Department of Chemistry, University of Sussex, Brighton, BN1 9QJ, UK.
Dalton Trans. 2011 Mar 28;40(12):3047-52. doi: 10.1039/c0dt01482f. Epub 2011 Feb 17.
Reduction at ambient temperature of each of the lithium benzamidinates [Li(L(1))(tmeda)] or [{Li(L(2))(OEt(2))(2)}(2)] with four equivalents of lithium metal in diethyl ether or thf furnished the brown crystalline [Li(3)(L(1))(tmeda)] (1) or [Li(thf)(4)][Li(5)(L(2))(2)(OEt(2))(2)] (2), respectively. Their structures show that in each the N(R(1))C(R(3))NR(2) moiety has the three negative charges largely localised on each of N, N' and R = Aryl); a consequence is that the "aromatic" 2,3- and 5,6-CC bonds of R(3) approximate to being double bonds. Multinuclear NMR spectra in C(6)D(6) and C(7)D(8) show that 1 and 2 exhibit dynamic behaviour. [The following abbreviations are used: L(1) = N(SiMe(3))C(Ph)N(SiMe(3)); L(2) = N(SiMe(3))C(C(6)H(4)Me-4)N(Ph); tmeda = (Me(2)NCH(2)-)(2); thf = tetrahydrofuran.] This reduction is further supported by a DFT analysis.
在环境温度下，将锂苯甲脒盐[Li(L(1))(tmeda)]或[{Li(L(2))(OEt(2))(2)}(2)]中的每一种与四当量的金属锂在二乙醚或四氢呋喃中反应，分别得到棕色结晶的[Li(3)(L(1))(tmeda)]（1）或[Li(thf)(4)][Li(5)(L(2))(2)(OEt(2))(2)]（2）。它们的结构表明，在每个[N(R(1))C(R(3))NR(2]（3-）部分中，三个负电荷主要定位于每个 N、N'和 R=芳基上）；其结果是，R(3)的“芳香”2,3-和 5,6-CC 键近似为双键。在 C(6)D(6)和 C(7)D(8)中的多核 NMR 光谱表明，1 和 2 表现出动态行为。[以下缩写用于：L(1)=N(SiMe(3))C(Ph)N(SiMe(3))；L(2)=N(SiMe(3))C(C(6)H(4)Me-4)N(Ph)；tmeda=(Me(2)NCH(2)-)(2)；thf=四氢呋喃。]这种还原作用进一步得到了 DFT 分析的支持。
