Synthesis and Catalytic Property of Iron Pincer Complexes Generated by C_sp³–H Activation

When the diphosphinito PCP ligand (Ph₂P­(C₆H₄))₂CH₂ (<b>1</b>) was treated with Fe­(PMe₃)₄ and FeMe₂(PMe₃)₄, the C_sp³–H activation products [(Ph₂P­(C₆H₄))₂CH]­Fe­(H)­(PMe₃)₂ (<b>2</b>) and [(Ph₂P­(C₆H₄))­(PhP­(C₆H₄)₂)­CH]­Fe­(PMe₃)₂ (<b>3</b>) were obtained at room temperature. The generation of product <b>3</b> underwent one C_sp³–H and one C_sp²–H bond activation process. The new iron hydride complex <b>2</b> showed good activity in the catalytic hydrosilylation of aldehydes and ketones by using (EtO)₃SiH as the hydrogen source under mild conditions. Complexes <b>2</b> and <b>3</b> were characterized by spectroscopic methods and X-ray diffraction analysis

Synthesis and Catalytic Property of Iron Pincer Complexes Generated by C_sp³–H Activation

When the diphosphinito PCP ligand (Ph₂P­(C₆H₄))₂CH₂ (<b>1</b>) was treated with Fe­(PMe₃)₄ and FeMe₂(PMe₃)₄, the C_sp³–H activation products [(Ph₂P­(C₆H₄))₂CH]­Fe­(H)­(PMe₃)₂ (<b>2</b>) and [(Ph₂P­(C₆H₄))­(PhP­(C₆H₄)₂)­CH]­Fe­(PMe₃)₂ (<b>3</b>) were obtained at room temperature. The generation of product <b>3</b> underwent one C_sp³–H and one C_sp²–H bond activation process. The new iron hydride complex <b>2</b> showed good activity in the catalytic hydrosilylation of aldehydes and ketones by using (EtO)₃SiH as the hydrogen source under mild conditions. Complexes <b>2</b> and <b>3</b> were characterized by spectroscopic methods and X-ray diffraction analysis

Imine Nitrogen Bridged Binuclear Nickel Complexes via N–H Bond Activation: Synthesis, Characterization, Unexpected C,N-Coupling Reaction, and Their Catalytic Application in Hydrosilylation of Aldehydes

The reactions of NiMe₂(PMe₃)₃ with 2,6-difluoroarylimines were explored. As a result, a series of binuclear nickel complexes (<b>5</b>–<b>8</b>,<b> 11</b>) were synthesized. Meanwhile, from the reactions of NiMe₂(PMe₃)₃ with [2-CH₃C₆H₄-C­(NH)-2,6-F₂C₆H₃] (<b>9</b>) and [2,6-(CH₃)₂C₆H₃-C­(NH)-2,6-F₂C₆H₃] (<b>10</b>), two unexpected C,N-coupling products (<b>12</b> and <b>13</b>) were obtained. It is believed that these coupling reactions underwent activation of the N–H and C–F bonds. The binuclear nickel complexes showed excellent catalytic activity in the hydrosilylation of aldehydes. The mechanism of the reaction was studied through stoichiometric reactions, and the double-(η²-Si–H)–Ni^II intermediate was detected by in situ ¹H NMR spectroscopy, which may be the key point in the catalytic cycle

Acid-Promoted Selective Carbon–Fluorine Bond Activation and Functionalization of Hexafluoropropene by Nickel Complexes Supported with Phosphine Ligands

The electron-rich complex Ni­(PMe₃)₄ was utilized to react with perfluoropropene to obtain Ni­(CF₂CFCF₃)­(PMe₃)₃ (<b>1</b>). The selective C–F bond activation process of the π-coordinated perfluoropropene in <b>1</b> was conducted with the promotion of Lewis acids (ZnCl₂, LiBr, and LiI) under mild conditions to afford the products Ni­(CF₃CCF₂)­(PMe₃)₂X (X = Cl (<b>2</b>), Br (<b>3</b>), I (<b>4</b>)). The structures of complexes <b>2</b> and <b>3</b> determined by X-ray single-crystal diffraction confirmed that the C–F bond activation occurred at the geminal position of the trifluoromethyl group. Surprisingly, CF₃COOH as a protonic acid could also carry out a similar activation reaction to give rise to Ni­(CF₃CCF₂)­(CF₃COO)­(PMe₃)₂ (<b>7</b>), while only the addition products Ni­(CF₂CFHCF₃)­(CH₃COO)­(PMe₃) (<b>5</b>) and Ni­(CF₂CFHCF₃)­(CH₃SO₃)­(PMe₃) (<b>6</b>) were obtained with CH₃COOH and CH₃SO₃H. The transmetalation products Ni­(CF₃CCF₂)­Ph­(PMe₃)₂ (<b>8</b>), Ni­(CF₃CCF₂)­(<i>p</i>-MeOPh)­(PMe₃)₂ (<b>9</b>), and Ni­(CF₃CCF₂)­(CCPh)­(PMe₃)₂ (<b>10</b>) were obtained through the reactions of Ni­(CF₃CCF₂)­(PMe₃)₂Cl (<b>2</b>) with PhMgBr, (<i>p</i>-MeOPh)­MgBr, and PhCCLi. In contrast, the reaction of complex <b>2</b> with PhCH₂CH₂MgBr delivered complex <b>11</b>, Ni­(CF₃CHC–CH₂CH₂Ph)­(PMe₃)₂, via double C–F bond activation. All of the C­(sp²)–F bonds in complex <b>11</b> were activated and cleaved. The structures of complexes <b>5</b> and <b>7</b>–<b>11</b> were determined by X-ray single-crystal structure analysis. A reasonable mechanism was proposed and partially experimentally verified through operando IR and <i>in situ</i> ¹H NMR spectroscopy

Synthesis and Reactivity of a Hydrido CNC Pincer Cobalt(III) Complex and Its Application in Hydrosilylation of Aldehydes and Ketones

Reaction of the <i>N</i>-benzylidene-1-naphthylamine with CoMe­(PMe₃)₄ afforded the hydrido CNC pincer cobalt complex CoH­(PMe₃)₂­[(C₆H₄)­CHN­(C₁₀H₆)] (<b>1</b>) via double C–H bond activation. In the ¹H NMR spectrum, a triplet at −18.98 ppm is the typical signal of the hydrido ligand (Co–H). Complex <b>1</b> reacted with haloalkane (CH₃I and EtBr) to deliver CoX­(PMe₃)₂((C₆H₄)­CHN­(C₁₀H₆)) (X = I (<b>2</b>); Br (<b>3</b>)). However, the reactions of complex <b>1</b> with HCl and trifluoroacetic acid (TFA) delivered HCoCl­(PMe₃)₂((C₆H₄)­CHN­(C₁₀H₇)) (<b>4</b>) and HCo­(OCOCF₃)­(PMe₃)₂­((C₆H₄)­CHN­(C₁₀H₇)) (<b>5</b>) with the cleavage of the Co–C­(naphthyl) bond. In the ¹H NMR spectra, the signals of the hydrido ligands were found at −21.31 (<b>4</b>) and −18.71 (<b>5</b>) ppm. A reaction of complex <b>1</b> with DCl was carried out to prove that the hydrogen atom eliminated to the naphthyl carbon comes from HCl. Complex <b>1</b> reacted with acetylacetone, resulting in the formation of Co­(acac)­(PMe₃)₂­((C₆H₅)­CHNH­(C₁₀H₆)) (<b>7</b>). Complex <b>1</b> was found to be an efficient catalyst for hydrosilylation of aldehydes and ketones. The molecular structures of complex <b>1</b>, <b>2</b>, <b>4</b>, and <b>7</b> were determined by X-ray single-crystal diffraction

Acid-Promoted Selective Carbon–Fluorine Bond Activation and Functionalization of Hexafluoropropene by Nickel Complexes Supported with Phosphine Ligands

The electron-rich complex Ni­(PMe₃)₄ was utilized to react with perfluoropropene to obtain Ni­(CF₂CFCF₃)­(PMe₃)₃ (<b>1</b>). The selective C–F bond activation process of the π-coordinated perfluoropropene in <b>1</b> was conducted with the promotion of Lewis acids (ZnCl₂, LiBr, and LiI) under mild conditions to afford the products Ni­(CF₃CCF₂)­(PMe₃)₂X (X = Cl (<b>2</b>), Br (<b>3</b>), I (<b>4</b>)). The structures of complexes <b>2</b> and <b>3</b> determined by X-ray single-crystal diffraction confirmed that the C–F bond activation occurred at the geminal position of the trifluoromethyl group. Surprisingly, CF₃COOH as a protonic acid could also carry out a similar activation reaction to give rise to Ni­(CF₃CCF₂)­(CF₃COO)­(PMe₃)₂ (<b>7</b>), while only the addition products Ni­(CF₂CFHCF₃)­(CH₃COO)­(PMe₃) (<b>5</b>) and Ni­(CF₂CFHCF₃)­(CH₃SO₃)­(PMe₃) (<b>6</b>) were obtained with CH₃COOH and CH₃SO₃H. The transmetalation products Ni­(CF₃CCF₂)­Ph­(PMe₃)₂ (<b>8</b>), Ni­(CF₃CCF₂)­(<i>p</i>-MeOPh)­(PMe₃)₂ (<b>9</b>), and Ni­(CF₃CCF₂)­(CCPh)­(PMe₃)₂ (<b>10</b>) were obtained through the reactions of Ni­(CF₃CCF₂)­(PMe₃)₂Cl (<b>2</b>) with PhMgBr, (<i>p</i>-MeOPh)­MgBr, and PhCCLi. In contrast, the reaction of complex <b>2</b> with PhCH₂CH₂MgBr delivered complex <b>11</b>, Ni­(CF₃CHC–CH₂CH₂Ph)­(PMe₃)₂, via double C–F bond activation. All of the C­(sp²)–F bonds in complex <b>11</b> were activated and cleaved. The structures of complexes <b>5</b> and <b>7</b>–<b>11</b> were determined by X-ray single-crystal structure analysis. A reasonable mechanism was proposed and partially experimentally verified through operando IR and <i>in situ</i> ¹H NMR spectroscopy

Transition-Metal-Free Synthesis of Fluorinated Arenes from Perfluorinated Arenes Coupled with Grignard Reagents

A simple method to obtain organofluorine compounds from perfluorinated arenes coupled with Grignard reagents in the absence of a transition-metal catalyst was reported. In particular, the perfluorinated arenes could react not only with aryl Grignard reagents but also with alkyl Grignard reagents in moderate to good yields

Synthesis and Reactivity of N‑Heterocyclic PSiP Pincer Iron and Cobalt Complexes and Catalytic Application of Cobalt Hydride in Kumada Coupling Reactions

The new N-heterocyclic σ-silyl pincer ligand HSiMe­(NCH₂PPh₂)₂C₆H₄ (<b>1</b>) was designed. A series of tridentate silyl pincer Fe and Co complexes were prepared. Most of them were formed by chelate-assisted Si–H activation. The typical iron hydrido complex FeH­(PMe₃)₂(SiMe­(NCH₂PPh₂)₂C₆H₄) (<b>2</b>) was obtained by Si–H activation of compound <b>1</b> with Fe­(PMe₃)₄. The combination of compound <b>1</b> with CoMe­(PMe₃)₄ afforded the Co­(I) complex Co­(PMe₃)₂(SiMe­(NCH₂PPh₂)₂C₆H₄) (<b>3</b>). The Co­(III) complex CoHCl­(PMe₃)­(SiMe­(NCH₂PPh₂)₂C₆H₄) (<b>5</b>) was generated by the reaction of complex <b>1</b> with CoCl­(PMe₃)₃ or the combination of complex <b>3</b> with HCl. However, when complex <b>3</b> was treated with MeI, the Co­(II) complex CoI­(PMe₃)­(SiMe­(NCH₂PPh₂)₂C₆H₄) (<b>4</b>), rather than the Co­(III) complex, was isolated. The catalytic performance of complex <b>5</b> for Kumada coupling reactions was explored. With a catalyst loading of 5 mol %, complex <b>5</b> displayed efficient catalytic activity for Kumada cross-coupling reactions of aryl chlorides and aryl bromides with Grignard reagents. This catalytic reaction mechanism is proposed and partially experimentally verified

Delay guaranteed joint user association and channel allocation for fog radio access networks

IEEE In the Fog Radio Access Networks (F-RANs), the local storage and computing capability of Fog Access Points (FAPs) provide new communication resources to address the latency and computing constraints for delay-sensitive applications. To achieve the ultra-low latency, a novel joint user association and channel allocation scheme is proposed in this paper, where the FAPs are clustered from a user-centric perspective. The delay performance is improved regarding both the control signaling procedure and the data transmission procedure. Specifically, the multiple access interference (MAI) between users is analyzed, where the closed-form expression for the effective rate of a typical user with multiple FAP connections and arbitrary interfering users is obtained. With the consideration of MAI, the proposed distributed joint user association and channel allocation algorithm provides a guaranteed delay violation probability. Moreover, the distributed algorithm can be conducted on individual FAPs, whose calculation is simplified by look-up tables. Simulation results show that the proposed algorithm is capable of providing statistical delay performance guarantee including both average delay and delay bound violation probability, which demonstrates its superiority in supporting delay-sensitive applications in F-RANs

Vinyl/Phenyl Exchange Reaction within Vinyl Nickel Complexes Bearing Chelate [P, S]-Ligands

Three nickel­(II) hydrides, [2-Ph₂P­(4-Me-C₆H₃)­S]­NiH­(PMe₃)₂ (<b>1</b>), [2-Ph₂P­(6-Me₃Si-C₆H₃)­S]­NiH­(PMe₃)₂ (<b>2</b>), and [2-Ph₂P­(4-Me₃Si -C₆H₃)­S]­NiH­(PMe₃)₂ (<b>3</b>), were synthesized via S–H bond activation through the reaction of Ni­(PMe₃)₄ with (2-diphenylphosphanyl)­thiophenols. The reactions of nickel­(II) hydrides (<b>1</b>–<b>3</b>) with different alkynes were investigated. Although the first step is the insertion of alkyne into the Ni–H bond for each reaction, different final products were isolated. Normal vinyl nickel complex [2-Ph₂P­(4-Me-C₆H₃)­S]­Ni­(CPhCH₂)­(PMe₃) (<b>4</b>) was obtained by the reaction of phenylacetylene with <b>1</b>. The nickelacyclopropane complexes [2-Ph₂P­(6-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CH₂] (<b>5</b>), [2-Ph₂P­(4-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CH₂] (<b>6</b>), [2-Ph₂P­(4-Me₃-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHPh] (<b>7</b>), [2-Ph₂P­(6-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHPh] (<b>8</b>), [2-Ph₂P­(4-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHPh] (<b>9</b>), [2-Ph₂P­(4-Me-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHSiMe₃] (<b>10</b>) or [2-Ph₂P­(4-Me-C₆H₃)­S]­Ni­[Me₃Si­(PMe₃)­C–CHPh] (<b>10</b>), [2-Ph₂P­(6-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHSiMe₃] (<b>11</b>) or [2-Ph₂P­(6-Me₃Si-C₆H₃)­S]­Ni­[Me₃Si­(PMe₃)­C–CHPh] (<b>11</b>), and [2-Ph₂P­(4-Me₃Si-C₆H₃)­S]­Ni­[Ph­(PMe₃)­C–CHSiMe₃] (<b>12</b>) or [2-Ph₂P­(4-Me₃Si-C₆H₃)­S]­Ni­[Me₃Si­(PMe₃)­C–CHPh] (<b>12</b>) containing a ylidic ligand were formed by the reaction of phenylacetylene, diphenylacetylene, and 1-phenyl-2-(trimethylsilyl)­acetylene with <b>1</b>, <b>2</b>, and <b>3</b>, respectively. The phenyl/vinyl exchange nickel­(II) complexes [2-(Ph­(CH₂CSiMe₃)­P­(4-Me-C₆H₃)­S]­Ni­(Ph)­(PMe₃) (<b>13</b>), [2-(Ph­(CH₂CSiMe₃)­P­((6-Me₃Si-C₆H₃)­S]­Ni­(Ph)­(PMe₃) (<b>14</b>), and [2-(Ph­(CH₂CSiMe₃)­P­((4-Me₃Si-C₆H₃)­S]­Ni­(Ph)­(PMe₃) (<b>15</b>) could be obtained by insertion of trimethylsilylacetylene into Ni–H bonds of <b>1</b>, <b>2</b>, and <b>3</b>. To the best of our knowledge, this is a novel reaction type between alkyne and nickel hydride. The results indicate that whether increasing the electronegativity on the benzene ring or on the alkyne leads to the instability of the vinyl nickel complex, and is beneficial to the C–P reductive elimination to form nickelacyclopropane complexes or phenyl nickel complexes via vinyl/phenyl exchange reaction in the case of the more electronegative nickel center. All the nickel complexes were fully detected by IR, NMR and the molecular structures of complexes <b>1</b>, <b>2</b>, <b>7</b>, <b>9</b>, <b>13</b>, and <b>14</b> were confirmed by single crystal X-ray diffraction