Hydride Abstraction from [MCp<sup>Bz</sup>(CO)<sub>3</sub>H] (M = Mo, W; Cp<sup>Bz</sup> = C<sub>5</sub>(CH<sub>2</sub>Ph)<sub>5</sub>): New Cationic Complexes Stabilized by η<sup>5</sup>:η<sup>2</sup>-C<sub>5</sub>H<sub>4</sub>:C<sub>6</sub>H<sub>5</sub> Bonding of the Pentabenzylcyclopentadienyl Ligand