Synthesis and reactivity of cobalt dinitrogen complex supported by nonsymmetrical pincer ligand

Chen, Yuanjin; Shi, Xianghui; Huang, Dajiang; Wei, Junnian; Xi, Zhenfeng

doi:10.1016/j.cclet.2023.109292

Cited by 2 publications

(3 citation statements)

References 40 publications

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“…Unfortunately, another fraction of the ligand redistribution product was not isolated. While the formation of this type of lutetium complex was proposed through the abstraction of the proton of the phenyl ring by the phosphoniomethylidene. a,a The bond length of Lu–C(26) (2.344(6) Å) in 6a is obviously shorter than the bond lengths of Er–C(51) (2.550(5) Å) and Dy–C(51) (2.541(5) Å) in 6b and 6c , but is comparable with Lu–C(alkylidene) (2.192(11) Å) in the lutetium phosphoniomethylidene complex a if the ionic radii difference between the central metal ions with different coordination numbers (4 coordination number in the lutetium alkylidene vs 5 coordination number in complex 6a ) and the difference in bond length between the monomeric and dimeric forms are taken into account.…”

Section: Resultsmentioning

confidence: 99%

“…Although the fundamental skeletons of pincer ligands are diverse, most of them are either fixed or nonfixed structures with central symmetry. In recent years, numerous reports have shown that nonsymmetric pincer ligands possess unique advantages compared with symmetric clamp ligands. ,, Therefore, the introduction of nonsymmetric functionality in pincer ligands for catalytic reactions and different molecule activations has become a great aspect of tunability. ,,− …”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

Zhu,

Wu,

Hong

et al. 2024

Inorg. Chem.

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The pincer rare-earth dialkyl complexes [κ 3 -LRE-(CH 2 SiMe 3 ) 2 (RE = Lu(1a), Yb(1b), Er(1c), Y(1d), Dy(1e))] with the indol-2-yl-based NCN pincer ligand were synthesized by the reactions of the proligand HL (L = 1-Me 2 NCH 2 CH 2 -3-(2-i PrC 6 H 5 N�CH)C 8 H 4 N) with RE(CH 2 SiMe 3 ) 3 (THF) 2 . These complexes exhibited a variety of reactivities toward organic compounds such as amines, triphenylphosphine ylide, N-phenylimidazole, pyridine derivatives, and o-carborane leading to σ-bond metathesis, migration insertion, and redox reaction products. The reactions of the dialkyl rare-earth metal complexes with ocarborane afforded the novel NCN pincer-ligated carborynebased metallacyclopropanes which reacted with diphenyl ketone to give insertion products of the RE−C 2-ind and one of the RE− C cage bonds, while the reaction of the carboryne-based metallacyclopropanes with diphenyldiazomethane produced the di-azametallacyclopentanes via the insertions of the N�N bond of the diphenyldiazomethane into two RE−C cage bonds and the RE− C 2-ind bond. The reactions of the dialkyl complexes with 2 equiv of 2,2′-bipyridine afforded the pincer-ligated bis(2,2′-bipyridyl monoanionic radical) complexes via the homolytic redox reaction.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

Zhu,

Wu,

Hong

et al. 2024

Inorg. Chem.

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“…一氧化碳、异腈和卡宾由于能同时提供 σ 电子和 π*轨道, 可以作为 π 酸配体稳定低价金属. 在前期工作中, 我们通过在氮气条件下还原 PNNCoCl 获得了低价钴氮气配合物 [24] . 作为对比研究, 在此, 我们对一氧化碳、异腈和卡宾与 PNNCoCl 在还原条件下的反应性进行了探索(图式 1).…”

Section: 结果与讨论unclassified

Reactivities of Nonsymmetric PNN Pincer Cobalt Complex Under Reductive Conditions

Chen,

Huang,

Shi

et al. 2024

Acta Chimica Sinica

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Nonsymmetric pincer complexes have received much attention due to their hemilability and more easily modulated spatial and electronic effects. However, their synthesis and reactivity studies remain considerably limited in comparison to symmetric pincer complexes. Common strategies to enhance the reactivity of complexes, such as reducing coordination sites or lowering metal center valences, invariably complicate synthesis. In this work, employing the strategy of introducing reducing agents, the PNNCoCl (1) (PNN: [6-( t Bu2PN)C5H3N-2-(3-Mes)C3H2N2]) reacts with various small molecules to yield a variety of nonsymmetric pincer cobalt complexes, which were characterized by single-crystal X-ray diffractometry analysis and spectroscopy. The reaction of PNNCoCl, potassium graphite (or KHBEt3) with 1 equiv. of CNXyl (2,6-dimethylphenyl isocyanide) or carbon monoxide successfully yielded the monovalent cobalt complexes 2 (PNNCoCNXyl) and 3 (PNNCo-CO) in 64% and 41% yields, respectively. Moreover, the reaction of complex 1 with N-heterocyclic carbene (1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene), involving C-H bond cleavage and Co-C bond formation, afforded the corresponding divalent cobalt complex 4. Furthermore, by using different reducing agents, we achieved the modulation of the selective reaction of azobenzene C-H or N＝N bonds. When KC8 (potassium graphite) was used as the reducing agent, the reaction of PNNCoCl and azobenzene in tetrahydrofuran afforded the azobenzene C-H bond-breaking product 5 in 53% yield. The cobalt atom is pentacoordinate in a tetragonal pyramid geometry. The N-N lengths of 0.12835(17) nm in complex 5 are in the range of normal N＝N double bonds (0.122～0.130 nm). In contrast, the reaction of 1 with azobenzene in the presence of KHBEt3 gave the cobalt complex PNNCoNHPh (6), as confirmed by X-ray diffraction analysis. The structure suggests N＝N double bond cleavage of azobenzene in the formation of the aniline complex. The N-H stretching bands of 6 were recorded at 3131 cm −1 , and the solution magnetic moment was µeff＝2.2 µB. In addition, the treatment of complex 1 with 3,5-di-tert-butyl-o-benzoquinone in the presence of 1.2 equiv. of KC8 gave rise to the cobalt complex 7. X-ray diffraction analysis of 7 revealed that the PNN ligand and o-benzoquinone parts are linked by forming a P-O single bond. The o-benzoquinone was reduced to the catechol ion. Complex 7 exhibits a high-spin electronic structure (S ＝ 3/2), as evidenced by the solution magnetic moment of 4.0 µB.

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Synthesis and reactivity of cobalt dinitrogen complex supported by nonsymmetrical pincer ligand

Cited by 2 publications

References 40 publications

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

Reactivities of Nonsymmetric PNN Pincer Cobalt Complex Under Reductive Conditions

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