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′′′=η 5 ‐C 5 H 2 ‐1,2,4‐ t Bu 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′′′}(μ,η 1:4 ‐P 4 )][CF 3 SO 3 ] ( 5 ), [{Cp BIG Mn(CO) 2 } 2 {CoCp′′′}(μ,η 1:1:4 ‐P 4 )] ( 6 ) and [{Cp BIG Mn(CO) 2 } 2 {ML 0 }(μ,η 1:1:4 ‐P 4 )] (Cp BIG =C 5 (C 6 H 4 n Bu) 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 π‐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 η 3 ‐coordinated ligand towards the cobalt center.