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 [MnL2] (L = -N(SiMe3)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)}L2] is observed. Interestingly, a solvent change from toluene to n-pentane leads to the formation of [(sIDipp)PK2(Et2O)4][MnL3] 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.