6 research outputs found
Yttrium Hydride Complex Bearing CpPN/Amidinate Heteroleptic Ligands: Synthesis, Structure, and Reactivity
The reaction of the yttrium dialkyls (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf) (<b>1</b>) with an excess
of <i>N</i>,<i>N′</i>-diisopropylcarbodiimide
gave
the yttrium monoalkyl complex (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)Â[<sup><i>i</i></sup>PrNî—»CÂ(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr] (<b>2</b>). <b>2</b> subsequently
reacted with 1 equiv of PhSiH<sub>3</sub> to generate the CpPN/amidinate
heteroleptic yttrium hydride {(C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ[<sup><i>i</i></sup>PrNî—»CÂ(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr]Â(μ-H)}<sub>2</sub> (<b>3</b>). Hydride <b>3</b> showed good reactivity
toward various substrates containing unsaturated C–C, C–N,
and N–N bonds, such as azobenzene, <i>p</i>-tolyacetylene,
1,4-bisÂ(trimethylsilyl)-1,3-butanediyne, <i>N</i>,<i>N′</i>-diisopropylcarbodiimide, and 4-dimethylaminopyridine,
affording the yttrium hydrazide complex <b>4</b> with a rare
η<sup>2</sup>-Cp bonding mode, yttrium terminal alkynyl complex <b>5</b>, yttrium η<sup>3</sup>-propargyl complex <b>6</b>, yttrium amidinate complex <b>7</b>, and yttrium 2-hydro-4-dimethylaminopyridyl
product <b>8</b>, respectively
Yttrium Hydride Complex Bearing CpPN/Amidinate Heteroleptic Ligands: Synthesis, Structure, and Reactivity
The reaction of the yttrium dialkyls (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf) (<b>1</b>) with an excess
of <i>N</i>,<i>N′</i>-diisopropylcarbodiimide
gave
the yttrium monoalkyl complex (C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)Â[<sup><i>i</i></sup>PrNî—»CÂ(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr] (<b>2</b>). <b>2</b> subsequently
reacted with 1 equiv of PhSiH<sub>3</sub> to generate the CpPN/amidinate
heteroleptic yttrium hydride {(C<sub>5</sub>H<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ[<sup><i>i</i></sup>PrNî—»CÂ(CH<sub>2</sub>SiMe<sub>3</sub>)–N<sup><i>i</i></sup>Pr]Â(μ-H)}<sub>2</sub> (<b>3</b>). Hydride <b>3</b> showed good reactivity
toward various substrates containing unsaturated C–C, C–N,
and N–N bonds, such as azobenzene, <i>p</i>-tolyacetylene,
1,4-bisÂ(trimethylsilyl)-1,3-butanediyne, <i>N</i>,<i>N′</i>-diisopropylcarbodiimide, and 4-dimethylaminopyridine,
affording the yttrium hydrazide complex <b>4</b> with a rare
η<sup>2</sup>-Cp bonding mode, yttrium terminal alkynyl complex <b>5</b>, yttrium η<sup>3</sup>-propargyl complex <b>6</b>, yttrium amidinate complex <b>7</b>, and yttrium 2-hydro-4-dimethylaminopyridyl
product <b>8</b>, respectively
Phosphazene-Functionalized Cyclopentadienyl and Its Derivatives Ligated Rare-Earth Metal Alkyl Complexes: Synthesis, Structures, and Catalysis on Ethylene Polymerization
Treatment of LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc, Y, and Lu) with 1 equiv of CpPN-type
ligands C<sub>5</sub>H<sub>4</sub>PPh<sub>2</sub>–NH–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R = Me, <b>L<sup>1</sup>(Me)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>1</sup>(<sup><i>i</i></sup>Pr)</b>) at room temperature readily generated
the corresponding CpPN-type bisÂ(alkyl) complexes <b>1</b> and <b>2a</b>–<b>2c</b>. Addition of 3 equiv of LiCH<sub>2</sub>SiMe<sub>3</sub> to a mixture of <b>L<sup>1</sup>(<sup><i>i</i></sup>Pr)</b> and LnCl<sub>3</sub>(thf)<sub>2</sub> (Ln = Sm and Nd) also afforded the CpPN-type bisÂ(alkyl) complexes <b>2d</b> and <b>2e</b>. The Cp moiety bonds to the central
metal in a classical η<sup>5</sup> mode in all CpPN-type complexes <b>1</b> and <b>2</b>. In contrast, the Cp<sup>Me</sup>PN-type
ligands C<sub>5</sub>Me<sub>4</sub>H–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R = Me, <b>L<sup>2</sup>(Me)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b>) behaved differently. <b>L<sup>2</sup>(Me)</b> did not react with ScÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub>. Similarly, <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b> was also inert to ScÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> even at 50 °C. When the
central metal was changed to yttrium, however, the equimolar reaction
between YÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> and <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b> in
the presence of LiCl afforded two bisÂ(alkyl) complexes <b>3a</b> and <b>3b</b>. In the main product <b>3a</b>, [C<sub>5</sub>HMe<sub>3</sub>(η<sup>3</sup>-CH<sub>2</sub>)–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>]ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf), the ligand bonds to the Y<sup>3+</sup> ion in a rare η<sup>3</sup>-allyl/κ-N mode, whereas in <b>3b</b>, <b>(</b>C<sub>5</sub>Me<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(LiCl)Â(thf), the Cp ring coordinates
to the Y<sup>3+</sup> ion in an η<sup>5</sup> mode, and a LiCl
unit is located between the Y<sup>3+</sup> ion and the nitrogen atom.
When the central metal was changed to lutetium, a bisÂ(alkyl) complex <b>4a</b>, [C<sub>5</sub>HMe<sub>3</sub>(η<sup>3</sup>-CH<sub>2</sub>)–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>]ÂLuÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf), and a bisÂ(alkyl) complex <b>4b</b>, (C<sub>5</sub>Me<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂLuÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>, were isolated. The protonolysis
reaction of the IndPN-type ligands C<sub>9</sub>H<sub>7</sub>–PPh<sub>2</sub>N–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R
= Me, <b>L<sup>3</sup>(Me)</b>; R = Et, <b>L<sup>3</sup>(Et)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>3</sup>(<sup><i>i</i></sup>Pr)</b>) with LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc, Y, and Lu) generated the
IndPN-type bisÂ(alkyl) complexes <b>5a</b>–<b>5c</b>, <b>6</b>, and <b>7a</b>–<b>7c</b>, selectively,
where the Ind moiety tends to adopt an η<sup>3</sup>-bonding
fashion. The more bulky FluPN-type ligands C<sub>13</sub>H<sub>9</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>4</sub>R (R = H, <b>L<sup>4</sup>(H)</b>; R = Me, <b>L<sup>4</sup>(Me)</b>) were treated with LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc and Lu) to afford the FluPN-type
bisÂ(alkyl) complexes <b>8</b> and <b>9a</b> and <b>9b</b>, where the Flu moiety has a rare η<sup>1</sup>-bonding
mode. Complexes <b>1</b>–<b>9</b> were fully characterized
by <sup>1</sup>H, <sup>13</sup>C, and <sup>31</sup>P NMR; X-ray; and
elemental analyses. Upon activation with AlR<sub>3</sub> and [Ph<sub>3</sub>C]Â[BÂ(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], the scandium
complexes showed good to high catalytic activity for ethylene polymerization.
The effects of the sterics and electronics of the ligand, the loading
and the type of AlR<sub>3</sub>, the polymerization temperature, and
the polymerization time on the catalytic activity were also discussed
Phosphazene-Functionalized Cyclopentadienyl and Its Derivatives Ligated Rare-Earth Metal Alkyl Complexes: Synthesis, Structures, and Catalysis on Ethylene Polymerization
Treatment of LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc, Y, and Lu) with 1 equiv of CpPN-type
ligands C<sub>5</sub>H<sub>4</sub>PPh<sub>2</sub>–NH–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R = Me, <b>L<sup>1</sup>(Me)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>1</sup>(<sup><i>i</i></sup>Pr)</b>) at room temperature readily generated
the corresponding CpPN-type bisÂ(alkyl) complexes <b>1</b> and <b>2a</b>–<b>2c</b>. Addition of 3 equiv of LiCH<sub>2</sub>SiMe<sub>3</sub> to a mixture of <b>L<sup>1</sup>(<sup><i>i</i></sup>Pr)</b> and LnCl<sub>3</sub>(thf)<sub>2</sub> (Ln = Sm and Nd) also afforded the CpPN-type bisÂ(alkyl) complexes <b>2d</b> and <b>2e</b>. The Cp moiety bonds to the central
metal in a classical η<sup>5</sup> mode in all CpPN-type complexes <b>1</b> and <b>2</b>. In contrast, the Cp<sup>Me</sup>PN-type
ligands C<sub>5</sub>Me<sub>4</sub>H–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R = Me, <b>L<sup>2</sup>(Me)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b>) behaved differently. <b>L<sup>2</sup>(Me)</b> did not react with ScÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub>. Similarly, <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b> was also inert to ScÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> even at 50 °C. When the
central metal was changed to yttrium, however, the equimolar reaction
between YÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> and <b>L<sup>2</sup>(<sup><i>i</i></sup>Pr)</b> in
the presence of LiCl afforded two bisÂ(alkyl) complexes <b>3a</b> and <b>3b</b>. In the main product <b>3a</b>, [C<sub>5</sub>HMe<sub>3</sub>(η<sup>3</sup>-CH<sub>2</sub>)–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>]ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf), the ligand bonds to the Y<sup>3+</sup> ion in a rare η<sup>3</sup>-allyl/κ-N mode, whereas in <b>3b</b>, <b>(</b>C<sub>5</sub>Me<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂYÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(LiCl)Â(thf), the Cp ring coordinates
to the Y<sup>3+</sup> ion in an η<sup>5</sup> mode, and a LiCl
unit is located between the Y<sup>3+</sup> ion and the nitrogen atom.
When the central metal was changed to lutetium, a bisÂ(alkyl) complex <b>4a</b>, [C<sub>5</sub>HMe<sub>3</sub>(η<sup>3</sup>-CH<sub>2</sub>)–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>]ÂLuÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>(thf), and a bisÂ(alkyl) complex <b>4b</b>, (C<sub>5</sub>Me<sub>4</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>3</sub><sup><i>i</i></sup>Pr<sub>2</sub>)ÂLuÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>2</sub>, were isolated. The protonolysis
reaction of the IndPN-type ligands C<sub>9</sub>H<sub>7</sub>–PPh<sub>2</sub>N–C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R
= Me, <b>L<sup>3</sup>(Me)</b>; R = Et, <b>L<sup>3</sup>(Et)</b>; R = <sup><i>i</i></sup>Pr, <b>L<sup>3</sup>(<sup><i>i</i></sup>Pr)</b>) with LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc, Y, and Lu) generated the
IndPN-type bisÂ(alkyl) complexes <b>5a</b>–<b>5c</b>, <b>6</b>, and <b>7a</b>–<b>7c</b>, selectively,
where the Ind moiety tends to adopt an η<sup>3</sup>-bonding
fashion. The more bulky FluPN-type ligands C<sub>13</sub>H<sub>9</sub>–PPh<sub>2</sub>î—»N–C<sub>6</sub>H<sub>4</sub>R (R = H, <b>L<sup>4</sup>(H)</b>; R = Me, <b>L<sup>4</sup>(Me)</b>) were treated with LnÂ(CH<sub>2</sub>SiMe<sub>3</sub>)<sub>3</sub>(thf)<sub>2</sub> (Ln = Sc and Lu) to afford the FluPN-type
bisÂ(alkyl) complexes <b>8</b> and <b>9a</b> and <b>9b</b>, where the Flu moiety has a rare η<sup>1</sup>-bonding
mode. Complexes <b>1</b>–<b>9</b> were fully characterized
by <sup>1</sup>H, <sup>13</sup>C, and <sup>31</sup>P NMR; X-ray; and
elemental analyses. Upon activation with AlR<sub>3</sub> and [Ph<sub>3</sub>C]Â[BÂ(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>], the scandium
complexes showed good to high catalytic activity for ethylene polymerization.
The effects of the sterics and electronics of the ligand, the loading
and the type of AlR<sub>3</sub>, the polymerization temperature, and
the polymerization time on the catalytic activity were also discussed