Mechanistic Studies of Alkyne Hydroboration by a Well-Defined Iron Pincer Complex: Direct Comparison of Metal-Hydride and Metal-Boryl Reactivity
Mechanistic Studies of Alkyne Hydroboration by a Well-Defined Iron Pincer Complex: Direct Comparison of Metal-Hydride and Metal-Boryl Reactivity
复制标题
通过明确的铁钳配合物进行炔烃硼氢化反应的机理研究：金属氢化物和金属硼基反应性的直接比较
DOI：
10.1021/acs.inorgchem.2c01325
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发表时间：
2022
影响因子：
4.6
通讯作者：
Tonzetich, Zachary J.
中科院分区：
文献类型：
--
作者：
Narro, Ana L.;Arman, Hadi D.;Tonzetich, Zachary J.
采用吡咯钳形配体tBuPNP（PNP = 2，5-二（二叔丁基膦甲基）吡咯的阴离子）负载的铁氢化物和铁硼基配合物，详细研究了内炔硼氢化反应的机理.几个新的配合物进行了分离和充分的特点，包括铁-乙烯基和铁-硼物种，这可能是催化硼氢化反应途径中的中间体。此外，炔插入到Fe-B键的产物已被分离和结构表征。硼氢化反应的机理研究有利于涉及活性铁氢化物物种[FeH（tBuPNP）]的途径，其容易地插入炔并经历随后与硼氢化物的反应以生成产物。铁硼物种，[Fe（BR 2）（tBuPNP）]（R2=销或猫），被认为是化学主管，虽然它在催化中的使用需要一个诱导期，从而产生的铁氢化物物种。进行化学计量反应和动力学实验，以描绘更全面的画面的炔硼氢化反应的机制，包括催化剂失活的途径和底物体积对催化效率的影响。
Iron-hydride and iron-boryl complexes supported by a pyrrole-based pincer ligand,tBuPNP (PNP = anion of 2,5-bis(di-tert-butylphosphinomethyl)pyrrole), were employed for a detailed mechanistic study on the hydroboration of internal alkynes. Several novel complexes were isolated and fully characterized, including iron-vinyl and iron-boryl species, which represent likely intermediates in the catalytic hydroboration pathway. In addition, the products of alkyne insertion into the Fe–B bond have been isolated and structurally characterized. Mechanistic studies of the hydroboration reaction favor a pathway involving an active iron-hydride species, [FeH(tBuPNP)], which readily inserts alkyne and undergoes subsequent reaction with hydroborane to generate product. The iron-boryl species, [Fe(BR2)(tBuPNP)] (R2= pin or cat), was found to be chemically competent, although its use in catalysis entailed an induction period whereby the iron-hydride species was generated. Stoichiometric reactions and kinetic experiments were performed to paint a fuller picture of the mechanism of alkyne hydroboration, including pathways for catalyst deactivation and the influence of substrate bulk on catalytic efficacy.