Selective White Phosphorus Activation and Functionalization with Inorganic Grignard Reagents

Abstract

We describe the targeted and selective functionalization of white phosphorus (P4) using ‘inorganic Grignard reagents’. Reactions of the Fe-Mg complexes [(DippBDI)Mg(THF)xFp] (Fp = CpFe(CO)2, 1: x = 0; 1 THF: x = 1, DippBDI = 2,6-diisopropylphenyl-1,3 diketiminate)) and [(DippBDI)MgFp*] (2, Fp* = Cp*Fe(CO)2) afford the compounds [(DippBDI)Mg(THF)x][Fp(μ-P4)] (3: x = 0; 3 THF: x = 1) and [(DippBDI)Mg][Fp*(μ-P4)] (4) featuring P42- ligands with a ‘butterfly’ structure bridging Fe and Mg. The coordination of the β-diketiminate magnesium cations [(DippBDI)Mg]+ plays a key role in stabilizing these reactive ‘P4-butterfly’ anions through non-covalent Mg–P bonds and dispersion forces. Thermolysis or photolysis of 3-THF and 4 afforded rare tetraphosphacyclopentadienolate complexes 7 and 8. Complex 4 exhibits unmitigated reactivity towards a wide range of main group element electrophiles (iPrNCNiPr, Ph2BCl, Ph3SnCl (Me3Si)3SiCl and Mes2PCl), furnishing rare examples of stable, mixed-substituted tetraphosphanes 9-13 as well as an octaphosphane 14 featuring a Sn2P8 core.