Synthesis of the open-shell 3d-transition metal(II) bis(phosphinidenide) [Mn{P(sIDipp)} 2 ].

The synthesis and characterization of the first homoleptic open-shell transition metal phosphinidenide is presented. By reacting [MnL 2 ] (L = -N(SiMe 3 ) 2 ) with [(sIDipp)PK] (sIDipp = 1,3-bis(2,6-di-iso-propylphenyl)-imidazolidine-2-ylidene), the formation of [Mn{P(sIDipp)} 2 ] instead of the initially expected adduct [KMn{P(sIDipp)}L 2 ] is observed. Interestingly, a solvent change from toluene to n -pentane leads to the formation of [(sIDipp)PK 2 (Et 2 O) 4 ][MnL 3 ] after work-up, which can be seen as intermediate in the formation process of [Mn{P(sIDipp)} 2 ]. Contrary to manganese, the highly reducing phosphinidenide [(sIDipp)P] - cannot be stabilized in an analogous fashion by coordination to a low-coordinate high-spin iron(II) center.