thumb|right|General ester of phosphonic acid; in fact, the phosphorus has a formal charge of +1, the oxygen above it has a formal charge of −1, and the bond between them is single.
thumb|right|General ester of phosphonic acid; in fact, the phosphorus has a formal charge of +1, the oxygen above it has a formal charge of −1, and the bond between them is single.
In organic chemistry, phosphonates or phosphonic acids are organophosphorus compounds containing groups, where R is an organic group (alkyl, aryl). If R is hydrogen then the compound is a dialkyl phosphite, which is a different functional group. Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly soluble in organic solvents, but soluble in water and common alcohols.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).