Solving the P–O/P–OH riddle: direct synthesis and neutron diffraction characterization of dianionic dithiophosphonates

We report the first definitive neutron diffraction study aimed at resolving the P-OH/PO structural ambiguity in metal dithiophosphonates. The small NH₄ counterion forces a rare <i>syn</i>-configuration <i>via</i> an extended hydrogen-bonding network. Neutron analysis definitively confirmed the fully deprotonated PO moiety, thus confirming the formation of a dianionic dithiophosphonate, a versatile synthon in homoleptic and heteroleptic coordination environments.