Metal-Assisted Opening of Intact P 4 Tetrahedra

The reactivity of ruthenium and manganese complexes bearing intact white phosphorus in the coordination sphere was investigated towards the low-valent transition-metal species [Cp???Co] (Cp???=? 5 -C 5 H 2 -1,2,4-tBu 3 ) and [L 0 M] (L 0 =CH[CHN(2,6-Me 2 C 6 H 3 )] 2 ; M=Fe, Co). Remarkably, and irrespective of the metal species, the reaction proceeds by the selective cleavage of two P-P edges and the formation of a square-planar cyclo-P 4 ligand. The reaction products [{CpRu(PPh 3 ) 2 }{CoCp???}(?,? 1:4 -P 4 )][CF 3 SO 3 ] (5), [{Cp BIG Mn(CO) 2 } 2 {CoCp???}(?,? 1:1:4 -P 4 )] (6) and [{Cp BIG Mn(CO) 2 } 2 {ML 0 }(?,? 1:1:4 -P 4 )] (Cp BIG =C 5 (C 6 H 4 nBu) 5 ; L 0 =CH[CHN(2,6-Me 2 C 6 H 3 )] 2 ; M=Fe (7 a), Co (7 b)), respectively, were fully characterized by single-crystal X-ray diffraction and spectroscopic methods. The electronic structure of the cyclo-P 4 ligand in the complexes 5-7 is best described as a ?-delocalized P 4 2- system, which is further stabilized by two and three metal moieties, respectively. DFT calculations envisaged a potential intermediate in the reaction to form 5, in which a quasi-butterfly-shaped P 4 moiety bridges the two metals and behaves as an ? 3 -coordinated ligand towards the cobalt center.