分离的结构被证明是四核物质[Li（OPh）（THF）]（4）（1）。通过单晶X-射线衍射将分离的其它“Li（OAr）（THF）（x）”产物表征为[Li（OAr）（THF）]（4）[OAr = oMP（2），OAr（3），oPP（4）1，[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和锥形O原子的对称立方体组成，末端THF溶剂分子结合到每个金属中心。三核物质5由交替的三角平面Li和桥接O原子的六元环组成，每个金属中心与一个THF溶剂分子结合。化合物6具有两个Li原子，采用四面体几何形状，涉及两个桥连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配体的空间体积，只有一个溶剂分子与7的每个Li金属中心结合。与结构不同的THF加合物相比，当py用作溶剂时，分离出合适的“Li（OAr）（py）（x）”络合物为[Li（OAr）（py）（2）]（2）（OAr = OPh（8），oMP（9），OAr（10），oPP（11），DIP（12），oBP（13））和[Li-（DBP）（py）]（2）（14）。化合物8-13采用双核，共边四面体配合物。对于14，由于DBP配体的空间拥挤，只有一个py是协调的，产生双核稠合三角平面排列。DIP配体还表征了另外两种结构类型：[Li（DIP）（H-DIP）（py）]（2）（12 b）和[Li-2（DIP）（2）（py）（3）]（12 c）。多核（Li-6、Li-7和C-13）固态MAS NMR光谱研究表明，对于四氢呋喃配合物的“过渡配体”，散装粉末具有几个Li环境;然而，py加合物仅具有一个Li环境，这与固态结构一致。溶液NMR研究表明，“过渡”化合物的THF前体显示多个物种在溶液中，而py加合物显示只有一个锂环境。
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)1, [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 [Li-2(DIP)(2)(py)(3)] (12c). Multinuclear (Li-6,Li-7 and C-13) 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.