Platinum Complexes with Chelating Acyclic Aminocarbene Ligands Work as Catalysts for Hydrosilylation of Alkynes



Chay, Rogerio S, Rocha, Bruno GM, Pombeiro, Armando JL, Kukushkin, Vadim Yu and Luzyanin, Konstantin V ORCID: 0000-0001-9312-7139
(2018) Platinum Complexes with Chelating Acyclic Aminocarbene Ligands Work as Catalysts for Hydrosilylation of Alkynes. ACS OMEGA, 3 (1). pp. 863-871.

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Abstract

This work describes the preparation of a series of platinum-aminocarbene complexes [PtCl{C(N=C <sup><i>a</i></sup> (C<sub>6</sub>R<sup>2</sup>R<sup>3</sup>R<sup>4</sup>R<sup>5</sup>CON <sup><i>b</i></sup> ))=N(H)R<sup>1</sup>}(CNR<sup>1</sup>)] <sup><i>a-b</i></sup> (<b>8</b>-<b>19</b>, 65-75% isolated yield) via the reaction of <i>cis</i>-[PtCl<sub>2</sub>(CNR<sup>1</sup>)<sub>2</sub>] (R<sup>1</sup> = Cy <b>1</b>, <i>t</i>-Bu <b>2</b>, Xyl <b>3</b>, 2-Cl-6-MeC<sub>6</sub>H<sub>3</sub> <b>4</b>) with 3-iminoisoindolin-1-ones HN=C <sup><i>a</i></sup> (C<sub>6</sub>R<sup>2</sup>R<sup>3</sup>R<sup>4</sup>R<sup>5</sup>CON <sup><i>b</i></sup> H) (R<sup>2</sup>-R<sup>5</sup> = H <b>5</b>; R<sup>3</sup> = Me, R<sup>2</sup>, R<sup>4</sup>, R<sup>5</sup> = H <b>6</b>; R<sup>3</sup>, R<sup>4</sup> = Cl, R<sup>2</sup>, R<sup>5</sup> = H <b>7</b>). New complexes <b>17</b>-<b>19</b> were characterized by elemental analyses (C, H, N), ESI<sup>+</sup>-MS, Fourier transform infrared spectroscopy (FT-IR), one-dimensional (<sup>1</sup>H, <sup>13</sup>C{<sup>1</sup>H}), and two-dimensional (<sup>1</sup>H,<sup>1</sup>H correlation spectroscopy (COSY), <sup>1</sup>H,<sup>13</sup>C heteronuclear multiple quantum correlation (HMQC)/<sup>1</sup>H,<sup>13</sup>C heteronuclear single quantum coherence (HSQC), <sup>1</sup>H,<sup>13</sup>C heteronuclear multiple bond correlation (HMBC)) NMR spectroscopy, and authenticity of known species <b>8</b>-<b>16</b> was confirmed by FT-IR and <sup>1</sup>H and <sup>13</sup>C{<sup>1</sup>H} NMR. Complexes <b>8</b>-<b>19</b> were assessed as catalysts for hydrosilylation of terminal alkynes with hydrosilanes to give vinyl silanes, and complex [PtCl{C(N=C <sup><i>a</i></sup> (C<sub>6</sub>H<sub>3</sub>(5-Me)CON <sup><i>b</i></sup> ))=N(H)(2-Cl-6-MeC<sub>6</sub>H<sub>3</sub>)}{CN(2-Cl-6-MeC<sub>6</sub>H<sub>3</sub>)}] <sup><i>a</i>-<i>b</i></sup> (<b>18</b>) showed the highest catalytic activity. The catalytic system proposed operates at 80-100 °C for 4-6 h in toluene and with catalyst loading of 0.1 mol %, enabling the reaction of a number of terminal alkynes (PhC≡CH, <i>t</i>-BuC≡CH, and 4-(<i>t</i>-Bu)C<sub>6</sub>H<sub>4</sub>C≡CH) with hydrosilanes (Et<sub>3</sub>SiH, Pr<sub>3</sub>SiH, <i>i</i>-Pr<sub>3</sub>SiH, and PhMe<sub>2</sub>SiH). Target vinyl silanes were prepared in 48-95% yields (as a mixture of α/β isomers) and with maximum turnover number of 8.4 × 10<sup>3</sup>. Hydrosilylation of internal alkynes (PhC≡CPh, Me(CH<sub>2</sub>)<sub>2</sub>C≡C(CH<sub>2</sub>)<sub>2</sub>Me, and PhC≡CMe) with hydrosilanes (Et<sub>3</sub>SiH, PhMe<sub>2</sub>SiH) led to the corresponding trisubstituted silylated alkenes in 86-94% yields. Initial observations on the mechanism of the catalytic action of platinum-ADC catalysts <b>8</b>-<b>19</b> suggested a molecular catalytic cycle.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 15 Jan 2018 14:57
Last Modified: 19 Jan 2023 06:44
DOI: 10.1021/acsomega.7b01688
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3016139