5 research outputs found
Synthesis and Characterization of Ferrocene-Chelating Heteroscorpionate Complexes of Nickel(II) and Zinc(II)
The first example of a ferrocene-chelating
heteroscorpionate, [LiÂ(THF)<sub>2</sub>]Â[fcÂ(PPh<sub>2</sub>)Â(BHÂ[(3,5-Me)<sub>2</sub>pz]<sub>2</sub>)] ((fc<sup>P,B</sup>)ÂLiÂ(THF)<sub>2</sub>,
fc = 1,1′-ferrocenediyl) is described. Starting from a previously
reported compound, fcBrÂ(PPh<sub>2</sub>), a series of ferrocene derivatives,
fcÂ(PPh<sub>2</sub>)Â(BÂ[OMe]<sub>2</sub>), [LiÂ(OEt<sub>2</sub>)]Â[fcÂ(PPh<sub>2</sub>)Â(BH<sub>3</sub>)], [LiÂ(THF)<sub>2</sub>]Â[fcÂ(PPh<sub>2</sub>)Â(BHÂ[(3,5-Me)<sub>2</sub>pz]<sub>2</sub>)] (pz = pyrazole), was isolated
and characterized. Compound (fc<sup>P,B</sup>)ÂLiÂ(THF)<sub>2</sub> allowed
the synthesis of the corresponding nickel and zinc complexes, (fc<sup>P,B</sup>)ÂNiCl, (fc<sup>P,B</sup>)ÂNiMe, (fc<sup>P,B</sup>)ÂZnCl, and
(fc<sup>P,B</sup>)ÂZnMe. 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>)ÂNiCl, (fc<sup>P,B</sup>)ÂNiMe, (fc<sup>P,B</sup>)ÂZnCl, and (fc<sup>P,B</sup>)ÂZnMe
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
The
synthesis of several novel nickelÂ(II) and palladiumÂ(II) ferrocene-bisÂ(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
Syntheses
of neutral halide and aryl vanadium bisimides are described.
Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)Â[NTMSÂ(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: VClÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VClÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VClÂ(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VClÂ(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 VBrÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VIÂ(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 VPhÂ(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 [VÂ(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>10</b>, [VÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>11</b>, and [VÂ(DMAP)Â(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(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 CpVÂ(N<sup><i>t</i></sup>Bu)ÂX<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
Syntheses
of neutral halide and aryl vanadium bisimides are described.
Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)Â[NTMSÂ(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: VClÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VClÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VClÂ(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VClÂ(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 VBrÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VIÂ(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 VPhÂ(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 [VÂ(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>10</b>, [VÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>11</b>, and [VÂ(DMAP)Â(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(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 CpVÂ(N<sup><i>t</i></sup>Bu)ÂX<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
Syntheses
of neutral halide and aryl vanadium bisimides are described.
Treatment of VCl<sub>2</sub>(N<i>t</i>Bu)Â[NTMSÂ(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: VClÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>3</b>, VClÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>4</b>, VClÂ(PMe<sub>2</sub>Ph)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>5</b>, and VClÂ(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 VBrÂ(PMe<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub> <b>7</b> and VIÂ(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 VPhÂ(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 [VÂ(PMe<sub>3</sub>)<sub>3</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>10</b>, [VÂ(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(PFTB)<sub>4</sub>] <b>11</b>, and [VÂ(DMAP)Â(PEt<sub>3</sub>)<sub>2</sub>(N<sup><i>t</i></sup>Bu)<sub>2</sub>]Â[AlÂ(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 CpVÂ(N<sup><i>t</i></sup>Bu)ÂX<sub>2</sub> (Cp = C<sub>5</sub>H<sub>5</sub><sup>1–</sup>)