First identification of unstable phosphino formic acid (H2PCOOH)

Abstract

The hitherto elusive phosphino formic acid molecule (H₂PCOOH) was detected for the first time in the gas phase. Theoretical calculations revealed an unexpected kinetic stability of H₂PCOOH compared to the isovalent carbamic acid (H₂NCOOH) although the replacement of a single nitrogen atom by phosphorus decreases the bond order from a partial double (–CN–) to a single (–C–P–) bond. This work provides a fundamental framework to explore the synthesis and stability of derivatives of carbonic acid (H₂CO₃), in which one or both hydroxyl groups (OH) are replaced by hydride moieties involving third row atoms.