Solvent-Free Hydrosilylation of Alkenes Catalyzed by Well-Defined Low-Valent Cobalt Catalysts

Xie, Shangqing; Dong, Yanhong; Du, Xinyu; Fan, Qingqing; Yang, Haiquan; Li, Xiaoyan; Sun, Hongjian; Fuhr, Olaf; Fenske, Dieter

doi:10.1021/acs.organomet.0c00766

Cited by 14 publications

(4 citation statements)

References 44 publications

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“…Co(PMe 3 ) 4 accelerated Markovnikov hydrosilylation of vinyl arenes, while CoCl-(PMe 3 ) 3 catalyzed anti-Markovnikov hydrosilylation of aliphatic olefins. 20 We also found that both activity than the Co(III) complex for the selective hydrosilylation of alkenes. 21 In addition, our study demonstrates that both [PSiP] pincer Co(I) and Co(III) complexes exhibit good catalytic activity for alkene hydrosilylation reactions.…”

Section: Introductionmentioning

confidence: 56%

“…In 2021, we utilized Co(PMe 3 ) 4 and CoCl(PMe 3 ) 3 as catalysts to realize olefin hydrosilylation with high selectivity and yield. Co(PMe 3 ) 4 accelerated Markovnikov hydrosilylation of vinyl arenes, while CoCl(PMe 3 ) 3 catalyzed anti -Markovnikov hydrosilylation of aliphatic olefins . We also found that both [P, C] – chelate Co(I) and Co(III) complexes could catalyze alkene hydrosilylation reactions, and the Co(I) complex exhibited more activity than the Co(III) complex for the selective hydrosilylation of alkenes …”

Section: Introductionmentioning

confidence: 71%

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Catalytic Properties of [PSiP] Pincer Cobalt(II) Chlorides Supported by Trimethylphosphine for Alkene Hydrosilylation Reactions

Zhang,

Dong,

et al. 2024

Inorg. Chem.

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In this paper, six silyl [PSiP] pincer cobalt(II) chlorides 1−6 [(2-Ph 2 PC 6 H 4 ) 2 MeSiCo(Cl)(PMe 3 )] (1), [(2-Ph 2 PC 6 H 4 ) 2 HSiCo(Cl)(PMe 3 )] (2), [(2-Ph 2 PC 6 H 4 ) 2 PhSiCo(Cl)- 6)) were prepared from the corresponding [PSiP] pincer preligands (L1−L6), CoCl 2 and PMe 3 by Si−H bond activation. The catalytic activity of complexes 1−6 for alkene hyrdosilylation was studied. It was confirmed that complex 1 is the best catalyst with excellent regioselectivity among the six complexes. Using 1 as the catalyst, the catalytic reaction was completed within 1 h at 50 °C, predominantly affording Markovnikov products for aryl alkenes and anti-Markovnikov products for aliphatic alkene substrates. During the investigation of the catalytic mechanism, the Co(II) hydrides [(2-Ph 2 PC 6 H 4 ) 2 MeSiCo(H)(PMe 3 )] ( 8) and [(2-i Pr 2 PC 6 H 4 ) 2 MeSiCo(H)(PMe 3 )] (9) were obtained from the stoichiometric reactions of complex 1 and 5 with NaBHEt 3 , respectively. Complexes 8 and 9 could also be obtained by the reactions of preligands L1 and L5 with Co(PMe 3 ) 4 via Si−H bond cleavage. More experiments corroborated that complex 8 is the real catalyst for this catalytic system. Under the same catalytic conditions as complex 1, using complex 8 as a catalyst, complete conversion of styrene was also achieved in 1 h, and the selectivity remained unchanged. Based on the experimental results, we propose a plausible mechanism for this catalytic reaction. The addition of B(C 6 F 5 ) 3 to catalyst 1 can reverse the selectivity of styrene hydrosilylation from the Markovnikov product as the main product (b/l = 99:1) to the anti-Markovnikov product as the main product (b/l = 40:60). Further study indicated that using the (CoCl 2 + L1) system instead of complex 1, the selectivity was changed from Markovnikov to anti-Markovnikov product (b/l = 1:99.7). Therefore, the selectivity for the substrate styrene is influenced by the presence of a PMe 3 ligand. The different selectivities may be caused by different active species. For the system of complex 1, a cobalt(II) hydride is the real catalyst, but for the (CoCl 2 + L1) system, a cobalt(I) complex is proposed as active species. The molecular structures of Co(II) compounds 5 and 9 were resolved by single-crystal X-ray diffraction.

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Section: Introductionmentioning

confidence: 56%

Section: Introductionmentioning

confidence: 71%

Catalytic Properties of [PSiP] Pincer Cobalt(II) Chlorides Supported by Trimethylphosphine for Alkene Hydrosilylation Reactions

Zhang,

Dong,

et al. 2024

Inorg. Chem.

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“…71 Shortly thereafter, Deming used the same cobalt(0) complex Co-27 as an efficient initiator for the controlled polymerization of αamino acid-N-carboxyanhydrides (NCAs) (Scheme 24b), 72 a procedure that is still used by this group for their numerous works in this field. More recently, Co(PMe 3 ) 4 (Co-27) has also been reported as an efficient catalyst for the reduction of alkynes and alkenes through hydrophosphorylation 73 and hydrosilylation, 74 respectively (Scheme 24c). This well-defined cobalt complex also played an important role in bond activations.…”

Section: Cobalt(0)mentioning

confidence: 99%

Well-Defined Low-Valent Cobalt Complexes in Catalysis: An Overview

Bories,

Sodreau,

Barbazanges

et al. 2024

Organometallics

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For decades, transition-metal catalysts based on noble metals have proven to be highly efficient for a wide range of organic transformations. However, due to their low abundance and highly volatile price the use of such metals is now critical for the economy. Thus, the use of more sustainable alternatives is mandatory and the more abundant first-row transition metals are becoming interesting challengers. Among them low-valent 3d transition metals appeared as the best candidates, as they are intrinsically more reactive than highvalent ones. However, this reactivity implies that these complexes are often generated in situ, putting further away the aspect of atom economy and low waste. To circumvent this and to get more insight on the mechanism of reaction, the concept of well-defined complexes has emerged. In this area, due to its historic development and the trouble associated with the preparation of other well-defined 3d transitionmetal complexes, cobalt appears as an important player. In this review, after a definition of what is a low-valent complex and the presentation of the concept of a well-defined (pre)catalyst also known as the "single-component" strategy we will report the syntheses and applications in catalysis of low-valent well-defined cobalt complexes classified by their oxidation state and ligand environment.

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“…In recent years, there are more and more reports on alkene hydrosilylation catalyzed by base metals such as iron, [4][5][6][7][8][9] cobalt [9][10][11][12][13][14][15][16][17] and nickel. [18][19][20][21][22] However, in the construction of a ligand skeleton, most catalysts are metal complexes supported by bidentate ligands 6,16,20 or pincer ligands ([NNN], 7,18,19 [NNP] 4,5 [CNC] 11 and [PSiP] 13,14 ).…”

Section: Introductionmentioning

confidence: 99%

Synthesis of aryl cobalt and iron complexes and their catalytic activity on hydrosilylation of alkenes

et al. 2022

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Solvent-Free Hydrosilylation of Alkenes Catalyzed by Well-Defined Low-Valent Cobalt Catalysts

Cited by 14 publications

References 44 publications

Catalytic Properties of [PSiP] Pincer Cobalt(II) Chlorides Supported by Trimethylphosphine for Alkene Hydrosilylation Reactions

Catalytic Properties of [PSiP] Pincer Cobalt(II) Chlorides Supported by Trimethylphosphine for Alkene Hydrosilylation Reactions

Well-Defined Low-Valent Cobalt Complexes in Catalysis: An Overview

Synthesis of aryl cobalt and iron complexes and their catalytic activity on hydrosilylation of alkenes

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