Pushing the s-Donor Strength in Iridium Pincer Complexes: Bis(silylene) and Bis(germylene) Ligands Are Stronger Donors than Bis(phosphorus(III)) Ligands
Pushing the s-Donor Strength in Iridium Pincer Complexes: Bis(silylene) and Bis(germylene) Ligands Are Stronger Donors than Bis(phosphorus(III)) Ligands
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DOI：
10.1002/anie.201205570
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Hartwig, John F.
中科院分区：
文献类型：
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作者：
Brueck, Andreas;Gallego, Daniel;Hartwig, John F.
开发新的配体来控制配合物中过渡金属(TM)中心的反应活性是有机金属化学的基本目标。[1]臂(E)通常由中性、两电子的Lewis基本施主基团(例如，E=Pr2、NR2或SR)组成，它们通过连接基(通常是CH2、N或O)连接到中性或单阴离子锚定中心(D；例如，吡啶或苯基)。作为金属中心的铱，钳形配体已被用于生成低配位、高电子丰富的络合物，用于激活强键，如氨或苯胺的N±H，[2]烯烃质子与重苯的选择性H-D交换，[3]和烷烃脱氢。[4]含有N-杂环稳定的二价硅(硅烯基)部分的钳形配体RSI：(R=酰胺或β二酮亚胺)，而不是普通的Pr2、NR2或给电子臂E似乎有望获得更强的σ供体性质，这可以促进更少的反应键的激活。测定了六元双酮配体L与[LNi(CO)_3]配合物的CO伸缩振动，发现A_1带最低为2046 cm±1，而L=PtBu3为2056 cm±1，L=1，3-双(2，6-二异丙基苯基)咪唑-1为2052 cm±1。
The development of new ligands to control the reactivity of transition-metal (TM) centers in complexes is a fundamental goal in organometallic chemistry. The “pincer”(EDE) motif describes tridentate, meridonal coordinating ligands that offer a plethora of opportunities to fine-tune the properties of TM complexes.[1] The arms (E) usually consist of neutral, two-electron Lewis basic donor moieties (for example, E= PR2, NR2, or SR), which are connected over a linker group (often CH2, N, or O) to the neutral or mono-anionic anchoring site (D; for example, a pyridyl or phenyl group). With respect to iridium as the metal center, pincer ligands have been used for the generation of low-coordinated, highly electron-rich complexes used in the activation of strong bonds such as the NÀH of ammonia or aniline,[2] the selective H–D exchange of olefinic protons with deuterobenzene,[3] and alkane dehydrogenation.[4]Pincer ligands containing N-heterocyclic-stabilized divalent silicon (silylenyl) moieties RSi:(R= amidinate or βdiketiminate) instead of the common PR2, NR2, or SR donor arms E appear promising to achieve stronger σ-donating properties, which could facilitate the activation of even less reactive bonds.[5] In fact, the determination of the CO stretching vibrations in [LNi (CO) 3] complexes with sixmembered diketiminate SiII ligands L revealed a A1 band as low as 2046cmÀ1 versus 2056 cmÀ1 for L= PtBu3, and 2052 cmÀ1 for L= 1, 3-bis (2, 6-di-isopropylphenyl) imidazoli-