Activation of B-H, Si-H, and C-F bonds with Tp'Rh(PMe3) complexes: kinetics, mechanism, and selectivity.
Activation of B-H, Si-H, and C-F bonds with Tp'Rh(PMe3) complexes: kinetics, mechanism, and selectivity.
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B-H、Si-H 和 C-F 键与 TpRh(PMe3) 配合物的活化：动力学、机制和选择性。
DOI：
10.1021/ja5113172
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发表时间：
2015
影响因子：
15
通讯作者：
Procacci B
中科院分区：
文献类型：
--
作者：
Procacci B
报道了Tp ' rh (PMe3)H2(1)的光化学反应和Tp ' rh (PMe3)(CH3)H （1a, Tp ' =三（3,5-二甲基吡唑基）硼酸盐）与含有B-H、Si-H、C-F和C-H键的底物的热反应。络合物1和1是已知的碳氢键活化剂，包括烷烃的活化剂。与HBpin和phsih3反应的动力学研究表明，h21的光解作用发生在底物攻击之前，而11的热反应是通过与底物的双分子反应进行的。观察到HBpin （pin = pinacolate）对B-H的完全分子内选择性激活导致Tp 'Rh (PMe3)(Bpin)H。同样，与et2sih2h的反应显示出Si-H比C-H活化的强烈偏好，生成Tp 'Rh (PMe3)(SiEt2H)H。根据DFT计算，Rh(Bpin)H和Rh(SiEt2H)H在苯中加热稳定，表明与苯的反应是能反应。与phsih3的分子内竞争分别产生约1:4的Tp 'Rh (PMe3)(C6H4SiH3)H和Tp 'Rh (PMe3)(SiPhH2)H混合物。与五氟吡啶反应生成Tp 'Rh (PMe3)(C5NF4)F，与2,3,5,6-四氟吡啶反应生成C-H和C-F活化产物的混合物。六氟苯是不活泼的。报道了B-H、Si-H和C-F活化产物的晶体结构，但在后者的情况下，形成了一种二氟化配合物Tp 'Rh (PMe3)(C5NF4)（FHF）。在核磁共振探针中，利用激光光解技术，研究了c6f6与苯和另一种底物（HBpin、PhSiH3或五氟吡啶）的分子间竞争反应，得到了广泛的动力学选择性图。分析了分子内选择和分子间选择的机制。
The photochemical reactions of Tp′Rh(PMe3)H2(1) and thermal reactions of Tp′Rh(PMe3)(CH3)H (1a, Tp′ = tris(3,5-dimethylpyrazolyl)borate) with substrates containing B–H, Si–H, C–F, and C–H bonds are reported. Complexes1and1aare known activators of C–H bonds, including those of alkanes. Kinetic studies of reactions with HBpin and PhSiH3show that photodissociation of H2from1occurs prior to substrate attack, whereas thermal reaction of1aproceeds by bimolecular reaction with the substrate. Complete intramolecular selectivity for B–H over C–H activation of HBpin (pin = pinacolate) leading to Tp′Rh(PMe3)(Bpin)H is observed. Similarly, the reaction with Et2SiH2shows a strong preference for Si–H over C–H activation, generating Tp′Rh(PMe3)(SiEt2H)H. The Rh(Bpin)H and Rh(SiEt2H)H products were stable to heating in benzene in accord with DFT calculations that showed that reaction with benzene is endoergic. The intramolecular competition with PhSiH3yields a ∼1:4 mixture of Tp′Rh(PMe3)(C6H4SiH3)H and Tp′Rh(PMe3)(SiPhH2)H, respectively. Reaction with pentafluoropyridine generates Tp′Rh(PMe3)(C5NF4)F, while reaction with 2,3,5,6-tetrafluoropyridine yields a mixture of C–H and C–F activated products. Hexafluorobenzene proves unreactive. Crystal structures are reported for B–H, Si–H, and C–F activated products, but in the latter case a bifluoride complex Tp′Rh(PMe3)(C5NF4)(FHF) was crystallized. Intermolecular competition reactions were studied by photoreaction of1in C6F6with benzene and another substrate (HBpin, PhSiH3, or pentafluoropyridine) employingin situlaser photolysis in the NMR probe, resulting in a wide-ranging map of kinetic selectivities. The mechanisms of intramolecular and intermolecular selection are analyzed.
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