Terminal FeI-N2 and FeII...H-C interactions supported by tris(phosphino)silyl ligands
Terminal FeI-N2 and FeII...H-C interactions supported by tris(phosphino)silyl ligands
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DOI：
10.1002/anie.200701188
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Peters, Jonas C.
中科院分区：
文献类型：
--
作者：
Mankad, Neal P.;Whited, Matthew T.;Peters, Jonas C.
近年来，铁的二氮配合物已成为众多合成研究的目标。[1]在此类系统中探索的一个不寻常且有趣的形式氧化态是铁 (I)，特别是在 Chatt 型 [2] FeI/IV N2 固定循环的背景下（即 FeIÀN2+ 3H！FeIV N+ NH3；FeIV N+ 3H！FeIÀN2+ NH3）。 Yandulov 和 Schrock 最近的工作通过建立概念上相关的 MoIII/VI N2 固定循环的合成可行性，为此类研究提供了动力。 [3]铁和钼都存在于 MoFe 固氮酶的 FeMo 辅因子中，[4] 并且伪四面体 FeIV N 物种（FeI/IV N2 固定机制的假设中间体）最近得到了表征。 [5] Holland 的研究小组和我们自己的研究小组都报道了形式+ 1 氧化态铁的三配位和四配位 N2 加合物的例子，但在这两种情况下都没有鉴定或分离出末端键合的 N2 物种；双核端基 Fe-NN-Fe 物种不可避免地获得。[6]对于 Schrock 三（酰氨基）胺 MoÀN2 系统，事实证明，在暴露感兴趣的 N2 固定化学物质之前，有必要使用高度的空间体积来防止双金属加合物的形成。我们尝试用磷原子处的大取代基改造{(PhBPR 3) Fe}支架([PhBPR 3]=[PhBP-(CH2PR2) 3] À)以防止双核反应途径，但迄今为止还无法使用[PhBPR 3]配体获得末端键合的FeIÀN2加合物。最近我们开始将注意力转向新的衍生物 经典的 Sacconi 型 NP3 配体（例如 N (CH2CH2PR2) 3）以实现末端键合的 FeIÀN2 合成子。 [7]虽然使用这些类型的配体很容易获得 {FeII (N2)(H)}+ 物质，[7] 尚未获得铁 (I) 的 N2 加合物。然而，我们发现替代品
Dinitrogen complexes of iron have been the target of numerous synthetic studies in recent years.[1] An unusual and intriguing formal oxidation state to explore in such systems is iron (I), especially in the context of a Chatt-type [2] FeI/IV N2 fixation cycle (ie FeIÀN2+ 3H! FeIV N+ NH3; FeIV N+ 3H! FeIÀN2+ NH3). Yandulov and Schrock s recent work has provided impetus for such studies by establishing the synthetic viability of a conceptually related MoIII/VI N2 fixation cycle.[3] Both iron and molybdenum are present in the FeMo cofactor of MoFe nitrogenases,[4] and a pseudotetrahedral FeIV N species, a hypothetical intermediate of an FeI/IV N2 fixation mechanism, has recently been characterized.[5] Both Holland s group and our own have reported examples of three-and four-coordinate N2 adducts of iron in the formal+ 1 oxidation state, but in neither case were terminally bonded N2 species identified or isolated; dinuclear end-on FeÀNNÀFe species were inevitably obtained.[6] For the Schrock tris (amido) amine MoÀN2 systems, it proved necessary to use a high degree of steric bulk to prevent bimetallic adduct formation before the N2 fixation chemistry of interest could be exposed. We have attempted to retrofit the {(PhBPR 3) Fe} scaffolds ([PhBPR 3]=[PhBP-(CH2PR2) 3] À) with bulky substituents at the phosphorus atoms to prevent dinuclear reaction pathways but have thus far been unable to obtain terminally bonded FeIÀN2 adducts using [PhBPR 3] ligands.Recently we began to turn our attention to new derivatives of the classic Sacconi-type NP3 ligands (eg N (CH2CH2PR2) 3) to achieve access to a terminally bonded FeIÀN2 synthon.[7] While {FeII (N2)(H)}+ species are readily accessible using ligands of these types,[7] N2 adducts of iron (I) have yet to be obtained. We find, however, that replacement