Comparison of an Internally Coordinated 2-Pentenyllithium with Its 4-Sila Analog. Structure and Dynamic Behavior: Unexpected <sup>13</sup>C<sup>7</sup>Li Spin Coupling
allyl moiety in each one is partially localized, and 7Li is spin coupled to both 31C1 and 13C2 of allyl. NMR line shape changes show that 9en, 9ex, 13en, and 13ex all undergo fast transfer of the lithium-coordinated ligand between faces of the allyl planes at low temperatures. Within each equilibrium system the compound with the exo-tethered ligand inverts faster than its endo analog. All four compounds
四种烯丙基锂化合物已被制备的栓系配位体,(CH 3 OCH 2 CH 2)2 NCH 2 C(CH 3)2 -大号,连接到末端碳烯丙酯。它们是3-等摩尔平衡混合物内切-大号与3- -allyllithium外型-大号-allyllithium,9en和9EX,分别与(单独)1-外-TMS -3-内-大号-allyllithium与1-外型- TMS-3-外型-大号-alallithium,13en和13ex。碳13 NMR分析表明,所有四种化合物均为单体且内部配位,每一个中的烯丙基部分均部分定位,并且7 Li与烯丙基的31 C 1和13 C 2旋转偶联。NMR线形变化表明,9en,9ex,13en和13ex都在低温下经历了烯丙基平面的各面之间的锂配位配体的快速转移。在每个平衡系统中,带有外链配体的化合物的转化速度快于其内模拟。与作为溶剂的二乙醚-d 10相比,这四种化合物在THF- d 1