In pursuit of a more sustainable production of phosphorous acid (H 3 PO 3 ), a versatile chemical with phosphorus in the +3 oxidation state, we herein report that condensed phosphates can be employed to phosphorylate hydride reagents under solvent-free mechanochemical conditions to furnish phosphite (HPO 3 2– ). Using potassium hydride as the hydride source, sodium trimetaphosphate (Na 3 P 3 O 9 ), triphosphate (Na 5 P 3 O 10 ), pyrophosphate (Na 4 P 2 O 7 ), fluorophosphate (Na 2 PO 3 F), and polyphosphate (“(NaPO 3 ) n ”) engendered phosphite in optimized yields of 44, 58, 44, 84, and 55% based on total P content, respectively. Formation of overreduced products including hypophosphite (H 2 PO 2 – ) was identified as a competing process, and mechanistic investigations revealed that hydride attack on in-situ-generated phosphorylated phosphite species is a potent pathway for overreduction. The phosphite generated from our method was easily isolated in the form of barium phosphite, a useful intermediate for production of phosphorous acid. This method circumvents the need to pass through white phosphorus (P 4 ) as a high-energy intermediate and mitigates involvement of environmentally hazardous chemicals. A bioproduced polyphosphate was found to be a viable starting material for the production of phosphite. These results demonstrate the possibility of accessing reduced phosphorus compounds in a more sustainable manner and, more importantly, a means to close the modern phosphorus cycle.

A new tripodal tris­(amido) ligand system featuring an arene anchor was developed and applied to the coordination chemistry of rare earth metals. Two tris­(amido) ligands with a 1,3,5-triphenylbenzene backbone were prepared in two steps from commercially available reagents on a gram scale. Salt metathesis and alkane elimination reactions were exploited to prepare mononuclear rare earth metal complexes in moderate to good yields. For salt metathesis reactions, while metal tribromides yielded neutral metal tris­(amido) complexes, metal trichlorides led to the formation of ate complexes with an additional chloride bound to the metal center. The new compounds were characterized by X-ray crystallography, elemental analysis, and 1H and 13C nuclear magnetic resonance spectroscopy. The rare earth metal complexes exhibit a trigonal planar coordination geometry for the [MN3] fragment in the solid state rather than a trigonal pyramidal geometry, commonly observed for rare earth metal tris­(amido) complexes such as M­[N­(SiMe3)2]3. Moreover, the arene anchor of the tripodal ligands is engaged in a nonnegligible interaction with the rare earth metal ions. Density functional theory calculations were performed to gain insight into the bonding interactions between the tripodal ligands and the rare earth metal ions. While LUMOs of these rare earth metal complexes are mainly π* orbitals of the arene with a minor component of metal-based orbitals, HOMO–15 and HOMO–16 of a lanthanum complex show that the arene anchor serves as a π donor to the trivalent lanthanum ion.

Commercial phosphorus pentoxide reacts with some N-donor bases to give the adducts P2O5L2 and P4O10L3 (L = DABCO, pyridine, 4-tert-butylpyridine). The DABCO adducts were structurally characterized by single-crystal X-ray diffraction. It is proposed that P2O5L2 and P4O10L3 undergo interconversion through a “phosphate-walk” mechanism, which was evaluated using DFT calculations. P2O5(pyridine)2 (1) efficiently transfers monomeric diphosphorus pentoxide to phosphorus oxyanion nucleophiles, yielding substituted trimetaphosphates and cyclo-phosphonate-diphosphates (P3O8R)2– (R1 = nucleosidyl, phosphoryl, alkyl, aryl, vinyl, alkynyl, H, F). Hydrolytic ring-opening of these compounds forms linear derivatives [R1(PO3)2PO3H]3–, and nucleophilic ring-opening gives linear disubstituted [R1(PO3)2PO2R2]3– compounds.

Herein is reported the structural characterization and scalable preparation of the elusive iron-phosphido complex FpP(tBu)(F) (2-F, Fp = (Fe(η5-C5H5)(CO)2)) and its precursor FpP(tBu)(Cl) (2-Cl) in 51% and 71% yields, respectively....