Institut für Anorganische Chemie, Universität Bonn, Bonn, Germany.
Chemistry. 2013 Apr 26;19(18):5676-86. doi: 10.1002/chem.201300017. Epub 2013 Feb 27.
A general approach to the first compounds that contain rhenium-germanium triple and double bonds is reported. Heating [ReCl(PMe3)5] (1) with the arylgermanium(II) chloride GeCl(C6H3-2,6-Trip2) (2; Trip=2,4,6-triisopropylphenyl) results in the germylidyne complex mer-[Cl2 (PMe3)3Re≡Ge-C6H3-2,6-Trip2] (4) upon PMe3 elimination. An equilibrium that is dependent on the PMe3 concentration exists between complexes 1 and 4. Removal of the volatile PMe3 shifts the equilibrium towards complex 4, whereas treatment of 4 with an excess of PMe3 gives a 1:1 mixture of 1 and the PMe3 adduct of 2, GeCl(C6H3-2,6-Trip2)(PMe3) (2-PMe3). Adduct 2-PMe3 can be selectively obtained by addition of PMe3 to chlorogermylidene 2. The NMR spectroscopic data for 2-PMe3 indicate an equilibrium between 2-PMe3 and its dissociation products, 2 and PMe3 , which is shifted far towards the adduct site at ambient temperature. NMR spectroscopic monitoring of the reaction of complex 1 with 2 and the reaction of complex 4 with PMe3 revealed the formation of two key intermediates, which were identified to be the chlorogermylidene complexes cis/trans-[Cl(PMe3)4 Re=Ge(Cl)C6H3-2,6-Trip2] (cis/trans-3) by using NMR spectroscopy. Labile chlorogermylidene complexes cis/trans-3 can be also generated from trans-[Cl(PMe3)4 Re≡Ge-C6H3-2,6-Trip2]BPh4 (9) and (nBu4N)Cl at low temperature, and decompose at ambient temperature to give a mixture of complexes 1 and 4. Complex 4 reacts with LiI to give the diiodido derivative mer-[I2(PMe3)3Re≡Ge-C6H3-2,6-Trip2] (5), which undergoes a metathetical iodide/hydride exchange with Na(BEt3H) to give the dihydrido germylidyne complex mer-[H2(PMe3)3Re≡Ge-C6H3-2,6-Trip2] (6). Carbonylation of 4 induces a chloride migration from rhenium to the germanium atom to afford the chlorogermylidene complex mer-[Cl(CO)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2] (7). Similarly, MeNC converts complex 4 into the methylisocyanide analogue mer-[Cl(MeNC)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2] (8). Chloride abstraction from 4 by NaBPh4 in the presence of PMe3 gives the cationic germylidyne complex trans-[Cl(PMe3)4 Re≡Ge-C6H3-2,6-Trip2]BPh4 (9). Heating complex 4 with cis-[Mo(PMe3)4(N2)2] induces a germylidyne ligand transfer from rhenium to molybdenum to afford the germylidyne complex trans-[Cl(PMe3)4Mo≡Ge-C6H3-2,6-Trip2] (10). All new compounds were fully characterized and their molecular structures studied by X-ray crystallography, which led to the first experimentally determined Re-Ge triple- and double-bond lengths.
报道了首例含有铼-锗三重键和双键的化合物的通用方法。加热[ReCl(PMe3)5]（1）与芳基锗（II）氯 GeCl(C6H3-2,6-Trip2)（2；Trip=2,4,6-三异丙基苯基），在 PMe3 消除后得到甲硅烷基复合物 mer-[Cl2(PMe3)3Re≡Ge-C6H3-2,6-Trip2]（4）。复合物 1 和 4 之间存在依赖于 PMe3 浓度的平衡。挥发性 PMe3 的去除将平衡推向复合物 4，而用过量的 PMe3 处理 4 则得到 1 和 2 的 PMe3 加合物 GeCl(C6H3-2,6-Trip2)(PMe3)（2-PMe3）的 1:1 混合物。通过向氯甲硅烷基 2 中添加 PMe3 可以选择性地获得 2-PMe3。2-PMe3 的 NMR 光谱数据表明，在环境温度下，其处于 2-PMe3 与其离解产物 2 和 PMe3 之间的平衡，该平衡强烈偏向于加合物位点。用 NMR 光谱监测复合物 1 与 2 的反应和复合物 4 与 PMe3 的反应，发现形成了两个关键中间体，通过 NMR 光谱鉴定为氯甲硅烷基复合物 cis/trans-[Cl(PMe3)4 Re=Ge(Cl)C6H3-2,6-Trip2]（cis/trans-3）。在低温下也可以从 trans-[Cl(PMe3)4 Re≡Ge-C6H3-2,6-Trip2]BPh4（9）和 (nBu4N)Cl 生成不稳定的氯甲硅烷基复合物 cis/trans-3，并在环境温度下分解，得到复合物 1 和 4 的混合物。复合物 4 与 LiI 反应得到二碘衍生物 mer-[I2(PMe3)3Re≡Ge-C6H3-2,6-Trip2]（5），它与 Na(BEt3H)进行碘化物/氢化物交换，得到二氢甲硅烷基复合物 mer-[H2(PMe3)3Re≡Ge-C6H3-2,6-Trip2]（6）。4 的羰基化作用导致从铼到锗的氯迁移，得到氯甲硅烷基复合物 mer-[Cl(CO)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2]（7）。类似地，MeNC 将复合物 4 转化为甲基异氰化物类似物 mer-[Cl(MeNC)(PMe3)3Re=Ge(Cl)C6H3-2,6-Trip2]（8）。在存在 PMe3 的情况下，用 NaBPh4 从 4 中抽去氯，得到阳离子甲硅烷基复合物 trans-[Cl(PMe3)4 Re≡Ge-C6H3-2,6-Trip2]BPh4（9）。加热复合物 4 与 cis-[Mo(PMe3)4(N2)2]，导致甲硅烷基配体从铼转移到钼，得到甲硅烷基复合物 trans-[Cl(PMe3)4Mo≡Ge-C6H3-2,6-Trip2]（10）。所有新化合物均通过 X 射线晶体学进行了充分表征和结构研究，这导致首次确定了铼-锗三重键和双键的实验确定长度。
