A Co2N2 diamond-core resting state of cobalt(I):: A three-coordinate CoI synthon invoking an unusual pincer-type rearrangement
A Co2N2 diamond-core resting state of cobalt(I):: A three-coordinate CoI synthon invoking an unusual pincer-type rearrangement
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DOI：
10.1002/anie.200504343
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Mindiola, Daniel J.
中科院分区：
文献类型：
--
作者：
Fout, Alison R.;Basuli, Falguni;Mindiola, Daniel J.
配位不饱和过渡金属配合物预计具有固有的反应性，并提供了研究新型转化的机会，如均相催化[1]和惰性底物（如N2）的活化。[2]然而，在这些系统中产生低配位环境通常会导致辅助配体的降解或重排。只有在少数情况下，辅助配体的重组是可逆的，从而产生能够表现为“掩蔽”低配位片段的静息状态。例如，康明斯及其同事报道了一种可逆的β-氢化物消除途径，导致能够还原裂解大气氮的掩蔽的三配位Mo III片段。[3]对于配合物[Fe-（PMe 3）5]也记录了类似的可逆β-氢化物消除，已证明该配合物与相应的铁（ii）异构体[Fe（H）（η2-CH 2 PMe 2）（PMe 3）3]和游离三甲基膦平衡。[4]在其他两价体系中，Fink及其同事[5]发现含有桥接双齿膦配体的双核Pd 0络合物可以与其单核支架平衡。本文报道了钳形骨架PNP（PNP=[N {2-P（CHMe 2）2-4-MeC 6 H3} 2] nH3）的配体重排。[6，7] PNP钳形配体从末端螯合模式到桥接模式的重组允许分离[{（μ2-PNP）Co} 2]，一种具有Co2 N2金刚石核心静止状态的复合物。[{(μ2-PNP）Co} 2]与底物反应时表现为三配位CoI合成子
Coordinatively unsaturated transition-metal complexes are expected to be inherently reactive and offer an opportunity to study novel transformations such as homogeneous catalysis [1] and the activation of inert substrates such as N2.[2] However, generating low-coordinate environments in these systems can often result in degradation or rearrangement of the ancillary ligand. Only in a few cases can reorganization of the ancillary ligand be reversible, thus generating resting states that are capable of behaving as “masked” low-coordinate fragments. For example, Cummins and co-workers reported a reversible β-hydride elimination pathway leading to a masked threecoordinate MoIII fragment capable of reductively cleaving atmospheric nitrogen.[3] A similar reversible β-hydride elimination has also been documented for the complex [Fe-(PMe3) 5], which has been shown to equilibrate with the corresponding iron (ii) isomer [Fe (H)(η2-CH2PMe2)(PMe3) 3] and free trimethylphosphine.[4] In other amphivalent systems, Fink and co-workers [5] discovered that a dinuclear Pd0 complex containing bridging bidentate phosphine ligands can equilibrate with its mononuclear scaffold. We report herein an unprecedented ligand rearrangement of a pincertype framework PNP(PNP=[N {2-P (CHMe2) 2-4-MeC6H3} 2] À).[6, 7] Reorganization of the PNP pincer ligand from a terminal chelating mode to a bridging mode allows for isolation of [{(μ2-PNP) Co} 2], a complex bearing a Co2N2 diamond-core resting state.[{(μ2-PNP) Co} 2] behaves as a three-coordinate CoI synthon when treated with substrates