24: Synthesis and reactivity of a paramagnetic Iron(II) Phosphaethynolate complex

Abstract: Low-coordinate transition metal centers with the phosphaethynolate (i.e. PCO-) ligand are attractive synthetic targets due to their potential as P-atom transfer reagents/catalysts. Salt metathesis between a β-diketiminate-supported Fe(II) chloride and NaPCO(dioxane)2.5 readily affords the corresponding, P-bound, Fe phosphaethynolate complex, which has been characterized via a full suite of spectroscopies (i.e. 1H NMR, IR, UV-Vis) and single crystal X-ray diffraction (ScXRD) studies. The 3-coordinate phosphaethynolate complex can be further used to synthesize a series of 4-coordinate phosphaethynolate complexes that have also been fully characterized. Upon irradiation, the PCO complex converts to an Fe(II) diphosphorus dimer. This species reacts with aryl and benzyl halides to regenerate Fe halide species and P1-organophosphorus products. These results show potential for the phosphorus metal complexes to be used as phosphorus delivery agents to form new phosphorus-carbon bonds.