Molybdenum(0) Dinitrogen Complexes Supported by Pentadentate Tetrapodal Phosphine Ligands: Structure, Synthesis, and Reactivity toward Acids HinrichsenSvea KindjajevAndrei AdomeitSven KrahmerJan NätherChristian TuczekFelix 2016 The syntheses of two pentadentate tetrapodal phosphine (pentaPod<sup>P</sup>) ligands, P<sub>2</sub><sup>Ph</sup>PP<sub>2</sub><sup>Ph</sup> and P<sub>2</sub><sup>Me</sup>PP<sub>2</sub><sup>Ph</sup>, are reported, which derive from the fusion of a tripod and a trident ligand. Reaction of the ligand P<sub>2</sub><sup>Ph</sup>PP<sub>2</sub><sup>Ph</sup> with [MoCl<sub>3</sub>(THF)<sub>3</sub>] followed by an amalgam reduction under N<sub>2</sub> does not lead to well-defined products. The same reactions performed with the ligand P<sub>2</sub><sup>Me</sup>PP<sub>2</sub><sup>Ph</sup> afford the mononuclear molybdenum dinitrogen complex [MoN<sub>2</sub>(P<sub>2</sub><sup>Me</sup>PP<sub>2</sub><sup>Ph</sup>)]. Because of the unprecedented topology of the pentaphosphine ligand, the Mo–P bond to the phosphine in the <i>trans</i> position to N<sub>2</sub> is significantly shortened, explaining the very strong activation of the dinitrogen ligand (ν̃<sub>NN</sub> = 1929 cm<sup>–1</sup>). The reactivity of this complex toward acids is investigated.