Currently there is a high interest in the development of environmentally friendly and atom-efficient strategies for the direct activation and functionalization of white phosphorus (P4) to organo-phosphorus products, polyphosphorus cages and other P-containing inorganic derivatives. A classic methodology for activating white phosphorus consists of using well identified or in-situ generated reduced metal complexes. Depending on the reducing ability, nature and coordination environment, a wide array of metal-phosphide species can be generated. Recently, we have identified new trivalent group 5 imido complexes supported by the bulky 2,6-diisopropylphenyl-β-diketiminate (BDI) ligand. These low-valent d2 metal species exhibit an extensive and rich reduction chemistry including semihydrogenation of alkynes, and activation of C-F bonds, arenes and azides through unusual pathways. Accordingly, we targeted the use of the unsaturated “(BDI)M=NtBu” (M = Nb, Ta) fragment to activate white phosphorus. This led to the isolation of rare examples of cyclo-tetraphosphide inverted sandwich complexes containing a P4 ring bridging two metal ions in a symmetrical fashion. We also observed that the cyclo-P4 motif can exist in various states of charge, allowing comparison of the properties of a series of structurally-related compounds to probe the nature of the metal-phosphorus bonding. The combined synthesis, reactivity, structural, spectroscopic and density functional theory analyses of this family of cyclo-P4 inverted sandwich niobium and tantalum complexes will be presented.

Activation of white phosphorus by low-valent group 5 complexes: Formation and reactivity of cyclo-P4 inverted sandwich compounds

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.