Cationic Ruthenium Hydrido−Carbonyls Derived from Metallocene-Based Pincers: Unusual Rearrangements and H<sub>2</sub> Evolution with Formation of Cationic Ruthenium Metallocenylidenes

Cationic ruthenium hydrido-carbonyls {RuH(CO)[<sup><i>t</i>Bu</sup>P,CH,P<sup>M</sup>]}BAr<sup>F</sup><sub>4</sub> (M = Fe, <b>3</b>; M = Ru, <b>4</b>) (Ar<sup>F </sup>= 3,5-(CF<sub>3</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>) obtained in the reaction of H<sub>2</sub> with RuCl(CO)[<sup><i>t</i>Bu</sup>P,C,P<sup>M</sup>] (M = Fe, <b>1</b>; M = Ru, <b>2</b>) in the presence of NaBAr<sup>F</sup><sub>4</sub> add CO smoothly, giving the corresponding dicarbonyl complexes {RuH(CO)<sub>2</sub>[<sup><i>t</i>Bu</sup>P,CH,P<sup>M</sup>]}BAr<sup>F</sup><sub>4</sub> (M = Fe, <b>11</b>; M = Ru, <b>12</b>). According to X-ray analysis of <b>11</b> and <b>12</b>, addition of extra CO to complexes <b>3</b> and <b>4</b> leads to strengthening of the C(1)−H(1)···Ru(1) agostic interaction. Simultaneously, CO addition to <b>3</b> and <b>4</b> triggers a sequence (up to three steps) of unprecedented intramolecular rearrangements including migration of H atoms. First metallocenylidene complexes {Ru(CO)<sub>2</sub>[<sup><i>t</i>Bu</sup>P,C,P<sup>M</sup>]}BAr<sup>F</sup><sub>4</sub> (M = Fe, <b>15</b>; M = Ru, <b>16</b>) were obtained in the course of these rearrangements accompanied by H<sub>2</sub> evolution.