Hyponitrous acid, also known as nitroxoic acid, has the chemical formula H2N2O2. It exists in two forms - the syn form and the anti form.

• Syn Form: In the syn form of hyponitrous acid, the two nitrogen atoms are cis to each other, which means they are on the same side of the molecule. This form is less stable compared to the anti form.
• Anti Form: In the anti form of hyponitrous acid, the two nitrogen atoms are trans to each other, meaning they are on opposite sides of the molecule. This form is more stable due to the repulsion between the lone pairs of electrons on the nitrogen atoms in the syn form.

The structure of hyponitrous acid can be visualized as a central oxygen atom bonded to two nitrogen atoms. Each nitrogen atom also has a hydrogen atom bonded to it. The arrangement of atoms and lone pairs of electrons determines the stability and reactivity of the molecule.
In the syn form, the close proximity of the two nitrogen atoms leads to repulsion between the lone pairs of electrons, making this form less stable. On the other hand, in the anti form, the nitrogen atoms are further apart, reducing the repulsion and increasing the stability of the molecule.
The structural differences between the syn and anti forms of hyponitrous acid play a crucial role in its chemical properties and reactivity. These forms can interconvert depending on the conditions, with the anti form being the more thermodynamically stable form.