Metal-Assisted Opening of Intact P4 Tetrahedra.

Abstract

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'''=η5 -C5 H2 -1,2,4-tBu3 ) and [L0 M] (L0 =CH[CHN(2,6-Me2 C6 H3 )]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-P4 ligand. The reaction products [{CpRu(PPh3 )2 }{CoCp'''}(μ,η1:4 -P4 )][CF3 SO3 ] (5), [{CpBIG Mn(CO)2 }2 {CoCp'''}(μ,η1:1:4 -P4 )] (6) and [{CpBIG Mn(CO)2 }2 {ML0 }(μ,η1:1:4 -P4 )] (CpBIG =C5 (C6 H4 nBu)5 ; L0 =CH[CHN(2,6-Me2 C6 H3 )]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-P4 ligand in the complexes 5-7 is best described as a π-delocalized P4 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 P4 moiety bridges the two metals and behaves as an η3 -coordinated ligand towards the cobalt center.