2 research outputs found
School census autumn 2017 : 16 to 19 reports : user guide
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synthesis of a series of cobalt NHC complexes of the types [Co(NHC)<sub>2</sub>(CO)(NO)] (NHC = <i>i</i>Pr<sub>2</sub>Im (<b>2</b>), <i>n</i>Pr<sub>2</sub>Im (<b>3</b>), Cy<sub>2</sub>Im (<b>4</b>), Me<sub>2</sub>Im (<b>5</b>), <i>i</i>Pr<sub>2</sub>ImMe (<b>6</b>), Me<sub>2</sub>ImMe
(<b>7</b>), Me<i>i</i>PrIm (<b>8</b>), Me<i>t</i>BuIm (<b>9</b>); R<sub>2</sub>Im = 1,3-dialkylimidazolin-2-ylidene) and [Co(NHC)(CO)<sub>2</sub>(NO)] (NHC = <i>i</i>Pr<sub>2</sub>Im (<b>13</b>), <i>n</i>Pr<sub>2</sub>Im (<b>14</b>), Me<sub>2</sub>Im (<b>15</b>), <i>i</i>Pr<sub>2</sub>ImMe (<b>16</b>), Me<sub>2</sub>ImMe (<b>17</b>), Me<i>i</i>PrIm
(<b>18</b>), Me<i>t</i>BuIm (<b>19</b>)) from
the reaction of the NHC with [Co(CO)<sub>3</sub>(NO)] (<b>1</b>) is reported. These complexes have been characterized using elemental
analysis, IR spectroscopy, multinuclear NMR spectroscopy, and in many
cases by X-ray crystallography. Bulky NHCs tend to form the mono-NHC-substituted
complexes [Co(NHC)(CO)<sub>2</sub>(NO)], even from the reaction with
an stoichiometric excess of the NHC, as demonstrated by the synthesis
of [Co(Dipp<sub>2</sub>Im)(CO)<sub>2</sub>(NO)] (<b>11</b>),
[Co(Mes<sub>2</sub>Im)(CO)<sub>2</sub>(NO)] (<b>12</b>), and
[Co(<sup>Me</sup>cAAC)(CO)<sub>2</sub>(NO)] (<b>20</b>). For <i>t</i>Bu<sub>2</sub>Im a preferred coordination via the NHC backbone
(“abnormal” coordination at the 4-position) was observed
and the complex [Co(<i>t</i>Bu<sub>2</sub><sup>a</sup>Im)(CO)<sub>2</sub>(NO)] (<b>10</b>) was isolated. All of these complexes
are volatile, are stable upon sublimation and prolonged storage in
the gas phase, and readily decompose at higher temperatures. Furthermore,
DTA/TG analyses revealed that the complexes [Co(NHC)<sub>2</sub>(CO)(NO)]
are seemingly more stable toward thermal decomposition in comparison
to the complexes [Co(NHC)(CO)<sub>2</sub>(NO)]. We thus conclude that
the cobalt complexes of the type [Co(NHC)(CO)<sub>2</sub>(NO)] and
[Co(NHC)<sub>2</sub>(CO)(NO)] have potential for application as precursors
in the vapor deposition of thin cobalt films
Preparing (Multi)Fluoroarenes as Building Blocks for Synthesis: Nickel-Catalyzed Borylation of Polyfluoroarenes via C–F Bond Cleavage
No full textThe [Ni(IMes)<sub>2</sub>]-catalyzed transformation of fluoroarenes
into arylboronic acid pinacol esters via C–F bond activation
and transmetalation with bis(pinacolato)diboron (B<sub>2</sub>pin<sub>2</sub>) is reported. Various partially fluorinated arenes with different
degrees of fluorination were converted into their corresponding boronate
esters
