Halogen oxoacids and anions

At room temperature hypofluorous acid HOF is a gas. Its colorless solid (mp = 156 K) melts to a pale yellow liquid. In the crystal structure, O-F = 144.2 pm, angle H-O-F =101°, and the HOF molecules are linked by O-H- O hydrogen bonds (bond length 289.5 pm and bond angle O-H- O 163°) to form a planar zigzag chain, as shown below  

In general, fluorine has a formal oxidation state of — 1, but in HOF and other hypohalous acids HOX, the formal oxidation state of F and X is +1. 

Hypochlorous acid HOC1 is more stable than HOBr and HOI, with Cl-O 169.3 pm and angle H-O-Cl 103° in the gas phase. 

Chlorous acid, HOCIO, is the least stable of the oxoacids of chlorine. It cannot be isolated in pure form, but exists in dilute aqueous solution. Likewise, HOBrO and HOIO are even less stable, showing only a transient existence in aqueous solution. 

The chlorite ion (ClOj ) in NaC102 and other salts has a bent structure (C2V symmetry) with Cl-O 156 pm, O-Cl-O 111°. 

---