10.1021/om500758j.s002 Papri Bhattacharya Papri Bhattacharya Jeanette A. Krause Jeanette A. Krause Hairong Guan Hairong Guan Activation of Dihydrogen and Silanes by Cationic Iron Bis(phosphinite) Pincer Complexes American Chemical Society 2014 HBF BF HCO 2H 2PO pincer structure hydride complexes electron transfer pathway iPr 2N H 2 pincer products acids CF 3CO alternative method H 2. Ph 3C iPr 2NEt basicity order hydride ligand CD 3CN results 2014-11-10 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Activation_of_Dihydrogen_and_Silanes_by_Cationic_Iron_Bis_phosphinite_Pincer_Complexes/2237188 Treatment of iron POCOP-pincer hydride complexes <i>cis</i>-[2,6-(<sup>i</sup>Pr<sub>2</sub>PO)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]­Fe­(H)­(PMe<sub>3</sub>)<sub>2</sub> (<b>1-H</b>), [2,6-(<sup>i</sup>Pr<sub>2</sub>PO)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]­Fe­(H)­(PMe<sub>3</sub>)­(CO) (<b>2-H</b>, <i>trans</i> H/CO; <b>2</b>′<b>-H</b>, <i>cis</i> H/CO), and <i>cis</i>-[2,6-(<sup>i</sup>Pr<sub>2</sub>PO)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]­Fe­(H)­(CO)<sub>2</sub> (<b>3-H</b>) with HBF<sub>4</sub>·Et<sub>2</sub>O in CD<sub>3</sub>CN/THF-<i>d</i><sub>8</sub> results in a rapid evolution of H<sub>2</sub>. Except for the reaction of <b>1-H</b>, which leads to decomposition of the pincer structure, all other hydrides are converted cleanly to acetonitrile-trapped cationic complexes. Protonation of these hydrides with the weaker acids CF<sub>3</sub>CO<sub>2</sub>H and HCO<sub>2</sub>H establishes the basicity order of <b>1-H</b> > <b>2-H</b> > <b>2</b>′<b>-H</b> > <b>3-H</b>, with <b>3-H</b> bearing the least basic hydride ligand. An alternative method of abstracting hydride by [Ph<sub>3</sub>C]<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup> gives complicated products; the reaction of <b>2-H</b> generates two pincer products, [HPMe<sub>3</sub>]<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup> and Gomberg’s dimer, which supports a single electron transfer pathway. Cationic complexes {[2,6-(<sup>i</sup>Pr<sub>2</sub>PO)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]­Fe­(CO)­(PMe<sub>3</sub>)­(CH<sub>3</sub>CN)}<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup> (<b>2</b><sup><b>+</b></sup><b>-BF</b><sub><b>4</b></sub>, <i>trans</i> CO/CH<sub>3</sub>CN) and <i>cis</i>-{[2,6-(<sup>i</sup>Pr<sub>2</sub>PO)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>]­Fe­(CO)<sub>2</sub>(CH<sub>3</sub>CN)}<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup> (<b>3</b><sup><b>+</b></sup><b>-BF</b><sub><b>4</b></sub>) are prepared from protonation of <b>2-H</b> (or <b>2</b>′<b>-H</b>) and <b>3-H</b> with HBF<sub>4</sub>·Et<sub>2</sub>O, respectively. Both compounds react with H<sub>2</sub> with the aid of <sup>i</sup>Pr<sub>2</sub>NEt to yield neutral hydride complexes and [<sup>i</sup>Pr<sub>2</sub>N­(H)­Et]<sup>+</sup>[BF<sub>4</sub>]<sup>−</sup>. In addition, they catalyze the hydrosilylation of benzaldehyde and acetophenone with (EtO)<sub>3</sub>SiH and show higher catalytic activity than the neutral hydrides <b>2-H</b>/<b>2</b>′<b>-H</b> and <b>3-H</b>. The mechanism for the formation of <b>2</b><sup><b>+</b></sup><b>-BF</b><sub><b>4</b></sub> and the X-ray structure of <b>2</b><sup><b>+</b></sup><b>-BF</b><sub><b>4</b></sub> are also described.