188527-56-2Relevant articles and documents
Luminescence properties of cyclometalated platinum(II) complexes in a dichloromethane/n-hexane system
Tao, Weitong,Chen, Yan,Lu, Lu,Liu, Chun
, (2021)
The luminescence properties of three neutral cyclometalated Pt(II) complexes were investigated in a CH2Cl2/n-hexane system. The diphenylamino and trifluoromethyl modified Pt2 exhibits aggregation-induced phosphorescent emission (AIPE
Structural Insights into the Nature of Fe0 and FeI Low-Valent Species Obtained upon the Reduction of Iron Salts by Aryl Grignard Reagents
Clémancey, Martin,Cantat, Thibault,Blondin, Geneviève,Latour, Jean-Marc,Dorlet, Pierre,Lefèvre, Guillaume
, p. 3834 - 3848 (2017)
Mechanistic studies of the reduction of FeIII and FeII salts by aryl Grignard reagents in toluene/tetrahydrofuran mixtures in the absence of a supporting ligand, as well as structural insights regarding the nature of the low-valent iron species obtained at the end of this reduction process, are reported. It is shown that several reduction pathways can be followed, depending on the starting iron precursor. We demonstrate, moreover, that these pathways lead to a mixture of Fe0 and FeI complexes regardless of the nature of the precursor. M?ssbauer and 1H NMR spectroscopies suggest that diamagnetic 16-electron bisarene complexes such as (η4-C6H5Me)2Fe0 can be formed as major species (85% of the overall iron quantity). The formation of a η6-arene-ligated low-spin FeI complex as a minor species (accounting for ca. 15% of the overall iron quantity) is attested by M?ssbauer spectroscopy, as well as by continuous-wave electron paramagnetic resonance (EPR) and pulsed-EPR (HYSCORE) spectroscopies. The nature of the FeI coordination sphere is discussed by means of isotopic labeling experiments and density functional theory calculations. It is shown that the most likely low-spin FeI candidate obtained in these systems is a diphenylarene-stabilized species [(η6-C6H5Me)FeIPh2]- exhibiting an idealized C2v topology. This enlightens the nature of the lowest valence states accommodated by iron during the reduction of FeIII and FeII salts by aryl Grignard reagents in the absence of any additional coligand, which so far remained rather unknown. The reactivity of these low-valent FeI and Fe0 complexes in aryl-heteroaryl Kumada cross-coupling conditions has also been investigated, and it is shown that the zerovalent Fe0 species can be used efficiently as a precursor in this reaction, whereas the FeI oxidation state does not exhibit any reactivity.
Synthesis, characterization, and electroluminescent properties of iridium(III) 2-phenylpyridine-type complexes containing trifluoromethyl substituents and various main-group moieties
Ho, Cheuk-Lam,Lam, Ching-Shan,Sun, Ning,Ma, Dongge,Liu, Li,Yu, Zhen-Qiang,Xue, Liqin,Lin, Zhenyang,Li, Hua,Lo, Yih Hsing,Wong, Wai-Yeung
, p. 999 - 1014 (2014)
New heteroleptic cyclometalated iridium(III) 2-phenylpyridine-type complexes with trifluoromethyl substituents and various main-group moieties were synthesized and their photophysical, electrochemical, and electroluminescent (EL) properties studied. The emission color can be tuned by a facile derivatization of the phenyl moiety of 2-phenylpyridine with various main-group moieties, and we have prepared new yellowish-green to orange triplet emitters with enhanced charge injection/charge transporting features, which can furnish attractive EL performance in phosphorescent organic light-emitting devices (OLEDs). Attempts were also made to fabricate two-color white-light OLEDs based on a combination of fluorescent blue and phosphorescent orange emitters.
Importance of Two-Electron Processes in Fe-Catalyzed Aryl-(hetero)aryl Cross-Couplings: Evidence of Fe0/FeIICouple Implication
Wowk, Vincent,Rousseau, Lidie,Lefèvre, Guillaume
supporting information, p. 3253 - 3266 (2021/10/12)
We demonstrate in this work that two drastically distinct mechanisms can be involved in aryl-(hetero)aryl Fe-mediated cross-couplings between Grignard reagents and organic halides, depending on the nature of the latter. (Hetero)aryl electrophiles, which easily undergo one-electron reduction, can be involved in a FeII/FeIII coupling sequence featuring an in situ generated organoiron(II) species, akin to their aliphatic analogues. On the other hand, less easily reduced substrates can be activated by transient Fe0 species formed by the reduction of the precatalyst. In this case, the coupling mechanism relies on two-electron elementary steps involving the Fe0/FeII redox couple and proceeds by an oxidative addition/reductive elimination sequence. Hammett analysis shows that both those elementary steps are faster for electrophiles substituted by electron-withdrawing groups. The two mechanisms discussed herein can be involved concomitantly for electrophiles displaying an average oxidative power. Attesting to the feasibility of the aforementioned bielectronic mechanism, high-spin organoiron(II) intermediates formed by two-electron oxidative addition onto (hetero)aryl halides in catalytically relevant conditions were also characterized for the first time. Those results are sustained by paramagnetic 1H NMR, kinetics monitoring, and density functional theory (DFT) calculations.
Base-Activated Latent Heteroaromatic Sulfinates as Nucleophilic Coupling Partners in Palladium-Catalyzed Cross-Coupling Reactions
Blakemore, David C.,Cook, Xinlan A. F.,Moses, Ian B.,Pantaine, Lo?c R. E.,Sach, Neal W.,Shavnya, Andre,Willis, Michael C.
, p. 22461 - 22468 (2021/09/09)
Heteroaromatic sulfinates are effective nucleophilic reagents in Pd0-catalyzed cross-coupling reactions with aryl halides. However, metal sulfinate salts can be challenging to purify, solubilize in reaction media, and are not tolerant to multi-step transformations. Here we introduce base-activated, latent sulfinate reagents: β-nitrile and β-ester sulfones. We show that under the cross-coupling conditions, these species generate the sulfinate salt in situ, which then undergo efficient palladium-catalyzed desulfinative cross-coupling with (hetero)aryl bromides to deliver a broad range of biaryls. These latent sulfinate reagents have proven to be stable through multi-step substrate elaboration, and amenable to scale-up.
Nickel-Catalyzed Reductive 2-Pyridination of Aryl Iodides with Difluoromethyl 2-Pyridyl Sulfone
Miao, Wenjun,Ni, Chuanfa,Xiao, Pan,Jia, Rulong,Zhang, Wei,Hu, Jinbo
, p. 711 - 715 (2021/01/26)
A novel nickel-catalyzed reductive cross-coupling between aryl iodides and difluoromethyl 2-pyridyl sulfone (2-PySO2CF2H) enables C(sp2)-C(sp2) bond formation through selective C(sp2)-S bond cleavage, which demonstrates the new reactivity of 2-PySO2CF2H reagent. This method employs readily available nickel catalyst and sulfones as cross-electrophile coupling partners, providing facile access to biaryls under mild reaction conditions without pregeneration of arylmetal reagents.
A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
Huang, Binbin,Guo, Lin,Xia, Wujiong
supporting information, p. 2095 - 2103 (2021/03/26)
A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
Selective Defluoroallylation of Trifluoromethylarenes
Luo, Chaosheng,Bandar, Jeffrey S.
supporting information, p. 14120 - 14125 (2019/10/11)
We report a fluoride-initiated coupling reaction between trifluoromethylarenes and allylsilanes to access allylated α,α-difluorobenzylic compounds. This method's utility is demonstrated through a 30 mmol scale reaction, a sequential allylation/derivatization protocol and multiple examples of site-selective trifluoromethylarene allylation. Initial mechanistic studies suggest a base-induced single electron transfer pathway is responsible for the high efficiency and selectivity of this novel C-F substitution process.
Transition-Metal-Free Desulfinative Cross-Coupling of Heteroaryl Sulfinates with Grignard Reagents
Wei, Jun,Liang, Huamin,Ni, Chuanfa,Sheng, Rong,Hu, Jinbo
supporting information, (2019/02/05)
A mild cross-coupling reaction of heteroaryl sulfinates with Grignard reagents has been developed under transition-metal-free conditions. This study provides an example of the SO22- as a leaving group in an aromatic system and an effective methodology for the construction of C-C bond.
Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) cobalt hydride for Kumada coupling reactions
Qi, Xinghao,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
, p. 2581 - 2588 (2018/02/28)
The electron-rich silylene Co(i) chloride 5 was obtained through the reaction of CoCl(PMe3)3 with chlorosilylene. Complex 5 reacted with 1,3-siladiazole HSiMe(NCH2PPh2)2C6H4 to give the silylene Co(iii) hydride 6 through chelate-assisted Si-H activation. To the best of our knowledge, complex 6 is the first example of Co(iii) hydride supported by N-heterocyclic silylene. Complexes 5 and 6 were fully characterized by spectroscopic methods and X-ray diffraction analysis. Complex 6 was used as an efficient precatalyst for Kumada cross-coupling reactions. Compared with the related complex 3 supported by only trimethylphosphine, complex 6 as a catalyst supported by both chlorosilylene and trimethylphosphine exhibits a more efficient performance for the Kumada cross-coupling reactions. A novel catalytic radical mechanism was suggested and experimentally verified. As an intermediate silylene cobalt(ii) chloride 6d was isolated and structurally characterized.
