5 research outputs found

    Synthesis and Characterization of Ferrocene-Chelating Heteroscorpionate Complexes of Nickel(II) and Zinc(II)

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    The first example of a ferrocene-chelating heteroscorpionate, [Li­(THF)<sub>2</sub>]­[fc­(PPh<sub>2</sub>)­(BH­[(3,5-Me)<sub>2</sub>pz]<sub>2</sub>)] ((fc<sup>P,B</sup>)­Li­(THF)<sub>2</sub>, fc = 1,1′-ferrocenediyl) is described. Starting from a previously reported compound, fcBr­(PPh<sub>2</sub>), a series of ferrocene derivatives, fc­(PPh<sub>2</sub>)­(B­[OMe]<sub>2</sub>), [Li­(OEt<sub>2</sub>)]­[fc­(PPh<sub>2</sub>)­(BH<sub>3</sub>)], [Li­(THF)<sub>2</sub>]­[fc­(PPh<sub>2</sub>)­(BH­[(3,5-Me)<sub>2</sub>pz]<sub>2</sub>)] (pz = pyrazole), was isolated and characterized. Compound (fc<sup>P,B</sup>)­Li­(THF)<sub>2</sub> allowed the synthesis of the corresponding nickel and zinc complexes, (fc<sup>P,B</sup>)­NiCl, (fc<sup>P,B</sup>)­NiMe, (fc<sup>P,B</sup>)­ZnCl, and (fc<sup>P,B</sup>)­ZnMe. All compounds were characterized by NMR spectroscopy, while the zinc and nickel complexes were also characterized by X-ray crystallography. The redox behavior of (fc<sup>P,B</sup>)­NiCl, (fc<sup>P,B</sup>)­NiMe, (fc<sup>P,B</sup>)­ZnCl, and (fc<sup>P,B</sup>)­ZnMe was studied by cyclic voltammetry and supported by density functional theory calculations

    Ferrocene-bis(phosphinimine) Nickel(II) and Palladium(II) Alkyl Complexes: Influence of the Fe–M (M = Ni and Pd) Interaction on Redox Activity and Olefin Coordination

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    The synthesis of several novel nickel­(II) and palladium­(II) ferrocene-bis­(phosphinimine) alkyl complexes containing iron–nickel and iron–palladium interactions is reported. The redox behavior of all complexes was evaluated electrochemically and chemically; in addition, reactions with weak nucleophiles, such as acetonitrile and olefins, were also investigated. DFT calculations were performed to understand the electronic structure of the alkyl metal complexes

    Vanadium Bisimide Bonding Investigated by X‑ray Crystallography, <sup>51</sup>V and <sup>13</sup>C Nuclear Magnetic Resonance Spectroscopy, and V L<sub>3,2</sub>-Edge X‑ray Absorption Near-Edge Structure Spectroscopy

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    Syntheses of neutral halide and aryl vanadium bisimides are described. Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)­[NTMS­(N<sup><i>t</i></sup>Bu)], <b>2</b>, with PMe<sub>3</sub>, PEt<sub>3</sub>, PMe<sub>2</sub>Ph, or pyridine gave vanadium bisimides via TMSCl elimination in good yield: VCl­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VCl­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VCl­(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VCl­(Py)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>6</b>. The halide series (Cl–I) was synthesized by use of TMSBr and TMSI to give VBr­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VI­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>8</b>. The phenyl derivative was obtained by reaction of <b>3</b> with MgPh<sub>2</sub> to give VPh­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>9</b>. These neutral complexes are compared to the previously reported cationic bisimides [V­(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>10</b>, [V­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>11</b>, and [V­(DMAP)­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>12</b> (DMAP = dimethylaminopyridine, PFTB = perfluoro-<i>tert</i>-butoxide). Characterization of the complexes by X-ray diffraction, <sup>13</sup>C NMR, <sup>51</sup>V NMR, and V L<sub>3,2</sub>-edge X-ray absorption near-edge structure (XANES) spectroscopy provides a description of the electronic structure in comparison to group 6 bisimides and the bent metallocene analogues. The electronic structure is dominated by π bonding to the imides, and localization of electron density at the nitrogen atoms of the imides is dictated by the cone angle and donating ability of the axial neutral supporting ligands. This phenomenon is clearly seen in the sensitivity of <sup>51</sup>V NMR shift, <sup>13</sup>C NMR Δδ<sub>αβ</sub>, and L<sub>3</sub>-edge energy to the nature of the supporting phosphine ligand, which defines the parameters for designing cationic group 5 bisimides that would be capable of breaking stronger σ bonds. Conversely, all three methods show little dependence on the variable equatorial halide ligand. Furthermore, this analysis allows for quantification of the electronic differences between vanadium bisimides and the structurally analogous mixed Cp/imide system CpV­(N<sup><i>t</i></sup>Bu)­X<sub>2</sub> (Cp = C<sub>5</sub>H<sub>5</sub><sup>1–</sup>)

    Vanadium Bisimide Bonding Investigated by X‑ray Crystallography, <sup>51</sup>V and <sup>13</sup>C Nuclear Magnetic Resonance Spectroscopy, and V L<sub>3,2</sub>-Edge X‑ray Absorption Near-Edge Structure Spectroscopy

    No full text
    Syntheses of neutral halide and aryl vanadium bisimides are described. Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)­[NTMS­(N<sup><i>t</i></sup>Bu)], <b>2</b>, with PMe<sub>3</sub>, PEt<sub>3</sub>, PMe<sub>2</sub>Ph, or pyridine gave vanadium bisimides via TMSCl elimination in good yield: VCl­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VCl­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VCl­(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VCl­(Py)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>6</b>. The halide series (Cl–I) was synthesized by use of TMSBr and TMSI to give VBr­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VI­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>8</b>. The phenyl derivative was obtained by reaction of <b>3</b> with MgPh<sub>2</sub> to give VPh­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>9</b>. These neutral complexes are compared to the previously reported cationic bisimides [V­(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>10</b>, [V­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>11</b>, and [V­(DMAP)­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>12</b> (DMAP = dimethylaminopyridine, PFTB = perfluoro-<i>tert</i>-butoxide). Characterization of the complexes by X-ray diffraction, <sup>13</sup>C NMR, <sup>51</sup>V NMR, and V L<sub>3,2</sub>-edge X-ray absorption near-edge structure (XANES) spectroscopy provides a description of the electronic structure in comparison to group 6 bisimides and the bent metallocene analogues. The electronic structure is dominated by π bonding to the imides, and localization of electron density at the nitrogen atoms of the imides is dictated by the cone angle and donating ability of the axial neutral supporting ligands. This phenomenon is clearly seen in the sensitivity of <sup>51</sup>V NMR shift, <sup>13</sup>C NMR Δδ<sub>αβ</sub>, and L<sub>3</sub>-edge energy to the nature of the supporting phosphine ligand, which defines the parameters for designing cationic group 5 bisimides that would be capable of breaking stronger σ bonds. Conversely, all three methods show little dependence on the variable equatorial halide ligand. Furthermore, this analysis allows for quantification of the electronic differences between vanadium bisimides and the structurally analogous mixed Cp/imide system CpV­(N<sup><i>t</i></sup>Bu)­X<sub>2</sub> (Cp = C<sub>5</sub>H<sub>5</sub><sup>1–</sup>)

    Vanadium Bisimide Bonding Investigated by X‑ray Crystallography, <sup>51</sup>V and <sup>13</sup>C Nuclear Magnetic Resonance Spectroscopy, and V L<sub>3,2</sub>-Edge X‑ray Absorption Near-Edge Structure Spectroscopy

    No full text
    Syntheses of neutral halide and aryl vanadium bisimides are described. Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)­[NTMS­(N<sup><i>t</i></sup>Bu)], <b>2</b>, with PMe<sub>3</sub>, PEt<sub>3</sub>, PMe<sub>2</sub>Ph, or pyridine gave vanadium bisimides via TMSCl elimination in good yield: VCl­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VCl­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VCl­(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VCl­(Py)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>6</b>. The halide series (Cl–I) was synthesized by use of TMSBr and TMSI to give VBr­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VI­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>8</b>. The phenyl derivative was obtained by reaction of <b>3</b> with MgPh<sub>2</sub> to give VPh­(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>9</b>. These neutral complexes are compared to the previously reported cationic bisimides [V­(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>10</b>, [V­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>11</b>, and [V­(DMAP)­(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]­[Al­(PFTB)<sub>4</sub>] <b>12</b> (DMAP = dimethylaminopyridine, PFTB = perfluoro-<i>tert</i>-butoxide). Characterization of the complexes by X-ray diffraction, <sup>13</sup>C NMR, <sup>51</sup>V NMR, and V L<sub>3,2</sub>-edge X-ray absorption near-edge structure (XANES) spectroscopy provides a description of the electronic structure in comparison to group 6 bisimides and the bent metallocene analogues. The electronic structure is dominated by π bonding to the imides, and localization of electron density at the nitrogen atoms of the imides is dictated by the cone angle and donating ability of the axial neutral supporting ligands. This phenomenon is clearly seen in the sensitivity of <sup>51</sup>V NMR shift, <sup>13</sup>C NMR Δδ<sub>αβ</sub>, and L<sub>3</sub>-edge energy to the nature of the supporting phosphine ligand, which defines the parameters for designing cationic group 5 bisimides that would be capable of breaking stronger σ bonds. Conversely, all three methods show little dependence on the variable equatorial halide ligand. Furthermore, this analysis allows for quantification of the electronic differences between vanadium bisimides and the structurally analogous mixed Cp/imide system CpV­(N<sup><i>t</i></sup>Bu)­X<sub>2</sub> (Cp = C<sub>5</sub>H<sub>5</sub><sup>1–</sup>)
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