121 research outputs found
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of a Cationic Geminal Zr<sup>+</sup>/P Pair with Small Molecules
The
metallocene cation complex [Cp*<sub>2</sub>ZrCH<sub>3</sub>]<sup>+</sup>[BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sup>ā</sup> inserts
the phosphino-substituted alkyne PhāCī¼CāPPh<sub>2</sub> into the [Zr]-CH<sub>3</sub> bond to form the internally
phosphane-stabilized cation [Cp*<sub>2</sub>ZrāCĀ(ī»CMePh)ĀPPh<sub>2</sub>]<sup>+</sup> (<b>10</b>). Complex <b>10</b> adds
alkyl isocyanides as well as pivalonitrile at a lateral site at the
bent metallocene wedge with retention of the ZrāP bond. Complex <b>10</b> acts as a reactive frustrated Lewis pair toward heterocumulenes,
undergoing Zr<sup>+</sup>/P addition reactions to the carbonyl groups
of an alkyl isocyanate and of carbon dioxide to form the respective
five-membered metallaheterocyclic adducts <b>13</b> and <b>14</b>. With mesityl azide complex <b>10</b> undergoes a
Zr<sup>+</sup>/P FLP N,N-addition reaction at the terminal azide nitrogen
atom to form the four-membered FLP cycloadduct <b>15</b>. The
Zr<sup>+</sup>/P FLP is a reactive hydrogen activator. In a stoichiometric
reaction it generates a hydridozirconocene cation that subsequently
serves as a hydrogenation catalyst for various olefinic or acetylenic
substrates. The Zr<sup>+</sup>/P pair <b>10</b> undergoes selective
1,4-addition reactions to conjugated enones and to a conjugated ynone
to give the corresponding seven-membered metallacyclic Zr<sup>+</sup>/P FLP addition products. Many compounds of this study were characterized
by X-ray diffraction
Frustrated Lewis Pair vs MetalāCarbon ĻāBond Insertion Chemistry at an <i>o</i>āPhenylene-Bridged Cp<sub>2</sub>Zr<sup>+</sup>/PPh<sub>2</sub> System
Methyl anion abstraction
from (<i>o</i>-diphenylphosphino)ĀphenylĀ(methyl)Āzirconocene
by trityl tetrakisĀ(pentafluorophenyl)Āborate gives the <i>o</i>-phenylene-bridged Zr<sup>+</sup>/P system <b>10</b>. It behaves
toward a variety of reagents as a typical Zr<sup>+</sup>/P frustrated
Lewis pair (FLP). It undergoes cooperative 1,4-addition reactions
to some chalcone derivatives and adds in a 1,2-fashion to a variety
of organic carbonyls and to several heterocumulenes. The reactive
ZrāC Ļ bond of the FLP <b>10</b> remains intact
in these reactions. Complex <b>10</b> splits dihydrogen, but
subsequently the ZrāC Ļ bond is protonolytically cleaved
in this case. Only a few special reagents, among them carbon monoxide,
undergo the usual insertion reaction into the ZrāCĀ(aryl) Ļ-bond
of the Zr<sup>+</sup>/P system <b>10</b>
Reactions of a Cationic Geminal Zr<sup>+</sup>/P Pair with Small Molecules
The
metallocene cation complex [Cp*<sub>2</sub>ZrCH<sub>3</sub>]<sup>+</sup>[BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sup>ā</sup> inserts
the phosphino-substituted alkyne PhāCī¼CāPPh<sub>2</sub> into the [Zr]-CH<sub>3</sub> bond to form the internally
phosphane-stabilized cation [Cp*<sub>2</sub>ZrāCĀ(ī»CMePh)ĀPPh<sub>2</sub>]<sup>+</sup> (<b>10</b>). Complex <b>10</b> adds
alkyl isocyanides as well as pivalonitrile at a lateral site at the
bent metallocene wedge with retention of the ZrāP bond. Complex <b>10</b> acts as a reactive frustrated Lewis pair toward heterocumulenes,
undergoing Zr<sup>+</sup>/P addition reactions to the carbonyl groups
of an alkyl isocyanate and of carbon dioxide to form the respective
five-membered metallaheterocyclic adducts <b>13</b> and <b>14</b>. With mesityl azide complex <b>10</b> undergoes a
Zr<sup>+</sup>/P FLP N,N-addition reaction at the terminal azide nitrogen
atom to form the four-membered FLP cycloadduct <b>15</b>. The
Zr<sup>+</sup>/P FLP is a reactive hydrogen activator. In a stoichiometric
reaction it generates a hydridozirconocene cation that subsequently
serves as a hydrogenation catalyst for various olefinic or acetylenic
substrates. The Zr<sup>+</sup>/P pair <b>10</b> undergoes selective
1,4-addition reactions to conjugated enones and to a conjugated ynone
to give the corresponding seven-membered metallacyclic Zr<sup>+</sup>/P FLP addition products. Many compounds of this study were characterized
by X-ray diffraction
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
Reactions of Modified Intermolecular Frustrated P/B Lewis Pairs with Dihydrogen, Ethene, and Carbon Dioxide
In this contribution, we discuss the reactivity of different
phosphanes
(XPhos (<b>1a</b>), <i><sup>t</sup></i>BuXPhos (<b>1b</b>), and Mes<sub>2</sub>PEt (<b>1c</b>)) and trisĀ(pentafluorophenyl)Āborane
(and in one case, EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub>) against
small molecules. <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> split
dihydrogen heterolytically to yield the phosphonium borate salts <b>2a</b>, <b>2b</b>, and <b>2c</b>, respectively. Control
experiments with D<sub>2</sub> gave the respective deuterated phosphonium
borates <b>2a</b>-D<sub>2</sub>, <b>2b</b>-D<sub>2</sub>, and <b>2c</b>-D<sub>2</sub>. The FLP systems <b>1b</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> underwent 1,2-addition reactions
with ethene, resulting in the generation of the ethylene-bridged phosphonium
borates <b>3b</b> and <b>3c</b>. As well, the Lewis pair
EtBĀ(C<sub>6</sub>F<sub>5</sub>)<sub>2</sub> and Mes<sub>2</sub>PEt
reacted with ethene to yield the corresponding 1,2-addition product <b>3d</b>. At low temperature, the FLP systems <b>1a</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> and <b>1c</b>/BĀ(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> coordinated carbon dioxide (<b>4a</b>, <b>4c</b>). The new compounds <b>2a</b>, <b>2b</b>, <b>3b</b>, <b>3c</b>, <b>3d</b>, <b>4a</b>, and <b>4c</b> were characterized by X-ray crystal structure
analyses
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